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{{#Wiki_filter:NiagaraMohawkNineMi>epointUnit2Eventof13August]991Reportby:MelvinL.CrensbamConsultingEngineerPo~erSystemsEngineeriagDepartmentGeneralElectricCompanySchenectady,NY8September1991 40 5iagaraMohawk5ineMilePointUnit2Eventof13August199105:4SQnAugust13,1991,at5:48AbftheUnit2phaseBgeneratorstep-uptranstormerfailed.OscillographicrecordsoftheeventareavailablefromadigitaldatarecorderattheScribaSubstation.Theyshowvarious345kVand11V5ksystemvoltagesandcurrents.FigureAwithnotationsisattached.Thefourcyclesprecedingthefaultshownosignsofagradualdegradationoradevelopingdisturbance.Theoscillographictracesandstationprotectiverelaytargetsreported,indicateagroundfaultoccurredonthehighvoltagewinding.Depressionofthe345kVphase8busvoltagetoabout39%ofthepriorvaluewasobservedfromtheoscillographictrace.Thissuggeststheinvolvementofonlyaportionoftheentirewinding.The345kVlinecurrentsandvoltagesshowrapiddevelopmentofthegroundfaultbeginningatpoint1withthegroundcurrentreachingaconstantvalueof1,300amperesin11/2cyclesatpoint4,Theflashoverinthefaultedtransformeroccursjustprecedingamaximuminphase2toneutralvoltage(aswouldhavebeenexpected)atpoint2.The345kVlinecurrentinanunfaultedphaseincreasesinstepfunctionmannerto350/ooftheprefaultvalueatpoint3,Nohighspeedrecordingsofvoltagesorcurrentswithintheplantwereavailable.Nosequenceofeventrecordingswereavailabletocorrelaterelayoperationtimes.Duetothelargeamountofmagneticenergycouplingthegeneratorrotorandstator,andknownelectricalparameters,thcdecayoffaultcurrentcontributedbythegeneratortothesolidlyconnectedtransformerwouldhavespannedanumberofsecondsasthcfielddecayed.Relayoperationtargetsreportedwere:l.TransformerDifferentialRelay(TypeBDD)onTransformer2MTX-XM1B.2.TransformerNeutralCurrentRelay(TypeIAC).3.OverallUnitDifferentialRelays(TypeBDD)inphases2and3.4.GeneratorPhaseOvercurrentRelays(TypePJC)inphases2and3.
{{#Wiki_filter:NiagaraMohawkNineMi>epointUnit2Eventof13August]991Reportby:MelvinL.CrensbamConsulting EngineerPo~erSystemsEngineeriag Department GeneralElectricCompanySchenectady, NY8September 1991 40 5iagaraMohawk5ineMilePointUnit2Eventof13August199105:4SQnAugust13,1991,at5:48AbftheUnit2phaseBgenerator step-uptranstormer failed.Oscillographic recordsoftheeventareavailable fromadigitaldatarecorderattheScribaSubstation.
r FvFollowingisolationofthegeneratorandfailedtransformerfromthepowergrid,marked5onFigureA.onlyasingle345kVphasetogroundvoltagerecordisavailable.Themagnitudeofthisvoltageonanunfaultedphaseis74foofthepre-faultvalue.Sincegeneratorneutralcurrentislimitedtolessthan8amperes.itisknownthatthefaultedtransformerappearsasalinetolinefaultwithsomeimpedancetothegenerator.Bytrialanderrorcalculation,generator.linecurrentsarefoundtobe0,1.9and1.9,multiplesoftheratedvalueof31,140amperes.Theline-to-linevoltageshavemagnitudes74lo74lo,and25%oftheratedvalueof25,000volts.Thedecayofthisvoltagefor0.2Ssecondsoftherecordinghasameasuredtimeconstantof2.7seconds.Thecalculatedvalueoftheimpedanceofthefaultedtransformerasseenbythegeneratoris0.23perunit.Conditionsprevailingduringthesixcycletimeperiodfollowingthefault,marked2onFigureA,cannotbedeterminedwithcertainty.Theexactnatureofthefaultwithinthetransformerisnotknownandthephysicalevidencewillbestronglyaffectedbythecontinuedflowofenergyfromthegeneratorduetotheinherenttimeconstant.TheflashoverofonlyaportionoftheHVwindingisevidentsincethe345linevoltagestoneutralremainat39%o,867oand86'1oofthepre-faultvalues.Thepresenceof"residual"inthemeasured345kVlinecurrentsprovidestheevidenceoftransformerneutraltogroundcurrent.Thisrequiresthatthefaultinvolvesapathforcurrenttogroundfromthehighvoltagewinding.Recordedvoltagesandcurrentsshowastepchangetonewvaluesandnodramaticchangeduringthetimeperiodoftherecord,whichtotalssomewhatlessthan1/2second.Itcouldbesaidtheyare"cleaner"andlessdistortedthancommonlyseenoscillographrecordingsoffaults.Giventheseobservationsandsinceboththegeneratorandthesystemweresupplyingfaultcurrentintothefaultedtransformer,generatorline-to-linevoltagesprecedingisolationwouldbeexpectedtobegreaterthanthoseimmediatelyfollowingisolation.Ithasbeenspeculatedthatveryhighfrequencyenergy(mHzregion)mayhavecausalmalfunctionoflogicandcontrolcircuitryintheUPSequipment.Abroad-rangeoffrequencieswouldbeexpectedinanyarcingphenomenonsuchasoccurredinthisfai1ure.Nothingintheavailabledataordesignparametersoftheplantequipmentwouldsuggestanextraordinarygenerationorpropagationofhigherfrequencycomponents.'Ihefailureofatransformerandinternalarcingisnotarareoccurrence.Comparisonofoscillographiccharts
Theyshowvarious345kVand11V5ksystemvoltagesandcurrents.
'Ijj fromsimilareventsinotherplantsshownothingunexpectedorunusualinthisparticularfailure.Itmustbeborneinmindthatthesamplingrateoftherecorderislistedas5.814kHzandfrequencycomponentsinexcessofperhaps500Hzwouldnotbeaccuratelyportrayed.GEexperienceintestingoftypicalpowertransformers(suchastheLnitAuxiliariesTransformers)providesanindicationoftheexpectedcouplingbetweenwindingsatradiofrequenciesintheregionof1megahertz:Theattenuationfactorsrangefrom1,000:1to10'softhousands:1.Directmeasurementscouldbemadeinthisplanttodetermineattenuationfactorsforindividualtransformersoverarangeoffrequencies.Thesetestswouldbemadeonnon-energizedtransformersusinganRFsignalgeneratorandasensitive,calibrateddetector.Attachedrecentarticlesonelectro-magneticinterference.Reference1discussesIEC801,4andthecharacteristicsofelectricallyfasttransients.Reference2discussestestingofgroundconnections.ViThepossibilityofelevationofthcstationgroundingsystemasaresultofthisdisturbancewaspostulated.Therelativelyhighlevelofgroundfaultcurrent,estimatedat1,300ampercsfromtheavailablerecording,wouldnothavebeenconductedintotheplant.ThiscurrentcanonlyfiowinRomthe345kVsystemforthe6cycleperiodrequiredforrelayandcircuitbreakeroperationtoachieveisolation.Thegeneratorgroundcurrentwouldhavebeenlimitedtolessthan8ampcresbytheneutralgroundingequipmcnt.Elevationordifferencesingroundpotentialwithintheplantwouldthereforenothavebeenexpectedduringthisevent.Reference1discussestheproblemofachievinga"super"groundandconcludesthatastablegroundreferenceforinterconnectedequipmentisofgreatersignificance.Sincenormallycirculatinggroundcurrentsarenotexpected,testingwithverylowvoltagesandcurrentsisrecommended.Noteespeciallytherecommendationtotestwithafrequencynon-harmonicallyrelatedtothepowerline&equcncy.Thetransformerssteppingthevoltagedowntosuccessivelylowervoltagelevelsareconnectedinamannertominimizecouplingofpowerfrequencyandhigherfrequency.componentsbetweenthcvariousbusses.Specificconfigurationsare:
FigureAwithnotations isattached.
1IIV l.NormalStationServiceTransformer-delta25kVtowye13.8kVwith400ampereresistivegroundingonthe13.8kVside.2.LoadCenterTransformers-delta13.8kVtowye4.16kUwith4Rampereresistivegroundingonthe4.16kVside..3.LoadCenterTransformers-delta13.8kVor4.16kVtowye600voltswithneutralsolidlygroundedonthe600voltside.4.ReserveStationServiceTransformers-wye115kV,delta4.16kV,wye13.8kV,The13.8kVneutralis400ampereresistivegrounded.The4.16kVcircuitisconnectedtoazig-zaggroundingtransformerwitharesistorintheneutralconnection,presumablyfor400amperes.Theseconfigurationsprovide"effectivelygrounded"distributionbussesasdefinedinTEEStandard142andwillservetolimittransientovervoltages.Thisisinaccordancewithdesignpracticesdeemedprudentandconservativewithinthepowerindustry.Theindustrycontinuestoreviewtheeffectsofgeomagneticdisturbancesonpowertransformers.Whilenoevidenceisseenofvoltagedistortioninthefourcyclespreceedingthefailure,excessivedutycouldhaveoccurredifthesetransformershadbeensubjectedtolowleveldirectcurrentpreviously.References3and4areattachedforperusal.  
Thefourcyclespreceding thefaultshownosignsofagradualdegradation oradeveloping disturbance.
Theoscillographic tracesandstationprotective relaytargetsreported, indicateagroundfaultoccurredonthehighvoltagewinding.Depression ofthe345kVphase8busvoltagetoabout39%ofthepriorvaluewasobservedfromtheoscillographic trace.Thissuggeststheinvolvement ofonlyaportionoftheentirewinding.The345kVlinecurrentsandvoltagesshowrapiddevelopment ofthegroundfaultbeginning atpoint1withthegroundcurrentreachingaconstantvalueof1,300amperesin11/2cyclesatpoint4,Theflashover inthefaultedtransformer occursjustpreceding amaximuminphase2toneutralvoltage(aswouldhavebeenexpected) atpoint2.The345kVlinecurrentinanunfaulted phaseincreases instepfunctionmannerto350/ooftheprefaultvalueatpoint3,Nohighspeedrecordings ofvoltagesorcurrentswithintheplantwereavailable.
Nosequenceofeventrecordings wereavailable tocorrelate relayoperation times.Duetothelargeamountofmagneticenergycouplingthegenerator rotorandstator,andknownelectrical parameters, thcdecayoffaultcurrentcontributed bythegenerator tothesolidlyconnected transformer wouldhavespannedanumberofsecondsasthcfielddecayed.Relayoperation targetsreportedwere:l.Transformer Differential Relay(TypeBDD)onTransformer 2MTX-XM1B.2.Transformer NeutralCurrentRelay(TypeIAC).3.OverallUnitDifferential Relays(TypeBDD)inphases2and3.4.Generator PhaseOvercurrent Relays(TypePJC)inphases2and3.
r FvFollowing isolation ofthegenerator andfailedtransformer fromthepowergrid,marked5onFigureA.onlyasingle345kVphasetogroundvoltagerecordisavailable.
Themagnitude ofthisvoltageonanunfaulted phaseis74foofthepre-fault value.Sincegenerator neutralcurrentislimitedtolessthan8amperes.itisknownthatthefaultedtransformer appearsasalinetolinefaultwithsomeimpedance tothegenerator.
Bytrialanderrorcalculation, generator.
linecurrentsarefoundtobe0,1.9and1.9,multiples oftheratedvalueof31,140amperes.Theline-to-line voltageshavemagnitudes 74lo74lo,and25%oftheratedvalueof25,000volts.Thedecayofthisvoltagefor0.2Ssecondsoftherecording hasameasuredtimeconstantof2.7seconds.Thecalculated valueoftheimpedance ofthefaultedtransformer asseenbythegenerator is0.23perunit.Conditions prevailing duringthesixcycletimeperiodfollowing thefault,marked2onFigureA,cannotbedetermined withcertainty.
Theexactnatureofthefaultwithinthetransformer isnotknownandthephysicalevidencewillbestronglyaffectedbythecontinued flowofenergyfromthegenerator duetotheinherenttimeconstant.
Theflashover ofonlyaportionoftheHVwindingisevidentsincethe345linevoltagestoneutralremainat39%o,867oand86'1oofthepre-fault values.Thepresenceof"residual" inthemeasured345kVlinecurrentsprovidestheevidenceoftransformer neutraltogroundcurrent.Thisrequiresthatthefaultinvolvesapathforcurrenttogroundfromthehighvoltagewinding.Recordedvoltagesandcurrentsshowastepchangetonewvaluesandnodramaticchangeduringthetimeperiodoftherecord,whichtotalssomewhatlessthan1/2second.Itcouldbesaidtheyare"cleaner" andlessdistorted thancommonlyseenoscillograph recordings offaults.Giventheseobservations andsinceboththegenerator andthesystemweresupplying faultcurrentintothefaultedtransformer, generator line-to-line voltagespreceding isolation wouldbeexpectedtobegreaterthanthoseimmediately following isolation.
Ithasbeenspeculated thatveryhighfrequency energy(mHzregion)mayhavecausalmalfunction oflogicandcontrolcircuitry intheUPSequipment.
Abroad-range offrequencies wouldbeexpectedinanyarcingphenomenon suchasoccurredinthisfai1ure.Nothingintheavailable dataordesignparameters oftheplantequipment wouldsuggestanextraordinary generation orpropagation ofhigherfrequency components.
'Ihefailureofatransformer andinternalarcingisnotarareoccurrence.
Comparison ofoscillographic charts
'Ijj fromsimilareventsinotherplantsshownothingunexpected orunusualinthisparticular failure.Itmustbeborneinmindthatthesamplingrateoftherecorderislistedas5.814kHzandfrequency components inexcessofperhaps500Hzwouldnotbeaccurately portrayed.
GEexperience intestingoftypicalpowertransformers (suchastheLnitAuxiliaries Transformers) providesanindication oftheexpectedcouplingbetweenwindingsatradiofrequencies intheregionof1megahertz:
Theattenuation factorsrangefrom1,000:1to10'softhousands:
1.Directmeasurements couldbemadeinthisplanttodetermine attenuation factorsforindividual transformers overarangeoffrequencies.
Thesetestswouldbemadeonnon-energized transformers usinganRFsignalgenerator andasensitive, calibrated detector.
Attachedrecentarticlesonelectro-magnetic interference.
Reference 1discusses IEC801,4andthecharacteristics ofelectrically fasttransients.
Reference 2discusses testingofgroundconnections.
ViThepossibility ofelevation ofthcstationgrounding systemasaresultofthisdisturbance waspostulated.
Therelatively highlevelofgroundfaultcurrent,estimated at1,300ampercsfromtheavailable recording, wouldnothavebeenconducted intotheplant.ThiscurrentcanonlyfiowinRomthe345kVsystemforthe6cycleperiodrequiredforrelayandcircuitbreakeroperation toachieveisolation.
Thegenerator groundcurrentwouldhavebeenlimitedtolessthan8ampcresbytheneutralgrounding equipmcnt.
Elevation ordifferences ingroundpotential withintheplantwouldtherefore nothavebeenexpectedduringthisevent.Reference 1discusses theproblemofachieving a"super"groundandconcludes thatastablegroundreference forinterconnected equipment isofgreatersignificance.
Sincenormallycirculating groundcurrentsarenotexpected, testingwithverylowvoltagesandcurrentsisrecommended.
Noteespecially therecommendation totestwithafrequency non-harmonically relatedtothepowerline&equcncy.
Thetransformers steppingthevoltagedowntosuccessively lowervoltagelevelsareconnected inamannertominimizecouplingofpowerfrequency andhigherfrequency.
components betweenthcvariousbusses.Specificconfigurations are:
1IIV l.NormalStationServiceTransformer-delta25kVtowye13.8kVwith400ampereresistive grounding onthe13.8kVside.2.LoadCenterTransformers-delta13.8kVtowye4.16kUwith4Rampereresistive grounding onthe4.16kVside..3.LoadCenterTransformers-delta13.8kVor4.16kVtowye600voltswithneutralsolidlygroundedonthe600voltside.4.ReserveStationServiceTransformers-wye115kV,delta4.16kV,wye13.8kV,The13.8kVneutralis400ampereresistive grounded.
The4.16kVcircuitisconnected toazig-zaggrounding transformer witharesistorintheneutralconnection, presumably for400amperes.Theseconfigurations provide"effectively grounded" distribution bussesasdefinedinTEEStandard142andwillservetolimittransient overvoltages.
Thisisinaccordance withdesignpractices deemedprudentandconservative withinthepowerindustry.
Theindustrycontinues toreviewtheeffectsofgeomagnetic disturbances onpowertransformers.
Whilenoevidenceisseenofvoltagedistortion inthefourcyclespreceeding thefailure,excessive dutycouldhaveoccurredifthesetransformers hadbeensubjected tolowleveldirectcurrentpreviously.
References 3and4areattachedforperusal.  


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fncfustrfalEqufpmentEISCtt'OfllCSIlllndLIStl'IgfAPPIiCatienSADiscussionofFundamentafENlCPrincfpfesforElectronicControllerslnanindustrialEnvironmentBy4t'iHiam0.Kimmel.PEKimmeiGerkeAssociates,LtdEDDICproblerrsi~:h:ndustra!ccnuoisareaggravatedbyharsheni.ronments.mixed:ec.'".noiogiesandalaclcofumformE!ifCguidebnes.T:isarLicie'>elconcentrateon;hecommonas;ec:sofelectroniccontrolsinan!ndustnalen>".ronment.whichisgenerallymucnharsher:bantheofGceenvirOnmenLWhatistheindustrialenviromentandwhatcanbecoreaboutit!Theenvironmenincludestheentiregamutof'.hebasicthreats.powerdisturbances.RFI.andESD.RFIandpowerdisturbancesmaybelocallygeneratedornot.Mixedtechnolo-giescompourd:heproblem.Digitalcircuitsareusedtoswitch."nevoltagesviarelays.Analogsensorsareinputdevices:odigitalcontrols.Increasingly.thereisaneedfora:ooperauveeffortbetweenthedesigners.manufacturersandinstailerstocomeupwitharock-solidsystem.Acommoncomplaintisthatthemstallersormainte-narcepeoplewon'tfollowtheinstaUationrequirements.Thismaybetrue,butitmustchange.smcethereareproblemswhichcannotbesolvedattheboardlevel.Itisalsotruethatmanufacturersoftenspecifyinstallation.equirementswhicharenotpracticaltoimpleinent,andtherearedocumentedcaseswheretheprescribedinstallauonprocedureswil!causerathertitancureaprobietts.The!adtofumikenguidelineshasham-peredEMCprtilessintheindustriatarena.Fortunately,theEuropeanCommu-nityisworkingtoadopttheIEC801.xspecilications.anddomesticcompanieswouldbewisetoadoptthem,evenifthereisnointentiontoexport.TheBasicThreatsThethreebasicthreatstoindustrialelectronicsarepowerdisturbances,radiofrequencyinterference,andESD.PowerDisturbances.Powerdistur-EMCTest4DesignbancesareaweHknownirdustralproblem.Iniac:.whenaproblemoccurs.ketirstthough':is:oblamethepowercompany.Oftenpowerqualityisaproblem(especiallyifgroundingissuesareinciudedl.buttheproblemisalmostalwaysgeneratedbyadjacentequipment.Tradiuonalproblemswithpowerincludespikesandtransients,sagsandsurges,andoutages.whichthreatentheeiectroiucsviathepowersupply.TheseproblemsarefairlyweildocumentedandareoftensolvedusingpowerconditionersorUPS.Themostcommonpowerproblemsconfrontingelectronicstodayisthesagwhich~icailyoccursduringturnonandthespikeswhichtypicallyoccurduringturnoffofheavyinductiveloads.~<..esagssimplystarvetheelectronics.ThehighfrequencyttansientsbarrelrightthroughthesupposedlySteredpowersupplytoattacktheelectronicsinside.Digitalcircuitsaremostvuhierabletospikeswhichcausedataettorsorworse.AnalogcircuitsaremostvukierabletocontinuousRFridingontopofthepower.FIPSPUB94providesguidelinesoneiectricalpowerforcommercialcomputers.Thisisgoodinfortnation,butbewarethatfactorypowerismuchnoisierthancommer-cialpower.TheguidehcesofIEC801.4speci5esanelectricallyfastuansient(EFT)thatsimu-latesarangandotherhighspeednoise.Ebsarequiteshortranged-theydiminishrapidlywithdistanceduetoinduc.tanceintheline.Butatshortrange,theyaredevastatmg.Unfortunately,attentionisplacedonthefrontendoftheelectronics,thepowersupply.Withindustrialcontrols,theprob-lemisthecontrolledelements.Iftheelectronicsiscontrollinglinepower,thedisturbancessneakinthebackendwherelittleornoprotectionexists.Systemground,whilenotbeingspecifl-callyapowerdisturbanceprob'.em.:s:.thecar..erofresidualeiiectsofo-.disturbances.Any'ind;sinaiorcommer:suucturehassigiu8cant.'ow~equencurrentscirculating:hrought.".egrousystem.sometimesbecausethe.nergyintentionallydumpedontotheground(s.aswithanarcweider)andsomeur..becauseofunintenuonalcouplingorvaninadvertentconnectionbetweenneuandgroundsomewhereinthe!aciiity.RadioFrequencyInterference.Rdiofrequencyinterfer~nceaffectsboanaloganddigitalcircuits.withana'ccircuitsbeinggenerallymoresusceptiblSurprisingtomany,thepnncipiethreatnottheTVorFMstauondowntheroaibutratheritisthehandheldL~snut:~carriedaroundbyfacilitiespersonnel.Aor.wattradiowillresultinanelectncne!d~(Nevolts/meterataonemeterdistanceenoughtoupsetmanyelectromcssystemsIEC801.3speciGesimmunitytoelec".Geldsofonetotenvoltspermetedependingontheequipment.withtivevoltspermeterbeingSelevelfortypicequipment.Ascanbeseenfromtheabovapproximation,threevoltspermeterisncanexcessiverequirement,andeven:evoltspermeterisfairlymodest.ElectrostaticDischarges.EiecLcstaticdischargeisanintenseshortdurauoipulse,havingariseameofaboutonenanosecond.Thisisequivalent:oaburs.of300MHsinterference.Staticbuildup.of15kVarenotuncommon.Dryclimates,includingnorthernclimate'.WhamKimmelisapn'ncipalwithKimme.GeromeAssociates.Ltd.Thefirmspecial.i@cainpreventingandsolvingelectromag.neticinterferenceandcompaabQity(E.MhEMC)problems.Mr.Kimmeicanreachedat3544NPascal,St.PauL.~i~55108,ortelephone612.330-3728.
fncfustrfal Equfpment EISCtt'OfllCS IlllndLIStl'Ig fAPPIiCatienS ADiscussion ofFundamentaf ENlCPrincfpfes forElectronic Controllers lnanindustrial Environment By4t'iHiam0.Kimmel.PEKimmeiGerkeAssociates, LtdEDDICproblerrs i~:h:ndustra!
ccnuoisareaggravated byharsheni.ronments.
mixed:ec.'".noiogies andalaclcofumformE!ifCguidebnes.
T:isarLicie'>elconcentrate on;hecommonas;ec:sofelectronic controlsinan!ndustnal en>".ronment.
whichisgenerally mucnharsher:ban theofGceenvirOnmenL Whatistheindustrial enviroment andwhatcanbecoreaboutit!Theenvironmen includestheentiregamutof'.hebasicthreats.powerdisturbances.
RFI.andESD.RFIandpowerdisturbances maybelocallygenerated ornot.Mixedtechnolo-giescompourd:he problem.Digitalcircuitsareusedtoswitch."ne voltagesviarelays.Analogsensorsareinputdevices:o digitalcontrols.
Increasingly.
thereisaneedfora:ooperauve effortbetweenthedesigners.
manufacturers andinstailers tocomeupwitharock-solid system.Acommoncomplaint isthatthemstallers ormainte-narcepeoplewon'tfollowtheinstaUation requirements.
Thismaybetrue,butitmustchange.smcethereareproblemswhichcannotbesolvedattheboardlevel.Itisalsotruethatmanufacturers oftenspecifyinstallation
.equirements whicharenotpractical toimpleinent, andtherearedocumented caseswheretheprescribed installauon procedures wil!causerathertitancureaprobietts.
The!adtofumikenguidelines hasham-peredEMCprtilessintheindustriat arena.Fortunately, theEuropeanCommu-nityisworkingtoadopttheIEC801.xspecilications.
anddomesticcompanies wouldbewisetoadoptthem,evenifthereisnointention toexport.TheBasicThreatsThethreebasicthreatstoindustrial electronics arepowerdisturbances, radiofrequency interference, andESD.PowerDisturbances.
Powerdistur-EMCTest4DesignbancesareaweHknownirdustral problem.Iniac:.whenaproblemoccurs.ketirstthough':is:oblamethepowercompany.Oftenpowerqualityisaproblem(especially ifgrounding issuesareinciudedl.
buttheproblemisalmostalwaysgenerated byadjacentequipment.
Tradiuonal problemswithpowerincludespikesandtransients, sagsandsurges,andoutages.whichthreatentheeiectroiucs viathepowersupply.Theseproblemsarefairlyweildocumented andareoftensolvedusingpowerconditioners orUPS.Themostcommonpowerproblemsconfronting electronics todayisthesagwhich~icailyoccursduringturnonandthespikeswhichtypically occurduringturnoffofheavyinductive loads.~<..esagssimplystarvetheelectronics.
Thehighfrequency ttansients barrelrightthroughthesupposedly Steredpowersupplytoattacktheelectronics inside.Digitalcircuitsaremostvuhierable tospikeswhichcausedataettorsorworse.Analogcircuitsaremostvukierable tocontinuous RFridingontopofthepower.FIPSPUB94providesguidelines oneiectrical powerforcommercial computers.
Thisisgoodinfortnation, butbewarethatfactorypowerismuchnoisierthancommer-cialpower.Theguidehces ofIEC801.4speci5esanelectrically fastuansient(EFT)thatsimu-latesarangandotherhighspeednoise.Ebsarequiteshortranged-theydiminishrapidlywithdistanceduetoinduc.tanceintheline.Butatshortrange,theyaredevastatmg.
Unfortunately, attention isplacedonthefrontendoftheelectronics, thepowersupply.Withindustrial
: controls, theprob-lemisthecontrolled elements.
Iftheelectronics iscontrolling linepower,thedisturbances sneakinthebackendwherelittleornoprotection exists.Systemground,whilenotbeingspecifl-callyapowerdisturbance prob'.em.:s:
.thecar..erofresidualeiiectsofo-.disturbances.
Any'ind;sinai orcommer:suucturehassigiu8cant
.'ow~equencurrentscirculating:hrough t.".egrousystem.sometimes becausethe.nergyintentionally dumpedontotheground(s.aswithanarcweider)andsomeur..becauseofunintenuonal couplingorvaninadvertent connection betweenneuandgroundsomewhere inthe!aciiity.
RadioFrequency Interference.
Rdiofrequency interfer~nce affectsboanaloganddigitalcircuits.
withana'ccircuitsbeinggenerally moresusceptibl Surprising tomany,thepnncipiethreatnottheTVorFMstauondowntheroaibutratheritisthehandheldL~snut:~carriedaroundbyfacilities personnel.
Aor.wattradiowillresultinanelectncne!d~(Nevolts/meter ataonemeterdistanceenoughtoupsetmanyelectromcs systemsIEC801.3speciGesimmunitytoelec".Geldsofonetotenvoltspermetedepending ontheequipment.
withtivevoltspermeterbeingSelevelfortypicequipment.
Ascanbeseenfromtheabovapproximation, threevoltspermeterisncanexcessive requirement, andeven:evoltspermeterisfairlymodest.Electrostatic Discharges.
EiecLcstaticdischarge isanintenseshortdurauoipulse,havingariseameofaboutonenanosecond.
Thisisequivalent:o aburs.of300MHsinterference.
Staticbuildup.of15kVarenotuncommon.
Dryclimates, including northernclimate'.
WhamKimmelisapn'ncipal withKimme.GeromeAssociates.
Ltd.Thefirmspecial.i@cainpreventing andsolvingelectromag.
neticinterference andcompaabQity (E.MhEMC)problems.
Mr.Kimmeicanreachedat3544NPascal,St.PauL.~i~55108,ortelephone 612.330-3728.
i  
i  
~~VcclinepouerItIiITRIACsuitcl.epiouerF:g.'re'..Amp'.'Gerdetnodulanon.Figu:e2.Transient!eedbackpath.:n~".nter.offeropportumty!orESD.Industnaienvironments.withthe:rmovingeqipment.areloadedwithpotenualESDsources:rubberrogers.belts,andproduc-uonou'.putsuchasplasncandpaperroUs.alladdup!oarealESDth:eat.andt."isr."meatismorelikelytooccurevenm;elanvelymoistenvironments.Look:oIEC801.2.'orESDstandards.Elec!ronicsDesignElectronics:sgenerallytheultimatevictimof:nterference.Thehter.'erenceGndsitswaythroughvariouspaths:otheelectronicsequipmentitself.Let'sconcen-trateonw'ratcannappentoyourelectronicsfrom!hebackdoor.thatis.bydirectradiationintotheelectronicsandbycon-ducted:nterferencethrough:hesignalandcont:oilines.Sensors.Lowlevelsensors.suchasther...ocouples.pressuresensors.etc..arecharacterizedbyverylowbandwidtbsand!owsignallevels.AmajorMeattothesesensorsisradiofrequencyinterference.eitherfromnearbyhandheldtransmittersormoredistancelandmobileorGxedtransmitters.But:hesearehighl'requency,muchabovethebandpassofyouramph6er.right?Wrong!Lowfrequencyamplifiersareplaguedbytwo,ybeaomena:outofbandresponseand<<stsorectification.Thesecombinetoprovidefalseinformationonlevelstothesystem.Allamplifiershaveanormalbandpass,typi6edbya20dB/decaderoUoformoreatthehighend.ButresonancesduetostrayinductanceandcapacitancewillgiverisetoamplifierresponseGveordersofmagnitudeormoreabovethenominalbandpassoftheamplifier.ThismeansanaudioamplifierwillrespondtosignalsinthehundredsofMHz.ThesecondaspectoccurswhenRFencourtersanoriinearitysuchasasemicon-ductordevice.AllsuchdevicesgiverisetoaDClevelshiftwhenconfrontedwithRF.lnaradioreceivertheyarecalleddetec-tors.Noniinearitiesareminimizedinlineardevices,but:hereisalwaysenoughtocauseproblems.Theupshotisthattheampli6erdemodulatestheRF.generatesanerrone-oussignal.andpassesthiserroron.Thiseffec'.isshowninFigure1.Outputhnesaresimilarlyaffected,withcapacitivecouphngbacktotheinput.ThesoluuonistopreventtheRFfromgettingtotheamplifier.eitherbyshieldingorfiltering.Themostcommonpathtotheamplifierisviaanexternalsignalinefromthesensor.butiftheekctronicsisnotshielded.directradiationtothecircuitboardmayalsopresentaproblem.Assumingfilteringisthesekctedmethod.useahigh~frequencyGlter,designedtobkicksignalsupto1GHzorevenmore.Usefemtesandhighfrequencycapacitors,DonotrelyonyourlowfrequencyGltertotakeoutRF.Attheopamp.youshouMalsodecoupleyourplusandminuspowertogroundattbechip.IfyourgroundiscarzyingRF,youcananticipatethesameprobkmmentionedabove,sinceitwillcomtptthereferencelevel.DataLines.DigitaldatalineswiUbeupsetbytheRFproblemasinanakig,buttbelevelsnecessarytoupsetarehigher.Instead.digitaldatalinesaretnucbmoresusceptibletotransientghtches.Allsignallinesshouldbe6lteredtopassonlythefrequenciesnecessaryforoperation.Ifthethreatliesinthebandpassoftbesignal,thenshieldingoropticallinkswillbeneeded.SwitchedPowerLines.Thisrefersspecificallytothepowerbeingcontro9edbythecontrollerdevice.Industrialcontrol-lersarecommonlytaskedtocontrolpowertoheavyequipment.wtuch.s;itc.-.hyheavystarting.'oadsandinducnve.a<<wnofTyptcaUYthee!ectroniccon:rswitchUnepowerusingrelaysor;;.-.Thisexposesthebackendofthecont;=tosubstantiallinetransients.whichcoi-backtothecircuitpowerandgrounddisruptthedigitalcircuitryasshownFigure2.Itismandatorythatthetransient:rentsbedivertedorblocked.since'igitalsystemcannotwithstandt.".e.-.~gtudeslikelytooccurwithaninducuvek:iunlessspecialstepsaretaken.SelfjamniingcanbeUnutedbycontrcliwhenyouswitch!heUne.usingzecrossingdevices.Ofpartic~importanisthemrnoff.sincedtatiswheninductivekickoccurs.lfa6powerswitchingusedzerocrossudevices.thetransientlevelsinthefactowoukibedramaticailyreduced.Unfor.nately,thatgoaliswelloffinthefutu:Untilthen,expectthathighvoltagepowtransientswlloccur,andtheymustbedewldl.Opticalcouplersandrelaysdonotprovisufficientisolationbythemselves.Ththighcapacitanceprovidesanexcegenthiifrequencypath,andiftheyarestackedtinanarray,tbecapacitancewi6adduppasssurprisinglylowfrequencies.The:capocitancesan'tbeelim'mated,butyccandesignyowcontrolcircuitstominimizcouphngpathsandtomaximizelowimpe<ancealternatepaths.Transientsuppressorsshouldbeinstalleattbekiad,whichisthesourceofthespihbuttheycanbeinstalledatthecontroUtasweal.AninterestmgeffectoccurswhenconbiningzerocrossingSCRregulatorswulowlevelMnsorswhichuselinefrequercnoisecanceHngtechniques.Veryseftsitivsensorssometimesaresampled.fortJQIL"Augusta~!
~~VcclinepouerItIiITRIACsuitcl.epiouerF:g.'re'..Amp'.'Ger detnodulanon.
Figu:e2.Transient!eedback path.:n~".nter.offeropportumty
!orESD.Industnai environments.
withthe:rmovingeqipment.areloadedwithpotenualESDsources:rubberrogers.belts,andproduc-uonou'.putsuchasplasncandpaperroUs.alladdup!oarealESDth:eat.andt."isr."meatismorelikelytooccurevenm;elanvely moistenvironments.
Look:oIEC801.2.'orESDstandards.
Elec!ronicsDesignElectronics:s generally theultimatevictimof:nterference.
Thehter.'erence Gndsitswaythroughvariouspaths:otheelectronics equipment itself.Let'sconcen-trateonw'ratcannappentoyourelectronics from!hebackdoor.thatis.bydirectradiation intotheelectronics andbycon-ducted:nterference through:he signalandcont:oilines.Sensors.Lowlevelsensors.suchasther...ocouples.
pressuresensors.etc..arecharacterized byverylowbandwidtbs and!owsignallevels.AmajorMeattothesesensorsisradiofrequency interference.
eitherfromnearbyhandheldtransmitters ormoredistancelandmobileorGxedtransmitters.
But:hesearehighl'requency, muchabovethebandpassofyouramph6er.right?Wrong!Lowfrequency amplifiers areplaguedbytwo,ybeaomena:
outofbandresponseand<<stsorectification.
Thesecombinetoprovidefalseinformation onlevelstothesystem.Allamplifiers haveanormalbandpass, typi6edbya20dB/decade roUoformoreatthehighend.Butresonances duetostrayinductance andcapacitance willgiverisetoamplifier responseGveordersofmagnitude ormoreabovethenominalbandpassoftheamplifier.
Thismeansanaudioamplifier willrespondtosignalsinthehundredsofMHz.ThesecondaspectoccurswhenRFencourtersanoriinearity suchasasemicon-ductordevice.AllsuchdevicesgiverisetoaDClevelshiftwhenconfronted withRF.lnaradioreceivertheyarecalleddetec-tors.Noniinearities areminimized inlineardevices,but:hereisalwaysenoughtocauseproblems.
Theupshotisthattheampli6erdemodulates theRF.generates anerrone-oussignal.andpassesthiserroron.Thiseffec'.isshowninFigure1.Outputhnesaresimilarly
: affected, withcapacitive couphngbacktotheinput.ThesoluuonistopreventtheRFfromgettingtotheamplifier.
eitherbyshielding orfiltering.
Themostcommonpathtotheamplifier isviaanexternalsignalinefromthesensor.butiftheekctronics isnotshielded.
directradiation tothecircuitboardmayalsopresentaproblem.Assumingfiltering isthesekctedmethod.useahigh~frequency Glter,designedtobkicksignalsupto1GHzorevenmore.Usefemtesandhighfrequency capacitors, Donotrelyonyourlowfrequency GltertotakeoutRF.Attheopamp.youshouMalsodecoupleyourplusandminuspowertogroundattbechip.IfyourgroundiscarzyingRF,youcananticipate thesameprobkmmentioned above,sinceitwillcomtptthereference level.DataLines.DigitaldatalineswiUbeupsetbytheRFproblemasinanakig,buttbelevelsnecessary toupsetarehigher.Instead.digitaldatalinesaretnucbmoresusceptible totransient ghtches.Allsignallinesshouldbe6lteredtopassonlythefrequencies necessary foroperation.
Ifthethreatliesinthebandpassoftbesignal,thenshielding oropticallinkswillbeneeded.SwitchedPowerLines.Thisrefersspecifically tothepowerbeingcontro9ed bythecontroller device.Industrial control-lersarecommonlytaskedtocontrolpowertoheavyequipment.
wtuch.s;itc.
-.hyheavystarting.'oadsandinducnve.a<<wnofTyptcaUYthee!ectronic con:rswitchUnepowerusingrelaysor;;.-.Thisexposesthebackendofthecont;=tosubstantial linetransients.
whichcoi-backtothecircuitpowerandgrounddisruptthedigitalcircuitry asshownFigure2.Itismandatory thatthetransient:
rentsbedivertedorblocked.since'igitalsystemcannotwithstand t.".e.-.~gtudeslikelytooccurwithaninducuvek:iunlessspecialstepsaretaken.SelfjamniingcanbeUnutedbycontrcliwhenyouswitch!heUne.usingzecrossingdevices.Ofpartic~importanisthemrnoff.sincedtatiswheninductive kickoccurs.lfa6powerswitching usedzerocrossudevices.thetransient levelsinthefactowoukibedramaticaily reduced.Unfor.nately,thatgoaliswelloffinthefutu:Untilthen,expectthathighvoltagepowtransients wlloccur,andtheymustbedewldl.Opticalcouplersandrelaysdonotprovisufficient isolation bythemselves.
Ththighcapacitance providesanexcegenthiifrequency path,andiftheyarestackedtinanarray,tbecapacitance wi6adduppasssurprisingly lowfrequencies.
The:capocitances an'tbeelim'mated, butyccandesignyowcontrolcircuitstominimizcouphngpathsandtomaximizelowimpe<ancealternate paths.Transient suppressors shouldbeinstalleattbekiad,whichisthesourceofthespihbuttheycanbeinstalled atthecontroUtasweal.Aninterestmg effectoccurswhenconbiningzerocrossingSCRregulators wulowlevelMnsorswhichuselinefrequercnoisecanceHngtechniques.
Veryseftsitiv sensorssometimes aresampled.fortJQIL"August a~!
i4II'  
i4II'  
'f80VACHighCurrentDC,burrouPouerIwlcCarinaPSElectroni>>:sFir're3.Commonindustnaipowe.supply.Figure4.awful:rplegroundpaths.enurepoweryc!etocanceitheinefreq'ncyconipohent.Ift..esamp!eoccursco.","u;.entlywi:hirepowersw'.tchingonoroif.:heaverage:orhesensorwillbe.pse'..andane.-.or~4"erecorded.SystemDesignandInstallationOnce>eelect:onicsisdesigned.itbecomesap.oblemof!hesystemintegratarandinstaller:oersurethatthcelectranicsiscravidedwuhtheenvironmentfarwhichitwasdes;gned.Mostofthcumc.thisworkisperformedbypowerexpertsandclectricians.andtheyarenotalwaysawareof:heintcrfererceprobkm.Often,onsite.rhepowerqualityisblamedforthcequip.rrentanomalies.Buttheproblemcanoftenbeavoidedbyfollowinga(ewbasicprina-ples.Theindustrialconuoldeviceiseitherintegratedintoasystemat!hefactoryorinstaL'edseparatelyonsite.Controllershandleavarictyofdevicessuchasmotorspeedcontrols.positioningdevices.weld-ers,etc.fnterferenccpresentedtotheelectronicscanbesigniGcandyreducedbyappropriatemeasuresoutsideoftheelec-uonicsbox.Thereisnowaytoaccuratelyassessdierhreatwithouttestdata.Butrcgardlcssofthebr(orationavai!ab!c.muchcanbeaccomplishedbycorrectinstagation,anditdoesn'tcostmuchifdoneatthestart.RetroGtsbecomecosdy.especiallyifac-companiedwithfactorydowntime.Let'sconsiderdscsameprob!cmsfromasystemstandpat.Yourgoalistolimittheinterferencewfskhmustbehandledbytheelectronics.Directradiationtotheelectronicsisnotoftenaprobleminanindustrialenviron-ment,butitdoesoccur,andmostoftenwithaplasucenclosure.TheNEiMAtypeenclosuresprovideenoughshieldingformostmdusuialneeds.Ifyoudon'twanttouseametalenclosure,besure!ogetelecuonicswhichwillwithstandtheRFwhichwilloccur.l(oreor'.eh'.heproblemisconducted.eirher'aapowerorgraurd.Theproblemoccursdue:opowerandg.ounddistur-bancescausedbytheequipment.Itisanalltoocommonpracdcetodrawcontroiierpowerf;omthesamesourceasfeedsthepowereqtupmcnt.T."ispowermayprovide:herecessaryenergytodrivetheequip-ment.butitisnotsuitabletopowertheelectroiucslFigurc3).Hopefully,allindusuialequipmentwiUhaveelectronicspoweredfromaseparatelowpower120voltcircuit.Itsolvesseveralproblems.First.itseparatestheelectron-icspowerfromtheprobablyverynoisyindusu@gradepower,prevendngtheswitchingtransientsandstartupsagsfromgenugtotheelectronics.Second,ifitisnecessarytoconditiontheelectronicspo~erfromanextet".Aproblem,itistarcheapertocondiuonthewattsnecdcd(orelectronicspowerthanitistoconditionthckilowansrequiredbythesystem.Ifpowercannotbeseparated.thenitisnecessarytoprovideabu!letproafpowersupply.preferablyincbrdinganisolationtransformer,toseparatetheentirepowersupplyfromtheelectricalequipment.GroundNoise.Groundnoise,inevita-bleinindustrialenvironments.mustbedivertedfromtheelectronicsmodu!c.MultiplegroundsinasystemwiGoftenresultingroundcurtentscircu!stingthroughthecquiprnent.andgroundnoisecircuhtingthroughthcelectronicspathwillcausernalfuncuon.Figure4showssometypicalgroundloopsituations.Acommonapproachistodemandasuper~arthground.Thisisgood,butitisnotacureall.andoftenasupergroundcannotbeachieved,nomatterhowyouuy.Howdoyougetasupergroundfromthethird4oor?Therealneedistogct'astablegroundreferencetoallinterconnectedequipments.Ifthisequipmentiscloselylocated,thenaverylowimpedanceinterconnectisfeasi-ble.Powerconditionersareo(tentaskedtoeliminateRFofg.oundnoise...atwork,but:heseproblemscanberc.withanisolat:onrant(armer:o=".-..-neutraltogroundnoiseand~~rh"~IIpo;lincGlters.Soyoumaywan:;otryinexpensiveapproachnrst.DataI.inks.Datalinksaresu.~ngovertheer'.tire!acirty.exposingther.:twoprinciplee((ects.groundraisearepickup.Groundnois>>;willcausedataer.-unlesstheelectronicshasbeendesigne"accornmodatcpotentialdifferencesof->>eralvoltsormore.Thisisaccampbs;withdif(crentialdriversandreceivers:f=.mustbedirectcoupled.Optical'hnks-eventuallytakeovertheselinks.TheotheraspectisRFpickup.Inexpesiveshieldedcableissuitable(ar:.'urpose.Groundborhends!DonotappsinglepointgroundtechniquestoRF.i!Iawfrequencygroundloopproblem:sthreat.thenoncendcanbecapaciuveSummaryIndustrialelectronicsaresubjectedrcharshenvironment.Gooddesignandinst.!ationtechniqueswillminimiaeproblemsthcGeld.AdhcrencctotheEurope;standards,IEC801.xisagoodstart,ev>>ifyouareonlymarkeunginthcUSA.BibliographyFIPSPUB94,GuidelineonElec'ac:PowerforADPInstallauons.Scptcmber1983,IEC801-2.Electromagneticcompatibilit.(orindustrial.processmeasurementan<controlequipmcnt,Elcctrostaucdischargrrequirements,1984.(EC801-3.Electromagneticcompatibi!it!(arindustrial.processmeasurementanIcontrolequipment,RadiatedelectromagceticGeldrequirements,1984.IEC8014,Electromagneticcompatrbilit:(orindustrial-processmeasuremcntar.:controlcquipmcnt.Electricalfast:ransrehtburstrequirements.1984.EMCTest8cDe.<n e
'f80VACHighCurrentDC,burrouPouerIwlcCarinaPSElectroni>>:s Fir're3.Commonindustnai powe.supply.Figure4.awful:rple groundpaths.enurepoweryc!etocanceitheinefreq'ncyconipohent.
industrialFquipmentEquipmentGroundBondlng-DesigningforPerformanceandLifeADiscussionofGroundConnectionFundamentalstoControlEMlByD.B.L.DurhamDytecnaLtd,UKTheproblemofachievingsatisfactoryearthbondsorgroundconnecuonshasplaguedEMCengineersformanyyears,notonlybecausethebondsareoftenvitalfortheachievementofsatisfactoryequipmentpei-formancebutbecausetheyaffectthelongtermperformanceofequipmentafterithasbeenintroducedintoservice.Recommendationsonbondinghaveex-istedintheformofmilitaryspeciBcations,suchasMilStd1310.Mil188-124AandMil-B.5081(ASG)forsomeyearsandthesehavegenerallyprovedsatisfactoryformostnewbuilds.However.thesespeci6cationshavecertainlimitationsinthattheygener-allydonotspectfyconsistentlylowlevelsofbondimpedance.norasuitabletestmethod.TheintroductionofncwEMCspeciGcationsinEuropewiththeEECDirectiveonEMCandtherequirementsforiongtennstabilityinEMCcharacteristicshasdirectedtheUKnuTitarytoreviewcidsutlgspcciEcaQonsandIntroduceancwDefenceStandardtotightenupperfonn-ancerequirementsfornurttaryequipment.DcfStan~(Part1)/1hasbeenintro-ducaltoaddressthiaareaasfarasmob9eandtranspottablccanmunicationsinstalla-tionsareconccnteia.buttherequirementsshouklhaveimplicationsinindustrialapph-cationsandoverthewlxHeekctronicsmarketiflongtermproductperformanceistobeguaranteed.BondDegradationEarthorgroundbondsaregeneraHyconsideredessenualnotonlyforsafetyreasons.butasameanofdivertingEMcurrents,"locking"circuitboardsand38eqtdpmenttoastablegroundpoint.achiev.ingadequatelevelsofcabkshiekhngandformanyotherreasons.Manydesignersun-derstandtherequirementforshort.fatbondleadstominimiacgroundinductance,butfewappreciatethatacriticalaspectistheconnectionresistancewithwhichthebondstrapisattachedtotheequipmentgroundpoint.Thcbasicrequirementofanybondisthatitshouldhaveaslowanimpedanceaspossible(uille55itisadchbcratcinduc-tivebondtolimitgroundcurrents).Tbeimpedanceisacombinationoftheresistiveandtheinductivecomponents.Thcresis-tiveelementisafuncnonofthcbondstrapresistivity,crosssectionalareaandlength.seeEquation1.whihttheinductivecompo-nentisamorecomplexfunctionofthcbondstrapcharacteristicsasshowninEquation2.R~-qf0AL-~ln-+05+02235-jiZ,j'fb+c"2icLb~c2fJ(2)whereRresistance,g~resistivity,f>length.A~area,p,pcrmeabiEtyoffreespace,L~inductance.p~feLttivcpermcabiTity,bstrapwidth,andcstttpthickness.Thefrequencyatwhichtheinductiveekmentdominatestheimpedanceexpres-sionwhencalcu!atingthctotalinductanceis,fromEquation3,typically1kHs.ltwglbeseenthereforethattoalintentsand"purposesthcbondexceptatDCandpowerfrequencies,maybeassumedtobeaninductance.Atveryhigh~equencies:rstraycapacitanceacrossthestrapdonunate.Thismeansthatthevolt"-:acrossabondisgenerailyafuncuoninductanceandfrequency.BasedonOhr.".LawthisvoltdropisshowninEquador.~Fortransientsthevoltagedropisgiver..Equation5.ZRt+cutLSVIZ~jauUd1dt(5whereZ~strapimpedance.cu~tacomafrequency,V~voltage,and1~current.Fromthis.thehigherthcinductancethmoreisolatedthecircuitorboxbecomefromground.Thscanhavesigru6caneffectsoaequipment.inchdingenhancementofnoiseinjecbonontoarcuits,reduc=nonofSterperformance,andlossoicoaunlmicationrange.FromaTEMPESTstandpointitmayresultinmoreradiationfromemanent.ltwouldseemfromthisthatthecntcriatoranybondistheinchlctanccandhencethcchoiceofshortfatDavidDuganservedfor21yeanitttheBrrtiabAnny,wherehcgainedhisChgreeiadectricafcnginceting.AfterserviceinavarietyofappointmentshcretiredtojointheRecalls'EScompanyastheTechmca/Mtnsgcrrcspottsiblc/orthecfes/gnanddevclopnsetttofcommcttticationsystems.fn198$hejainefDytecnaastheiManagerofthe&ginecnttgDivision.andnowtscurrcntfyTchtaica/MarftctingManage..JulytAugust!991 5P sc';orc(cgq(r~rri.~~~cwc"-av~l-l'sis~fNf$QskgRrrfNT'N,ff'Srnryort:4icsir:i.rrenl',:!0iQA.osJVA5Hf5rrlltfRscarc5errVOUAGE&ifASI'REhlENTFigure!.Bondresisurce.Figure2.Fourwirebridgemethod.bondstraps.However.ananaiys'sof:hebondinductancfshowsJiatI'orabondstrapof100mm!org,15mm~~deand2mmIhcktheimpedanceat1MHawillbe3.8Ohms.Itsoundsextremelysin:pie.butworkperformedin'.heUSA'ndI:Kshowsthatifanetrotismade'inthewaythestrapisternunatedthenaprogressiveincreasein:heresisunceofthebondstraptoboxjuncnoncanoccurastheequipmentages.Eventuailytheresisuncewillbegintoexceedhundredsofohmsandmayeventu-allygoopenccuit.ThiscannegatethceffectofthebondstrapcompletelyaspartoftheE!rIIprotecdon.tVhathappenswithbondstocausethischange!Essentiallyagroundconnecuonisaseriesofirrpedancesfromthcstrapthroughtothegrourdmaterial,asshowninFigure1.Eachpointofcontactcontrib-utestothetotalbondper'.onnancc;.Asaresult.achangeinanycontactconditioncanresultinachangeinthetotalbondresistance.Asisweilappreciated,the"contactresistancebetweentwometalsur-facesisahnctionofthepressure.Thepressureexertedbythetipofadrawingpinisvastlygreaterthanthatfromthethumbpressingbyitself.Thusthecontactfromasharppoultgivesatsochhigherprcssuret.'unaOatpointand4gtiforclowercontactresisuncc.MeasutetatahaveshownthatsharppointsenableContactrcsisunccofafewnicroohmtobeachievedwhilstsimilarpressuresonOatsurfacesresultinmil-liohmsofconuctresistance.Itmightbefeltthatthereislittleornodifferencebetweenthesevalues,butinrealitythereis.Anessennaiaspectofagoodbondisthatitshouldremainsoaftertheequipmenthasenteredusc.Highpressuresalsohavetheeffectolsqueesingoutcorrosivemateri-alsandinsulating6lms.TheformercausesEMCTest&Designprogressivedegradationntbonds,whilstthelattercanreducetheef'ciencyofthebondf;omthemomentitisinstalled.Itisparticuiariyimportantincommunicationssystems,where6ltersareinsuiiedandshieldedcableternunationsaremadeJiatthebordsareof',owresistanceandreuintheirperfonnance.BondPerformanceandMtaalaremcntExperiencehasshownoveranumberofyearsthatforlongtennconsistentbondperformancealowvalueofresistancemustbeachieved.Thisistypically1-5milhohms.InDefStan~(Part1)/1thevahiehasbeensetatamaximumol2miUiohms.Thislevelismeasuredthroughtheindividualbonds.Thclogicbehindthislevelistwoloid.Firstly.experienchasshownthatwithcommunicaionsequipmentinparticu-larthisvalueolbondresisunceisrequiredifconsistentperformanceistobeachievedintermsofreceptionef6ciencyandtrans-missioncharacteristic.ThisisparticulartysoforTEMPESTprotectedequipments.Tbesecondpointisthatifthebondhasahigherresistancethenthereisasigni8cantlikelihoodthatprogressivedegradationwilloccurandthebondresistancewigincreaseinvalue.Therewillthenbeaprogressivelossinperfonnance.Themainproblemwithmeasuringbondresistancesisthatitshouldbcmeasuredusingalowvoltage/curtenttcchtilquc,Moattechniquestodateforassessingsafety'nvolvesdrivingalargecurrentthroughthebond.Thischecksthebond'sabiRtytocarrycurrentbutdoesnotnecessarilycheckitsEMIprotectionperfonnance.Therea-sonisthatmanybondsmaywheninnormalusehaveahighresistanceduetooxideandgreasy6lms.butwhensubjectedtoahighcurrentthclayersheatupandarevapo-rised.Afterthecurrentisremovedt.".eSmcanreturn.Thushighcurrerttechmquesarenotrecommendedror:esangEMIbonds.ThenewDefenceStandardintheUKspeci6esamaximumprobevoitageoi100mictovolts.Thisreprcsenutypicallyaprobecurrentol50milliampsundershorcitciit(<1mQ)condiuons.This-:sinsuf6cienttodestroysurface5lms.Thechssicmethodformeasuringlowresisuncehasbeentouseafour:erminalbndgeasshowninFigure2.Inthiscase'thecurrentisdrivenbetweentwopointsandAeVOltageaCtOSStheSampleiSmeaSuredwitNahighresisunceprobe.ThisremovesJiecfcctsotthcptobecontactresistanceandleadresistance.Thisisgenerallyconsid-eredtobealaboratorymethodastheuseoffourcontactscanbeawkward.Iftheleadresistancecanberemovedbyacalibrauonteclniqucthenthcfourterminalsmaybereplacedwithatwoterminalsystem.hfurtherpossiblere6ncmenttothetecluiqueistouseafrequencythatisnotDCor50/60/iOOHx.Inthiscase10.4Hahaabeenchosen.Ifanactive6lterisusedtoSterouta9otherelectricanoise,thenitisposgblctousethebondresistancemeteronpoweredupsystems.Itisworthnotingthatatthisfrequencytheimpedanceiastolhtgclyrepresentedbyresistanceratherthaninductance.ThetwotermmalmethodisshowninFigure3.TheintroductionofnewEMC/EMIspcci6cationsinEuropehasmadeitmoreimportantthatoncemadethebondshavecoilslatentlong'tcrlilperformance.ThsmeansmeasurinonperiodicinspecnonardaRctmaintenance.Itisanessentialaspectofinsutmgconsistentperfonnance.IthasbeenshownthatwithinmonthsapparenJygoodbondscandeteriorateto.-ighresis.  
Ift..esamp!eoccursco.","u;.ently wi:hirepowersw'.tching onoroif.:heaverage:orhesensorwillbe.pse'..andane.-.or~4"erecorded.
SystemDesignandInstallation Once>eelect:onics isdesigned.
itbecomesap.oblemof!hesystemintegratar andinstaller:o ersurethatthcelectranics iscravidedwuhtheenvironment farwhichitwasdes;gned.
Mostofthcumc.thisworkisperformed bypowerexpertsandclectricians.
andtheyarenotalwaysawareof:heintcrfererce probkm.Often,onsite.rhepowerqualityisblamedforthcequip.rrentanomalies.
Buttheproblemcanoftenbeavoidedbyfollowing a(ewbasicprina-ples.Theindustrial conuoldeviceiseitherintegrated intoasystemat!hefactoryorinstaL'ed separately onsite.Controllers handleavarictyofdevicessuchasmotorspeedcontrols.
positioning devices.weld-ers,etc.fnterferencc presented totheelectronics canbesigniGcandy reducedbyappropriate measuresoutsideoftheelec-uonicsbox.Thereisnowaytoaccurately assessdierhreatwithouttestdata.Butrcgardlcss ofthebr(oration avai!ab!c.
muchcanbeaccomplished bycorrectinstagation, anditdoesn'tcostmuchifdoneatthestart.RetroGtsbecomecosdy.especially ifac-companied withfactorydowntime.Let'sconsiderdscsameprob!cmsfromasystemstandpat.
Yourgoalistolimittheinterference wfskhmustbehandledbytheelectronics.
Directradiation totheelectronics isnotoftenaprobleminanindustrial environ-ment,butitdoesoccur,andmostoftenwithaplasucenclosure.
TheNEiMAtypeenclosures provideenoughshielding formostmdusuialneeds.Ifyoudon'twanttouseametalenclosure, besure!ogetelecuonics whichwillwithstand theRFwhichwilloccur.l(oreor'.eh'.heproblemisconducted.
eirher'aapowerorgraurd.Theproblemoccursdue:opowerandg.ounddistur-bancescausedbytheequipment.
Itisanalltoocommonpracdcetodrawcontroiier powerf;omthesamesourceasfeedsthepowereqtupmcnt.
T."ispowermayprovide:herecessary energytodrivetheequip-ment.butitisnotsuitabletopowertheelectroiucs lFigurc3).Hopefully, allindusuial equipment wiUhaveelectronics poweredfromaseparatelowpower120voltcircuit.Itsolvesseveralproblems.
First.itseparates theelectron-icspowerfromtheprobablyverynoisyindusu@gradepower,prevendng theswitching transients andstartupsagsfromgenugtotheelectronics.
Second,ifitisnecessary tocondition theelectronics po~erfromanextet".Aproblem,itistarcheapertocondiuonthewattsnecdcd(orelectronics powerthanitistocondition thckilowansrequiredbythesystem.Ifpowercannotbeseparated.
thenitisnecessary toprovideabu!letproaf powersupply.preferably incbrding anisolation transformer, toseparatetheentirepowersupplyfromtheelectrical equipment.
GroundNoise.Groundnoise,inevita-bleinindustrial environments.
mustbedivertedfromtheelectronics modu!c.MultiplegroundsinasystemwiGoftenresultingroundcurtentscircu!sting throughthecquiprnent.
andgroundnoisecircuhting throughthcelectronics pathwillcausernalfuncuon.
Figure4showssometypicalgroundloopsituations.
Acommonapproachistodemandasuper~arthground.Thisisgood,butitisnotacureall.andoftenasupergroundcannotbeachieved, nomatterhowyouuy.Howdoyougetasupergroundfromthethird4oor?Therealneedistogct'astablegroundreference toallinterconnected equipments.
Ifthisequipment iscloselylocated,thenaverylowimpedance interconnect isfeasi-ble.Powerconditioners areo(tentaskedtoeliminate RFofg.oundnoise...at work,but:heseproblemscanberc.withanisolat:on rant(armer:o
=".-..-neutraltogroundnoiseand~~rh"~IIpo;lincGlters.Soyoumaywan:;otryinexpensive approachnrst.DataI.inks.Datalinksaresu.~ngovertheer'.tire!acirty.
exposingther.:twoprinciple e((ects.groundraisearepickup.Groundnois>>;willcausedataer.-unlesstheelectronics hasbeendesigne"accornmodatc potential differences of->>eralvoltsormore.Thisisaccampbs; withdif(crential driversandreceivers:f
=.mustbedirectcoupled.Optical'hnks-eventually takeovertheselinks.TheotheraspectisRFpickup.Inexpesiveshieldedcableissuitable(ar:.'urpose.
Groundborhends!Donotappsinglepointgroundtechniques toRF.i!Iawfrequency groundloopproblem:s threat.thenoncendcanbecapaciuve SummaryIndustrial electronics aresubjected rcharshenvironment.
Gooddesignandinst.!ationtechniques willminimiaeproblemsthcGeld.Adhcrencc totheEurope;standards, IEC801.xisagoodstart,ev>>ifyouareonlymarkeunginthcUSA.Bibliography FIPSPUB94,Guideline onElec'ac:PowerforADPInstallauons.
Scptcmber 1983,IEC801-2.Electromagnetic compatibilit.
(orindustrial.
processmeasurement an<controlequipmcnt, Elcctrostauc dischargr requirements, 1984.(EC801-3.Electromagnetic compatibi!it!
(arindustrial.
processmeasurement anIcontrolequipment, Radiatedelectromag ceticGeldrequirements, 1984.IEC8014,Electromagnetic compatrbilit:
(orindustrial-process measuremcnt ar.:controlcquipmcnt.
Electrical fast:ransreht burstrequirements.
1984.EMCTest8cDe.<n e
industrial Fquipment Equipment GroundBondlng-Designing forPerformance andLifeADiscussion ofGroundConnection Fundamentals toControlEMlByD.B.L.DurhamDytecnaLtd,UKTheproblemofachieving satisfactory earthbondsorgroundconnecuons hasplaguedEMCengineers formanyyears,notonlybecausethebondsareoftenvitalfortheachievement ofsatisfactory equipment pei-formancebutbecausetheyaffectthelongtermperformance ofequipment afterithasbeenintroduced intoservice.Recommendations onbondinghaveex-istedintheformofmilitaryspeciBcations, suchasMilStd1310.Mil188-124AandMil-B.5081 (ASG)forsomeyearsandthesehavegenerally provedsatisfactory formostnewbuilds.However.thesespeci6cations havecertainlimitations inthattheygener-allydonotspectfyconsistently lowlevelsofbondimpedance.
norasuitabletestmethod.Theintroduction ofncwEMCspeciGcations inEuropewiththeEECDirective onEMCandtherequirements foriongtennstability inEMCcharacteristics hasdirectedtheUKnuTitarytoreviewcidsutlgspcciEcaQons andIntroduce ancwDefenceStandardtotightenupperfonn-ancerequirements fornurttaryequipment.
DcfStan~(Part1)/1hasbeenintro-ducaltoaddressthiaareaasfarasmob9eandtranspottablc canmunications installa-tionsareconccnteia.
buttherequirements shouklhaveimplications inindustrial apph-cationsandoverthewlxHeekctronics marketiflongtermproductperformance istobeguaranteed.
BondDegradation EarthorgroundbondsaregeneraHyconsidered essenualnotonlyforsafetyreasons.butasameanofdiverting EMcurrents, "locking" circuitboardsand38eqtdpment toastablegroundpoint.achiev.ingadequatelevelsofcabkshiekhngandformanyotherreasons.Manydesigners un-derstandtherequirement forshort.fatbondleadstominimiacgroundinductance, butfewappreciate thatacriticalaspectistheconnection resistance withwhichthebondstrapisattachedtotheequipment groundpoint.Thcbasicrequirement ofanybondisthatitshouldhaveaslowanimpedance aspossible(uille55itisadchbcratc induc-tivebondtolimitgroundcurrents).
Tbeimpedance isacombination oftheresistive andtheinductive components.
Thcresis-tiveelementisafuncnonofthcbondstrapresistivity, crosssectional areaandlength.seeEquation1.whihttheinductive compo-nentisamorecomplexfunctionofthcbondstrapcharacteristics asshowninEquation2.R~-qf0AL-~ln-+05+02235-jiZ,j'fb+c"2icLb~c2fJ(2)whereRresistance, g~resistivity, f>length.A~area,p,pcrmeabiEty offreespace,L~inductance.
p~feLttivcpermcabiTity, bstrapwidth,andcstttpthickness.
Thefrequency atwhichtheinductive ekmentdominates theimpedance expres-sionwhencalcu!ating thctotalinductance is,fromEquation3,typically 1kHs.ltwglbeseentherefore thattoalintentsand"purposesthcbondexceptatDCandpowerfrequencies, maybeassumedtobeaninductance.
Atveryhigh~equencies:r straycapacitance acrossthestrapdonunate.
Thismeansthatthevolt"-:acrossabondisgeneraily afuncuoninductance andfrequency.
BasedonOhr.".LawthisvoltdropisshowninEquador.~Fortransients thevoltagedropisgiver..Equation5.ZRt+cutLSVIZ~jauUd1dt(5whereZ~strapimpedance.
cu~tacomafrequency, V~voltage,and1~current.Fromthis.thehigherthcinductance thmoreisolatedthecircuitorboxbecomefromground.Thscanhavesigru6can effectsoaequipment.
inchdingenhancementofnoiseinjecbonontoarcuits,reduc=nonofSterperformance, andlossoicoaunlmication range.FromaTEMPESTstandpoint itmayresultinmoreradiation fromemanent.ltwouldseemfromthisthatthecntcriatoranybondistheinchlctancc andhencethcchoiceofshortfatDavidDuganservedfor21yeanitttheBrrtiabAnny,wherehcgainedhisChgreeiadectricaf cnginceting.
Afterserviceinavarietyofappointments hcretiredtojointheRecalls'ES companyastheTechmca/Mtnsgcrrcspottsiblc
/orthecfes/gnanddevclopnsettt ofcommctttication systems.fn198$hejainefDytecnaastheiManagerofthe&ginecnttg Division.
andnowtscurrcntfy Tchtaica/
Marftcting Manage..JulytAugust
!991 5P sc';orc(cgq(r~rri.~~~cwc"-av~l-l'sis~fNf$QskgRrrfNT'N,ff'Srnryort:4icsir:i.rrenl
',:!0iQA.osJVA5Hf5rrlltfRscarc5errVOUAGE&ifASI'REhlENTFigure!.Bondresisurce.
Figure2.Fourwirebridgemethod.bondstraps.However.ananaiys'sof:hebondinductancf showsJiatI'orabondstrapof100mm!org,15mm~~deand2mmIhcktheimpedance at1MHawillbe3.8Ohms.Itsoundsextremely sin:pie.butworkperformed in'.heUSA'ndI:Kshowsthatifanetrotismade'inthewaythestrapisternunated thenaprogressive increasein:heresisunce ofthebondstraptoboxjuncnoncanoccurastheequipment ages.Eventuaily theresisunce willbegintoexceedhundredsofohmsandmayeventu-allygoopenccuit.Thiscannegatethceffectofthebondstrapcompletely aspartoftheE!rIIprotecdon.
tVhathappenswithbondstocausethischange!Essentially agroundconnecuon isaseriesofirrpedances fromthcstrapthroughtothegrourdmaterial, asshowninFigure1.Eachpointofcontactcontrib-utestothetotalbondper'.onnancc;.
Asaresult.achangeinanycontactcondition canresultinachangeinthetotalbondresistance.
Asisweilappreciated, the"contactresistance betweentwometalsur-facesisahnctionofthepressure.
Thepressureexertedbythetipofadrawingpinisvastlygreaterthanthatfromthethumbpressingbyitself.Thusthecontactfromasharppoultgivesatsochhigherprcssuret.'unaOatpointand4gtiforclowercontactresisuncc.
Measutetata haveshownthatsharppointsenableContactrcsisuncc ofafewnicroohmtobeachievedwhilstsimilarpressures onOatsurfacesresultinmil-liohmsofconuctresistance.
Itmightbefeltthatthereislittleornodifference betweenthesevalues,butinrealitythereis.Anessennaiaspectofagoodbondisthatitshouldremainsoaftertheequipment hasenteredusc.Highpressures alsohavetheeffectolsqueesing outcorrosive materi-alsandinsulating 6lms.TheformercausesEMCTest&Designprogressive degradation ntbonds,whilstthelattercanreducetheef'ciency ofthebondf;omthemomentitisinstalled.
Itisparticuiariy important incommunications systems,where6ltersareinsuiiedandshieldedcableternunations aremadeJiatthebordsareof',owresistance andreuintheirperfonnance.
BondPerformance andMtaalaremcnt Experience hasshownoveranumberofyearsthatforlongtennconsistent bondperformance alowvalueofresistance mustbeachieved.
Thisistypically 1-5milhohms.
InDefStan~(Part1)/1thevahiehasbeensetatamaximumol2miUiohms.
Thislevelismeasuredthroughtheindividual bonds.Thclogicbehindthislevelistwoloid.Firstly.experienc hasshownthatwithcommunicaions equipment inparticu-larthisvalueolbondresisunce isrequiredifconsistent performance istobeachievedintermsofreception ef6ciency andtrans-missioncharacteristic.
Thisisparticularty soforTEMPESTprotected equipments.
Tbesecondpointisthatifthebondhasahigherresistance thenthereisasigni8cant likelihood thatprogressive degradation willoccurandthebondresistance wigincreaseinvalue.Therewillthenbeaprogressive lossinperfonnance.
Themainproblemwithmeasuring bondresistances isthatitshouldbcmeasuredusingalowvoltage/curtent tcchtilquc, Moattechniques todateforassessing safety'nvolves drivingalargecurrentthroughthebond.Thischecksthebond'sabiRtytocarrycurrentbutdoesnotnecessarily checkitsEMIprotection perfonnance.
Therea-sonisthatmanybondsmaywheninnormalusehaveahighresistance duetooxideandgreasy6lms.butwhensubjected toahighcurrentthclayersheatupandarevapo-rised.Afterthecurrentisremovedt.".eSmcanreturn.Thushighcurrerttechmques arenotrecommended ror:esang EMIbonds.ThenewDefenceStandardintheUKspeci6esamaximumprobevoitageoi100mictovolts.
Thisreprcsenu typically aprobecurrentol50milliamps undershorcitciit(<1mQ)condiuons.
This-:sinsuf6cient todestroysurface5lms.Thechssicmethodformeasuring lowresisunce hasbeentouseafour:erminal bndgeasshowninFigure2.Inthiscase'thecurrentisdrivenbetweentwopointsandAeVOltageaCtOSStheSampleiSmeaSuredwitNahighresisunce probe.ThisremovesJiecfcctsotthcptobecontactresistance andleadresistance.
Thisisgenerally consid-eredtobealaboratory methodastheuseoffourcontactscanbeawkward.Iftheleadresistance canberemovedbyacalibrauon teclniquc thenthcfourterminals maybereplacedwithatwoterminalsystem.hfurtherpossiblere6ncment tothetecluique istouseafrequency thatisnotDCor50/60/iOOHx.
Inthiscase10.4Hahaabeenchosen.Ifanactive6lterisusedtoSterouta9otherelectrica noise,thenitisposgblctousethebondresistance meteronpoweredupsystems.Itisworthnotingthatatthisfrequency theimpedance iastolhtgclyrepresented byresistance ratherthaninductance.
ThetwotermmalmethodisshowninFigure3.Theintroduction ofnewEMC/EMIspcci6cations inEuropehasmadeitmoreimportant thatoncemadethebondshavecoilslatentlong'tcrlilperformance.
Thsmeansmeasurinonperiodicinspecnon ardaRctmaintenance.
Itisanessential aspectofinsutmgconsistent perfonnance.
IthasbeenshownthatwithinmonthsapparenJygoodbondscandeteriorate to.-ighresis.  


AAeqT~ic'oKue45uI>eNreiieootsisascg0FIXEDRKSlSTANCELEAOSFigure3.Twotermmalbridgemethod.404y4Ic<~~4cc>~~~c~(olnpi4lllAQ~+c~~(4eeoc4((i+yo~befit%CUSTOMQAGTi4.++++"9t~o'4+a~~>tiQNCQMNCRfAC.0odgottc~'e+b~+.=nuators,CoaxialTerm.%/@<y<c<4~connectors,~4.~b,~Cata~pc+q4.attestlE11?0-1?bnCOlnAvenue.FOlbrOOk.;4Y11741(S16)~85.)4tX1FAXi16.~BR>l14INFO/CARO29tance.Ther.io.et.'ivcesii'-.~suo)ecttotestingand.xa.-..;.-.a:.cn-asama:ntenancetas~.LK~militaryExperienceTherehaveoeen'.wo~lcr-.::causedbypoorbonusexpenencedegradauon.nericrmance~ready-uonedin:tusa.-.icle.The:ossi;cir,-cationrange.poorEMlpe.",'ormanceothereifectsaL'onrnbu'.etoacons:dertreductionmequi".-..entNc:encyanna.ability.Thesecordei;ectwnichis-.difficulttodenufy:s:hataiNoFaultF.(NFF)problems.AnanalysisofreN'."failuresfrommilitaryreiiaLiitydata.shownthatNFFinc:dentscanaeextre.-.high,particulariy:nhunud;timates.hasbeenpartiallyconfirtnedbyreports.':theGulfSarwhenaHforcesrepor-.e.increaseinavailabilityofequipmen:.;.'rierclunate.Manyfau!tsaredueto"electricacontactsinconnectors.bu:alarnumberhavebeenidenufiedasexcess:EMIinducedthroughpoorgroundonncThismaybecausedbyeitheraloosegroistraporconnectorterminauonto:he':cAsignificantimprovementInequipmeavailabilityandperfonnanceisexpec:ewhenmorerecentstatisucsareanalysed.Theintroduction:ntotheBnushAr.-.serviceofAeDyteaaBondResistancTestSet-DTl09hasenabledtheL":mihtarytomeasurebondresistancesinstalledequipmentandreduce;hecurancesofNFFerrors.TheUKmi:armeasurementprocedureusesatwo:er-...:nalbridgemethodandanaccuratemiiliohmcalibrationstar.dard.ThismeasurementprocedureandequipmentisalsinusebyotherNATOnationsande!sewherebyiniTitaryandnavalforceswrohavrecognizedthesameproblem.CottclueiottaTheproblemswithgroundbondshavebecomesignificantwiththedevelopmento:sensitiveandsecurecommunicationsequi"-ment.ThiscoupledwithanincreasingreedtoachievehigherandhigherlevehofKMfprotectiwthasleadtoanincreasedemphasisbengplacedontheeffectivenessofalltypesofsystetttgrounds.These.furthercom-binedwitharequirementtoensurethelonglifeofsystemsonceinservice.haveresultedintheassessmentthatbondsandterminationsareoneoftheprimarycausesofEMfaBuresinsystems.Therequire-menttotesttheseisclear.howeverthemeanstodosohavenotalwaysbeenavailabletoengineers.July.Aug.st'.9o'.  
AAeqT~ic'oKue45uI>eNr eiieootsisascg0FIXEDRKSlSTANCE LEAOSFigure3.Twotermmalbridgemethod.404y4Ic<~~4cc>~~~c~(olnpi4lllA Q~+c~~(4eeoc4((i+yo~befit%CUSTOMQAG Ti4.++++"9t~o'4+a~~>tiQNCQMNCRfAC.0odgottc~'e+b~+.=nuators, CoaxialTerm.%/@<y<c<4~connectors,
~4.~b,~Cata~pc+q4.attestlE11?0-1?bnCOlnAvenue.FOlbrOOk.;4Y 11741(S16)~85.)4tX1 FAXi16.~BR>l14INFO/CARO 29tance.Ther.io.e t.'ivcesii'-.~suo)ecttotestingand.xa.-..;.-.a:.cn-asama:ntenance tas~.LK~military Experience Therehaveoeen'.wo~lcr-.::causedbypoorbonusexpenence degradauon
.nericrmance
~ready-uonedin:tusa.-.icle.
The:ossi;cir,-cationrange.poorEMlpe.",'ormance othereifectsaL'onrnbu'.e toacons:dert reduction mequi".-..ent Nc:encyanna.ability.Thesecordei;ectwnichis-.difficult todenufy:s:hat aiNoFaultF.(NFF)problems.
AnanalysisofreN'."failuresfrommilitaryreiiaLiity data.shownthatNFFinc:dents canaeextre.-.high,particulariy:n hunud;timates.
hasbeenpartially confirtned byreports.':theGulfSarwhenaHforcesrepor-.e.
increaseinavailability ofequipmen:
.;.'rierclunate.Manyfau!tsaredueto"electrica contactsinconnectors.
bu:alarnumberhavebeenidenufied asexcess:EMIinducedthroughpoorgroundonncThismaybecausedbyeitheraloosegroistraporconnector terminauon to:he':cAsignificant improvement Inequipmeavailability andperfonnance isexpec:ewhenmorerecentstatisucs areanalysed.
Theintroduction:nto theBnushAr.-.serviceofAeDyteaaBondResistanc TestSet-DTl09hasenabledtheL":mihtarytomeasurebondresistances installed equipment andreduce;he curancesofNFFerrors.TheUKmi:armeasurement procedure usesatwo:er-...:
nalbridgemethodandanaccuratemiiliohmcalibration star.dard.Thismeasurementprocedure andequipment isalsinusebyotherNATOnationsande!sewherebyiniTitary andnavalforceswrohavrecognized thesameproblem.Cottclueiotta Theproblemswithgroundbondshavebecomesignificant withthedevelopment o:sensitive andsecurecommunications equi"-ment.Thiscoupledwithanincreasing reedtoachievehigherandhigherlevehofKMfprotectiwt hasleadtoanincreased emphasisbengplacedontheeffectiveness ofalltypesofsystetttgrounds.These.furthercom-binedwitharequirement toensurethelonglifeofsystemsonceinservice.haveresultedintheassessment thatbondsandterminations areoneoftheprimarycausesofEMfaBuresinsystems.Therequire-menttotesttheseisclear.howeverthemeanstodosohavenotalwaysbeenavailable toengineers.
July.Aug.st
'.9o'.  


PanelSessIonPESSummerMeeting,JulylQ,1988LongBeach,CaHforniaJohnG.Kappenman,ChairmanPowerSystemSusceptibilityToGeomagneticDisturbances:PresentAndFutureConcernsJohnC.Kappenman,MinnesotaPowerTheeffectsofSolar.GeomagneticOlaturbanceahavebeenobservedfordecades.onpowersystems.However,thepro-foundimpactoftheMarch13,1989geomagneticdistur-bancehascreatedamuchgreaterlevelofconcernaboutthephenomenainthepowerindustry.Severalman.madesystemshavesufferedd)eruptionstotheir-normaloperationd)aatotheoccurrenceofgeomagneticphe-nomena.Moatoftheman~esystems,suchaacommu-nications,havebrettmadelesssusceptibletothephenom-enathroughtechnologicalevolution(microwaveandfiber-optlchavereplacedmetall)cwiresystems).However,thebulktransmissionsystem,Ifanything,ismoresusceptibl~todaythaneverbeforetogeomagneticdisturbanceevents.Andlfthepresenttrendscontinue,itlalikelythebulktrans-missionnetworkwillbecomemoresusceptibleInthefuture.Someofthemostconcerningtrendsare:1)Th>>transmissionsystemsoftodayspangreaterdistancesofearth-surface-potentialwhichresultIntheflowoflargergeomagneticaily-IEEEPowerEalineeciagReview,October1989Induced.currentsinthesystem,2)theinterconnectedsys-temstendtobemorestressedbylargeregion-to.regiontransfers.combinedwithGICwhichwillsimultaneouslyturneverytransformerinthebulksystemintoalargereactivepowerconsumerandharmoniccurrentgeneratorand3)ingeneral,largeFHVtransformers,staticvarcompensstorsandrelaysystemsaremoresusceptibletoadverseinfluenceandmicroperationduetoQIC.TRhNSFORMEROPERhTIONTheprimaryconcernwithGeomagnetlcally-InducedCur-rentslatheeffectthattheyhaveupontheoperationoflargepowertransformers.ThethreemajoreffectsproducedbyGICintransformersIa1)theIncreasedvarconsumptionottheeffectedtransformer,2ltheincreasedevenandoddharmon-Icageneratedbythehalf.cyclesaturation,and3)thepossi-bilitiesofequipmentdamagingstrayf)uxheating.Asisweildocumented,thepresenceofevenasmallamountofGICI20empaorless)wNcausealargepowertransformertohalf-cyclesaturate.Thehaif~c)esaturationdistortedexcit-ingcurrentlsrichlnevenandoddharmonicawhichbecomeintroducedtothepowersystem.Thedistortionoftheexcit-ingcurrentalsodeterm)nestherealandreactivepowerre-quirernentsofthetransformer.Thesaturationofthecoresteel,underhaif~c)~saturation,cancausestrayfluxtoen-terstructuraltankmembersorcurrantwlndlngswhichhasthepotentialtoproduceseveretransformerheat)no.15 tI tr:rscs&#x17d;rrei'-ryes.-e'io:est'esul!Strct~:ste'.na;StogieCnaSesr5.'"r-..erS;ai'CVCleSaturatemuCnmereeasilvano!04-"cngreatercegree;hanccrricarable.;nreeonaseunits.."ese:.ansformersproducehighermag.nnucesofharnonicsand"orsume!argeramountsofrese-!rvepowerwhencomPareOwiththreephasedeslgnS.ItELhyHANDPROTECTIVESYSTEMS>herearethreeba5icfaitiremodesofrelayandprotectiveSvs!ems:natcanoeattr:buteotoggeomagheticdistur-bances:r~u~>>~neear!:id,<<3g.4!'4C4drageonag,"et.'cstormswhen!heyare-''-4,~de~~"~SUNSPOTCYCLEShNDGEOMAGNETICDISTLRBhNCECYCLESOntheaverage,solaractivity.asmeasuredbyt."enuroer".monthlysunspots.followsan11yearcvcl'e.he"esen!sunsootcycle22haditsminimumtnSeoten.oer1986.a."cisexoectedtooeakin1990-1991.Geomagnetic'elao5~tvrbancecyclesdonothavethesameshaoeas:nesunscotnumbercycles.eventhOughtheyarecyclical.FSure1snowsthenatureofthesunspotnumbersandgeomagnetic3C!i"".v~.alseOperationof:."eprotectionsystem.suchashav-ingOCCurreOrOrSVC.CabaCitarandlinerelayOpera-tionswhere:te!towofharmoniccurrentsaremisin-:erpreter2OVthereiaVaSaraultOrOVerlOadCOnditicn.Thisisthemostcommonfailuremode.~FailuretoOperatewhenanoperationisdesirable,thishasshowntobeaproblemfortransformerdifferentialprotectionschemesandforsituationsinwhich;heoutputofthecurrenttransformerisdistorted.~SlowerthanDesiredOperation.thepresenceofGlCcaneasilybuilduphighlevelsofoffsetorremanentttuxinacurrenttransformer.ThehighGICinducedoff-setcansignificantlyreducetheCTtime.to.saturationforoffsetfaultcurrents.4uit'ocrorC(rtwortsCctrsrrrrapr25SurtsIre4i431~1444Cyclei7CyclelaCycleiaCyote20Cyci~21iIr~)40;120lirumoereliOlslureetdOdyVyear150tISuitspoiHumber~00IIiiIii)IrIIl00j50j,~~d0Iidei40I~20~~.~014540uiII\!40035eecSMostoftherelayandprotectivesystemmisoperationsthatareattributedtoGICaredirectlycausedbysomemalfunc-tionouetotheharshharmonicenvironmentresultingfromlargepowertransformerhalf-cyclesaturation.Currenttrans-formerresponseerrorsaremoredifficulttodirectlyassociatewiththeGICevent.ForexampfeinthecaseotCTremen-encc.theCTresponseerrormaynotoccuruntilseveraldaysaftertheGlCeventthatproducedtheremanence.Therefore.thesetypesoffaituresaremoredifficulttosubstantiate.50554045707540Figure1.VaitstfonsoftheYearty-AveraeedSunspotNumberenidQetsmaenettealtyOlsturbedOaysfrom'1932-1SBB.cyclesfrom1932to1988i2,3l.NotethatthegeomagneticdleturbanCeCyCleeCanhaVeadOublepeak,OneOfWhiChCanlagthesunspotcyclepeak.Whilegeomagneticactivityinthepresentcycleisexpectedtomaximizeinapproximately1993-1994,severegeomagneticstormscanoccuratanytimeduringthecycle;theK-9stormofMarch13,1989wasastrikingexample.CONCLUSIONSAsevidentbytheMarch13thblackoutintheHydroQuebecsystemandtransformerheatingfailuresintheeasternUS,thepowerindustryisfacinganimmediateandseriouschal-lenge.Thepowerindustryismoresusceptiblethanevertotheinfluenceofgeomagneticdisturbances.Andtheindustrywillcontinuetobecomemoresusceptibletothisphenome-nonuntessconcenedeffortsaremadetodevelopmitigationtechniques.EhRTHQURFhCE.POTENTIhLhNDGEOMhGNETIChLLY.INDUCEDWURREVTSTheauroralelectrojeteproducetransientfluctuationsintheeanh'5magnettcfieldduringmagneticstorms.Theearthisaconductingsphereandportionsofftexperiencethistime-varyingmagneticfield,resultinginaninducedearth-surface-potentlallfSP)thatcanhavevetueeof1.2to8volta/kmt2to10volte/mile)duringseveregeomagnetfcstormsinre-gionsoflowearthconductivityl4),GeomagneticDisturbanceCausesAndPowerSystemEEectsflectricpowersystemsbecomeexposedtothe8SPthroughthegroundedneutralsofwye-connectedtransformersattheoppositeendsoflongtransmissionlines,aeshowninFigure2.ThefSPactaaeantdealvoltagesourceimpressedbe.tweenthegroundedneutrateendhasafrequencyofonetoafewmittfhene.Thegsomagnetlcally-fnducedcurrentslGIC}arethendeterminedbydividingtheESPbytheequivalentdcresistanceoftheparalleledtransformerwindingsandlineconductors.TheGIClssques%tractcurrent,andvaluesinexcseeof100empersehavebeenrrNaeuredintransformerneutrals,VernonD.Albettsw2UniversityofiiIJnaaotaPOWERSYSTEMEFFECTSOFGICThepsr.phsesGlCinpowertransformerwindingscanbeIEEEPowerEngineeringReview.October1989SOLhRORIGINSOPGEOMhGNETICSTORMSThesolarwindiesrsrffiedplasmaofprotonsandelectronsemittedfromthesun.Thesolarwindfsaffectedbysolarflares,coronalholes,anddisappearingfilaments,andtheso-larwindpanicleeinteractwiththeeenh'emagneticfieldtoproduceauroralcurrents,orauroraletectrojste,thatfoltowgenerallycircularpathsaroundthegeomagneticpate!atal-titudeeof100kilometersormorel1).Theauroraborealisievisualevidenceoftheauroralelectrojetsinthenorthernl6 1~
PanelSessIonPESSummerMeeting,JulylQ,1988LongBeach,CaHfornia JohnG.Kappenman, ChairmanPowerSystemSusceptibility ToGeomagnetic Disturbances:
44~Inaia.sat~tat.ahn-richI:.tarsgr~ersauseclaymisoperatontet~44Al=.sr~ti.RFACS~I~9T-SARvii-SuRFACS<T5hti41.~t'igui~2.Induced5aich.Surtact-PoitntialISSP)ProducingQtamtg.htticaliyInducedCunehisIQICIinPowerSytttmt.io.aimanytimeslargerthan:heRMSacmagnetizingcurrent,re-sultinginadcbiasaftransformercoreflux,asinFigure3.IIlo,plI~REFEHENCES1.Akasatu.S.I"TheOyhtmiCAurcra,'ciehutCAme":~Mageziht.May1989.pp.90972.Jactlyh.J.A.."Reel-TimePtedicuchotGfcbalGoonagrtiActivny,SaltrWindMagnetosphereCauphi'g,"p.141.TarrtSciehuflcPublishingCompany.oxvo.'986.3Thompsah.R.J.,"TheAmplitudeatSaiarC.cie22,RiidiaehdSpaceSewiciisTtchhiCalReportTR8703,ctcbti1987.4V.O.AlbertganehdJ.A.VthBatten,"Utcuicphdhlaghe.;iFieldsatthtStnh'sSurfacedutioAurartlCunenls."i55iTcahaaCIiohsahPowerApparatusandSystems.Val.PAS39hia.2.April1970.pp.578-584.5.J.Q.Kappehmtn,V.O.Albtrtaon.9.Mohan."CurserTrahatarmtrahdRelayPtrtolmtnCtihthePresenceotGtcmagneticallyInducedCurrents."ISEETriiheactiansahPawe~ApparatusahdSystems,Vai.PAS.100.No.3,pp.1078-1088.March1981.TheHydro-QuebecSystemBlackoutOfMarch31,l989<<ICI<<r~Rgurt3.OCBtt!afTrtntfarmtrCartRulcOuttoQIC.Thehalf.cyclesaturationoftransformersonepowersystemisthesourceofnearlyalloperatingandequipmentproblemscausedbyGIC'sduringmagneticstorms.Thedirectconse-quencesafthehalf-cycletransformersaturationere:~Thetransformerbecomesarichsourceofevenandoddharmonics~Agreatincreaseininducttveversdrawnbythetrans-former~Possibledrasticstrayleakagefiuxeffectsinthetrans-formerwithresultingexcessivelocalizedheating.Thereareanumberofeffectsduotathogenerationofhighlevelsofharmonicsbysyatimpowertransformers.includ-ing,Overloadingotcapacitorbanda~Possiblerntsaperottanofrelays~Sustainedovervoltogosonlang.lineenergizattanHighersocondoryarccurrentsduringsingle.poleswitching.~HighercfratffCMakerrecoveryvoltage~OvorlaadtnoofharmonicfttfyrsofHVOCconverterter-minals,anddtotantanintfioacvoltagewaveshapethatmayresultinlossotdcpowertransmission.Theincreasedtnductfvovoradrawnbysystemtransformersduringhalfwycl~soturat)anaresufficienttocauseintoler-abtosystemvoltagedepression,unusualswingsinMWandMVARflowontransmissionlinea.andproblemswithgener-atorvarlimitsinsomeinstances.Inadditiontothehalt-cyclosaturationotpowertrans-formers,highlevelsofGICcanproduceadlstartedresponseIEEEPowerEngiaeerintfReview,Octoberf989DanielSaulier,Hydro-QuebecOnMarch13.1989.anexceptionallyintensemagneticstormcausedsevenStaticVarCarnpensatorsISYC)onthe735-kYnetworktotriporshutdown.Thesecompensetorsarees-sentialforvoltagecontrolandsystemstability.Withtheirloss.voltagedroppedandfrequencyincreased.ThistedtosystarttinstabilityandthetrippingofalltheLaGrandetrans-missionlinestherebydeprivingtheHQsystemof9500MWofgeneration.ThoremainingpowersystemcallapsedwithinsecondsoftholossoftheLaGrandenetwork.Thesystemblackoutaffected~itbutafewsubstationsisolatedantolo-calgene~stingstations.Pawerwasgraduallyrestoredoveraninehoursperiod.Oe-leyainrestoringpowerworeencountereabecauseofdam-agedequipmentonthoLaGranden>>twarkandproblemswithcaidloadpickup.SYSTEMCONDITIONPRIORTOTHEEVENTSTatalsystemgoneratfonpriortotheeventswas21500MW.mastofitcomingfromremotepower-generatingstationsatLaGrande,MantcouagonandChurchf8Felts.ExportstoneighboringSystemstotalled1848MWofwhich1352MWwereonOCinterconnections.The735-kVtransmissionnet-warkwasladedat90%ofttsstabilitylimft.SEQUENCEOFEVENTSAt2:45o,m.onMarch13,averyintensemagneticstormtedtotheconaequortttaltrtporshutdownofsevenSVC's,Contafnlngthoimpactofthoeventthroughoporatarinter-yentionwasimpassibleattSVC'ahavingtrippedatcaaaodtofunctionwithinoanominuteperiod.Afowsecondsl8-8s.)aftertholossaftholastSVC,~IIfive735.kVlinesoftheLoGrandetransmissionnetwarktrippedduotoanoutofstepcondition.TheseItnetripsdeprivedthesystemot9500MWotgenerationandsubsequentlytedtoacamptetosystemcattapao.17 1\
PresentAndFutureConcernsJohnC.Kappenman, Minnesota PowerTheeffectsofSolar.Geomagnetic Olaturbancea havebeenobservedfordecades.onpowersystems.However,thepro-foundimpactoftheMarch13,1989geomagnetic distur-bancehascreatedamuchgreaterlevelofconcernaboutthephenomena inthepowerindustry.
iO~:ecuonancere~airir9'curSVC'ssnotsownovcaoactor~oitageuncaianceprctec::o.">>aivsisotvootageanocur.rentosc:itogramstaxenat:neCtioougamausitebeforetneSVCtnpssnowedtne'.oitowingnarmoniccontents..wC,hCCurrentarl6kyHarnaiiicVcliageOrderat.35kyTCABraccheTSCBrasche100'"o1OO3'ioa~Iifo3~o'&#xc3;"9ofIOof5OofI~3~oI00~o36~o24~}6~o5%16ifoaffQuasiDCcurrentsgeneratedby:hemagneticdisturbance,saturatingintneSVCcouplingtransformersarethoughttobethecauseforsuchatargesecondharmoniccomponentofcurrantintheTSCbranch.DIsturoancesOnPoiyerTransformersHooertJHingjceJamesB.StewartPowerTechttoloip'esInc.Thisdiscussionaddressestheeffectsofgeomagnet:ccistii"oancesonpowertransformers.Theprimarveffect:scuetccoresaturationresulting!romgeomagneticaltvincuceacr~rents.GICs.Coresaturationcanimooseseveretemoeratureproblemsinwindings.ieads,tankplateanastructuraimer.-barsoftransformersandplaceheavyvarandharmonicoi.r~densonthepowersystemandvoltagesupportequiprriant.GIC'sof10to100amperesaremore:henmerenuisancesinthaoperationofpowertransformers,thernanr.erof!Iowcanresultinsaturationofthecoreandconsequentchangesinsystemvarrequirements.increasesinharmoniccurren.magnituctes.increasedtransformerstrayanaeadytosses.andproblemswithsystemvoltagecontrol.GENEAhLOBSEAVhTIONSONTHESYSTEMBEHhVIOAThesystemblackoutwascausedbylossofallSVConI.aGrandeNetwork.SevenSVCtrippedorstoppedfunctioning.PriortoandduringtheeventalltheOCinterconnectionsbe-havedproperly.Norelayfalsetripsormisoperationofspecialprotectionsystemswereobserved.Telecommunicationswarenotaffected.Noequipmentdamagewasdirectlyattrib-utabletoGICbutoncethesystemsplit,someequipmentwaadamagedduetoloadrejectionovervoltagea.RF'VIEDIhLhCTIONSThKEViSincetheevent.thefollowingactionswereimplemented:~SVCprotectioncircuitshavebeenreadjustedonfourSVC'ssoastorendertheiroperationreliableduringmagneticstormssimilarworkisbeingperformedonthefourremainingSVC's,~Energy,MinesandResourceCanadanowprovidesHy-dro.Quebecwithupdatedforecastsontheprobabilityofmagneticdisturbances.ThaaoforecastsareusedbytheSystemControlCenterdispatchertopositionthetransmissionsystemwithinsecurelimits.~A.C.voltageasymmetryiamonitoredatfourkoylo-cationsonthesystem(Bouchorvitto,Amaud,LG2,Chhtgeaguay).Upondetectionofo3%voltageaaym-rnetryatanyonalocation,theayotomcontrolcenterdispatcheriaalarmedandwillimmediatelyta'koactiontopositionsystemtranaforlevelswithinsecurelimitsifthishaan'talreadybeendanebecauseofforecastedmagneticactivity.OPERhTINGLIMNIDURINGMhGNETICDISTURShNCES(hNDhLERTSITUhTIONS)Thefallowingoperatinglimitsarenowbeingappliedt~10%safetymarginshallbeappliedonmaximumtrans-ferlimits.'Maximumtransferlimitsshellnottakeintoaccountthoavailabilityofstaticcomponaatorsdeemedunreliable.~AdjusttheloadingonHVOCcircuitstobewithintho40%to90%,orloaa.ofthonormalfullloadrating.l8CICEFFECTSVERSUSCOREhNDWIIOoDINCCOiVFIGURhTIONSPrincipalconcernsinthisdiscussionareforEHVsystemswithgroundedYtransformerbanksprovidingconductingpathsforGICandzerosequencecurrents.Coraandwindingconfigurationsresponddifferentlytozerosequenceopen.cir-cuitcurrentsendtoGICa.Note:aausedhere.theterm"opencircuit"referstotestsperformedwithalldeltaconnectionsopenedor"broken."Forexample,thethree.phasethreelegcoreformtransformersarolesspronetoGICinducedsatu-rationthanthree-phaseshallformtransformers.But.bothcoreformandshellformsinglephasetransformersaresus.ceptibl~toGICinducedsaturation.WindingandleadarrangemantaresponddifferentlytoGICinducedcoresaturationaawell.Forexample,thecurrentdis-tributionwithinpareil~Iwindingpathsandwithinlowvoltageloadsdependsupontheleakagefluxpathsandmutualcou-pling.Loaaeawithinwindingaandleadsmaychangesignifi-cantlyunderGICinducedsaturationowingtothechangeinmagneticfieldintensity.H,andtheresultantchangesintheboundaryconditionsfortheleakagefieldpath.EDDYLOSSESINSTEELMEMBERSThechangesinthemagneticintensity.H,andthemagneticboundaryconditionaresultingfromtheGICexcttationbiascanincreasetholoaaoainsteelplate,thelossesforfieldsparalleltotheplaneoftheplatoincreasenearlyaathesquareofH.Notealsothattheleveloflossesincreaseapproxi~matelyaathesquarerootofthefrequencyotH.owingtotheeffectofdepthofpenetration.ThomagneticfieldalongyokeclampsandlegplatesincoreformtransformersandinTeebeamsandtankplateInahoNformtransformerscloselymatchesthomagneticgradientlnthocore.Areasofthetankandcoreclampsaresubjectedtothowindingleakagefield.Ifthecorosaturates,themagneticfieldimpresseduponthesteelmembersmayrisetontoonehundredtimesnormalduotothesaturationandtheoffoctooftheleakagefield.Theloaaoointhestoolmomborowillriaohundredsoftimesnor-mal,evenunderhalf-cyclesaturation.Onthosteelsurfaces.eddylosedensitymoyrisetontothirtywattsparsquareinch,approachingthethermalfluxdensityotan~lactricrangeele.ment.SurfacetemperaturesriaorapidlywiththisthermalfluxandcanresultindegradationofinsulationtouchingtnesteelIEEEPowerEatpaeeriagReview.Octoberl989 r
Severalman.madesystemshavesufferedd)eruptions totheir-normaloperation d)aatotheoccurrence ofgeomagnetic phe-nomena.Moatoftheman~esystems,suchaacommu-nications, havebrettmadelesssusceptible tothephenom-enathroughtechnological evolution (microwave andfiber-optlchavereplacedmetall)cwiresystems).
DestgnOcftcfencyOcllrlentvendoraafma1UPShaSnobatterytestCII'CUItVendornaINIa1naintenancesectloAdocsAOIQCAtIOAbatteries.DesignDeficiencyBattefieshavenotbeenreplacedin6ycafsDesignDeficiencyACinputtologicpoucrsaltyisnaihtchahccpreferredBackupbatteriesdegradedordeadk.Srelaycharactertst-ICSPfCveAtStransfertoinverteroutput.BreakerffcIctionperdesignGroundfaultoccursonBphaseofaaintransfofncrVoltagctraflicntoAstatloflACpouersteeplyACpouertologicnoduleforUPStA.D,GcspcrIchccsthetransientoutpu'IvoltagegoestoulogictripsOApoucrSISIPtyfailure.2VSSUPStA,S,C,O,GtripBreakersCS-I,23open;Ch-Cdoesnotcloseupsloadsdohotautotransfertomint.supplylossofallloadsonUPS1AD,riFault1$clcafcdin6cycles;transfercocptetcdin12cyclesPernisstvesprohibItCSCbreakerfrozeclo>IngCS'4ncsvh<toIfunsfernaIntsullplytolnvcltcfoutput r
However,thebulktransmission system,Ifanything, ismoresusceptibl
1.StaticDCtestingwasperformedonindividualchipsfromtheeffectedcircuitsinordertocharacterizeLatch-upsusceptibility.Statictestingisperformedwithfixedvoltagesettings.Thetestingwasperformedonthe4049,4011,4044and4068devices.Thetestschemeincluded:A.OutputvoltagebelowVss(Vssisthegroundornegativepowersupply).B.OutputvoltageaboveVdd(Vddinthepositivevoltagepowersupply).C.InputvoltageaboveVdd.D.Powersupplyovervoltage.Vss>>VddThetestingrevealedthatpermanentphysicaldamagewasinducedbytestsCandD.TestBdidnotinducelatch-upbuttestAconsistentlyinducedlatch-uponthe4049andathighervoltagedifferentialsontheotherdevices-The4049wasquitesensitivetothistest.2.VoltageDropouttesting,wheretheVddwascutoutandrestoredduringtimeperiodsrangingfrom20mSto2secondsdidnotresultinlatch-upbehaviorontheindividualcomponents.A"breadboard"testcircuitwasfabricatedtosimulateatypicalcircuitpath,i.e.a4044latchdrivinga4049invertordrivinga4068gatedrivinga4011gatedrivinganMC1615lampdriver.Slowratedropouttestingofthetestcircuitdidnotresultinlatch-uporotheranomalousbehavior.3.BoardleveltestinghasbeenperformedontheA13A21cardsf'romUPSunitsA,BandG.Astockcardhasalsobeentested.Atestfixturewasfabricatedtoholdthecardsandsupplypaverandinputselectionandoutputmonitoring.AnMC1615lampdriverchipwithLED's(lightemittingdiodes)wasconnectedtothecardoutputs.StaticboaeftestingrevealednoanomaliesontheAcard,adamagedU104049oNtheBcard,NoanomaliesontheCcardandafailuretoset,anyofthe4044latchesontheGcard.(Notethatlatchingofthe4044chipsisnormalwhilelatch-upisanabnormalcondition.)The.functionalfailureoftheGboardhasbeentracedtotheKlrelayand/ortheSW1resetsvitchonthecircuitboard.FailuresimulationtestingonthefunctionalAboardhasrevealedthatthelightingpatternreportedduringtheincident,wherothelampsonthecardwereextinguishedand"downstream"lampsremainede  
~todaythaneverbeforetogeomagnetic disturbance events.Andlfthepresenttrendscontinue, itlalikelythebulktrans-missionnetworkwillbecomemoresusceptible Inthefuture.Someofthemostconcerning trendsare:1)Th>>transmission systemsoftodayspangreaterdistances ofearth-surface-potential whichresultIntheflowoflargergeomagneticaily-IEEEPowerEalineeciag Review,October1989Induced.currentsinthesystem,2)theinterconnected sys-temstendtobemorestressedbylargeregion-to.region transfers.
combinedwithGICwhichwillsimultaneously turneverytransformer inthebulksystemintoalargereactivepowerconsumerandharmoniccurrentgenerator and3)ingeneral,largeFHVtransformers, staticvarcompensstors andrelaysystemsaremoresusceptible toadverseinfluence andmicroperation duetoQIC.TRhNSFORMER OPERhTION TheprimaryconcernwithGeomagnetlcally-Induced Cur-rentslatheeffectthattheyhaveupontheoperation oflargepowertransformers.
ThethreemajoreffectsproducedbyGICintransformers Ia1)theIncreased varconsumption ottheeffectedtransformer, 2ltheincreased evenandoddharmon-Icagenerated bythehalf.cyclesaturation, and3)thepossi-bilitiesofequipment damagingstrayf)uxheating.Asisweildocumented, thepresenceofevenasmallamountofGICI20empaorless)wNcausealargepowertransformer tohalf-cycle saturate.
Thehaif~c)esaturation distorted excit-ingcurrentlsrichlnevenandoddharmonica whichbecomeintroduced tothepowersystem.Thedistortion oftheexcit-ingcurrentalsodeterm)nes therealandreactivepowerre-quirernents ofthetransformer.
Thesaturation ofthecoresteel,underhaif~c)~saturation, cancausestrayfluxtoen-terstructural tankmembersorcurrantwlndlngswhichhasthepotential toproduceseveretransformer heat)no.15 tI tr:rscs&#x17d;rr ei'-ryes.-e'io:est'esul!Strct~:ste'.na;StogieCnaSesr5.'"r-..erS;ai'CVCle SaturatemuCnmereeasilvano!04-"cngreatercegree;han ccrricarable
.;nreeonaseunits.."ese:.ansformers producehighermag.nnucesofharnonicsand"orsume!arger amountsofrese-!rvepowerwhencomPareOwiththreephasedeslgnS.ItELhyHANDPROTECTIVE SYSTEMS>herearethreeba5icfaitiremodesofrelayandprotective Svs!ems:nat canoeattr:buteo toggeomaghetic distur-bances:r~u~>>~neear!:id,<<3g.4!'4C4drageonag,"et.'c stormswhen!heyare-''-4,~de~~"~SUNSPOTCYCLEShNDGEOMAGNETIC DISTLRBhNCE CYCLESOntheaverage,solaractivity.
asmeasuredbyt."enuroer".monthlysunspots.
followsan11yearcvcl'e.he"esen!sunsootcycle22haditsminimumtnSeoten.oer 1986.a."cisexoectedtooeakin1990-1991.
Geomagnetic
'elao5~tvrbancecyclesdonothavethesameshaoeas:nesunscotnumbercycles.eventhOughtheyarecyclical.
FSure1snowsthenatureofthesunspotnumbersandgeomagnetic 3C!i"".v~.alseOperation of:."eprotection system.suchashav-ingOCCurreOrOrSVC.CabaCitar andlinerelayOpera-tionswhere:te!towofharmoniccurrentsaremisin-:erpreter2 OVthereiaVaSaraultOrOVerlOadCOnditicn.
Thisisthemostcommonfailuremode.~FailuretoOperatewhenanoperation isdesirable, thishasshowntobeaproblemfortransformer differential protection schemesandforsituations inwhich;heoutputofthecurrenttransformer isdistorted.
~SlowerthanDesiredOperation.
thepresenceofGlCcaneasilybuilduphighlevelsofoffsetorremanentttuxinacurrenttransformer.
ThehighGICinducedoff-setcansignificantly reducetheCTtime.to.saturation foroffsetfaultcurrents.
4uit'ocrorC(rtworts Cctrsrrrrapr25SurtsIre4 i431~1444Cyclei7CyclelaCycleiaCyote20Cyci~21iIr~)40;120lirumoereliOlslureetd OdyVyear150tISuitspoiHumber~00IIiiIii)IrIIl00j50j,~~d0Iidei40I~20~~.~014540uiII\!40035eecSMostoftherelayandprotective systemmisoperations thatareattributed toGICaredirectlycausedbysomemalfunc-tionouetotheharshharmonicenvironment resulting fromlargepowertransformer half-cycle saturation.
Currenttrans-formerresponseerrorsaremoredifficult todirectlyassociate withtheGICevent.ForexampfeinthecaseotCTremen-encc.theCTresponseerrormaynotoccuruntilseveraldaysaftertheGlCeventthatproducedtheremanence.
Therefore.
thesetypesoffaituresaremoredifficult tosubstantiate.
50554045707540Figure1.Vaitstfons oftheYearty-Averaeed SunspotNumberenidQetsmaenettealty Olsturbed Oaysfrom'1932-1SBB.
cyclesfrom1932to1988i2,3l.Notethatthegeomagnetic dleturbanCe CyCleeCanhaVeadOublepeak,OneOfWhiChCanlagthesunspotcyclepeak.Whilegeomagnetic activityinthepresentcycleisexpectedtomaximizeinapproximately 1993-1994, severegeomagnetic stormscanoccuratanytimeduringthecycle;theK-9stormofMarch13,1989wasastrikingexample.CONCLUSIONS AsevidentbytheMarch13thblackoutintheHydroQuebecsystemandtransformer heatingfailuresintheeasternUS,thepowerindustryisfacinganimmediate andseriouschal-lenge.Thepowerindustryismoresusceptible thanevertotheinfluence ofgeomagnetic disturbances.
Andtheindustrywillcontinuetobecomemoresusceptible tothisphenome-nonuntessconcenedeffortsaremadetodevelopmitigation techniques.
EhRTHQURFhCE.POTENTIhL hNDGEOMhGNETIChLLY.INDUCEDWURREVTS Theauroralelectrojete producetransient fluctuations intheeanh'5magnettcfieldduringmagneticstorms.Theearthisaconducting sphereandportionsofftexperience thistime-varyingmagneticfield,resulting inaninducedearth-surface-potentlal lfSP)thatcanhavevetueeof1.2to8volta/kmt2to10volte/mile) duringseveregeomagnetfc stormsinre-gionsoflowearthconductivity l4),Geomagnetic Disturbance CausesAndPowerSystemEEectsflectricpowersystemsbecomeexposedtothe8SPthroughthegroundedneutralsofwye-connected transformers attheoppositeendsoflongtransmission lines,aeshowninFigure2.ThefSPactaaeantdealvoltagesourceimpressed be.tweenthegroundedneutrateendhasafrequency ofonetoafewmittfhene.
Thegsomagnetlcally-fnduced currentslGIC}arethendetermined bydividingtheESPbytheequivalent dcresistance oftheparalleled transformer windingsandlineconductors.
TheGIClssques%tract current,andvaluesinexcseeof100empersehavebeenrrNaeured intransformer
: neutrals, VernonD.Albettsw2 University ofiiIJnaaota POWERSYSTEMEFFECTSOFGICThepsr.phses GlCinpowertransformer windingscanbeIEEEPowerEngineering Review.October1989SOLhRORIGINSOPGEOMhGNETIC STORMSThesolarwindiesrsrffiedplasmaofprotonsandelectrons emittedfromthesun.Thesolarwindfsaffectedbysolarflares,coronalholes,anddisappearing filaments, andtheso-larwindpanicleeinteractwiththeeenh'emagneticfieldtoproduceauroralcurrents, orauroraletectrojste, thatfoltowgenerally circularpathsaroundthegeomagnetic pate!atal-titudeeof100kilometers ormorel1).Theauroraborealisievisualevidenceoftheauroralelectrojets inthenorthernl6 1~
44~Inaia.sat~tat.ah n-richI:.tarsgr~ersauseclaymisoperat ontet~44Al=.sr~ti.RFACS~I~9T-SARvii-SuRFACS
<T5hti41.
~t'igui~2.Induced5aich.Surtact-Poitntial ISSP)Producing Qtamtg.htticaliy InducedCunehisIQICIinPowerSytttmt.io.aimanytimeslargerthan:heRMSacmagnetizing current,re-sultinginadcbiasaftransformer coreflux,asinFigure3.IIlo,plI~REFEHENCES1.Akasatu.S.I"TheOyhtmiCAurcra,'ciehutCAme":~Mageziht.
May1989.pp.90972.Jactlyh.J.A.."Reel-Time Ptedicuch otGfcbalGoonagrtiActivny,SaltrWindMagnetosphere Cauphi'g, "p.141.TarrtSciehuflc Publishing Company.oxvo.'986.3Thompsah.
R.J.,"TheAmplitude atSaiarC.cie22,RiidiaehdSpaceSewiciisTtchhiCal ReportTR8703,ctcbti1987.4V.O.Albertgan ehdJ.A.VthBatten,"Utcuicphdhlaghe.;i FieldsatthtStnh'sSurfacedutioAurartlCunenls."
i55iTcahaaCIiohs ahPowerApparatus andSystems.Val.PAS39hia.2.April1970.pp.578-584.5.J.Q.Kappehmtn, V.O.Albtrtaon.
9.Mohan."CurserTrahatarmtr ahdRelayPtrtolmtnCt ihthePresenceotGtcmagnetically InducedCurrents."
ISEETriiheactians ahPawe~Apparatus ahdSystems,Vai.PAS.100.No.3,pp.1078-1088.March1981.TheHydro-Quebec SystemBlackoutOfMarch31,l989<<ICI<<r~Rgurt3.OCBtt!afTrtntfarmtr CartRulcOuttoQIC.Thehalf.cycle saturation oftransformers onepowersystemisthesourceofnearlyalloperating andequipment problemscausedbyGIC'sduringmagneticstorms.Thedirectconse-quencesafthehalf-cycle transformer saturation ere:~Thetransformer becomesarichsourceofevenandoddharmonics
~Agreatincreaseininducttve versdrawnbythetrans-former~Possibledrasticstrayleakagefiuxeffectsinthetrans-formerwithresulting excessive localized heating.Thereareanumberofeffectsduotathogeneration ofhighlevelsofharmonics bysyatimpowertransformers.
includ-ing,Overloading otcapacitor banda~Possiblerntsaperottan ofrelays~Sustained overvoltogos onlang.lineenergizattan Highersocondory arccurrentsduringsingle.poleswitching
.~HighercfratffCMakerrecoveryvoltage~Ovorlaadtno ofharmonicfttfyrsofHVOCconverter ter-minals,anddtotantan intfioacvoltagewaveshapethatmayresultinlossotdcpowertransmission.
Theincreased tnductfvo voradrawnbysystemtransformers duringhalfwycl~soturat)an aresufficient tocauseintoler-abtosystemvoltagedepression, unusualswingsinMWandMVARflowontransmission linea.andproblemswithgener-atorvarlimitsinsomeinstances.
Inadditiontothehalt-cyclo saturation otpowertrans-formers,highlevelsofGICcanproduceadlstarted responseIEEEPowerEngiaeerintf Review,Octoberf989DanielSaulier,Hydro-Quebec OnMarch13.1989.anexceptionally intensemagneticstormcausedsevenStaticVarCarnpensators ISYC)onthe735-kYnetworktotriporshutdown.Thesecompensetors arees-sentialforvoltagecontrolandsystemstability.
Withtheirloss.voltagedroppedandfrequency increased.
Thistedtosystarttinstability andthetrippingofalltheLaGrandetrans-missionlinestherebydepriving theHQsystemof9500MWofgeneration.
Thoremaining powersystemcallapsed withinsecondsoftholossoftheLaGrandenetwork.Thesystemblackoutaffected~itbutafewsubstations isolatedantolo-calgene~sting stations.
Pawerwasgradually restoredoveraninehoursperiod.Oe-leyainrestoring powerworeencounterea becauseofdam-agedequipment onthoLaGranden>>twarkandproblemswithcaidloadpickup.SYSTEMCONDITION PRIORTOTHEEVENTSTatalsystemgoneratfon priortotheeventswas21500MW.mastofitcomingfromremotepower-generating stationsatLaGrande,Mantcouagon andChurchf8Felts.Exportstoneighboring Systemstotalled1848MWofwhich1352MWwereonOCinterconnections.
The735-kVtransmission net-warkwasladedat90%ofttsstability limft.SEQUENCEOFEVENTSAt2:45o,m.onMarch13,averyintensemagneticstormtedtotheconaequortttal trtporshutdownofsevenSVC's,Contafnlng thoimpactofthoeventthroughoporatarinter-yentionwasimpassible attSVC'ahavingtrippedatcaaaodtofunctionwithinoanominuteperiod.Afowsecondsl8-8s.)aftertholossaftholastSVC,~IIfive735.kVlinesoftheLoGrandetransmission netwarktrippedduotoanoutofstepcondition.
TheseItnetripsdeprivedthesystemot9500MWotgeneration andsubsequently tedtoacamptetosystemcattapao.17 1\
iO~:ecuonancere~airir9'curSVC'ssnotsownovcaoactor~oitageuncaiance prctec::o."
>>aivsisotvootageanocur.rentosc:itograms taxenat:neCtioougamau sitebeforetneSVCtnpssnowedtne'.oitowing narmoniccontents.
.wC,hCCurrentarl6kyHarnaiiic VcliageOrderat.35kyTCABraccheTSCBrasche100'"o1OO3'ioa~Iifo3~o'&#xc3;"9ofIOof5OofI~3~oI00~o36~o24~}6~o5%16ifoaffQuasiDCcurrentsgenerated by:hemagneticdisturbance, saturating intneSVCcouplingtransformers arethoughttobethecauseforsuchatargesecondharmoniccomponent ofcurrantintheTSCbranch.DIsturoances OnPoiyerTransformers HooertJHingjceJamesB.StewartPowerTechttoloip'es Inc.Thisdiscussion addresses theeffectsofgeomagnet:c cistii"oancesonpowertransformers.
Theprimarveffect:scuetccoresaturation resulting!rom geomagneticaltv incuceacr~rents.GICs.Coresaturation canimooseseveretemoerature problemsinwindings.
ieads,tankplateanastructurai mer.-barsoftransformers andplaceheavyvarandharmonicoi.r~densonthepowersystemandvoltagesupportequiprriant.
GIC'sof10to100amperesaremore:henmerenuisances inthaoperation ofpowertransformers, thernanr.erof!Iowcanresultinsaturation ofthecoreandconsequent changesinsystemvarrequirements.
increases inharmoniccurren.magnituctes.
increased transformer strayanaeadytosses.andproblemswithsystemvoltagecontrol.GENEAhLOBSEAVhTIONS ONTHESYSTEMBEHhVIOAThesystemblackoutwascausedbylossofallSVConI.aGrandeNetwork.SevenSVCtrippedorstoppedfunctioning.
PriortoandduringtheeventalltheOCinterconnections be-havedproperly.
Norelayfalsetripsormisoperation ofspecialprotection systemswereobserved.
Telecommunications warenotaffected.
Noequipment damagewasdirectlyattrib-utabletoGICbutoncethesystemsplit,someequipment waadamagedduetoloadrejection overvoltagea.
RF'VIEDIhL hCTIONSThKEViSincetheevent.thefollowing actionswereimplemented:
~SVCprotection circuitshavebeenreadjusted onfourSVC'ssoastorendertheiroperation reliableduringmagneticstormssimilarworkisbeingperformed onthefourremaining SVC's,~Energy,MinesandResourceCanadanowprovidesHy-dro.Quebec withupdatedforecasts ontheprobability ofmagneticdisturbances.
Thaaoforecasts areusedbytheSystemControlCenterdispatcher topositionthetransmission systemwithinsecurelimits.~A.C.voltageasymmetry iamonitored atfourkoylo-cationsonthesystem(Bouchorvitto, Amaud,LG2,Chhtgeaguay).
Upondetection ofo3%voltageaaym-rnetryatanyonalocation, theayotomcontrolcenterdispatcher iaalarmedandwillimmediately ta'koactiontopositionsystemtranaforlevelswithinsecurelimitsifthishaan'talreadybeendanebecauseofforecasted magneticactivity.
OPERhTING LIMNIDURINGMhGNETICDISTURShNCES (hNDhLERTSITUhTIONS)
Thefallowing operating limitsarenowbeingappliedt~10%safetymarginshallbeappliedonmaximumtrans-ferlimits.'Maximumtransferlimitsshellnottakeintoaccountthoavailability ofstaticcomponaators deemedunreliable.
~AdjusttheloadingonHVOCcircuitstobewithintho40%to90%,orloaa.ofthonormalfullloadrating.l8CICEFFECTSVERSUSCOREhNDWIIOoDINC COiVFIGURhTIONS Principal concernsinthisdiscussion areforEHVsystemswithgroundedYtransformer banksproviding conducting pathsforGICandzerosequencecurrents.
Coraandwindingconfigurations responddifferently tozerosequenceopen.cir-cuitcurrentsendtoGICa.Note:aausedhere.theterm"opencircuit"refers totestsperformed withalldeltaconnections openedor"broken."
Forexample,thethree.phasethreelegcoreformtransformers arolesspronetoGICinducedsatu-rationthanthree-phase shallformtransformers.
But.bothcoreformandshellformsinglephasetransformers aresus.ceptibl~toGICinducedsaturation.
Windingandleadarrangemanta responddifferently toGICinducedcoresaturation aawell.Forexample,thecurrentdis-tribution withinpareil~Iwindingpathsandwithinlowvoltageloadsdependsupontheleakagefluxpathsandmutualcou-pling.Loaaeawithinwindingaandleadsmaychangesignifi-cantlyunderGICinducedsaturation owingtothechangeinmagneticfieldintensity.
H,andtheresultant changesintheboundaryconditions fortheleakagefieldpath.EDDYLOSSESINSTEELMEMBERSThechangesinthemagneticintensity.
H,andthemagneticboundaryconditiona resulting fromtheGICexcttation biascanincreasetholoaaoainsteelplate,thelossesforfieldsparalleltotheplaneoftheplatoincreasenearlyaathesquareofH.Notealsothattheleveloflossesincreaseapproxi~matelyaathesquarerootofthefrequency otH.owingtotheeffectofdepthofpenetration.
Thomagneticfieldalongyokeclampsandlegplatesincoreformtransformers andinTeebeamsandtankplateInahoNformtransformers closelymatchesthomagneticgradientlnthocore.Areasofthetankandcoreclampsaresubjected tothowindingleakagefield.Ifthecorosaturates, themagneticfieldimpressed uponthesteelmembersmayrisetontoonehundredtimesnormalduotothesaturation andtheoffoctooftheleakagefield.Theloaaoointhestoolmomborowillriaohundredsoftimesnor-mal,evenunderhalf-cycle saturation.
Onthosteelsurfaces.
eddylosedensitymoyrisetontothirtywattsparsquareinch,approaching thethermalfluxdensityotan~lactricrangeele.ment.Surfacetemperatures riaorapidlywiththisthermalfluxandcanresultindegradation ofinsulation touchingtnesteelIEEEPowerEatpaeeriag Review.Octoberl989 r
DestgnOcftcfencyOcllrlentvendoraafma1UPShaSnobatterytestCII'CUItVendornaINIa1naintenancesectloAdocsAOIQCAtIOAbatteries.
DesignDeficiency Battefies havenotbeenreplacedin6ycafsDesignDeficiency ACinputtologicpoucrsaltyisnaihtchahcc preferred Backupbatteries degradedordeadk.Srelaycharactertst-ICSPfCveAtStransfertoinverteroutput.BreakerffcIctionperdesignGroundfaultoccursonBphaseofaaintransfofncr Voltagctraflicnt oAstatloflACpouersteeplyACpouertologicnoduleforUPStA.D,G cspcrIchccs thetransient outpu'IvoltagegoestoulogictripsOApoucrSISIPtyfailure.2VSSUPStA,S,C,O,GtripBreakersCS-I,23open;Ch-Cdoesnotcloseupsloadsdohotautotransfertomint.supplylossofallloadsonUPS1AD,riFault1$clcafcdin6cycles;transfercocptetcd in12cyclesPernisstves prohibItCSCbreakerfrozeclo>IngCS'4ncsvh<toIfunsfernaIntsullplytolnvcltcfoutput r
1.StaticDCtestingwasperformed onindividual chipsfromtheeffectedcircuitsinordertocharacterize Latch-upsusceptibility.
Statictestingisperformed withfixedvoltagesettings.
Thetestingwasperformed onthe4049,4011,4044and4068devices.Thetestschemeincluded:
A.OutputvoltagebelowVss(Vssisthegroundornegativepowersupply).B.OutputvoltageaboveVdd(Vddinthepositivevoltagepowersupply).C.InputvoltageaboveVdd.D.Powersupplyovervoltage.
Vss>>VddThetestingrevealedthatpermanent physicaldamagewasinducedbytestsCandD.TestBdidnotinducelatch-upbuttestAconsistently inducedlatch-uponthe4049andathighervoltagedifferentials ontheotherdevices-The4049wasquitesensitive tothistest.2.VoltageDropouttesting,wheretheVddwascutoutandrestoredduringtimeperiodsrangingfrom20mSto2secondsdidnotresultinlatch-upbehaviorontheindividual components.
A"breadboard" testcircuitwasfabricated tosimulateatypicalcircuitpath,i.e.a4044latchdrivinga4049invertordrivinga4068gatedrivinga4011gatedrivinganMC1615lampdriver.Slowratedropouttestingofthetestcircuitdidnotresultinlatch-uporotheranomalous behavior.
3.Boardleveltestinghasbeenperformed ontheA13A21cardsf'romUPSunitsA,BandG.Astockcardhasalsobeentested.Atestfixturewasfabricated toholdthecardsandsupplypaverandinputselection andoutputmonitoring.
AnMC1615lampdriverchipwithLED's(lightemittingdiodes)wasconnected tothecardoutputs.Staticboaeftestingrevealednoanomalies ontheAcard,adamagedU104049oNtheBcard,Noanomalies ontheCcardandafailuretoset,anyofthe4044latchesontheGcard.(Notethatlatchingofthe4044chipsisnormalwhilelatch-upisanabnormalcondition.)
The.functional failureoftheGboardhasbeentracedtotheKlrelayand/ortheSW1resetsvitchonthecircuitboard.Failuresimulation testingonthefunctional Aboardhasrevealedthatthelightingpatternreportedduringtheincident, wherothelampsonthecardwereextinguished and"downstream" lampsremainede  


illuminated,hasbeenduplicatedbysettingthePSF-notlatch,loweringtheDCvoltagetoapproximately4VDCandlifting(floating)theDCgroundforseveralseconds.IftheDCvoltageremainslowafterthegroundfaultthelampsontheboardwillresetandtheexternallamps(UPSfail,LogicfailandtheSSTRlines)willremainilluminated.Thesimulationconditionsareunlikelytobethoseofthefailureevent,however,ithasbeendemonstratedthattheboardcanoperateinanthisillogicalstate.Amorecomplicatedfailuresimulation(approximatingtheactualevent)mayproducethesameresults.4.HighSpeedtransient.testingonthepowerlinesisplannedanddelayedpendinglaboratoryanalysisofthedegradedsamplesdiscussedinthefollowingsection.MC0A.NEGATIVEVOLTAGEONTHEOUTPUTOFTHE4049MILLINVARIABLYCAUSELATCH-UP-INJECTINGNEGATIVEVOLTAGEINTOTHEOUTPUTISIDENTICALTORAISINGTHEGROUNDVssABOVETHEOUTPUT.B.THEINITIALFAILURECONDITIONINTERMSOFTHELAMPSETTINGSCANBEDUPLICATEDUNDERUNLIKELYCONDITIONSANDMAYBEPOSSIBLEUNDERMOREPLAUSIBLECIRCUITCONDITIONS.Thefollowingsampleshavebeensubmittedforlaboratoryanalysis:1.Onebatterypack.Batterypack1fromUPS1C.n'.Two(2)integratedcircuitsfromafailedA20card.A4049anda4011.3.AfailedU104049fromtheA13121,UPSBcard.4.TheU104049fromtheA13A21cardsfromUPS'sAandG5.TheUPS6KlrelayandSWlswitch.Thefollowingresultshavebeenobtained.1.Two(2)oftheThree(3)batteriesfromUPS1Cweredriedout.Waterwasaddedandchargingdidnotresultinrecoveryofthecell.Itisconcludedthatthecellfaileddueoldagewearout.Analysisiscontinuingontheothertwo(2)cells.2.The4011fromtheA20cardiselectricallygood.Internal IJ~~I  
illuminated, hasbeenduplicated bysettingthePSF-notlatch,loweringtheDCvoltagetoapproximately 4VDCandlifting(floating) theDCgroundforseveralseconds.IftheDCvoltageremainslowafterthegroundfaultthelampsontheboardwillresetandtheexternallamps(UPSfail,LogicfailandtheSSTRlines)willremainilluminated.
~~~lj~.inspectionoftheDierevealednoanomalies.The4049is'electricallybad.Acatastrophicfailure.InternalinspectionofthedierevealedseveredamagecenteredontheVssandVddpowerlinesandseveralinput/outputs.TheinitiatingoverstresswasintroducedontheVddorVsslinesasindicatedbyarc-overdamageacosstheoxidebetweenthetwopowerlines.3.ElectricaltestingoftheU104049fromA13A21,UPSBrevealedthatitwasnotfunctional.Internalinspectionofthedierevealedafusedaluminummetallizationlinetoonepartoftheinternalcircuitry.Probingrevealedno)unctiondamageoneithersideofthefusesite.ThisdamageischaracteristicofclassicSCRlatch-up.4.Electricaltestingofthetwo(2)additional4049'swasperformedduringcircuitboardtest.Thedeviceswerefunctional.Internaldieexaminationrevealednodamageoneitherdevice.5.ElectricaltestingoftheA13A21circuitboardfromUPSGrevealedthatSW1wasintermittentlyopencircuitedinthenormallyclosedposition.Thisconditionwouldprovidecontinuousresetsignalstothe4044latchesthroughtheK1relay.TheswitchwasisolatedandagoodswitchwasplacedacrosstheKlrelay.Thecircuitboardinputsstillwouldnolatchthelamps.TheKlrelaywasremovedandtestingrevealedthatitwaselectricallygood.ThefindingsrevealthateithertheKlrelayiseitherintermittentlybadorthereareotherproblemcomponentsonthecircuitboard.Analysisiscontinuing.R0U0A.THEDAMAGENOTEDONTHE4049FAILEDINTEGRATEDCIRCUITFROMUPSBWASINDUCEDONTHEVss(GROUND)SIDEANDSUGGESTSAGROUNDTRANSIENTMAYHAVEOCCURRED.THEDAMAGEONTHE4049FROMTHEA20.BOARDINDICATESTHATTHEDAMAGEWASINITIATEDBYATRANSIENTONEITHERTHEVddORVssLINE,BUTITMAYALSOHAVEBEENINITIATEDBYLATCH"UP.B.ATLEASTONEOFTHEBATTERIESFAILEDDUETOOLDAGEWEAROUT.C.THECAQNEOFTHEFAILUREOFTHEUPSGTOSETTHELATCHESZSUNKNOWNATTHISTIME.THESWSWITCHHASBEENFOUNDTOBEDEFECTIVEANDANALYST'SWILLDETERMINEIFTHECOMPONENTISRELIABILITYRISK.
Thesimulation conditions areunlikelytobethoseofthefailureevent,however,ithasbeendemonstrated thattheboardcanoperateinanthisillogical state.Amorecomplicated failuresimulation (approximating theactualevent)mayproducethesameresults.4.HighSpeedtransient.
testingonthepowerlinesisplannedanddelayedpendinglaboratory analysisofthedegradedsamplesdiscussed inthefollowing section.MC0A.NEGATIVEVOLTAGEONTHEOUTPUTOFTHE4049MILLINVARIABLY CAUSELATCH-UP-INJECTING NEGATIVEVOLTAGEINTOTHEOUTPUTISIDENTICAL TORAISINGTHEGROUNDVssABOVETHEOUTPUT.B.THEINITIALFAILURECONDITION INTERMSOFTHELAMPSETTINGSCANBEDUPLICATED UNDERUNLIKELYCONDITIONS ANDMAYBEPOSSIBLEUNDERMOREPLAUSIBLE CIRCUITCONDITIONS.
Thefollowing sampleshavebeensubmitted forlaboratory analysis:
1.Onebatterypack.Batterypack1fromUPS1C.n'.Two(2)integrated circuitsfromafailedA20card.A4049anda4011.3.AfailedU104049fromtheA13121,UPSBcard.4.TheU104049fromtheA13A21cardsfromUPS'sAandG5.TheUPS6KlrelayandSWlswitch.Thefollowing resultshavebeenobtained.
1.Two(2)oftheThree(3)batteries fromUPS1Cweredriedout.Waterwasaddedandchargingdidnotresultinrecoveryofthecell.Itisconcluded thatthecellfaileddueoldagewearout.Analysisiscontinuing ontheothertwo(2)cells.2.The4011fromtheA20cardiselectrically good.Internal IJ~~I  
~~~lj~.inspection oftheDierevealednoanomalies.
The4049is'electrically bad.Acatastrophic failure.Internalinspection ofthedierevealedseveredamagecenteredontheVssandVddpowerlinesandseveralinput/outputs.
Theinitiating overstress wasintroduced ontheVddorVsslinesasindicated byarc-overdamageacosstheoxidebetweenthetwopowerlines.3.Electrical testingoftheU104049fromA13A21,UPSBrevealedthatitwasnotfunctional.
Internalinspection ofthedierevealedafusedaluminummetallization linetoonepartoftheinternalcircuitry.
Probingrevealedno)unctiondamageoneithersideofthefusesite.Thisdamageischaracteristic ofclassicSCRlatch-up.
4.Electrical testingofthetwo(2)additional 4049'swasperformed duringcircuitboardtest.Thedeviceswerefunctional.
Internaldieexamination revealednodamageoneitherdevice.5.Electrical testingoftheA13A21circuitboardfromUPSGrevealedthatSW1wasintermittently opencircuited inthenormallyclosedposition.
Thiscondition wouldprovidecontinuous resetsignalstothe4044latchesthroughtheK1relay.TheswitchwasisolatedandagoodswitchwasplacedacrosstheKlrelay.Thecircuitboardinputsstillwouldnolatchthelamps.TheKlrelaywasremovedandtestingrevealedthatitwaselectrically good.ThefindingsrevealthateithertheKlrelayiseitherintermittently badorthereareotherproblemcomponents onthecircuitboard.Analysisiscontinuing.
R0U0A.THEDAMAGENOTEDONTHE4049FAILEDINTEGRATED CIRCUITFROMUPSBWASINDUCEDONTHEVss(GROUND)SIDEANDSUGGESTSAGROUNDTRANSIENT MAYHAVEOCCURRED.
THEDAMAGEONTHE4049FROMTHEA20.BOARDINDICATES THATTHEDAMAGEWASINITIATED BYATRANSIENT ONEITHERTHEVddORVssLINE,BUTITMAYALSOHAVEBEENINITIATED BYLATCH"UP.
B.ATLEASTONEOFTHEBATTERIES FAILEDDUETOOLDAGEWEAROUT.C.THECAQNEOFTHEFAILUREOFTHEUPSGTOSETTHELATCHESZSUNKNOWNATTHISTIME.THESWSWITCHHASBEENFOUNDTOBEDEFECTIVE ANDANALYST'S WILLDETERMINE IFTHECOMPONENT ISRELIABILITY RISK.
I  
I  
-UPSlA1B1GTESTSUMMARYpage1Purpose:ToprovethattheDClogicpowerfortheExideUPSispoweredfromtheB-phasemaintenancesupply.TheK-5pickupanddropoutvoltagesandtheDCtrip-pointo=theDClogicwillberecordedforUPSlA,notforUPS13andUPS1G.Theinternalbatterieswillbetestedandreplaced.ResultsSummary:1.)OnUPS1A,UPS1BandUPS1G,itwasverifiedthattheDClogicpowersuppliesarefedfromtheB-phasemaintenancesupply.2.)TheK-5relaydropoutandpickupvoltageswererecordedforUPS1AandtheywerefoundtobebelowthetrippointoftheDClogicpower.3.)OnUPS1A,UPS1B,UPS1G,themaintenancesupplywasopenedwiththeUPSfeedingtheloadsandnoUPStripsoccuzredo4.)OnUPSlA,UPS1BandUPS1G,thebatterieswerereplaced.CONCUThistestprovesthattheDClogicpowerisfedbytheByhaaemaintenancepower.ItprovesthattheinternalbatCOrieswereeffectivelydead.ForUPS1Aitprovesthatonaslowtransientthat.theDClogicpowerwilldropoutbeforetheK-5relaywilltransfertoUPSpower.  
-UPSlA1B1GTESTSUMMARYpage1Purpose:ToprovethattheDClogicpowerfortheExideUPSispoweredfromtheB-phasemaintenance supply.TheK-5pickupanddropoutvoltagesandtheDCtrip-point o=theDClogicwillberecordedforUPSlA,notforUPS13andUPS1G.Theinternalbatteries willbetestedandreplaced.
ResultsSummary:1.)OnUPS1A,UPS1BandUPS1G,itwasverifiedthattheDClogicpowersuppliesarefedfromtheB-phasemaintenance supply.2.)TheK-5relaydropoutandpickupvoltageswererecordedforUPS1AandtheywerefoundtobebelowthetrippointoftheDClogicpower.3.)OnUPS1A,UPS1B,UPS1G,themaintenance supplywasopenedwiththeUPSfeedingtheloadsandnoUPStripsoccuzredo 4.)OnUPSlA,UPS1BandUPS1G,thebatteries werereplaced.
CONCUThistestprovesthattheDClogicpowerisfedbytheByhaaemaintenance power.ItprovesthattheinternalbatCOries wereeffectively dead.ForUPS1Aitprovesthatonaslowtransient that.theDClogicpowerwilldropoutbeforetheK-5relaywilltransfertoUPSpower.  


NumericalResults:page21.)TheUPS1ADClogictripsat<16.7VDC.(with.75.6VAConinput).2.)UPS1A:K-5relaydropout-47VDCK-5relaypickup-52VDC4.)Theinternalbatteryvoltagewasmeasured:UPS1A:UPS1B:UPS16:Positive-Negative-Positive-Negative-Positive-Negative-0.546.218.30.69  
Numerical Results:page21.)TheUPS1ADClogictripsat<16.7VDC.(with.75.6 VAConinput).2.)UPS1A:K-5relaydropout-47VDCK-5relaypickup-52VDC4.)Theinternalbatteryvoltagewasmeasured:
)J 2VBB-UPS1CTESTSUMMARYpage1Purpose:ToprovethattheDClogicpowerfortheExideUPSispoweredfromtheB-phasemaintenancesupplyandthatifatransientoccursonthemaintenancesupplyitcaneffecttheDClogicsuchthatitwilltriptheunit.Thistestisdonewiththeoldinternallogicbatteriesandthenrepeatedwithnewones.EachoftheinvertertripswillbetestedtoverifythateachcircuitisstillintactexceptDCOV.,AnACinputtransienttoUPSwillbesimulatedtoverifythattheunitcan"rideout"anormalACinputtransientwithouttripping.TheK-5relaypickupanddropoutvoltagesandtheDCtrip-pointoftheDClogicwillberecorded.ResultsSummary:1.)ZtwasverifiedthattheDClogicpowersuppliesarefedfromtheB-phasemaintenancesupply.2.)ArapidopenandclosingoftheupstreamnormalACinputbreakertotheUPSwasdoneandtheunitdidnottriporgoonbattery.NonoticeableeffectwasseenontheUPSoutput.3.)EachinvertertripcircuitexceptDCOVwastestedandeachfunctionedasdesigned.4.)Fasttransienttests:Withtheoldbatteriesstillinstalledavoltageinterruptionof100-150msecdurationwasgiventotheACinputtotheDClogicofUPS1C.TheDClogicwasinitiallyat19.86VDC.Theunittripped3outof4times.Thiswasdonefirstwiththeloadson.xaintenancesupplyandthenalsowiththeloadsonUPSpower~Withthenewbatteriesinstalledtherewasnotripwhenthefasttransienttestwasperformed25successivetimes.TherewerenotripsbutarepeatedSCRshortalarmoccurredwhichisindicativeofnoisespikeswithintheunit.  
UPS1A:UPS1B:UPS16:Positive-Negative-Positive-Negative-Positive-Negative-0.546.218.30.69  
)J 2VBB-UPS1C TESTSUMMARYpage1Purpose:ToprovethattheDClogicpowerfortheExideUPSispoweredfromtheB-phasemaintenance supplyandthatifatransient occursonthemaintenance supplyitcaneffecttheDClogicsuchthatitwilltriptheunit.Thistestisdonewiththeoldinternallogicbatteries andthenrepeatedwithnewones.EachoftheinvertertripswillbetestedtoverifythateachcircuitisstillintactexceptDCOV.,AnACinputtransient toUPSwillbesimulated toverifythattheunitcan"rideout"anormalACinputtransient withouttripping.
TheK-5relaypickupanddropoutvoltagesandtheDCtrip-point oftheDClogicwillberecorded.
ResultsSummary:1.)ZtwasverifiedthattheDClogicpowersuppliesarefedfromtheB-phasemaintenance supply.2.)ArapidopenandclosingoftheupstreamnormalACinputbreakertotheUPSwasdoneandtheunitdidnottriporgoonbattery.Nonoticeable effectwasseenontheUPSoutput.3.)EachinvertertripcircuitexceptDCOVwastestedandeachfunctioned asdesigned.
4.)Fasttransient tests:Withtheoldbatteries stillinstalled avoltageinterruption of100-150msecdurationwasgiventotheACinputtotheDClogicofUPS1C.TheDClogicwasinitially at19.86VDC.Theunittripped3outof4times.Thiswasdonefirstwiththeloadson.xaintenance supplyandthenalsowiththeloadsonUPSpower~Withthenewbatteries installed therewasnotripwhenthefasttransient testwasperformed 25successive times.TherewerenotripsbutarepeatedSCRshortalarmoccurredwhichisindicative ofnoisespikeswithintheunit.  


page25.)TheK-5relaydropoutwasrecordedandwasfoundtobebelowthetrippointoftheDClogicpower.6.)Normaltransfersweredone,UPStomaintenanceandmaintenancetoUPS,withdeadbatteriesandtherewerenotripsoftheUPS.ThemaintenancesupplywasopenedwiththeUPSfeedingtheloadsandnoUPStripsoccurred.CONCLUSZONThistestprovesthattheDClogicpowerisfedbytheBphasemaintenancepowerandthatitissusceptibletovoltagetransientsonthemaintenancesupply.Ztmaybesusceptibletoothertransientsaswellbecauseitisdirectlytiedtomaintenancesupply.ThetestDOESNOTprovethelevelofsusceptibility,thatis,itdoesnotprovethatthetransientwasofanysetvoltageorduration.Thetestimpliesthatthebatteriesmayhavemitigatedthetripbutisnotconclusive.Eachtripcircuitwastestedsuccessfullysonofailuretoanyoftheseoccurredthatcausedthetrip.Thefastopen/closeofthenormalACinputbreakerprovesthattheunitwouldwithstandanACinputtransientwithoutfailureorwithoutgoingonbatterypower.
page25.)TheK-5relaydropoutwasrecordedandwasfoundtobebelowthetrippointoftheDClogicpower.6.)Normaltransfers weredone,UPStomaintenance andmaintenance toUPS,withdeadbatteries andtherewerenotripsoftheUPS.Themaintenance supplywasopenedwiththeUPSfeedingtheloadsandnoUPStripsoccurred.
CONCLUSZON ThistestprovesthattheDClogicpowerisfedbytheBphasemaintenance powerandthatitissusceptible tovoltagetransients onthemaintenance supply.Ztmaybesusceptible toothertransients aswellbecauseitisdirectlytiedtomaintenance supply.ThetestDOESNOTprovethelevelofsusceptibility, thatis,itdoesnotprovethatthetransient wasofanysetvoltageorduration.
Thetestimpliesthatthebatteries mayhavemitigated thetripbutisnotconclusive.
Eachtripcircuitwastestedsuccessfully sonofailuretoanyoftheseoccurredthatcausedthetrip.Thefastopen/close ofthenormalACinputbreakerprovesthattheunitwouldwithstand anACinputtransient withoutfailureorwithoutgoingonbatterypower.
I'5~
I'5~
NumericalResults:1.)FastTransientTests-a.)W'texistinbatteriespage31.)Withloadsonmaintenance:At19.86VDC(90.0VAC)-~tri(150msec.)At19.86VDC(120VAC)-~t'150msec.)2.)WithloadsonUPSpower:2Tries,1~ti(200msec.)b.)W'tnewbatter'es-1.)Approx.20.0VDC-25times,~notri.(100msec.)2.)TheDClogictripsat<16.9VDC.(with84.59VAConinput).3.)K-5relaydropout-45VACK-5relaypickup-**notrecorded4.)Thefollowingtripstestsweredone:a.)b.)c.)d.)e.)f.)g)h.).OV/UVACUVACOVDCUVFrequencyfailLogicFailurePowersupplyfailureClockfailure5.)Theinternalbatteryvoltagewasmeasured:Positive-+0.6Negative-+0.04 l~45 5.)Xndividualcellvoltages:page41.)2.)3.)4.)5.)6.)BatteVoltae1.192.482.240.170.791.78NewBatteVoltae6.106.076.106.096.106.12  
Numerical Results:1.)FastTransient Tests-a.)W'texistinbatteries page31.)Withloadsonmaintenance:
At19.86VDC(90.0VAC)-~tri(150msec.)At19.86VDC(120VAC)-~t'150msec.)2.)WithloadsonUPSpower:2Tries,1~ti(200msec.)b.)W'tnewbatter'es-1.)Approx.20.0VDC-25times,~notri.(100msec.)2.)TheDClogictripsat<16.9VDC.(with84.59VAConinput).3.)K-5relaydropout-45VACK-5relaypickup-**notrecorded4.)Thefollowing tripstestsweredone:a.)b.)c.)d.)e.)f.)g)h.).OV/UVACUVACOVDCUVFrequency failLogicFailurePowersupplyfailureClockfailure5.)Theinternalbatteryvoltagewasmeasured:
Positive-+0.6Negative-+0.04 l~45 5.)Xndividual cellvoltages:
page41.)2.)3.)4.)5.)6.)BatteVoltae1.192.482.240.170.791.78NewBatteVoltae6.106.076.106.096.106.12  


V-UPDSSpagePurpose:ToprovethattheDClogicpowerfortheExideUPSispoweredfromtheB-phasemaintenancesupplyandthatifatransientoccursonthemaintenancesupplyitcaneffecttheDClogicsuchthatitwilltriptheunit.Thistestisdonewiththeoldinternallogicbatteriesandthenrepeatedwithnewones.TheK-5pickupanddropoutvoltagesandtheDCtrip-pointoftheDClogicwillberecorded.ResultsSummary:1.)Itwasverifiedthatthe'ClogicpowersuppliesarefedfromtheB-phasemaintenancesupply.2.)Fasttransienttests;Withtheoldbatteriesstillinstalledavoltageinterruptionof100-150msecdurationwasgiventotheACinputtotheDClogicofUPS1D.TheDClogicwasat20.9VDC.Theunitwouldnottrip.TheACinputvoltagetotheDClogicwasthenreducedsuchthattheDClogicwasat20.0volts.WhenthetestwasperformedwiththeDClogicpowerat20.0VDCtheunittripped.ThiswasdonefirstwiththeloadsonmaintenancesupplyandthenalsowiththeloadsonUPSpower.WiththenewbatteriesinstalledtherewasnotripwhenthefasttransienttestwasperformedthoughtherewassignificanthitsshownontheDClogicpowerbusasseenbytheoscilloscope.3.)TheK-5relaydropoutandpickupvoltageswererecordedandtheywerefoundtobebelowthetrippoint.oftheDClogicpower.4.)Normaltransfersweredone,UPStomaintenanceandmaintenancetoUPS,withdeadbatteriesandtherewerenotripsoftheUPS.ThemaintenancesupplywasopenedwiththeUPSfeedingtheloadsandnoUPStripsoccurred.
V-UPDSSpagePurpose:ToprovethattheDClogicpowerfortheExideUPSispoweredfromtheB-phasemaintenance supplyandthatifatransient occursonthemaintenance supplyitcaneffecttheDClogicsuchthatitwilltriptheunit.Thistestisdonewiththeoldinternallogicbatteries andthenrepeatedwithnewones.TheK-5pickupanddropoutvoltagesandtheDCtrip-point oftheDClogicwillberecorded.
Ia pllt4iV1i,~CONCpage2ThistestprovesthattheDClogicpowerisfedbytheBphasemaintenancepowerandthatitissusceptibletovoltagetransientsonthemaintenancesupply.Itmaybesusceptibletoothertransientsaswellbecauseitisdirectlytiedtomaintenancesupply.ThetestDOESNOTprovethelevelofsusceptibility,thatis,itdoesnot,provethatthetransientwasofanysetvoltageorduration.Thetestimpliesthatthebatteriesmayhavemitigatedthetripbutthatisnotconclusive.
ResultsSummary:1.)Itwasverifiedthatthe'ClogicpowersuppliesarefedfromtheB-phasemaintenance supply.2.)Fasttransient tests;Withtheoldbatteries stillinstalled avoltageinterruption of100-150msecdurationwasgiventotheACinputtotheDClogicofUPS1D.TheDClogicwasat20.9VDC.Theunitwouldnottrip.TheACinputvoltagetotheDClogicwasthenreducedsuchthattheDClogicwasat20.0volts.Whenthetestwasperformed withtheDClogicpowerat20.0VDCtheunittripped.Thiswasdonefirstwiththeloadsonmaintenance supplyandthenalsowiththeloadsonUPSpower.Withthenewbatteries installed therewasnotripwhenthefasttransient testwasperformed thoughtherewassignificant hitsshownontheDClogicpowerbusasseenbytheoscilloscope.
ta0 NumericalResults:1.)FastTransientTestsa.)W'teistinbatteriespage3Withloadsonmaintenance:At20.9VDC-fivetries,notrips.At20.7VDC-onetry,one~tri.(150msec.)2.)WithloadsonUPSpower:At20.06VDC-one~t'(100msec.)b.)W'tnewbatteries1.)At20.05VDC-Fivetries,~sotris.-noticeableDChitoneachtransient.2.)TheDClogictripsat<17.3VDC.(with84.5VAConinput).3.)K-5relaydropout-42VDCK-5relaypickup-55VDC4.)Theinternalbatteryvoltagewasmeasured:Positive-Negative-+0.6+0.14(thenegativebatterysetwasactuallyslightlypositive).5.)individualcellvoltages:tVtaewBatteVotae2.)3.)4~)5.).254.5701.03.071~176'06'66~106'06'3 t0 It6.)1.396'9, 1
3.)TheK-5relaydropoutandpickupvoltageswererecordedandtheywerefoundtobebelowthetrippoint.oftheDClogicpower.4.)Normaltransfers weredone,UPStomaintenance andmaintenance toUPS,withdeadbatteries andtherewerenotripsoftheUPS.Themaintenance supplywasopenedwiththeUPSfeedingtheloadsandnoUPStripsoccurred.
resulteduntilsuchtimethepowertotheseUPS'swasrestored.However,oneormoreoftheotherlightingsystemsnamely,emergency,normaland8hourbatterypackwereavailableinthesea'reasduringthisevent.Thestairwellsareprovidedwithessentiallightingonlyexceptwhere8hourbatterypacklightingisaddedforAppendixRcompliance.IlluminationtothesestairwellswasnotavailableduetolossofnormalUPS.The8hourbatterypacklightingdidnotenergizebecausetherewasnolossofnormalpower.EventEvaluationTherootcauseoflossofpowerfromnormalUPSisevaluatedseparatelyinanotherreport.Duringtheevent,someareasoftheplantlostpartialilluminationsprovidedbyessentiallightingforsometime.AreascriticalforsafeshutdownwherethislightingareidentifiedareprovidedinAttachment7.Duringthiseventtheplantwassafelyshutdownfromthecontrolroom.Becausethecontrolroomisprovidedwithadequatelightingwithouttheessentiallighting,lossofessentiallightingdidnotadverselyaffecttheoperatoractionsneededtobringtheplanttosafeshutdown.TheaccessrouteusedbytheoperatorsduringthiseventforrestorationofthenormalUPSpower(Attachment8)supplieswasilluminatedfromnormallightingexceptforthestairwellwhereportablehandheldlightswereused.(FSARSec.9.5.3.3allowstheuseofportablelightingintheformofhandheldflashlightsforshortexcursionsintotheplant).ThenormalUPSlocationswereilluminatedbynormallighting.Therefore,restorationofUPSpowerwasunaffectedbylossofessentiallighting.EventhoughtheessentialandegresslightingarepoweredbythreenormalUPS's,during,thiseventduetomultiple'ailuresofallnormalUPS's,essentialandegresslightingsystemswerenotavailable.Theexistingessentialandegresslightingdesignisadequate,however,therootcauseofthemultiplefailuresofthenormalUPS'swillbedetermined/evaluatedandappropriatecorrectiveactiontakenifrequiredtoensurethatmultiplenormalUPS'sfailurewillnotreoccur.Theproposedplantmodification89-042willenhancethereliabilityofstairwelllightingwhere8hourbatterypacklightingisprovided.NSK214  
Ia pllt4iV1i,~CONCpage2ThistestprovesthattheDClogicpowerisfedbytheBphasemaintenance powerandthatitissusceptible tovoltagetransients onthemaintenance supply.Itmaybesusceptible toothertransients aswellbecauseitisdirectlytiedtomaintenance supply.ThetestDOESNOTprovethelevelofsusceptibility, thatis,itdoesnot,provethatthetransient wasofanysetvoltageorduration.
Thetestimpliesthatthebatteries mayhavemitigated thetripbutthatisnotconclusive.
ta0 Numerical Results:1.)FastTransient Testsa.)W'teistinbatteries page3Withloadsonmaintenance:
At20.9VDC-fivetries,notrips.At20.7VDC-onetry,one~tri.(150msec.)2.)WithloadsonUPSpower:At20.06VDC-one~t'(100msec.)b.)W'tnewbatteries 1.)At20.05VDC-Fivetries,~sotris.-noticeable DChitoneachtransient.
2.)TheDClogictripsat<17.3VDC.(with84.5VAConinput).3.)K-5relaydropout-42VDCK-5relaypickup-55VDC4.)Theinternalbatteryvoltagewasmeasured:
Positive-Negative-
+0.6+0.14(thenegativebatterysetwasactuallyslightlypositive).
5.)individual cellvoltages:
tVtaewBatteVotae2.)3.)4~)5.).254.5701.03.071~176'06'66~106'06'3 t0 It6.)1.396'9, 1
resulteduntilsuchtimethepowertotheseUPS'swasrestored.
However,oneormoreoftheotherlightingsystemsnamely,emergency, normaland8hourbatterypackwereavailable inthesea'reasduringthisevent.Thestairwells areprovidedwithessential lightingonlyexceptwhere8hourbatterypacklightingisaddedforAppendixRcompliance.
Illumination tothesestairwells wasnotavailable duetolossofnormalUPS.The8hourbatterypacklightingdidnotenergizebecausetherewasnolossofnormalpower.EventEvaluation TherootcauseoflossofpowerfromnormalUPSisevaluated separately inanotherreport.Duringtheevent,someareasoftheplantlostpartialilluminations providedbyessential lightingforsometime.
Areascriticalforsafeshutdownwherethislightingareidentified areprovidedinAttachment 7.Duringthiseventtheplantwassafelyshutdownfromthecontrolroom.Becausethecontrolroomisprovidedwithadequatelightingwithouttheessential
: lighting, lossofessential lightingdidnotadversely affecttheoperatoractionsneededtobringtheplanttosafeshutdown.
Theaccessrouteusedbytheoperators duringthiseventforrestoration ofthenormalUPSpower(Attachment 8)supplieswasilluminated fromnormallightingexceptforthestairwell whereportablehandheldlightswereused.(FSARSec.9.5.3.3allowstheuseofportablelightingintheformofhandheldflashlights forshortexcursions intotheplant).ThenormalUPSlocations wereilluminated bynormallighting.
Therefore, restoration ofUPSpowerwasunaffected bylossofessential lighting.
Eventhoughtheessential andegresslightingarepoweredbythreenormalUPS's,during,thiseventduetomultiple'ailuresofallnormalUPS's,essential andegresslightingsystemswerenotavailable.
Theexistingessential andegresslightingdesignisadequate, however,therootcauseofthemultiplefailuresofthenormalUPS'swillbedetermined/evaluated andappropriate corrective actiontakenifrequiredtoensurethatmultiplenormalUPS'sfailurewillnotreoccur.Theproposedplantmodification 89-042willenhancethereliability ofstairwell lightingwhere8hourbatterypacklightingisprovided.
NSK214  


StatusofNormalReactorBuildinLihtinDuringtheeventonAugust13,1991,itwasreportedbytheoperatorsinthereactorbuildingthatsomeareasofthereactorbuildinglostlightingmomentarily.EventEvaluationNormallightingforreactorbuildinggeneralareas,workarea'sandelectricalequipmentareasisprovidedwithlowwattagehighpressuresodiumvaporlights.Intheeventofpowerinterruptionsorvoltagediplastingformorethanonecycle,thesefixturesextinguishanddonotrestartuntilthelampcoolsandpressuredecreases.Whenapowersupplytocontinuouslyenergizedsodiumvaporlightisinterrupted,ithasacooldownperiodbeforearestrikeofthelightingcanoccur.Thecooldownperioddependsupontheratingofthelightbulbs.Duringtheevent,theemergencydistributionsystemexperienceda,transientduetothefaultonthePhaseBmaintransformer.Duringtheevent,theReactorsBuildingnormallightingincertainareaswherethesehighpressuresodiumvaporfixturesareprovided,wasinterruptedforapproximately30seconds.Thismomentarylossoflightingwasduetotheinherentdesignoflowwattagehighpressuresodiumvaporlightingwhichrequirescooldownperiodpriortorestrikewheneverpowerisinterrupted.Thesamescenariocouldoccurintheplantwhereverpowersupplytohighpressuresodiumvaporfixtureisinterruptedmomentarily,however,thereisnoindicationofsuchalossinotherareasoftheplant.Therefore,itisconsistentwithNMP2lightingdesignandUSARSection9.5.3.h)Grou9IsolationValvesClosureThegroup9primarycontainmentisolationvalvesarepartofcontainmentpurgesystem.ThesevalvesarelistedinTechnicalSpecificationTable3.6.3-1,Page3/46-24andUSARTable6.2.56,Pagellof24.Thefunctionofgroup9isolationvalvesistolimitthepotentialreleaseofradioactivematerialsfromprimarycontainment.Theseisolationvalvesareopenedduringpoweroperationonlyatinfrequentintervalstoallowinjectionofnitrogenintoprimarycontainmenttoinertorde-inerttheprimarycontainmentatadesiredpressure.Thesevalves,ifopen,receivesignaltocloseifanyofthefollowinghappen:NSK215  
StatusofNormalReactorBuildinLihtinDuringtheeventonAugust13,1991,itwasreportedbytheoperators inthereactorbuildingthatsomeareasofthereactorbuildinglostlightingmomentarily.
EventEvaluation Normallightingforreactorbuildinggeneralareas,workarea'sandelectrical equipment areasisprovidedwithlowwattagehighpressuresodiumvaporlights.Intheeventofpowerinterruptions orvoltagediplastingformorethanonecycle,thesefixturesextinguish anddonotrestartuntilthelampcoolsandpressuredecreases.
Whenapowersupplytocontinuously energized sodiumvaporlightisinterrupted, ithasacooldownperiodbeforearestrikeofthelightingcanoccur.Thecooldownperioddependsupontheratingofthelightbulbs.Duringtheevent,theemergency distribution systemexperienced a,transient duetothefaultonthePhaseBmaintransformer.
Duringtheevent,theReactorsBuildingnormallightingincertainareaswherethesehighpressuresodiumvaporfixturesareprovided, wasinterrupted forapproximately 30seconds.Thismomentary lossoflightingwasduetotheinherentdesignoflowwattagehighpressuresodiumvaporlightingwhichrequirescooldownperiodpriortorestrikewheneverpowerisinterrupted.
Thesamescenariocouldoccurintheplantwhereverpowersupplytohighpressuresodiumvaporfixtureisinterrupted momentarily, however,thereisnoindication ofsuchalossinotherareasoftheplant.Therefore, itisconsistent withNMP2lightingdesignandUSARSection9.5.3.h)Grou9Isolation ValvesClosureThegroup9primarycontainment isolation valvesarepartofcontainment purgesystem.ThesevalvesarelistedinTechnical Specification Table3.6.3-1,Page3/46-24andUSARTable6.2.56,Pagellof24.Thefunctionofgroup9isolation valvesistolimitthepotential releaseofradioactive materials fromprimarycontainment.
Theseisolation valvesareopenedduringpoweroperation onlyatinfrequent intervals toallowinjection ofnitrogenintoprimarycontainment toinertorde-inerttheprimarycontainment atadesiredpressure.
Thesevalves,ifopen,receivesignaltocloseifanyofthefollowing happen:NSK215  


a)Highradiationthroughstandbygastreatmentsystem(SGTS).TheSGTSradiationmonitorlocatedinthemainstackisdesignedtocontinuouslymonitoroffsitereleaseandprovideisolationsignalstotheseisolationvalves.b)Highdrywellpressure.c)Reactorlowwaterlevel.d)Manualisolationofmainsteamisolationvalves.EventEvaluationDuringthisevent,thegroup9primarycontainmentisolationvalvesclosed.Thisisolationisthesafemodeofoperationlimitingpotentialreleasesofradioactivematerialfromprimarycontainment.Theinitiatingconditionforthesevalvesoccurredasaresultoflossofpowertoradiationmonitor2GTS-RE105whenUPSpowertotheDRMScomputerwasinterrupted.TheactualisolationoccurredwhenthelogicwasreenergizeduponrestorationoftheUPSpowersupplytothemonitor'sauxiliaryrelaycircuit.Therefore,group9isolationvalvesclosedasdesignedandisconsistentwithUSARSection6.2.5.2.4,Page6.2-77.j)ReactorManualControlSstemThereactormanualcontrolsystem(RMCS)providestheoperatorwithmeanstomakechangesinnuclearreactivityviathemanipulationofcontrolrodssothatreactorpowerlevelandcorepowerdistributioncanbecontrolled.Thissystemisapowergenerationsystemandisnotclassifiedassafetyrelated.TheRMCSreceiveselectricalpowerfromthe120VACnormalUPS.TheRMCSdoesnotincludeanyofthecircuitryordevicesusedtoautomaticallyormanuallyscramthereactor.TheRMCScontrolandpositionindicationcircuitryisnotrequiredforanyplantsafetyfunctionnorisitrequiredtooperateduringanyassociatedDBAortransientoccurrence.Thereactormanualcontrolcircuitryisrequiredtooperateonlyinthenormalplantenvironmentduringnormalpowergenerationoperations.ThediscussionofRMCSisconsistentwithUSARSections7.7.1.1,Pages7.7-1,2,14.NSK216  
a)Highradiation throughstandbygastreatment system(SGTS).TheSGTSradiation monitorlocatedinthemainstackisdesignedtocontinuously monitoroffsitereleaseandprovideisolation signalstotheseisolation valves.b)Highdrywellpressure.
c)Reactorlowwaterlevel.d)Manualisolation ofmainsteamisolation valves.EventEvaluation Duringthisevent,thegroup9primarycontainment isolation valvesclosed.Thisisolation isthesafemodeofoperation limitingpotential releasesofradioactive materialfromprimarycontainment.
Theinitiating condition forthesevalvesoccurredasaresultoflossofpowertoradiation monitor2GTS-RE105 whenUPSpowertotheDRMScomputerwasinterrupted.
Theactualisolation occurredwhenthelogicwasreenergized uponrestoration oftheUPSpowersupplytothemonitor's auxiliary relaycircuit.Therefore, group9isolation valvesclosedasdesignedandisconsistent withUSARSection6.2.5.2.4, Page6.2-77.j)ReactorManualControlSstemThereactormanualcontrolsystem(RMCS)providestheoperatorwithmeanstomakechangesinnuclearreactivity viathemanipulation ofcontrolrodssothatreactorpowerlevelandcorepowerdistribution canbecontrolled.
Thissystemisapowergeneration systemandisnotclassified assafetyrelated.TheRMCSreceiveselectrical powerfromthe120VACnormalUPS.TheRMCSdoesnotincludeanyofthecircuitry ordevicesusedtoautomatically ormanuallyscramthereactor.TheRMCScontrolandpositionindication circuitry isnotrequiredforanyplantsafetyfunctionnorisitrequiredtooperateduringanyassociated DBAortransient occurrence.
Thereactormanualcontrolcircuitry isrequiredtooperateonlyinthenormalplantenvironment duringnormalpowergeneration operations.
Thediscussion ofRMCSisconsistent withUSARSections7.7.1.1,Pages7.7-1,2,14.NSK216  


EventAnalsisTheRMCSwaslostduringthiseventbecauseitspowersource,thenormalnonsafetyrelatedUPS,waslost.ThelossofRMCSisnotaconcernduringthisevent.Sincetheplantwasautomaticallyscrammedduringthisevent,theRMCSneednotperformanyfunctionafterthescram.ThisRMCSisusedbyoperatoronlyduringnormalplantoperations.Therefore,iftheplanthadnotautomaticallyscrammedduringtheevent,lossofRMCSwouldnothavecausedasafetyconcernbaseduponthefollowing:2)EOP'sprovideguidancetotheoperatorundersituationsinvolvingfailuretoscram,andvariousATWSmitigatingdesignaspectsoftheplantwerefullyoperablethroughouttheevent.Althoughthissystemwaslost'duringthisevent,itsimportancediminishedoncetheautomaticscramoccurred.ThereforeitisconcludedthattheRMCSfunctionwasconsistentwithUSARSection7.7.1.1.k)FeedwaterControlSstemThefeedwatercontrolsystemcontrolstheflowoffeedwaterintothereactorvesseltomaintainthevesselwaterlevelwithinpredeterminedlimitsduringallnormalplantoperatingmodes.Duringnormalplantoperation,thefeedwatercontrolsystemautomaticallyregulatesfeedwaterflowintothereactorvessel.Thesystemcanbemanuallyoperated.Thefeedwaterflowcontrolinstrumentationmeasuresthewaterlevelinthereactorvessel,thefeedwaterflowrateintothereactorvesselandthesteamflowratefromthereactorvessel.Duringautomaticoperation,thesethreemeasurementsareusedforcontrollingfeedwaterflow.ThefeedwatercontrolsystemreceivesitsnormalpowersupplyfromthenormalUPS.Thefeedwatercontrolsystemisdesignedtolockinitslastpositionuponalossofpowertoitscontrolelectronics.ThefeedwatercontrolsystemisdiscussedinUSARSection7.7.-1.3,Page7.7-23.EventAnalsisDuringthisevent,uponlossofthenormalUPS's,thefeedwatercontrolsystemperformedasdesignedandfailedinitslastposition.Therefore,itisconcludedthatthefeedwatercontrolsystemfunctionwasconsistentwithUSARSection7.7.1.3.NSK217 h'1 l)FeedwaterPumTriFeedwaterisprovidedtotheReactorPressureVessel(RPV)viatheCondensatePumps',CondensateBoosterPumpsandtheReactorFeedPumpsshowninAttachment9.TheCondensatePumpdrawscondensatewaterfromtheCondenserandprovidesthenecessaryNetPositiveSuctionHead(NPSH)fortheBoosterPumps.TheCondensateBoosterPumpsprovidethenecessaryNPSHfortheReactorFeedPumps.Aminimumflowcontrolheaderisprovidedoffthedischargeheaderofeachpumptoensurethattheminimumflowismaintainedthroughtheassociatedpump.Theminimumflowcontrolvalvesandassociatedinstrumentationactuatestomaintainthisminimumflow.Themainfeedwatercontrolvalves(LV10),locatedonthedischargeheaderoftheReactorFeedPumps,modulatetocontrolreactorwaterlevel.ThefeedwatercontrolsystemispoweredbynormalUPSpowersupplies.TheabovediscussionisconsistentwithUSARSection10.4.7.EventEvaluationItwasreportedduringthiseventthatfeedwaterpumpstripped.AnevaluationofthisconditionrevealsthatreportedhappeningsareconsistentwiththesystemasdesignedandisinconsistencewithUSARSection10.4.7.Theinstrumentationcontrollingtheminimumflowrecirculationvalvesonthecondensate,condensateboosterandthefeedwaterpumpsispoweredfromthenormalUPS's.Theseinstrumentsarealsodesignedtoopenthevalveuponlossofpowerinordertoprotectthepumps.UponlossofnormalUPS,thefeedwatercontrolvalvesfaillockedintheirlastposition.Followingtheturbinetrip,anATWSsignalwouldattempttodrivethefeedwatercontrolvalvesclosed,howeversinceanATWSsignalwasnotpresent,thisdidnotoccur.Withthefeedwatercontrolvalvesfailedlockedandtheminimumflowcontrolvalves(FV2)drivenfullopen,feedwaterflowincreasesandapproachespumprun-out.TheReactorFeedPumpNPSHdecreasestothelow-lowpressuretrippoint,trippingtheFeedwaterPumps.TheFeedwaterpumpcontrolcircuitdoesnotutilizeanautotransferlogictostandbyFeedwaterPump;therefore,feedwaterflowislost.TheinstrumentationcircuitsforallotherminimumflowcontrolvalvesarealsopoweredbynormalUPSpowersupplies.ThesevalvesallfailintheopenpositionwiththelossofUPSandcontributetothelossofFeedwaterpumpandcondensateboosterpump.ThisisconsistentwithUSARSection10.4.7.NSK218  
EventAnalsisTheRMCSwaslostduringthiseventbecauseitspowersource,thenormalnonsafety relatedUPS,waslost.ThelossofRMCSisnotaconcernduringthisevent.Sincetheplantwasautomatically scrammedduringthisevent,theRMCSneednotperformanyfunctionafterthescram.ThisRMCSisusedbyoperatoronlyduringnormalplantoperations.
'II m)AnnunciatorsandComutersTheplantannunciatorsystemprovidesinformationtotheplantoperatorsbywindowslocatedonthemainoperatorpanelboardsandonbackpanelswithinthePowerGenerationControlComplex(PGCC).Thissystemdoesnotincludeannunciatorsonlocalpanelsthroughouttheplantandonspecialpanels,e.g.,fireprotection,withinthePGCC.Theplantannunciatorsystemisnon-safetyrelatedandisconnectedtothenormalpowerdistributionsystemthroughnormalUPS's.TheplantannunciatorsystemisnotdiscussedintheUSAR.Severalcomputerdisplays,withinter-activekeyboards,arelocatedinthePGCC.Thesedisplaysarefromthefollowingcomputersystems.PMS-PlantProcessComputerLWS-LiquidRadwasteComputer,whichhasthefollowingsubsystems:LWS-LiquidRadwasteControlGENTEMP-GeneratorTemperatureMonitoringERF-EmergencyParameterDisplaySystemSPDS-SafetyParameterDisplaySystemDRMS-DigitalRadiationMonitoringSystem3DMonicore-AsystemusedprimarilyforcorecalculationsandmonitoringInaddition,noblegasinformationisprovidedtotheplantoperatorsfromtheGEMS(GaseousEffluentMonitoringSystem)computerbychartrecordersonabackpanel;andtheoperatorshaveaccesstotheGETARS(GeneralElectricTransientAnalysis&RecordingSystem)computer.Alloftheabovecomputersystemsarenon-safetyrelatedandareconnectedtothenormalpowerdistributionsystemsthroughnormalUPS's.TherearesomesafetyrelatedradiationmonitoringskidsthatprovideinputtotheDRMScomputer.However,theseskidsalsoprovidesafetyrelatedindicationinthePGCCthatisindependentoftheDRMScomputer.NSK219  
Therefore, iftheplanthadnotautomatically scrammedduringtheevent,lossofRMCSwouldnothavecausedasafetyconcernbaseduponthefollowing:
2)EOP'sprovideguidancetotheoperatorundersituations involving failuretoscram,andvariousATWSmitigating designaspectsoftheplantwerefullyoperablethroughout theevent.Althoughthissystemwaslost'during thisevent,itsimportance diminished oncetheautomatic scramoccurred.
Therefore itisconcluded thattheRMCSfunctionwasconsistent withUSARSection7.7.1.1.k)Feedwater ControlSstemThefeedwater controlsystemcontrolstheflowoffeedwater intothereactorvesseltomaintainthevesselwaterlevelwithinpredetermined limitsduringallnormalplantoperating modes.Duringnormalplantoperation, thefeedwater controlsystemautomatically regulates feedwater flowintothereactorvessel.Thesystemcanbemanuallyoperated.
Thefeedwater flowcontrolinstrumentation measuresthewaterlevelinthereactorvessel,thefeedwater flowrateintothereactorvesselandthesteamflowratefromthereactorvessel.Duringautomatic operation, thesethreemeasurements areusedforcontrolling feedwater flow.Thefeedwater controlsystemreceivesitsnormalpowersupplyfromthenormalUPS.Thefeedwater controlsystemisdesignedtolockinitslastpositionuponalossofpowertoitscontrolelectronics.
Thefeedwater controlsystemisdiscussed inUSARSection7.7.-1.3, Page7.7-23.EventAnalsisDuringthisevent,uponlossofthenormalUPS's,thefeedwater controlsystemperformed asdesignedandfailedinitslastposition.
Therefore, itisconcluded thatthefeedwater controlsystemfunctionwasconsistent withUSARSection7.7.1.3.NSK217 h'1 l)Feedwater PumTriFeedwater isprovidedtotheReactorPressureVessel(RPV)viatheCondensate Pumps',Condensate BoosterPumpsandtheReactorFeedPumpsshowninAttachment 9.TheCondensate Pumpdrawscondensate waterfromtheCondenser andprovidesthenecessary NetPositiveSuctionHead(NPSH)fortheBoosterPumps.TheCondensate BoosterPumpsprovidethenecessary NPSHfortheReactorFeedPumps.Aminimumflowcontrolheaderisprovidedoffthedischarge headerofeachpumptoensurethattheminimumflowismaintained throughtheassociated pump.Theminimumflowcontrolvalvesandassociated instrumentation actuatestomaintainthisminimumflow.Themainfeedwater controlvalves(LV10),locatedonthedischarge headeroftheReactorFeedPumps,modulatetocontrolreactorwaterlevel.Thefeedwater controlsystemispoweredbynormalUPSpowersupplies.
Theabovediscussion isconsistent withUSARSection10.4.7.EventEvaluation Itwasreportedduringthiseventthatfeedwater pumpstripped.Anevaluation ofthiscondition revealsthatreportedhappenings areconsistent withthesystemasdesignedandisinconsistence withUSARSection10.4.7.Theinstrumentation controlling theminimumflowrecirculation valvesonthecondensate, condensate boosterandthefeedwater pumpsispoweredfromthenormalUPS's.Theseinstruments arealsodesignedtoopenthevalveuponlossofpowerinordertoprotectthepumps.UponlossofnormalUPS,thefeedwater controlvalvesfaillockedintheirlastposition.
Following theturbinetrip,anATWSsignalwouldattempttodrivethefeedwater controlvalvesclosed,howeversinceanATWSsignalwasnotpresent,thisdidnotoccur.Withthefeedwater controlvalvesfailedlockedandtheminimumflowcontrolvalves(FV2)drivenfullopen,feedwater flowincreases andapproaches pumprun-out.TheReactorFeedPumpNPSHdecreases tothelow-lowpressuretrippoint,trippingtheFeedwater Pumps.TheFeedwater pumpcontrolcircuitdoesnotutilizeanautotransferlogictostandbyFeedwater Pump;therefore, feedwater flowislost.Theinstrumentation circuitsforallotherminimumflowcontrolvalvesarealsopoweredbynormalUPSpowersupplies.
ThesevalvesallfailintheopenpositionwiththelossofUPSandcontribute tothelossofFeedwater pumpandcondensate boosterpump.Thisisconsistent withUSARSection10.4.7.NSK218  
'II m)Annunciators andComutersTheplantannunciator systemprovidesinformation totheplantoperators bywindowslocatedonthemainoperatorpanelboards andonbackpanelswithinthePowerGeneration ControlComplex(PGCC).Thissystemdoesnotincludeannunciators onlocalpanelsthroughout theplantandonspecialpanels,e.g.,fireprotection, withinthePGCC.Theplantannunciator systemisnon-safetyrelatedandisconnected tothenormalpowerdistribution systemthroughnormalUPS's.Theplantannunciator systemisnotdiscussed intheUSAR.Severalcomputerdisplays, withinter-active keyboards, arelocatedinthePGCC.Thesedisplaysarefromthefollowing computersystems.PMS-PlantProcessComputerLWS-LiquidRadwasteComputer, whichhasthefollowing subsystems:
LWS-LiquidRadwasteControlGENTEMP-Generator Temperature Monitoring ERF-Emergency Parameter DisplaySystemSPDS-SafetyParameter DisplaySystemDRMS-DigitalRadiation Monitoring System3DMonicore-Asystemusedprimarily forcorecalculations andmonitoring Inaddition, noblegasinformation isprovidedtotheplantoperators fromtheGEMS(GaseousEffluentMonitoring System)computerbychartrecorders onabackpanel;andtheoperators haveaccesstotheGETARS(GeneralElectricTransient Analysis&Recording System)computer.
Alloftheabovecomputersystemsarenon-safety relatedandareconnected tothenormalpowerdistribution systemsthroughnormalUPS's.Therearesomesafetyrelatedradiation monitoring skidsthatprovideinputtotheDRMScomputer.
However,theseskidsalsoprovidesafetyrelatedindication inthePGCCthatisindependent oftheDRMScomputer.
NSK219  


ThePlantProcessComputerisdiscussedinSection7.7.1.6oftheUSAR,whereitismentionedthatthecomputerisnon-safetyrelated.USARSection11.2.1.2coverstheLiquidRadwasteSystemdesignbasisandstatesthatthepowersupplyforallRadwasteSystemcomponentsisprovidedfromnon-Class1Epowersources.ThisiscompatiblewiththeSafety-ParameterDisplayrequirementssinceNUREG-0737,Supplement1statesthattheSPDSneednotbequalifiedtoClass1Erequirements.Theprocessandeffluentradiologicalmonitoringandsamplingsystems,whichincludetheDRMSandGEMScomputers,arediscussedinUSARSection11.5.Thissectiondefineswhichmonitorsaresafetyrelatedandwhicharenon-safetyrelated.TheDRMSandGEMSdesigncomplieswiththisUSARsection.Arearadiationandairborneradioactivitymonitoringinstrumentation,whichincludetheDRMSandGEMScomputers,arediscussedinUSARSection12.3.4.1.Thissectiondefineswhichmonitorsaresafetyrelatedandwhicharenon-safetyrelated.TheDRMSandGEMSdesigncomplieswiththisUSARsection.Adescriptionofthe3DMonicorecomputersystemwasaddedtoUSARSection7.7.1.6byLDCNU-1235.ThisLDCNstatesthatthe3DMonicoresystemisnon-safetyrelated.Thedesignationofthecomputersystemsmentionedaboveasnon-safetyrelatedisconsistentwiththeexplanationoftheUninterruptiblePowerSupplySysteminUSARSection8.3.1.1.2.Inthissectionitisstatedthat2VBB-UPS1Afeedstheradwastecomputerhardware,2VBB-UPS1Bfeedslocalnon-safetyrelatedradiationmonitoringmicroprocessors,and2VBB-UPS1Gfeedsplantcomputerloads.EventEvaluationWiththelossofthenormalUPS's,theplantannunciationsystemandthecomputersystemslistedabovebecameinoperativeduetothelossofpower.ThisisconsistentwiththeplantdesignandthedescriptionoftheplantintheUSAR.Thesesystemsarenon-safetyrelatedand,hence,arenotrequiredtoshutdowntheplantfollowingadesignbasisevent.NSK220  
ThePlantProcessComputerisdiscussed inSection7.7.1.6oftheUSAR,whereitismentioned thatthecomputerisnon-safety related.USARSection11.2.1.2coverstheLiquidRadwasteSystemdesignbasisandstatesthatthepowersupplyforallRadwasteSystemcomponents isprovidedfromnon-Class 1Epowersources.Thisiscompatible withtheSafety-Parameter Displayrequirements sinceNUREG-0737, Supplement 1statesthattheSPDSneednotbequalified toClass1Erequirements.
Theprocessandeffluentradiological monitoring andsamplingsystems,whichincludetheDRMSandGEMScomputers, arediscussed inUSARSection11.5.Thissectiondefineswhichmonitorsaresafetyrelatedandwhicharenon-safety related.TheDRMSandGEMSdesigncomplieswiththisUSARsection.Arearadiation andairborneradioactivity monitoring instrumentation, whichincludetheDRMSandGEMScomputers, arediscussed inUSARSection12.3.4.1.
Thissectiondefineswhichmonitorsaresafetyrelatedandwhicharenon-safety related.TheDRMSandGEMSdesigncomplieswiththisUSARsection.Adescription ofthe3DMonicorecomputersystemwasaddedtoUSARSection7.7.1.6byLDCNU-1235.ThisLDCNstatesthatthe3DMonicoresystemisnon-safety related.Thedesignation ofthecomputersystemsmentioned aboveasnon-safety relatedisconsistent withtheexplanation oftheUninterruptible PowerSupplySysteminUSARSection8.3.1.1.2.
Inthissectionitisstatedthat2VBB-UPS1A feedstheradwastecomputerhardware, 2VBB-UPS1B feedslocalnon-safety relatedradiation monitoring microprocessors, and2VBB-UPS1G feedsplantcomputerloads.EventEvaluation WiththelossofthenormalUPS's,theplantannunciation systemandthecomputersystemslistedabovebecameinoperative duetothelossofpower.Thisisconsistent withtheplantdesignandthedescription oftheplantintheUSAR.Thesesystemsarenon-safety relatedand,hence,arenotrequiredtoshutdowntheplantfollowing adesignbasisevent.NSK220  


CONCLUSIONBasedontheaboveevaluation,itcanbeconcludedthattheplantresponsesduringtheeventon8/13/91isconsistentwithUSARdescriptions..RECOMMENDATIONSBasedontheaboveevaluation,thefollowinglongtermrecommendationsareprovided.1)PlantOscillograph-Thein-plantoscillographshouldbereplacedwithamorereliableandfunctionalunit.Ifthisoscillographwasfunctionalduringtheeventon8/13/91,adequatedatacouldhavebeenavailabletoaccuratelyevaluatethecauseofthedisturbance.2)EssentialLighting-Theproposedmodification89-042shouldbeimplementedassoonaspossibletoenhancetherel'iabilityofstairwelllightingwhere8hourbatterypacklightingisprovided.3)ControlPowerSupplies-DuringtheElectricalDistributionSystemevaluation,itwasrevealedthatmostofthesystemsimportanttoplantoperationssuchasfeedwatersystem,annunciationsystem,etc,receivetheircontrolpowerfromeithernormalUPS1A,1Borboth.ItisrecommendedthatcontrolpowersuppliesforthesesystemsbeevaluatedandreconfiguredtoavoidplanttransientduetolossofsinglenormalUPS.4)MainGenerator-Itisrecommendedthatathoroughvisualinspectionbeperformedofthegeneratorstatorandwindingsupportsystemduringthenextrefuelingoutage(seeAttachment10).NSK2  
CONCLUSION Basedontheaboveevaluation, itcanbeconcluded thattheplantresponses duringtheeventon8/13/91isconsistent withUSARdescriptions..
RECOMMENDATIONS Basedontheaboveevaluation, thefollowing longtermrecommendations areprovided.
1)PlantOscillograph
-Thein-plantoscillograph shouldbereplacedwithamorereliableandfunctional unit.Ifthisoscillograph wasfunctional duringtheeventon8/13/91,adequatedatacouldhavebeenavailable toaccurately evaluatethecauseofthedisturbance.
2)Essential Lighting-Theproposedmodification 89-042shouldbeimplemented assoonaspossibletoenhancetherel'iability ofstairwell lightingwhere8hourbatterypacklightingisprovided.
3)ControlPowerSupplies-DuringtheElectrical Distribution Systemevaluation, itwasrevealedthatmostofthesystemsimportant toplantoperations suchasfeedwater system,annunciation system,etc,receivetheircontrolpowerfromeithernormalUPS1A,1Borboth.Itisrecommended thatcontrolpowersuppliesforthesesystemsbeevaluated andreconfigured toavoidplanttransient duetolossofsinglenormalUPS.4)MainGenerator
-Itisrecommended thatathoroughvisualinspection beperformed ofthegenerator statorandwindingsupportsystemduringthenextrefueling outage(seeAttachment 10).NSK2  


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3889.5A2SPUY823889-5A2SPMXBI2HTX-HIAHAINXFHR292KV-24~KV498/457MVAOA/FOA&89-SACOREGAP2SPHXBI63-163-1pe65HGA25989-5A39-139-1HAA3898-SA3898-SA2MTX-HIB63-63-pe65HGA258M-SA39-39-3BM-SA2MTX-HIC63-63-pe65HGA25889-5A8-2SPUZBI1289-SA2SPMZBIpe662HTX-MIDSPARE5951IAC22-2YXCNBI63-463-4pe65HGA8787PB65BDD39-439-cP864BDOHAA86-1P866HEAI[6Ipe66~HEAIP866HFAI86-1IP864~HEAIP864~HEAPSa<~MFAI86-1IPBSS~HEAIPBSS~HEAP865HFA-15889-SA2SPGZB245989-5ACOREGAP2SPUY922GHS-GlGEN.13<e.iMvnBPFFIELD25K'BBRpM75PSIGH23PH6BNZIpe67pscz2-2YxcNBIIr-86-1P867~HEAI6-P867~HEAIP867~MFA45988-5A2SPUY822STX-XNSIAwhcHeemgPACjpg~gATTACHHENTQ
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LISTOFPROTECTIVERELAYACTUATEDONAUGUST131991UnitProtectionAlt1ProtectiveRelaLockoutRelaActionRef.Dwg,87-2SPMX01MainTransformerDifferentialProtectionRelay86-1-2SPUX0186-2-2SPUX02~InitiateTurbineTripESK-8SPU01~InitiateFastTransferESK-8SPU02toReserveStationESK-5NPS13TransformerESK-5NPS14UnitProtectionAlt2ProtectiveRela87-2SPUY02UnitDifferentialProtectionRelayLockoutRela86-1-2SPUY0186-2-2SPUY01Action~InitiateTurbineTrip~InitiateFastTransfertoReserveStationTransformerESK-8SPU01ESK-8SPU03ESK-5NPS13ESK-5NPS1463-2SPMY01FaultPressureTransformerUnitProtectionBackuProtectiveRela86-1-2SPUY0186-2-2SPUY01LockoutRela~InitiateTurbineTripESK-8SPU03~InitiateFastTransferSh.2toReserveStationESK-8SPU03TransformerSh.1ESK-5NPS13ESK-5NPS14Action50/51N2SPMZ01ProtectionRelay86-1-2SPUZ0186-2-2SPUZ01~InitiateTurbineTripESK-8SPU04~InitiateSlowTransferESK-5NPS13After30Sec.ESK-5NPS14BlockFastTransferAfter6CyclesGeneratorProtectionProtectiveRelaGen.PhaseOCDuringStartup50-2SPGZ02LockoutRela86-1-2SPGZ0186-3-2SPGZ01Action~InitiateTurbineTrip~InitiateSlowTransferAfter30Sec.BlockFastTransfer~ThisRelayPicksUpOnlyWhenUnitisOffLineRef,D~ESK-8SPG01ESK-8SPG04ESK-5NPS13ESK-5NPS14HSKl II AXTACEKNT3PAGE3of3Switchear2ENS*SWG103DegradedVoltageLockoutRela27BA-2ENSB2427BB-2ENSB2427BC-2ENSB24ActionNoActionTookPlaceDegradedVoltageStaysDuringFaultConditionsRef.DwESK-5ENS18ESK-8ENS022ENS*SWG10127BA-2ENSA2427BB-2ENSA2427BC-2ENSA24NoActionTookPlaceDegradedVoltageStaysDuringFaultConditionsESK-5ENS14ESK-8ENS012ENS*SWG10227BA-2ENSC0827BB-2ENSC0827BC-2ENSC08NoActionTookPlaceDegradedVoltageStaysDuringFaultConditions807E183TYSh7NSK1 J'
LISTOFPROTECTIVE RELAYACTUATEDONAUGUST131991UnitProtection Alt1Protective RelaLockoutRelaActionRef.Dwg,87-2SPMX01 MainTransformer Differential Protection Relay86-1-2SPUX01 86-2-2SPUX02
~InitiateTurbineTripESK-8SPU01
~InitiateFastTransferESK-8SPU02 toReserveStationESK-5NPS13 Transformer ESK-5NPS14 UnitProtection Alt2Protective Rela87-2SPUY02 UnitDifferential Protection RelayLockoutRela86-1-2SPUY01 86-2-2SPUY01 Action~InitiateTurbineTrip~InitiateFastTransfertoReserveStationTransformer ESK-8SPU01 ESK-8SPU03 ESK-5NPS13 ESK-5NPS14 63-2SPMY01 FaultPressureTransformer UnitProtection BackuProtective Rela86-1-2SPUY01 86-2-2SPUY01 LockoutRela~InitiateTurbineTripESK-8SPU03
~InitiateFastTransferSh.2toReserveStationESK-8SPU03 Transformer Sh.1ESK-5NPS13 ESK-5NPS14 Action50/51N2SPMZ01Protection Relay86-1-2SPUZ01 86-2-2SPUZ01
~InitiateTurbineTripESK-8SPU04
~InitiateSlowTransferESK-5NPS13 After30Sec.ESK-5NPS14 BlockFastTransferAfter6CyclesGenerator Protection Protective RelaGen.PhaseOCDuringStartup50-2SPGZ02 LockoutRela86-1-2SPGZ01 86-3-2SPGZ01 Action~InitiateTurbineTrip~InitiateSlowTransferAfter30Sec.BlockFastTransfer~ThisRelayPicksUpOnlyWhenUnitisOffLineRef,D~ESK-8SPG01 ESK-8SPG04 ESK-5NPS13 ESK-5NPS14 HSKl II AXTACEKNT 3PAGE3of3Switchear2ENS*SWG103 DegradedVoltageLockoutRela27BA-2ENSB24 27BB-2ENSB24 27BC-2ENSB24 ActionNoActionTookPlaceDegradedVoltageStaysDuringFaultConditions Ref.DwESK-5ENS18 ESK-8ENS02 2ENS*SWG101 27BA-2ENSA24 27BB-2ENSA24 27BC-2ENSA24 NoActionTookPlaceDegradedVoltageStaysDuringFaultConditions ESK-5ENS14 ESK-8ENS01 2ENS*SWG102 27BA-2ENSC08 27BB-2ENSC08 27BC-2ENSC08 NoActionTookPlaceDegradedVoltageStaysDuringFaultConditions 807E183TY Sh7NSK1 J'
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Line 78: Line 436:


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lNTHINAl.CONIRSfONDSHCINON11154%~I$41MOPROgh.R.-.LAk~ToDistrQT~kCHei~PREi~FWgv>~~~NineMilePointNuclearstationOATL15August91FfLXCOalNineMilePointFireprotectionProgramPostEventXnterviewsAfterinterviewsconductedtodaywithFireChiefBernieHarvey,andFiremenFatBrennanandNarkLocurcio,andconcurrencewithTerryVermilyea,SystemExpertPireDetectionandJohnPavlickoofCautionEquipmentEnc.,Xhavereachedthefollowingconclusions.1~Ofthe20firepanelsatUnit2,18maintainedanormalpowersupplyo2a.TwoCirepanelsLFCP113and123transferredtointernalbatterybackup.'b.Thesetwopanelswb'ileonbatterywillstillfunctionnormallyaslongasthe120VACisavailableintheLPCF,whichitwas.Therewasnointerruptionordecreaseoffireproteotionidetection/suppressionatthelocalfirepanels.FirePanels849and200/1beingfedfromQNdidhaveapowerinterruption.ThiswouldhaveleftthecontrolswitchesoperableatPanel849,(astheyarefedfromLPCP),butcontrolRoomwithnoCireannunciation.Anyfiresuppression/indicationcouldalsohavebeeninitiatedlocally.ABA:dlcT,TomlinsonA.Julka(FAX7225-SN)D.Pringle  
lNTHINAl.
CONIRSfONDSHCI NON11154%~I$41MOPROgh.R.-.LAk~ToDistrQT~kCHei~
PREi~FWgv>~~~NineMilePointNuclearstationOATL15August91FfLXCOalNineMilePointFireprotection ProgramPostEventXnterviews Afterinterviews conducted todaywithFireChiefBernieHarvey,andFiremenFatBrennanandNarkLocurcio, andconcurrence withTerryVermilyea, SystemExpertPireDetection andJohnPavlickoofCautionEquipment Enc.,Xhavereachedthefollowing conclusions.
1~Ofthe20firepanelsatUnit2,18maintained anormalpowersupplyo2a.TwoCirepanelsLFCP113and123transferred tointernalbatterybackup.'b.
Thesetwopanelswb'ileonbatterywillstillfunctionnormallyaslongasthe120VACisavailable intheLPCF,whichitwas.Therewasnointerruption ordecreaseoffireproteotioni detection/suppression atthelocalfirepanels.FirePanels849and200/1beingfedfromQNdidhaveapowerinterruption.
ThiswouldhaveleftthecontrolswitchesoperableatPanel849,(astheyarefedfromLPCP),butcontrolRoomwithnoCireannunciation.
Anyfiresuppression/indication couldalsohavebeeninitiated locally.ABA:dlcT,Tomlinson A.Julka(FAX7225-SN)D.Pringle  


QJQ15'9115'ttttKTNa&#xc3;CSs~DTSINTSHNALCOhllSNKNDRNCKINN'tMAeSNpg4gyLoen~ToFiISUSJCCT+~AD-+8'~4CLopfg7P.3NineM5.1ePointNuclearStation15'AugustQlRLRCOOINin<<MilePoint,Unit2FireProtectionProgramFeetRvent8/13/91Interviews?ireDept.PersonnelInterviews(PoetIveatofaugust13(1901BernieHarvey-Chieflnearlyfoxcoverage,interviewedforlosscfpowerinContxolBuilding.Lightsblinked,loudnoise(louderthaneverheardinplant),wasinFireDept.office(toldshifttogetoutintoplant.PatWilsonwasinRxBldg>switchedradiostoChannel10,standardFireDept.practiceifsuspectloseofrepeator.PatBxennanwasintheFoamRoomandproceededtotheChief(sdesk.ChiefHarveyheardfirepanelalarmingwhenhegottoControlBuilding.WentpastFir~Panel114inTurbinebuildf.ngpassageway(noaudiblealarms(seemednormal.Mar}cLocurclowenttoPanel12d-214elev.whileChiefHarveywenttoPanel127>>244elev.ttheseweresoundingtroublealarmandD&wasclear.WentpastPanels120(121(128ftheywerenormal-noaudible.PxiortoSiteAeaEmergency(SAE)messageandevacuationbeingannounced-PatbrennanreportedPanelsR.B.normal,calledcnGaitronics-hadtosilencePanels113onI,B.250andthansilencedallFaneleinR.Be(Panels101,103(104(105(10d(10>andXQ8.ChierHarveywaeCofnptotri~eetagewetlnRh.a.ndhaveaaninR.s.cnardeLynnRoon,accocpanledhyLarrycchaner,calledhfasupervisor,whentheysawtransformerblow.ChiefHarveywou14havelikedtOgettotransfcrmerquf.okerfor".ireevaluation.Hefeelsitwasatleastonehourbefore,'OV41QLCiOt1ech'fHarveyfeelsFireDept.shouldhavebeenpartof'n''linvestigation/inspectionteamwithOperationse
QJQ15'9115'ttttKTNa&#xc3;CSs~DTSINTSHNALCOhllSNKNDRNCK INN'tMAeSNpg4gyLoen~ToFiISUSJCCT+~AD-+8'~
4CLopfg7P.3NineM5.1ePointNuclearStation15'AugustQlRLRCOOINin<<MilePoint,Unit2FireProtection ProgramFeetRvent8/13/91Interviews
?ireDept.Personnel Interviews(
PoetIveatofaugust13(1901BernieHarvey-Chieflnearlyfoxcoverage, interviewed forlosscfpowerinContxolBuilding.
Lightsblinked,loudnoise(louderthaneverheardinplant),wasinFireDept.office(toldshifttogetoutintoplant.PatWilsonwasinRxBldg>switchedradiostoChannel10,standardFireDept.practiceifsuspectloseofrepeator.
PatBxennanwasintheFoamRoomandproceeded totheChief(sdesk.ChiefHarveyheardfirepanelalarmingwhenhegottoControlBuilding.
WentpastFir~Panel114inTurbinebuildf.ng passageway(
noaudiblealarms(seemednormal.Mar}cLocurclowenttoPanel12d-214elev.whileChiefHarveywenttoPanel127>>244elev.ttheseweresoundingtroublealarmandD&wasclear.WentpastPanels120(121(128ftheywerenormal-noaudible.PxiortoSiteAeaEmergency (SAE)messageandevacuation beingannounced
-PatbrennanreportedPanelsR.B.normal,calledcnGaitronics
-hadtosilencePanels113onI,B.250andthansilencedallFaneleinR.Be(Panels101,103(104(105(10d(10>andXQ8.ChierHarveywaeCofnptotri~eetagewetlnRh.a.ndhaveaaninR.s.cnardeLynnRoon,accocpanled hyLarrycchaner,calledhfasupervisor, whentheysawtransformer blow.ChiefHarveywou14havelikedtOgettotransfcrmer quf.okerfor".ireevaluation.
Hefeelsitwasatleastonehourbefore,'OV41QLCiOt1 ech'fHarveyfeelsFireDept.shouldhavebeenpartof'n''linvestigation/inspection teamwithOperationse


QJQf5'9t15~41tt%JKTl%WT&CCttlDTS19911'nterviev(Cont'4)P.45'ff'Acp-m~y-gp~r-ggpgPatPatminfoamRoomapproximately0550>heardloudnoise,venttoChief"'sofficeandaskedwhatnoisewas.Lightingdimmed,onestringoflightsoff(NOTE:thesefeedframEmergency-UPSshouldhavegoneoff)Thenheventonrover-heardalarms-whichvereonvatertreatmentsystempanel,thenventtoPanel123.TherewerenodisplaysonDAXpanel,vasblanknolightsvereon.Powerlightsvoreoff.TrouhleLightblinking.RenttoT.S,261NN,eignedsheet,stairtowerdark'noproblem,knewvayaround),TurbineTraokBay4imlylighted.WonttoT.S.306-OK,sign>>4sheetTBSvgr277OK)signedsheetT.Q.250byFeedpumps-notednotrunningbyPanel113-noLightson,noaudibleortroublealarmestimat>>stimeapproximately0605ContinuedraverroundstoPanel106SouthStairtoverR.S.249vasalarmingdisplaysai4"oninternalclock"hadtvotroublesdisplayedWenttoQ.B.215tirepanel103alarming-silencedR.B.190Fir~panel101alarmingsilencedbothpanelswereintrouble-unknovnR.B.175SignedsheetR.B.261SBCTS-OXPanel105-silencedtroublesCQ2Room,aboutt?)istime,evacuationalarmsoundedwenttoUnit2ControlRoomassemblypointWalkedaroundwithPatBrennanon8-15-91taPanel123andPanel113,poweronlightvasburnedoutonPanel123."Poweron"Lightwason,onPanel113~  
QJQf5'9t15~41tt%JKTl%WT&CCttlDTS19911'nterviev (Cont'4)P.45'ff'Acp-m~y-gp~r-ggpgPatPatminfoamRoomapproximately 0550>heardloudnoise,venttoChief"'sofficeandaskedwhatnoisewas.Lightingdimmed,onestringoflightsoff(NOTE:thesefeedframEmergency
-UPSshouldhavegoneoff)Thenheventonrover-heardalarms-whichvereonvatertreatment systempanel,thenventtoPanel123.TherewerenodisplaysonDAXpanel,vasblanknolightsvereon.Powerlightsvoreoff.TrouhleLightblinking.
RenttoT.S,261NN,eignedsheet,stairtower dark'noproblem,knewvayaround),TurbineTraokBay4imlylighted.WonttoT.S.306-OK,sign>>4sheetTBSvgr277OK)signedsheetT.Q.250byFeedpumps
-notednotrunningbyPanel113-noLightson,noaudibleortroublealarmestimat>>s timeapproximately 0605Continued raverroundstoPanel106SouthStairtover R.S.249vasalarmingdisplaysai4"oninternalclock"hadtvotroublesdisplayed WenttoQ.B.215tirepanel103alarming-silencedR.B.190Fir~panel101alarmingsilencedbothpanelswereintrouble-unknovnR.B.175SignedsheetR.B.261SBCTS-OXPanel105-silencedtroublesCQ2Room,aboutt?)istime,evacuation alarmsoundedwenttoUnit2ControlRoomassemblypointWalkedaroundwithPatBrennanon8-15-91taPanel123andPanel113,poweronlightvasburnedoutonPanel123."Poweron"Lightwason,onPanel113~  


.AJG15'9115:41N1leMGKIScCOPFlDTSP.5Aff~Alm8NggP08+opppostI+gtkuy.13,1991Xnterview(Cont'4)CMarkZcNtok,o(Calle4athome)HaslocatedintheFireDept.Officewhenlightsflickeredandnoisewasheard.Radiocommunicationwasgone,HearHerewasout.ChiefHarveydirectedpersonneltocovervitalareas.PatwilsonwasinRXBldg.PatBrennanwasrovingT.B.BerniefHarkweretccoverControlBldg.TriptoC.B.uneventfulPanelsPassedinroute)Panel114Elect.BayElv.261'anel120C.5~Elv.261'anel128C.5.Elv.261~Panel121C.B.Elv,261'anel125C.B.Zlv.261'anel127C.B.Elv.2i4'anel126C.B.Elv.214'ormalNormalNormalNormalNormalTrouble,Hornsounding-SU,enaodTroubleHornsounding-lilenoed,alsoanamberlightwaslitonpanelCheckedvalveroomonC.b.elv.2ii'ightwasoninroom.Noindicationofsystemactuation.stairwellsweredark,Elv,261'.B.wasdark.s.A.E.announcementandreportedtoControlRoom.
.AJG15'9115:41N1leMGKIScCOPFlDTSP.5Aff~Alm8Ng gP08+opppostI+gtkuy.13,1991Xnterview (Cont'4)CMarkZcNtok,o(Calle4athome)HaslocatedintheFireDept.Officewhenlightsflickered andnoisewasheard.Radiocommunication wasgone,HearHerewasout.ChiefHarveydirectedpersonnel tocovervitalareas.PatwilsonwasinRXBldg.PatBrennanwasrovingT.B.BerniefHarkweretccoverControlBldg.TriptoC.B.uneventful PanelsPassedinroute)Panel114Elect.BayElv.261'anel120C.5~Elv.261'anel128C.5.Elv.261~Panel121C.B.Elv,261'anel125C.B.Zlv.261'anel127C.B.Elv.2i4'anel126C.B.Elv.214'ormal NormalNormalNormalNormalTrouble,Hornsounding-SU,enaodTroubleHornsounding-
I A<7~mgur7pt)c,pk~NMP2LIGHTINGSYSTEMPOWERSOURCEANDMINIM)StILLUHINATIONAVAILABLE-CRIT]CALAREASMODESOFOPERATIONPAGEILOCAStSEISMICWITHLOOPTRANSIENTWITHOUTLOOPILLIILSIXRCE6PROVIDEDBYPOWERSIXRCEMIN.AVAIL(FOOTCAN)LE)XMIN.POWERAVAIL.SDUIKES~~~<FOOTBYPOWERCANDLE)SIXRCEPOWERSIXRCESXHIN.AVAIIPOWERBYPOWERCANDLE)PROVIDED)FOOT~ESSOURCEXOFPROVIDEDCANDLE)(FOOTSOURCEXOFPOWERSOURCESPROVIDEDSOURCEMIN.ESSENTIALAVAIL.LIGHTING(FOOTUPSPAtELCANDLE)ILCIXITROLROOHIDPERATINGAREA5RELAYPANELAREA)CONTROLBLDLEL.336'E-65EN)RMAL58ESSENTIAL)9EHEROE498NXRBAT.PACK~ESSENTIAL188NXRBAT.PACK159NORMALESSENTIALEMERGE8NXRBAT+PACKESSENTIAL8NXRBAToPACKNORHAL58ESSENTIAL18EHERGENC48SNXRBAT.PACKNONESNXRBATT.PACKHANXACTIRER-EXIDI(TYPICAL)CONTROLROONMRTM-SOUTHCDRMDORS)CONTROLBLDLEL3P&'E-&5ECONTROLROOM(SHIFTSLPERVISOROFFICE)CINTROLBLDLELo3P&'E-65ERELAYANDCO)4'UTERROOMRELAYPAMPAS)CONTROLBLDLEL28F-6'E~RELAYANDCOtPUZERCQ4%6EAIKXNOCONTROLBLDG.EL288'-6'E-650HORHAL189BAT.PAtxNONE8NXRNRHAL58BAT.PA)XNONESNXRSNXRBAT+PACKSNXRBATPACK8NXRBAT.PACKNORHAL58ESSENTIAL18SNXRBAT.PACKNORHAL58ESSENTIAL18EMERGENC49SNXRBAT.PACKNORHAL'QESSENTIAL188NXRBAT.PACKSNXRBAT.PACKNORHALESSENTIEMERGENCSNXRBAT+PACKNORHALESSENTIALSNXRBAT.PACKESSENTIA.SNXRBATePACKYES16SNXRBAT+PACKNORHALEHERGESNXRBAT.PACKESSENTIALEHERGESNXRBAT.PACKSNXRBAT+PACKYES16SNXRBAT.PA)XNORMAL58ESSENTIAL18EMERGENCi8SNXRBAT.PACKESSENTIAL18EMERGENC<9SNXRBAT.PACKESSENTIAL188'NXRBAT+PACK2VBB-UPSID2VBB-UPSID2VBB-UPSIDNTHELIGHTINGWINGS,CIRCUITSTARTINGWITHAN'NICATENRMALPOWIWITHA%'H)ICATEESSENTIALPOWER,WIT)AN'E'INDICATEEMERGEN:YPOWER.  
: lilenoed, alsoanamberlightwaslitonpanelCheckedvalveroomonC.b.elv.2ii'ightwasoninroom.Noindication ofsystemactuation.
stairwells weredark,Elv,261'.B.wasdark.s.A.E.announcement andreportedtoControlRoom.
I A<7~mgur7pt)c,pk~NMP2LIGHTINGSYSTEMPOWERSOURCEANDMINIM)StILLUHINATION AVAILABLE
-CRIT]CALAREASMODESOFOPERATION PAGEILOCAStSEISMICWITHLOOPTRANSIENT WITHOUTLOOPILLIILSIXRCE6PROVIDEDBYPOWERSIXRCEMIN.AVAIL(FOOTCAN)LE)XMIN.POWERAVAIL.SDUIKES~~~<FOOTBYPOWERCANDLE)SIXRCEPOWERSIXRCESXHIN.AVAIIPOWERBYPOWERCANDLE)PROVIDED)FOOT~ESSOURCEXOFPROVIDEDCANDLE)(FOOTSOURCEXOFPOWERSOURCESPROVIDEDSOURCEMIN.ESSENTIAL AVAIL.LIGHTING(FOOTUPSPAtELCANDLE)ILCIXITROLROOHIDPERATING AREA5RELAYPANELAREA)CONTROLBLDLEL.336'E-65E N)RMAL58ESSENTIAL
)9EHEROE498NXRBAT.PACK~ESSENTIAL 188NXRBAT.PACK159NORMALESSENTIAL EMERGE8NXRBAT+PACKESSENTIAL 8NXRBAToPACKNORHAL58ESSENTIAL 18EHERGENC48SNXRBAT.PACKNONESNXRBATT.PACKHANXACTIRER-EXIDI (TYPICAL)
CONTROLROONMRTM-SOUTH CDRMDORS)
CONTROLBLDLEL3P&'E-&5E CONTROLROOM(SHIFTSLPERVISOR OFFICE)CINTROLBLDLELo3P&'E-65E RELAYANDCO)4'UTER ROOMRELAYPAMPAS)CONTROLBLDLEL28F-6'E~RELAYANDCOtPUZERCQ4%6EAIKXNOCONTROLBLDG.EL288'-6'E-650 HORHAL189BAT.PAtxNONE8NXRNRHAL58BAT.PA)XNONESNXRSNXRBAT+PACKSNXRBATPACK8NXRBAT.PACKNORHAL58ESSENTIAL 18SNXRBAT.PACKNORHAL58ESSENTIAL 18EMERGENC49SNXRBAT.PACKNORHAL'QESSENTIAL 188NXRBAT.PACKSNXRBAT.PACKNORHALESSENTIEMERGENCSNXRBAT+PACKNORHALESSENTIAL SNXRBAT.PACKESSENTIA.
SNXRBATePACKYES16SNXRBAT+PACKNORHALEHERGESNXRBAT.PACKESSENTIAL EHERGESNXRBAT.PACKSNXRBAT+PACKYES16SNXRBAT.PA)XNORMAL58ESSENTIAL 18EMERGENCi8SNXRBAT.PACKESSENTIAL 18EMERGENC<9SNXRBAT.PACKESSENTIAL 188'NXRBAT+PACK2VBB-UPSID 2VBB-UPSID 2VBB-UPSID NTHELIGHTINGWINGS,CIRCUITSTARTINGWITHAN'NICATENRMALPOWIWITHA%'H)ICATE ESSENTIAL POWER,WIT)AN'E'INDICATE EMERGEN:Y POWER.  


AtrocmC~r7PAcEX,~<<'MP2LIGHTINGSYSTEMPOWERSOURCEANDMINIMUMILLUMINATIONAVAILABLEHOOESOFOPERATIDNPAGE2LOCAttSEIS)GCWITHLOOPTRANSIENTWITHOUTLOOPItOF~RILLLSLSOURCESPRDVIOEDBYPOWERSOLSCEMIN.AVAIL.LFOOTCQOLE)ILLLSL2DFPRLMDEDAVAILBYPOWERC~E)LFOOTSOURCEPOWERSDLRCES2OFAVAIL.POWERBYPOWERCAN)LE)LFOOTSOURCESSOURCEHl)L/OFILLLSLAVAILPOWERILLUMPROVIDEDLFDOTSOURCESPROVIDEDBYPOWERCANDLE)SOURCEBYPOWERSOURCEMIN.AVAIL.LFOOTCANDLE)ESSENTIALLIGHTINGUPSPANELIILRELAYAN)CQ%'UTERROOMLCLXLRIDLRS)CONTROLBLDG.EL288'-6'E-65DDIESELGEtKRATORBUILDINGtWORKINGAREA)EL261'E-6BCDIESELGEtKMORBLBLDINGLELECTRICALEQ)IPMENTAREA)EL.261'E-6BCDIESELGENERATORBUILDINGLGENERALAREA)EL261'E-68CESSENTIAL18SNXRBAT.PAIXN)RMAL78SNXRBAT.PA)X~NORHAL78ESSENTIAL18EMERGE28SNOLRBAT.PAtxNNORHAL98ESSENTIAL18SNXRBAT.PALX~BAT.PACKSNOLRNORHAL78ESSENTIAL18SNXRBAT.PACKNORMAL78ESSENTIAL18EMERGENC28SNXRBAT.PACKNORMAL98ESSENT)AL18SNXRBAT.PACKNORMALESSENTIALSNXRBAT.PACKNORHALESSENTIALEHERGESNOLRBAT.PACKNORHALESSENTIALSNOIRBAT.PACKNORHALESSENTIALSNOLRBAT.PACKYESYESSNXRBAT.PACKNORHALSNXRBAT.PACKNORHALESSENTIALSHOLRBAT,PACKNORMALESSENTIALSNXRBAT.PACKYESYESNORHAL98ESSENTIAL18BAT.PACKSHOLRNORMAL78ESSENTlAL18EMEROENC28SHOLRBAT.PACKNORMAL78ESSENTIAL18EHERGENC28SHOLRBAT.PACKNORHAL98ESSENTIAL18SNOtRBAT.PaX382VBB-ASS2VBB-UPSID2VBB-UPSID2VBB"UPSIO 11 HHP2LIGHTINGSYSTEHPOWERSOURCEANDHINIHJHILLUHINATIONAVAILABLE.HXKSOFOPERATIONPAGE3LOCA8SEISHICWITHLOOPTRANSIENTWITHOUTLOOPPOWERSO(SCES2OFPROVIDEDBYPOWERCA)b)LE)(FOOTSOURCEPOWERSOURCESHl)L2IROY)GEOAVAIL.BYPOWER(FOOTSOURCEPOWERSOURCES2OFILLUH.PROVIDEDBYPOWERSOURCEHIlL2AVAIL+POWERPROVIDEDCANDLE)BYPOWERSO(SCEHIN.IOFAVAIL.POWER(FOOTS~ESPROVIDEDCANDLE)BYPOWERSOURCEHIN.ESSENTIALAVAIL.LIGHTIW(FOOTUPSPAtKLCANDLE)IILREHARKSREHOTESHUTDOWNROOHCONTROLBLDLEL261'E-&5CEE-165CEHERGE88XRBAT.PACKYES16.58HOLRBAT.PACKYESEHERGE8HOLABAT.PACKYESIL5EHERGENCYESBAT.PACK8HOLRNORHALYESEHERGENCYESBAT.PoxNE8dnaSTANDBYSWITCHGEARROOHa)SWG.PANELS(2)HCCFRONTSCONTROLBLDG.EL261'E-65CEE-165CEPICSSWITCtSEARRQOHCONTROLBLDG.EL261'E-65CEE-165CSTANDBYSWITCH%EARROOH(CORRIDORS)CONTROLBLDLEL+26)'E-65CEE-16SCN(RHALESSENTIALEHERGE8BXRBAT.PACK8BXRBAT+PACK8NXRBAT.PACKESSENTIAL8HOLRBAT.PACKNORHALESSENTIALEHERGENCaexaBAT.PACKNORHALESSENTIAL8NQLRBAT.PACKNORHALESSENTIALEHERGE8N(XRBAT.PACKNORHALESSENTIALEHERGE8(XXRBAT.PACKESSENTIAL8HRRBAT.PACKYES3515ESSENTIALYESEHERGEYESBAT.PACK8HXRNORHALNONEESSENTIALYESEHERGENCYESBAT,PACK8IRLRESSENTI(V.YESBAT.PA(X8NXR15NORHALYESESSENTIALYESEHERGENCYES8HOLRBAT.PACKNORHALYESESSENTIALYESEHERGENCYES8(K)LHBAT.PA(XNORHALYESESSENTIALYESBATPACKNONE8N(na2VBB-UPSID2VBB-UPSID2VBB-UPSID  
AtrocmC~r 7PAcEX,~<<'MP2LIGHTINGSYSTEMPOWERSOURCEANDMINIMUMILLUMINATION AVAILABLE HOOESOFOPERATIDN PAGE2LOCAttSEIS)GCWITHLOOPTRANSIENT WITHOUTLOOPItOF~RILLLSLSOURCESPRDVIOEDBYPOWERSOLSCEMIN.AVAIL.LFOOTCQOLE)ILLLSL2DFPRLMDEDAVAILBYPOWERC~E)LFOOTSOURCEPOWERSDLRCES2OFAVAIL.POWERBYPOWERCAN)LE)LFOOTSOURCESSOURCEHl)L/OFILLLSLAVAILPOWERILLUMPROVIDEDLFDOTSOURCESPROVIDEDBYPOWERCANDLE)SOURCEBYPOWERSOURCEMIN.AVAIL.LFOOTCANDLE)ESSENTIAL LIGHTINGUPSPANELIILRELAYAN)CQ%'UTERROOMLCLXLRIDLRS)
CONTROLBLDG.EL288'-6'E-65D DIESELGEtKRATOR BUILDINGtWORKINGAREA)EL261'E-6BC DIESELGEtKMORBLBLDINGLELECTRICAL EQ)IPMENT AREA)EL.261'E-6BC DIESELGENERATOR BUILDINGLGENERALAREA)EL261'E-68C ESSENTIAL 18SNXRBAT.PAIXN)RMAL78SNXRBAT.PA)X~NORHAL78ESSENTIAL 18EMERGE28SNOLRBAT.PAtxNNORHAL98ESSENTIAL 18SNXRBAT.PALX~BAT.PACKSNOLRNORHAL78ESSENTIAL 18SNXRBAT.PACKNORMAL78ESSENTIAL 18EMERGENC28SNXRBAT.PACKNORMAL98ESSENT)AL 18SNXRBAT.PACKNORMALESSENTIAL SNXRBAT.PACKNORHALESSENTIAL EHERGESNOLRBAT.PACKNORHALESSENTIAL SNOIRBAT.PACKNORHALESSENTIAL SNOLRBAT.PACKYESYESSNXRBAT.PACKNORHALSNXRBAT.PACKNORHALESSENTIAL SHOLRBAT,PACKNORMALESSENTIAL SNXRBAT.PACKYESYESNORHAL98ESSENTIAL 18BAT.PACKSHOLRNORMAL78ESSENTlAL 18EMEROENC28SHOLRBAT.PACKNORMAL78ESSENTIAL 18EHERGENC28SHOLRBAT.PACKNORHAL98ESSENTIAL 18SNOtRBAT.PaX382VBB-ASS2VBB-UPSID 2VBB-UPSID 2VBB"UPSIO 11 HHP2LIGHTINGSYSTEHPOWERSOURCEANDHINIHJHILLUHINATION AVAILABLE
.HXKSOFOPERATION PAGE3LOCA8SEISHICWITHLOOPTRANSIENT WITHOUTLOOPPOWERSO(SCES2OFPROVIDEDBYPOWERCA)b)LE)(FOOTSOURCEPOWERSOURCESHl)L2IROY)GEOAVAIL.BYPOWER(FOOTSOURCEPOWERSOURCES2OFILLUH.PROVIDEDBYPOWERSOURCEHIlL2AVAIL+POWERPROVIDEDCANDLE)BYPOWERSO(SCEHIN.IOFAVAIL.POWER(FOOTS~ESPROVIDEDCANDLE)BYPOWERSOURCEHIN.ESSENTIAL AVAIL.LIGHTIW(FOOTUPSPAtKLCANDLE)IILREHARKSREHOTESHUTDOWNROOHCONTROLBLDLEL261'E-&5C EE-165CEHERGE88XRBAT.PACKYES16.58HOLRBAT.PACKYESEHERGE8HOLABAT.PACKYESIL5EHERGENCYESBAT.PACK8HOLRNORHALYESEHERGENCYESBAT.PoxNE8dnaSTANDBYSWITCHGEAR ROOHa)SWG.PANELS(2)HCCFRONTSCONTROLBLDG.EL261'E-65C EE-165CEPICSSWITCtSEAR RQOHCONTROLBLDG.EL261'E-65C EE-165CSTANDBYSWITCH%EAR ROOH(CORRIDORS)
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NMP2LIGHTINGSYSTEHPOWERSOURCEANDMIHINJMILLUMINATIONAVAILABLEMODESOFDPERATIDNPAGELOCA4SEISHICWITHLOOPTRANSIENTWITHOUTLOOPTLRB.BLDG.GRMM)FLOORCORfODORELe258'E-66BPOWERSOURCESESSEHTIALXILLL&#xc3;.PROVIDEDBYPOWERSOLRCEMIN.IAVAIL.POWERILL(FOOTSOURCESPROVIDEDCA)K)LE)BYPOWERSDLRCENORMALYESESSEHTIALYESMIH.AVAIL.IFOOTCANDLE)POWERAVAIL.SOURCESIFOOTBYPOWERC~E)SOURCEHORMALNONEESSENTIALNONEPOWERSOURCESNORMALESSENTIALOFPROVIOEOBYPOWERC~E)(FOOTSOURCEYESPOWERSOURCESESSENTIALILLU)LXOFpRovloEoAVAIL.BYPOWERC~E)(FOOTSOURCEYESYESESSENTIALLIGHTINGO'SPANELID.2VBB-LPS1DSAFES)IJTDOWNPATHO)l.YNoELXJIPPKNTTURLBLDLCLEANACCESSAREAEL.2QYEL2Q'L.288'-8'L.396'E-66HTtSLBLOLCLEANACCESSAREASTAIRSEL+258'L2Q'L288'-8'L386'E-66H8NXRBAT+PACKNORMALESSENTIAL8)KXRBAT.PACKbHOLRBAToPACK8HLXRBAT+PACKNORMALYESESSENTIALYES8HL)LRBAT.PACKESSEHTI)V.YES8HOLRBAT.PACK8HOLABATsPACKYESSHXRBATPACKYESESSENTIALNONE8HXRBATPACKNORHALNONEESSENTIALNONE8NXRBAT+PACKNORMALESSENTIALS)NLRBAT.PACKSHOLRBAToPACKYESYES8HOLRBATePACKNORMALESSENTIALSHOLRBAT.PACKESSENTIAL8HOLRBAT.PACKYESYESYES2VBB-UPSIO2VBB-UPSIC2VBB-UPSICSAFESHUTDOWNPATHD)LYNOEOUIPMENTSAFESWTDOWNPATHM.YNDEIXJIPPKNT IU ACCESSROUTETAKENBYOPERATORFROMCONTROLROOMTOUPSROOMINNORMALSWITCHGEARBUILDINGON8-13-91ThefollowingroutewastakenbyoperatorfromcontrolroomtogotoUPSroominswitchgearbuildingtotransferalternatepowersourcetoUPSunits,OperatorleftthecontrolroomEL306throughsouthdoorandproceededtowest.Thenheturnednorthalongthecorridoronthewestsideofthecontrolroom.ThenheexitedthecontrolroombuildingthroughnorthwestdoorEL306toAuxiliarybuilding.HethentookthestairwayjustsouthoftheelevatortogotoEL261.ThenatEL261ofAuxiliarybuilding,heproceededtosouthandenteredthecorridor(ElectricalequipmentTunnel).FromthecorridorheenteredthenormalswitchgearbuildingEL261andproceededtostairwaylocatedinthecenterofthebuilding(Westhalf)downtoEL237wheretheUPSunits2VBB-UPS1A,1B,1Cand1Darelocated.HethentransferredtheUPSpowertomaintenancepowersource.AfterrestoringpowertotheaboveUPSunits,theoperatorproceededtoUPS2VBB-UPS1Gviathedoorontheeastendoftheroom,wentsouthdownthehall,throughthedooronhisleft(eastside)andenteredthecontrolbuilding.HethentookthestairsdowntoEL214whereUPS2VBB-UPS1Gislocatedandtransferredthepowertothemaintenancepower.  
NMP2LIGHTINGSYSTEHPOWERSOURCEANDMIHINJMILLUMINATION AVAILABLE MODESOFDPERATIDN PAGELOCA4SEISHICWITHLOOPTRANSIENT WITHOUTLOOPTLRB.BLDG.GRMM)FLOORCORfODORELe258'E-66B POWERSOURCESESSEHTIAL XILLL&#xc3;.PROVIDEDBYPOWERSOLRCEMIN.IAVAIL.POWERILL(FOOTSOURCESPROVIDEDCA)K)LE)BYPOWERSDLRCENORMALYESESSEHTIAL YESMIH.AVAIL.IFOOTCANDLE)POWERAVAIL.SOURCESIFOOTBYPOWERC~E)SOURCEHORMALNONEESSENTIAL NONEPOWERSOURCESNORMALESSENTIAL OFPROVIOEOBYPOWERC~E)(FOOTSOURCEYESPOWERSOURCESESSENTIAL ILLU)LXOFpRovloEoAVAIL.BYPOWERC~E)(FOOTSOURCEYESYESESSENTIAL LIGHTINGO'SPANELID.2VBB-LPS1D SAFES)IJTDOWN PATHO)l.YNoELXJIPPKNT TURLBLDLCLEANACCESSAREAEL.2QYEL2Q'L.288'-8'L.
396'E-66H TtSLBLOLCLEANACCESSAREASTAIRSEL+258'L2Q'L288'-8'L386'E-66H 8NXRBAT+PACKNORMALESSENTIAL 8)KXRBAT.PACKbHOLRBAToPACK8HLXRBAT+PACKNORMALYESESSENTIAL YES8HL)LRBAT.PACKESSEHTI)V.
YES8HOLRBAT.PACK8HOLABATsPACKYESSHXRBATPACKYESESSENTIAL NONE8HXRBATPACKNORHALNONEESSENTIAL NONE8NXRBAT+PACKNORMALESSENTIAL S)NLRBAT.PACKSHOLRBAToPACKYESYES8HOLRBATePACKNORMALESSENTIAL SHOLRBAT.PACKESSENTIAL 8HOLRBAT.PACKYESYESYES2VBB-UPSIO 2VBB-UPSIC 2VBB-UPSIC SAFESHUTDOWNPATHD)LYNOEOUIPMENT SAFESWTDOWNPATHM.YNDEIXJIPPKNT IU ACCESSROUTETAKENBYOPERATORFROMCONTROLROOMTOUPSROOMINNORMALSWITCHGEAR BUILDINGON8-13-91Thefollowing routewastakenbyoperatorfromcontrolroomtogotoUPSroominswitchgear buildingtotransferalternate powersourcetoUPSunits,Operator leftthecontrolroomEL306throughsouthdoorandproceeded towest.Thenheturnednorthalongthecorridoronthewestsideofthecontrolroom.ThenheexitedthecontrolroombuildingthroughnorthwestdoorEL306toAuxiliary building.
HethentookthestairwayjustsouthoftheelevatortogotoEL261.ThenatEL261ofAuxiliary
: building, heproceeded tosouthandenteredthecorridor(Electrical equipment Tunnel).Fromthecorridorheenteredthenormalswitchgear buildingEL261andproceeded tostairwaylocatedinthecenterofthebuilding(Westhalf)downtoEL237wheretheUPSunits2VBB-UPS1A, 1B,1Cand1Darelocated.Hethentransferred theUPSpowertomaintenance powersource.Afterrestoring powertotheaboveUPSunits,theoperatorproceeded toUPS2VBB-UPS1G viathedoorontheeastendoftheroom,wentsouthdownthehall,throughthedooronhisleft(eastside) andenteredthecontrolbuilding.
HethentookthestairsdowntoEL214whereUPS2VBB-UPS1G islocatedandtransferred thepowertothemaintenance power.  


CONDENSATE/FEEOMATERSIMPLIFIEDSKETCHlCQOCMJEANSFEll4IIIIIIQlZEMSATEBOOSTERIIFVRi)FOI)MFlOPAWLIIIIIIIIIIIiFEEOvATERCOMlROLLOO)C)II)IILVIBFLFVgPRESS)I)REDREAC)TX)VESSELO'RVIC(&#xc3;H6ATEPAPHIM.FLOMIEgKRICQI+QNCOMPENSATE)MISTERPNTPHDLFLOMTEAOERFEEOPUH'lM.FLOVTRACERFOXBOROPANELTRAINA-2CEC-PNL825TRAINB-2CEC-PNL826TRAINC-2CEC-PNL827FEEDWATERCONTROLPANEL2CEC-PNL6I2(TYPICALTRAINA,8,8,CCROSSOVERHEADERSBETWEENTRAINSPROVIDECROSSOVERFLOW
CONDENSATE/FEEOMATER SIMPLIFIED SKETCHlCQOCMJEANSFEll4IIIIIIQlZEMSATE BOOSTERIIFVRi)FOI)MFlOPAWLIIIIIIIIIIIiFEEOvATER COMlROLLOO)C)II)IILVIBFLFVgPRESS)I)RED REAC)TX)VESSELO'RVIC(&#xc3;H6ATEPAPHIM.FLOMIEgKRICQI+QNCOMPENSATE
)MISTERPNTPHDLFLOMTEAOERFEEOPUH'lM.
FLOVTRACERFOXBOROPANELTRAINA-2CEC-PNL825 TRAINB-2CEC-PNL826 TRAINC-2CEC-PNL827 FEEDWATER CONTROLPANEL2CEC-PNL6I2 (TYPICALTRAINA,8,8,CCROSSOVER HEADERSBETWEENTRAINSPROVIDECROSSOVER FLOW


OeGEIndustrialA,TrAQftttl+IIf'/QapowerSystemsPROPomrGenerationServicesDepartmentGeneralElectricCompany3532JamesSt..PO.Bott484t,Syraorse.Nyt322tNIAGARAMOHAWKPOWERCORPORATIONNINEMILEPOINTNUCLEARSTATIONUNITg2rGENERATORg180X632GENERATORINSPECTION-POSSIBLEPHASE-TO-PHASEFAULTcc:NIAGARAMOHAWKPOWERCORP.R.AbbottN.KabarwalM.McCormickGENERALELECTRICCOMPANYAugust28,1991L.Jordan(37-3)W.JuddS.KolbR.SmithW.TurkMr.AnilK.JulkaNIAGARAMOHAWKPOWERCORPORATION301PlainfieldRoadNorthSyracuse,NewYork13212
OeGEIndustrial A,TrAQftttl+IIf'/QapowerSystemsPROPomrGeneration ServicesDepartment GeneralElectricCompany3532JamesSt..PO.Bott484t,Syraorse.
Nyt322tNIAGARAMOHAWKPOWERCORPORATION NINEMILEPOINTNUCLEARSTATIONUNITg2rGENERATOR g180X632GENERATOR INSPECTION
-POSSIBLEPHASE-TO-PHASE FAULTcc:NIAGARAMOHAWKPOWERCORP.R.AbbottN.KabarwalM.McCormick GENERALELECTRICCOMPANYAugust28,1991L.Jordan(37-3)W.JuddS.KolbR.SmithW.TurkMr.AnilK.JulkaNIAGARAMOHAWKPOWERCORPORATION 301Plainfield RoadNorthSyracuse, NewYork13212


==DearMr.Julka:==
==DearMr.Julka:==
DuetotheAugust13,1991failureofthephaseBstep-uptransformeronNineMilePointUnitg2,GeneralElectricGeneratorEngineeringrecommendsperformingathoroughvisualinspectionofthegeneratorstatorendwindingsupportsystematthenextconvenientopportunity.Theinspectionshouldincludeallaccessiblecomponentsofthestatorendwindingsupportsystem,includingstatorbarendarms,blocks,tiesnoserings,andouteraxialsupports.ThisinspectionshouldbeaccomplishedbyaGEGeneratorSpecialisttrainedtodetectthepotentiallysubtleindicationsofdamage.Theaboverecommendationisbaseduponthepossibilityofphase-to-phasegeneratorshortcircuitcurrentsthroughthefailedtransformerashighas5pu.Theinitialrecommendationfortheimmediategeneratorinspectionconsideredthepossibilityofhighercurrents,resultinginseveraltimesgreaterendwindingforces.Physicalevidenceofhighcurrentforcesatthetransformer.lowsidewastheprimarydriverforthisrecommendation,sincemeasurementsofgeneratorcurrentswerenotavailable.Ourengineerscontinuedtoreviewthelimiteddataavailableandsubsequentlyconcludedthatcurrentshighenoughtodoprobabledamagetothegeneratorwerenotlikely.Thisconclusionwasreachedprimarilybyconsideringameasurementofdepressedgeneratorvoltageduringtheincident,inferringgeneratorcurrents,andspecificcapabilitiesofthegeneratordesign.  
DuetotheAugust13,1991failureofthephaseBstep-uptransformer onNineMilePointUnitg2,GeneralElectricGenerator Engineering recommends performing athoroughvisualinspection ofthegenerator statorendwindingsupportsystematthenextconvenient opportunity.
'k PageIIMr.,AnilK.JulkaAugust28,1991Shouldyouhaveanyquestionsregardingthisrecommendation,pleasecontactme.VeryrulyyoursJeph.KirchMaagerEngineringServicesPowrGeneratioServices"SYRACUSEOFFICEJAK/bsJAK-059  
Theinspection shouldincludeallaccessible components ofthestatorendwindingsupportsystem,including statorbarendarms,blocks,tiesnoserings,andouteraxialsupports.
Thisinspection shouldbeaccomplished byaGEGenerator Specialist trainedtodetectthepotentially subtleindications ofdamage.Theaboverecommendation isbaseduponthepossibility ofphase-to-phase generator shortcircuitcurrentsthroughthefailedtransformer ashighas5pu.Theinitialrecommendation fortheimmediate generator inspection considered thepossibility ofhighercurrents, resulting inseveraltimesgreaterendwindingforces.Physicalevidenceofhighcurrentforcesatthetransformer
.lowsidewastheprimarydriverforthisrecommendation, sincemeasurements ofgenerator currentswerenotavailable.
Ourengineers continued toreviewthelimiteddataavailable andsubsequently concluded thatcurrentshighenoughtodoprobabledamagetothegenerator werenotlikely.Thisconclusion wasreachedprimarily byconsidering ameasurement ofdepressed generator voltageduringtheincident, inferring generator
: currents, andspecificcapabilities ofthegenerator design.  
'k PageIIMr.,AnilK.JulkaAugust28,1991Shouldyouhaveanyquestions regarding thisrecommendation, pleasecontactme.VeryrulyyoursJeph.KirchMaagerEngineringServicesPowrGeneratio Services"SYRACUSE OFFICEJAK/bsJAK-059  
.rI~T}}
.rI~T}}

Revision as of 02:40, 29 June 2018

Niagara Mohawk Nine Mile Point Unit 2 Event of 910813.
ML18038A375
Person / Time
Site: Nine Mile Point Constellation icon.png
Issue date: 09/05/1991
From: CRENSHAW M L
GENERAL ELECTRIC CO.
To:
Shared Package
ML18038A373 List:
References
CON-IIT07-751-91, CON-IIT7-751-91 NUREG-1455, NUDOCS 9109110283
Download: ML18038A375 (134)
v • d • e


Text

{{#Wiki_filter:NiagaraMohawkNineMi>epointUnit2Eventof13August]991Reportby:MelvinL.CrensbamConsulting EngineerPo~erSystemsEngineeriag Department GeneralElectricCompanySchenectady, NY8September 1991 40 5iagaraMohawk5ineMilePointUnit2Eventof13August199105:4SQnAugust13,1991,at5:48AbftheUnit2phaseBgenerator step-uptranstormer failed.Oscillographic recordsoftheeventareavailable fromadigitaldatarecorderattheScribaSubstation. Theyshowvarious345kVand11V5ksystemvoltagesandcurrents. FigureAwithnotations isattached. Thefourcyclespreceding thefaultshownosignsofagradualdegradation oradeveloping disturbance. Theoscillographic tracesandstationprotective relaytargetsreported, indicateagroundfaultoccurredonthehighvoltagewinding.Depression ofthe345kVphase8busvoltagetoabout39%ofthepriorvaluewasobservedfromtheoscillographic trace.Thissuggeststheinvolvement ofonlyaportionoftheentirewinding.The345kVlinecurrentsandvoltagesshowrapiddevelopment ofthegroundfaultbeginning atpoint1withthegroundcurrentreachingaconstantvalueof1,300amperesin11/2cyclesatpoint4,Theflashover inthefaultedtransformer occursjustpreceding amaximuminphase2toneutralvoltage(aswouldhavebeenexpected) atpoint2.The345kVlinecurrentinanunfaulted phaseincreases instepfunctionmannerto350/ooftheprefaultvalueatpoint3,Nohighspeedrecordings ofvoltagesorcurrentswithintheplantwereavailable. Nosequenceofeventrecordings wereavailable tocorrelate relayoperation times.Duetothelargeamountofmagneticenergycouplingthegenerator rotorandstator,andknownelectrical parameters, thcdecayoffaultcurrentcontributed bythegenerator tothesolidlyconnected transformer wouldhavespannedanumberofsecondsasthcfielddecayed.Relayoperation targetsreportedwere:l.Transformer Differential Relay(TypeBDD)onTransformer 2MTX-XM1B.2.Transformer NeutralCurrentRelay(TypeIAC).3.OverallUnitDifferential Relays(TypeBDD)inphases2and3.4.Generator PhaseOvercurrent Relays(TypePJC)inphases2and3. r FvFollowing isolation ofthegenerator andfailedtransformer fromthepowergrid,marked5onFigureA.onlyasingle345kVphasetogroundvoltagerecordisavailable. Themagnitude ofthisvoltageonanunfaulted phaseis74foofthepre-fault value.Sincegenerator neutralcurrentislimitedtolessthan8amperes.itisknownthatthefaultedtransformer appearsasalinetolinefaultwithsomeimpedance tothegenerator. Bytrialanderrorcalculation, generator. linecurrentsarefoundtobe0,1.9and1.9,multiples oftheratedvalueof31,140amperes.Theline-to-line voltageshavemagnitudes 74lo74lo,and25%oftheratedvalueof25,000volts.Thedecayofthisvoltagefor0.2Ssecondsoftherecording hasameasuredtimeconstantof2.7seconds.Thecalculated valueoftheimpedance ofthefaultedtransformer asseenbythegenerator is0.23perunit.Conditions prevailing duringthesixcycletimeperiodfollowing thefault,marked2onFigureA,cannotbedetermined withcertainty. Theexactnatureofthefaultwithinthetransformer isnotknownandthephysicalevidencewillbestronglyaffectedbythecontinued flowofenergyfromthegenerator duetotheinherenttimeconstant. Theflashover ofonlyaportionoftheHVwindingisevidentsincethe345linevoltagestoneutralremainat39%o,867oand86'1oofthepre-fault values.Thepresenceof"residual" inthemeasured345kVlinecurrentsprovidestheevidenceoftransformer neutraltogroundcurrent.Thisrequiresthatthefaultinvolvesapathforcurrenttogroundfromthehighvoltagewinding.Recordedvoltagesandcurrentsshowastepchangetonewvaluesandnodramaticchangeduringthetimeperiodoftherecord,whichtotalssomewhatlessthan1/2second.Itcouldbesaidtheyare"cleaner" andlessdistorted thancommonlyseenoscillograph recordings offaults.Giventheseobservations andsinceboththegenerator andthesystemweresupplying faultcurrentintothefaultedtransformer, generator line-to-line voltagespreceding isolation wouldbeexpectedtobegreaterthanthoseimmediately following isolation. Ithasbeenspeculated thatveryhighfrequency energy(mHzregion)mayhavecausalmalfunction oflogicandcontrolcircuitry intheUPSequipment. Abroad-range offrequencies wouldbeexpectedinanyarcingphenomenon suchasoccurredinthisfai1ure.Nothingintheavailable dataordesignparameters oftheplantequipment wouldsuggestanextraordinary generation orpropagation ofhigherfrequency components. 'Ihefailureofatransformer andinternalarcingisnotarareoccurrence. Comparison ofoscillographic charts 'Ijj fromsimilareventsinotherplantsshownothingunexpected orunusualinthisparticular failure.Itmustbeborneinmindthatthesamplingrateoftherecorderislistedas5.814kHzandfrequency components inexcessofperhaps500Hzwouldnotbeaccurately portrayed. GEexperience intestingoftypicalpowertransformers (suchastheLnitAuxiliaries Transformers) providesanindication oftheexpectedcouplingbetweenwindingsatradiofrequencies intheregionof1megahertz: Theattenuation factorsrangefrom1,000:1to10'softhousands: 1.Directmeasurements couldbemadeinthisplanttodetermine attenuation factorsforindividual transformers overarangeoffrequencies. Thesetestswouldbemadeonnon-energized transformers usinganRFsignalgenerator andasensitive, calibrated detector. Attachedrecentarticlesonelectro-magnetic interference. Reference 1discusses IEC801,4andthecharacteristics ofelectrically fasttransients. Reference 2discusses testingofgroundconnections. ViThepossibility ofelevation ofthcstationgrounding systemasaresultofthisdisturbance waspostulated. Therelatively highlevelofgroundfaultcurrent,estimated at1,300ampercsfromtheavailable recording, wouldnothavebeenconducted intotheplant.ThiscurrentcanonlyfiowinRomthe345kVsystemforthe6cycleperiodrequiredforrelayandcircuitbreakeroperation toachieveisolation. Thegenerator groundcurrentwouldhavebeenlimitedtolessthan8ampcresbytheneutralgrounding equipmcnt. Elevation ordifferences ingroundpotential withintheplantwouldtherefore nothavebeenexpectedduringthisevent.Reference 1discusses theproblemofachieving a"super"groundandconcludes thatastablegroundreference forinterconnected equipment isofgreatersignificance. Sincenormallycirculating groundcurrentsarenotexpected, testingwithverylowvoltagesandcurrentsisrecommended. Noteespecially therecommendation totestwithafrequency non-harmonically relatedtothepowerline&equcncy. Thetransformers steppingthevoltagedowntosuccessively lowervoltagelevelsareconnected inamannertominimizecouplingofpowerfrequency andhigherfrequency. components betweenthcvariousbusses.Specificconfigurations are: 1IIV l.NormalStationServiceTransformer-delta25kVtowye13.8kVwith400ampereresistive grounding onthe13.8kVside.2.LoadCenterTransformers-delta13.8kVtowye4.16kUwith4Rampereresistive grounding onthe4.16kVside..3.LoadCenterTransformers-delta13.8kVor4.16kVtowye600voltswithneutralsolidlygroundedonthe600voltside.4.ReserveStationServiceTransformers-wye115kV,delta4.16kV,wye13.8kV,The13.8kVneutralis400ampereresistive grounded. The4.16kVcircuitisconnected toazig-zaggrounding transformer witharesistorintheneutralconnection, presumably for400amperes.Theseconfigurations provide"effectively grounded" distribution bussesasdefinedinTEEStandard142andwillservetolimittransient overvoltages. Thisisinaccordance withdesignpractices deemedprudentandconservative withinthepowerindustry. Theindustrycontinues toreviewtheeffectsofgeomagnetic disturbances onpowertransformers. Whilenoevidenceisseenofvoltagedistortion inthefourcyclespreceeding thefailure,excessive dutycouldhaveoccurredifthesetransformers hadbeensubjected tolowleveldirectcurrentpreviously. References 3and4areattachedforperusal.

I~~.rT~v!LALI4>EII>3~La+~II,ed'-.~>J444Jape.2VIV'gn:~I'.!i'VVV>.pi~~cIC.IIIC(IVI.-$LJIC9.cpNil(lt~IH0L~IJ~h'~r>>t.SkAVCIIOOI>>I>>IsccrrMFeudsAJtI>latir~g g(.CrCeShr>>J I1~~ fncfustrfal Equfpment EISCtt'OfllCS IlllndLIStl'Ig fAPPIiCatienS ADiscussion ofFundamentaf ENlCPrincfpfes forElectronic Controllers lnanindustrial Environment By4t'iHiam0.Kimmel.PEKimmeiGerkeAssociates, LtdEDDICproblerrs i~:h:ndustra! ccnuoisareaggravated byharsheni.ronments. mixed:ec.'".noiogies andalaclcofumformE!ifCguidebnes. T:isarLicie'>elconcentrate on;hecommonas;ec:sofelectronic controlsinan!ndustnal en>".ronment. whichisgenerally mucnharsher:ban theofGceenvirOnmenL Whatistheindustrial enviroment andwhatcanbecoreaboutit!Theenvironmen includestheentiregamutof'.hebasicthreats.powerdisturbances. RFI.andESD.RFIandpowerdisturbances maybelocallygenerated ornot.Mixedtechnolo-giescompourd:he problem.Digitalcircuitsareusedtoswitch."ne voltagesviarelays.Analogsensorsareinputdevices:o digitalcontrols. Increasingly. thereisaneedfora:ooperauve effortbetweenthedesigners. manufacturers andinstailers tocomeupwitharock-solid system.Acommoncomplaint isthatthemstallers ormainte-narcepeoplewon'tfollowtheinstaUation requirements. Thismaybetrue,butitmustchange.smcethereareproblemswhichcannotbesolvedattheboardlevel.Itisalsotruethatmanufacturers oftenspecifyinstallation .equirements whicharenotpractical toimpleinent, andtherearedocumented caseswheretheprescribed installauon procedures wil!causerathertitancureaprobietts. The!adtofumikenguidelines hasham-peredEMCprtilessintheindustriat arena.Fortunately, theEuropeanCommu-nityisworkingtoadopttheIEC801.xspecilications. anddomesticcompanies wouldbewisetoadoptthem,evenifthereisnointention toexport.TheBasicThreatsThethreebasicthreatstoindustrial electronics arepowerdisturbances, radiofrequency interference, andESD.PowerDisturbances. Powerdistur-EMCTest4DesignbancesareaweHknownirdustral problem.Iniac:.whenaproblemoccurs.ketirstthough':is:oblamethepowercompany.Oftenpowerqualityisaproblem(especially ifgrounding issuesareinciudedl. buttheproblemisalmostalwaysgenerated byadjacentequipment. Tradiuonal problemswithpowerincludespikesandtransients, sagsandsurges,andoutages.whichthreatentheeiectroiucs viathepowersupply.Theseproblemsarefairlyweildocumented andareoftensolvedusingpowerconditioners orUPS.Themostcommonpowerproblemsconfronting electronics todayisthesagwhich~icailyoccursduringturnonandthespikeswhichtypically occurduringturnoffofheavyinductive loads.~<..esagssimplystarvetheelectronics. Thehighfrequency ttansients barrelrightthroughthesupposedly Steredpowersupplytoattacktheelectronics inside.Digitalcircuitsaremostvuhierable tospikeswhichcausedataettorsorworse.Analogcircuitsaremostvukierable tocontinuous RFridingontopofthepower.FIPSPUB94providesguidelines oneiectrical powerforcommercial computers. Thisisgoodinfortnation, butbewarethatfactorypowerismuchnoisierthancommer-cialpower.Theguidehces ofIEC801.4speci5esanelectrically fastuansient(EFT)thatsimu-latesarangandotherhighspeednoise.Ebsarequiteshortranged-theydiminishrapidlywithdistanceduetoinduc.tanceintheline.Butatshortrange,theyaredevastatmg. Unfortunately, attention isplacedonthefrontendoftheelectronics, thepowersupply.Withindustrial

controls, theprob-lemisthecontrolled elements.

Iftheelectronics iscontrolling linepower,thedisturbances sneakinthebackendwherelittleornoprotection exists.Systemground,whilenotbeingspecifl-callyapowerdisturbance prob'.em.:s: .thecar..erofresidualeiiectsofo-.disturbances. Any'ind;sinai orcommer:suucturehassigiu8cant .'ow~equencurrentscirculating:hrough t.".egrousystem.sometimes becausethe.nergyintentionally dumpedontotheground(s.aswithanarcweider)andsomeur..becauseofunintenuonal couplingorvaninadvertent connection betweenneuandgroundsomewhere inthe!aciiity. RadioFrequency Interference. Rdiofrequency interfer~nce affectsboanaloganddigitalcircuits. withana'ccircuitsbeinggenerally moresusceptibl Surprising tomany,thepnncipiethreatnottheTVorFMstauondowntheroaibutratheritisthehandheldL~snut:~carriedaroundbyfacilities personnel. Aor.wattradiowillresultinanelectncne!d~(Nevolts/meter ataonemeterdistanceenoughtoupsetmanyelectromcs systemsIEC801.3speciGesimmunitytoelec".Geldsofonetotenvoltspermetedepending ontheequipment. withtivevoltspermeterbeingSelevelfortypicequipment. Ascanbeseenfromtheabovapproximation, threevoltspermeterisncanexcessive requirement, andeven:evoltspermeterisfairlymodest.Electrostatic Discharges. EiecLcstaticdischarge isanintenseshortdurauoipulse,havingariseameofaboutonenanosecond. Thisisequivalent:o aburs.of300MHsinterference. Staticbuildup.of15kVarenotuncommon. Dryclimates, including northernclimate'. WhamKimmelisapn'ncipal withKimme.GeromeAssociates. Ltd.Thefirmspecial.i@cainpreventing andsolvingelectromag. neticinterference andcompaabQity (E.MhEMC)problems. Mr.Kimmeicanreachedat3544NPascal,St.PauL.~i~55108,ortelephone 612.330-3728. i ~~VcclinepouerItIiITRIACsuitcl.epiouerF:g.'re'..Amp'.'Ger detnodulanon. Figu:e2.Transient!eedback path.:n~".nter.offeropportumty !orESD.Industnai environments. withthe:rmovingeqipment.areloadedwithpotenualESDsources:rubberrogers.belts,andproduc-uonou'.putsuchasplasncandpaperroUs.alladdup!oarealESDth:eat.andt."isr."meatismorelikelytooccurevenm;elanvely moistenvironments. Look:oIEC801.2.'orESDstandards. Elec!ronicsDesignElectronics:s generally theultimatevictimof:nterference. Thehter.'erence Gndsitswaythroughvariouspaths:otheelectronics equipment itself.Let'sconcen-trateonw'ratcannappentoyourelectronics from!hebackdoor.thatis.bydirectradiation intotheelectronics andbycon-ducted:nterference through:he signalandcont:oilines.Sensors.Lowlevelsensors.suchasther...ocouples. pressuresensors.etc..arecharacterized byverylowbandwidtbs and!owsignallevels.AmajorMeattothesesensorsisradiofrequency interference. eitherfromnearbyhandheldtransmitters ormoredistancelandmobileorGxedtransmitters. But:hesearehighl'requency, muchabovethebandpassofyouramph6er.right?Wrong!Lowfrequency amplifiers areplaguedbytwo,ybeaomena: outofbandresponseand<<stsorectification. Thesecombinetoprovidefalseinformation onlevelstothesystem.Allamplifiers haveanormalbandpass, typi6edbya20dB/decade roUoformoreatthehighend.Butresonances duetostrayinductance andcapacitance willgiverisetoamplifier responseGveordersofmagnitude ormoreabovethenominalbandpassoftheamplifier. Thismeansanaudioamplifier willrespondtosignalsinthehundredsofMHz.ThesecondaspectoccurswhenRFencourtersanoriinearity suchasasemicon-ductordevice.AllsuchdevicesgiverisetoaDClevelshiftwhenconfronted withRF.lnaradioreceivertheyarecalleddetec-tors.Noniinearities areminimized inlineardevices,but:hereisalwaysenoughtocauseproblems. Theupshotisthattheampli6erdemodulates theRF.generates anerrone-oussignal.andpassesthiserroron.Thiseffec'.isshowninFigure1.Outputhnesaresimilarly

affected, withcapacitive couphngbacktotheinput.ThesoluuonistopreventtheRFfromgettingtotheamplifier.

eitherbyshielding orfiltering. Themostcommonpathtotheamplifier isviaanexternalsignalinefromthesensor.butiftheekctronics isnotshielded. directradiation tothecircuitboardmayalsopresentaproblem.Assumingfiltering isthesekctedmethod.useahigh~frequency Glter,designedtobkicksignalsupto1GHzorevenmore.Usefemtesandhighfrequency capacitors, Donotrelyonyourlowfrequency GltertotakeoutRF.Attheopamp.youshouMalsodecoupleyourplusandminuspowertogroundattbechip.IfyourgroundiscarzyingRF,youcananticipate thesameprobkmmentioned above,sinceitwillcomtptthereference level.DataLines.DigitaldatalineswiUbeupsetbytheRFproblemasinanakig,buttbelevelsnecessary toupsetarehigher.Instead.digitaldatalinesaretnucbmoresusceptible totransient ghtches.Allsignallinesshouldbe6lteredtopassonlythefrequencies necessary foroperation. Ifthethreatliesinthebandpassoftbesignal,thenshielding oropticallinkswillbeneeded.SwitchedPowerLines.Thisrefersspecifically tothepowerbeingcontro9ed bythecontroller device.Industrial control-lersarecommonlytaskedtocontrolpowertoheavyequipment. wtuch.s;itc. -.hyheavystarting.'oadsandinducnve.a<<wnofTyptcaUYthee!ectronic con:rswitchUnepowerusingrelaysor;;.-.Thisexposesthebackendofthecont;=tosubstantial linetransients. whichcoi-backtothecircuitpowerandgrounddisruptthedigitalcircuitry asshownFigure2.Itismandatory thatthetransient: rentsbedivertedorblocked.since'igitalsystemcannotwithstand t.".e.-.~gtudeslikelytooccurwithaninducuvek:iunlessspecialstepsaretaken.SelfjamniingcanbeUnutedbycontrcliwhenyouswitch!heUne.usingzecrossingdevices.Ofpartic~importanisthemrnoff.sincedtatiswheninductive kickoccurs.lfa6powerswitching usedzerocrossudevices.thetransient levelsinthefactowoukibedramaticaily reduced.Unfor.nately,thatgoaliswelloffinthefutu:Untilthen,expectthathighvoltagepowtransients wlloccur,andtheymustbedewldl.Opticalcouplersandrelaysdonotprovisufficient isolation bythemselves. Ththighcapacitance providesanexcegenthiifrequency path,andiftheyarestackedtinanarray,tbecapacitance wi6adduppasssurprisingly lowfrequencies. The:capocitances an'tbeelim'mated, butyccandesignyowcontrolcircuitstominimizcouphngpathsandtomaximizelowimpe<ancealternate paths.Transient suppressors shouldbeinstalleattbekiad,whichisthesourceofthespihbuttheycanbeinstalled atthecontroUtasweal.Aninterestmg effectoccurswhenconbiningzerocrossingSCRregulators wulowlevelMnsorswhichuselinefrequercnoisecanceHngtechniques. Veryseftsitiv sensorssometimes aresampled.fortJQIL"August a~! i4II' 'f80VACHighCurrentDC,burrouPouerIwlcCarinaPSElectroni>>:s Fir're3.Commonindustnai powe.supply.Figure4.awful:rple groundpaths.enurepoweryc!etocanceitheinefreq'ncyconipohent. Ift..esamp!eoccursco.","u;.ently wi:hirepowersw'.tching onoroif.:heaverage:orhesensorwillbe.pse'..andane.-.or~4"erecorded. SystemDesignandInstallation Once>eelect:onics isdesigned. itbecomesap.oblemof!hesystemintegratar andinstaller:o ersurethatthcelectranics iscravidedwuhtheenvironment farwhichitwasdes;gned. Mostofthcumc.thisworkisperformed bypowerexpertsandclectricians. andtheyarenotalwaysawareof:heintcrfererce probkm.Often,onsite.rhepowerqualityisblamedforthcequip.rrentanomalies. Buttheproblemcanoftenbeavoidedbyfollowing a(ewbasicprina-ples.Theindustrial conuoldeviceiseitherintegrated intoasystemat!hefactoryorinstaL'ed separately onsite.Controllers handleavarictyofdevicessuchasmotorspeedcontrols. positioning devices.weld-ers,etc.fnterferencc presented totheelectronics canbesigniGcandy reducedbyappropriate measuresoutsideoftheelec-uonicsbox.Thereisnowaytoaccurately assessdierhreatwithouttestdata.Butrcgardlcss ofthebr(oration avai!ab!c. muchcanbeaccomplished bycorrectinstagation, anditdoesn'tcostmuchifdoneatthestart.RetroGtsbecomecosdy.especially ifac-companied withfactorydowntime.Let'sconsiderdscsameprob!cmsfromasystemstandpat. Yourgoalistolimittheinterference wfskhmustbehandledbytheelectronics. Directradiation totheelectronics isnotoftenaprobleminanindustrial environ-ment,butitdoesoccur,andmostoftenwithaplasucenclosure. TheNEiMAtypeenclosures provideenoughshielding formostmdusuialneeds.Ifyoudon'twanttouseametalenclosure, besure!ogetelecuonics whichwillwithstand theRFwhichwilloccur.l(oreor'.eh'.heproblemisconducted. eirher'aapowerorgraurd.Theproblemoccursdue:opowerandg.ounddistur-bancescausedbytheequipment. Itisanalltoocommonpracdcetodrawcontroiier powerf;omthesamesourceasfeedsthepowereqtupmcnt. T."ispowermayprovide:herecessary energytodrivetheequip-ment.butitisnotsuitabletopowertheelectroiucs lFigurc3).Hopefully, allindusuial equipment wiUhaveelectronics poweredfromaseparatelowpower120voltcircuit.Itsolvesseveralproblems. First.itseparates theelectron-icspowerfromtheprobablyverynoisyindusu@gradepower,prevendng theswitching transients andstartupsagsfromgenugtotheelectronics. Second,ifitisnecessary tocondition theelectronics po~erfromanextet".Aproblem,itistarcheapertocondiuonthewattsnecdcd(orelectronics powerthanitistocondition thckilowansrequiredbythesystem.Ifpowercannotbeseparated. thenitisnecessary toprovideabu!letproaf powersupply.preferably incbrding anisolation transformer, toseparatetheentirepowersupplyfromtheelectrical equipment. GroundNoise.Groundnoise,inevita-bleinindustrial environments. mustbedivertedfromtheelectronics modu!c.MultiplegroundsinasystemwiGoftenresultingroundcurtentscircu!sting throughthecquiprnent. andgroundnoisecircuhting throughthcelectronics pathwillcausernalfuncuon. Figure4showssometypicalgroundloopsituations. Acommonapproachistodemandasuper~arthground.Thisisgood,butitisnotacureall.andoftenasupergroundcannotbeachieved, nomatterhowyouuy.Howdoyougetasupergroundfromthethird4oor?Therealneedistogct'astablegroundreference toallinterconnected equipments. Ifthisequipment iscloselylocated,thenaverylowimpedance interconnect isfeasi-ble.Powerconditioners areo(tentaskedtoeliminate RFofg.oundnoise...at work,but:heseproblemscanberc.withanisolat:on rant(armer:o =".-..-neutraltogroundnoiseand~~rh"~IIpo;lincGlters.Soyoumaywan:;otryinexpensive approachnrst.DataI.inks.Datalinksaresu.~ngovertheer'.tire!acirty. exposingther.:twoprinciple e((ects.groundraisearepickup.Groundnois>>;willcausedataer.-unlesstheelectronics hasbeendesigne"accornmodatc potential differences of->>eralvoltsormore.Thisisaccampbs; withdif(crential driversandreceivers:f =.mustbedirectcoupled.Optical'hnks-eventually takeovertheselinks.TheotheraspectisRFpickup.Inexpesiveshieldedcableissuitable(ar:.'urpose. Groundborhends!Donotappsinglepointgroundtechniques toRF.i!Iawfrequency groundloopproblem:s threat.thenoncendcanbecapaciuve SummaryIndustrial electronics aresubjected rcharshenvironment. Gooddesignandinst.!ationtechniques willminimiaeproblemsthcGeld.Adhcrencc totheEurope;standards, IEC801.xisagoodstart,ev>>ifyouareonlymarkeunginthcUSA.Bibliography FIPSPUB94,Guideline onElec'ac:PowerforADPInstallauons. Scptcmber 1983,IEC801-2.Electromagnetic compatibilit. (orindustrial. processmeasurement an<controlequipmcnt, Elcctrostauc dischargr requirements, 1984.(EC801-3.Electromagnetic compatibi!it! (arindustrial. processmeasurement anIcontrolequipment, Radiatedelectromag ceticGeldrequirements, 1984.IEC8014,Electromagnetic compatrbilit: (orindustrial-process measuremcnt ar.:controlcquipmcnt. Electrical fast:ransreht burstrequirements. 1984.EMCTest8cDe.<n e industrial Fquipment Equipment GroundBondlng-Designing forPerformance andLifeADiscussion ofGroundConnection Fundamentals toControlEMlByD.B.L.DurhamDytecnaLtd,UKTheproblemofachieving satisfactory earthbondsorgroundconnecuons hasplaguedEMCengineers formanyyears,notonlybecausethebondsareoftenvitalfortheachievement ofsatisfactory equipment pei-formancebutbecausetheyaffectthelongtermperformance ofequipment afterithasbeenintroduced intoservice.Recommendations onbondinghaveex-istedintheformofmilitaryspeciBcations, suchasMilStd1310.Mil188-124AandMil-B.5081 (ASG)forsomeyearsandthesehavegenerally provedsatisfactory formostnewbuilds.However.thesespeci6cations havecertainlimitations inthattheygener-allydonotspectfyconsistently lowlevelsofbondimpedance. norasuitabletestmethod.Theintroduction ofncwEMCspeciGcations inEuropewiththeEECDirective onEMCandtherequirements foriongtennstability inEMCcharacteristics hasdirectedtheUKnuTitarytoreviewcidsutlgspcciEcaQons andIntroduce ancwDefenceStandardtotightenupperfonn-ancerequirements fornurttaryequipment. DcfStan~(Part1)/1hasbeenintro-ducaltoaddressthiaareaasfarasmob9eandtranspottablc canmunications installa-tionsareconccnteia. buttherequirements shouklhaveimplications inindustrial apph-cationsandoverthewlxHeekctronics marketiflongtermproductperformance istobeguaranteed. BondDegradation EarthorgroundbondsaregeneraHyconsidered essenualnotonlyforsafetyreasons.butasameanofdiverting EMcurrents, "locking" circuitboardsand38eqtdpment toastablegroundpoint.achiev.ingadequatelevelsofcabkshiekhngandformanyotherreasons.Manydesigners un-derstandtherequirement forshort.fatbondleadstominimiacgroundinductance, butfewappreciate thatacriticalaspectistheconnection resistance withwhichthebondstrapisattachedtotheequipment groundpoint.Thcbasicrequirement ofanybondisthatitshouldhaveaslowanimpedance aspossible(uille55itisadchbcratc induc-tivebondtolimitgroundcurrents). Tbeimpedance isacombination oftheresistive andtheinductive components. Thcresis-tiveelementisafuncnonofthcbondstrapresistivity, crosssectional areaandlength.seeEquation1.whihttheinductive compo-nentisamorecomplexfunctionofthcbondstrapcharacteristics asshowninEquation2.R~-qf0AL-~ln-+05+02235-jiZ,j'fb+c"2icLb~c2fJ(2)whereRresistance, g~resistivity, f>length.A~area,p,pcrmeabiEty offreespace,L~inductance. p~feLttivcpermcabiTity, bstrapwidth,andcstttpthickness. Thefrequency atwhichtheinductive ekmentdominates theimpedance expres-sionwhencalcu!ating thctotalinductance is,fromEquation3,typically 1kHs.ltwglbeseentherefore thattoalintentsand"purposesthcbondexceptatDCandpowerfrequencies, maybeassumedtobeaninductance. Atveryhigh~equencies:r straycapacitance acrossthestrapdonunate. Thismeansthatthevolt"-:acrossabondisgeneraily afuncuoninductance andfrequency. BasedonOhr.".LawthisvoltdropisshowninEquador.~Fortransients thevoltagedropisgiver..Equation5.ZRt+cutLSVIZ~jauUd1dt(5whereZ~strapimpedance. cu~tacomafrequency, V~voltage,and1~current.Fromthis.thehigherthcinductance thmoreisolatedthecircuitorboxbecomefromground.Thscanhavesigru6can effectsoaequipment. inchdingenhancementofnoiseinjecbonontoarcuits,reduc=nonofSterperformance, andlossoicoaunlmication range.FromaTEMPESTstandpoint itmayresultinmoreradiation fromemanent.ltwouldseemfromthisthatthecntcriatoranybondistheinchlctancc andhencethcchoiceofshortfatDavidDuganservedfor21yeanitttheBrrtiabAnny,wherehcgainedhisChgreeiadectricaf cnginceting. Afterserviceinavarietyofappointments hcretiredtojointheRecalls'ES companyastheTechmca/Mtnsgcrrcspottsiblc /orthecfes/gnanddevclopnsettt ofcommctttication systems.fn198$hejainefDytecnaastheiManagerofthe&ginecnttg Division. andnowtscurrcntfy Tchtaica/ Marftcting Manage..JulytAugust !991 5P sc';orc(cgq(r~rri.~~~cwc"-av~l-l'sis~fNf$QskgRrrfNT'N,ff'Srnryort:4icsir:i.rrenl ',:!0iQA.osJVA5Hf5rrlltfRscarc5errVOUAGE&ifASI'REhlENTFigure!.Bondresisurce. Figure2.Fourwirebridgemethod.bondstraps.However.ananaiys'sof:hebondinductancf showsJiatI'orabondstrapof100mm!org,15mm~~deand2mmIhcktheimpedance at1MHawillbe3.8Ohms.Itsoundsextremely sin:pie.butworkperformed in'.heUSA'ndI:Kshowsthatifanetrotismade'inthewaythestrapisternunated thenaprogressive increasein:heresisunce ofthebondstraptoboxjuncnoncanoccurastheequipment ages.Eventuaily theresisunce willbegintoexceedhundredsofohmsandmayeventu-allygoopenccuit.Thiscannegatethceffectofthebondstrapcompletely aspartoftheE!rIIprotecdon. tVhathappenswithbondstocausethischange!Essentially agroundconnecuon isaseriesofirrpedances fromthcstrapthroughtothegrourdmaterial, asshowninFigure1.Eachpointofcontactcontrib-utestothetotalbondper'.onnancc;. Asaresult.achangeinanycontactcondition canresultinachangeinthetotalbondresistance. Asisweilappreciated, the"contactresistance betweentwometalsur-facesisahnctionofthepressure. Thepressureexertedbythetipofadrawingpinisvastlygreaterthanthatfromthethumbpressingbyitself.Thusthecontactfromasharppoultgivesatsochhigherprcssuret.'unaOatpointand4gtiforclowercontactresisuncc. Measutetata haveshownthatsharppointsenableContactrcsisuncc ofafewnicroohmtobeachievedwhilstsimilarpressures onOatsurfacesresultinmil-liohmsofconuctresistance. Itmightbefeltthatthereislittleornodifference betweenthesevalues,butinrealitythereis.Anessennaiaspectofagoodbondisthatitshouldremainsoaftertheequipment hasenteredusc.Highpressures alsohavetheeffectolsqueesing outcorrosive materi-alsandinsulating 6lms.TheformercausesEMCTest&Designprogressive degradation ntbonds,whilstthelattercanreducetheef'ciency ofthebondf;omthemomentitisinstalled. Itisparticuiariy important incommunications systems,where6ltersareinsuiiedandshieldedcableternunations aremadeJiatthebordsareof',owresistance andreuintheirperfonnance. BondPerformance andMtaalaremcnt Experience hasshownoveranumberofyearsthatforlongtennconsistent bondperformance alowvalueofresistance mustbeachieved. Thisistypically 1-5milhohms. InDefStan~(Part1)/1thevahiehasbeensetatamaximumol2miUiohms. Thislevelismeasuredthroughtheindividual bonds.Thclogicbehindthislevelistwoloid.Firstly.experienc hasshownthatwithcommunicaions equipment inparticu-larthisvalueolbondresisunce isrequiredifconsistent performance istobeachievedintermsofreception ef6ciency andtrans-missioncharacteristic. Thisisparticularty soforTEMPESTprotected equipments. Tbesecondpointisthatifthebondhasahigherresistance thenthereisasigni8cant likelihood thatprogressive degradation willoccurandthebondresistance wigincreaseinvalue.Therewillthenbeaprogressive lossinperfonnance. Themainproblemwithmeasuring bondresistances isthatitshouldbcmeasuredusingalowvoltage/curtent tcchtilquc, Moattechniques todateforassessing safety'nvolves drivingalargecurrentthroughthebond.Thischecksthebond'sabiRtytocarrycurrentbutdoesnotnecessarily checkitsEMIprotection perfonnance. Therea-sonisthatmanybondsmaywheninnormalusehaveahighresistance duetooxideandgreasy6lms.butwhensubjected toahighcurrentthclayersheatupandarevapo-rised.Afterthecurrentisremovedt.".eSmcanreturn.Thushighcurrerttechmques arenotrecommended ror:esang EMIbonds.ThenewDefenceStandardintheUKspeci6esamaximumprobevoitageoi100mictovolts. Thisreprcsenu typically aprobecurrentol50milliamps undershorcitciit(<1mQ)condiuons. This-:sinsuf6cient todestroysurface5lms.Thechssicmethodformeasuring lowresisunce hasbeentouseafour:erminal bndgeasshowninFigure2.Inthiscase'thecurrentisdrivenbetweentwopointsandAeVOltageaCtOSStheSampleiSmeaSuredwitNahighresisunce probe.ThisremovesJiecfcctsotthcptobecontactresistance andleadresistance. Thisisgenerally consid-eredtobealaboratory methodastheuseoffourcontactscanbeawkward.Iftheleadresistance canberemovedbyacalibrauon teclniquc thenthcfourterminals maybereplacedwithatwoterminalsystem.hfurtherpossiblere6ncment tothetecluique istouseafrequency thatisnotDCor50/60/iOOHx. Inthiscase10.4Hahaabeenchosen.Ifanactive6lterisusedtoSterouta9otherelectrica noise,thenitisposgblctousethebondresistance meteronpoweredupsystems.Itisworthnotingthatatthisfrequency theimpedance iastolhtgclyrepresented byresistance ratherthaninductance. ThetwotermmalmethodisshowninFigure3.Theintroduction ofnewEMC/EMIspcci6cations inEuropehasmadeitmoreimportant thatoncemadethebondshavecoilslatentlong'tcrlilperformance. Thsmeansmeasurinonperiodicinspecnon ardaRctmaintenance. Itisanessential aspectofinsutmgconsistent perfonnance. IthasbeenshownthatwithinmonthsapparenJygoodbondscandeteriorate to.-ighresis.

AAeqT~ic'oKue45uI>eNr eiieootsisascg0FIXEDRKSlSTANCE LEAOSFigure3.Twotermmalbridgemethod.404y4Ic<~~4cc>~~~c~(olnpi4lllA Q~+c~~(4eeoc4((i+yo~befit%CUSTOMQAG Ti4.++++"9t~o'4+a~~>tiQNCQMNCRfAC.0odgottc~'e+b~+.=nuators, CoaxialTerm.%/@<y<c<4~connectors, ~4.~b,~Cata~pc+q4.attestlE11?0-1?bnCOlnAvenue.FOlbrOOk.;4Y 11741(S16)~85.)4tX1 FAXi16.~BR>l14INFO/CARO 29tance.Ther.io.e t.'ivcesii'-.~suo)ecttotestingand.xa.-..;.-.a:.cn-asama:ntenance tas~.LK~military Experience Therehaveoeen'.wo~lcr-.::causedbypoorbonusexpenence degradauon .nericrmance ~ready-uonedin:tusa.-.icle. The:ossi;cir,-cationrange.poorEMlpe.",'ormance othereifectsaL'onrnbu'.e toacons:dert reduction mequi".-..ent Nc:encyanna.ability.Thesecordei;ectwnichis-.difficult todenufy:s:hat aiNoFaultF.(NFF)problems. AnanalysisofreN'."failuresfrommilitaryreiiaLiity data.shownthatNFFinc:dents canaeextre.-.high,particulariy:n hunud;timates. hasbeenpartially confirtned byreports.':theGulfSarwhenaHforcesrepor-.e. increaseinavailability ofequipmen: .;.'rierclunate.Manyfau!tsaredueto"electrica contactsinconnectors. bu:alarnumberhavebeenidenufied asexcess:EMIinducedthroughpoorgroundonncThismaybecausedbyeitheraloosegroistraporconnector terminauon to:he':cAsignificant improvement Inequipmeavailability andperfonnance isexpec:ewhenmorerecentstatisucs areanalysed. Theintroduction:nto theBnushAr.-.serviceofAeDyteaaBondResistanc TestSet-DTl09hasenabledtheL":mihtarytomeasurebondresistances installed equipment andreduce;he curancesofNFFerrors.TheUKmi:armeasurement procedure usesatwo:er-...: nalbridgemethodandanaccuratemiiliohmcalibration star.dard.Thismeasurementprocedure andequipment isalsinusebyotherNATOnationsande!sewherebyiniTitary andnavalforceswrohavrecognized thesameproblem.Cottclueiotta Theproblemswithgroundbondshavebecomesignificant withthedevelopment o:sensitive andsecurecommunications equi"-ment.Thiscoupledwithanincreasing reedtoachievehigherandhigherlevehofKMfprotectiwt hasleadtoanincreased emphasisbengplacedontheeffectiveness ofalltypesofsystetttgrounds.These.furthercom-binedwitharequirement toensurethelonglifeofsystemsonceinservice.haveresultedintheassessment thatbondsandterminations areoneoftheprimarycausesofEMfaBuresinsystems.Therequire-menttotesttheseisclear.howeverthemeanstodosohavenotalwaysbeenavailable toengineers. July.Aug.st '.9o'.

PanelSessIonPESSummerMeeting,JulylQ,1988LongBeach,CaHfornia JohnG.Kappenman, ChairmanPowerSystemSusceptibility ToGeomagnetic Disturbances: PresentAndFutureConcernsJohnC.Kappenman, Minnesota PowerTheeffectsofSolar.Geomagnetic Olaturbancea havebeenobservedfordecades.onpowersystems.However,thepro-foundimpactoftheMarch13,1989geomagnetic distur-bancehascreatedamuchgreaterlevelofconcernaboutthephenomena inthepowerindustry. Severalman.madesystemshavesufferedd)eruptions totheir-normaloperation d)aatotheoccurrence ofgeomagnetic phe-nomena.Moatoftheman~esystems,suchaacommu-nications, havebrettmadelesssusceptible tothephenom-enathroughtechnological evolution (microwave andfiber-optlchavereplacedmetall)cwiresystems). However,thebulktransmission system,Ifanything, ismoresusceptibl ~todaythaneverbeforetogeomagnetic disturbance events.Andlfthepresenttrendscontinue, itlalikelythebulktrans-missionnetworkwillbecomemoresusceptible Inthefuture.Someofthemostconcerning trendsare:1)Th>>transmission systemsoftodayspangreaterdistances ofearth-surface-potential whichresultIntheflowoflargergeomagneticaily-IEEEPowerEalineeciag Review,October1989Induced.currentsinthesystem,2)theinterconnected sys-temstendtobemorestressedbylargeregion-to.region transfers. combinedwithGICwhichwillsimultaneously turneverytransformer inthebulksystemintoalargereactivepowerconsumerandharmoniccurrentgenerator and3)ingeneral,largeFHVtransformers, staticvarcompensstors andrelaysystemsaremoresusceptible toadverseinfluence andmicroperation duetoQIC.TRhNSFORMER OPERhTION TheprimaryconcernwithGeomagnetlcally-Induced Cur-rentslatheeffectthattheyhaveupontheoperation oflargepowertransformers. ThethreemajoreffectsproducedbyGICintransformers Ia1)theIncreased varconsumption ottheeffectedtransformer, 2ltheincreased evenandoddharmon-Icagenerated bythehalf.cyclesaturation, and3)thepossi-bilitiesofequipment damagingstrayf)uxheating.Asisweildocumented, thepresenceofevenasmallamountofGICI20empaorless)wNcausealargepowertransformer tohalf-cycle saturate. Thehaif~c)esaturation distorted excit-ingcurrentlsrichlnevenandoddharmonica whichbecomeintroduced tothepowersystem.Thedistortion oftheexcit-ingcurrentalsodeterm)nes therealandreactivepowerre-quirernents ofthetransformer. Thesaturation ofthecoresteel,underhaif~c)~saturation, cancausestrayfluxtoen-terstructural tankmembersorcurrantwlndlngswhichhasthepotential toproduceseveretransformer heat)no.15 tI tr:rscsŽrr ei'-ryes.-e'io:est'esul!Strct~:ste'.na;StogieCnaSesr5.'"r-..erS;ai'CVCle SaturatemuCnmereeasilvano!04-"cngreatercegree;han ccrricarable .;nreeonaseunits.."ese:.ansformers producehighermag.nnucesofharnonicsand"orsume!arger amountsofrese-!rvepowerwhencomPareOwiththreephasedeslgnS.ItELhyHANDPROTECTIVE SYSTEMS>herearethreeba5icfaitiremodesofrelayandprotective Svs!ems:nat canoeattr:buteo toggeomaghetic distur-bances:r~u~>>~neear!:id,<<3g.4!'4C4drageonag,"et.'c stormswhen!heyare--4,~de~~"~SUNSPOTCYCLEShNDGEOMAGNETIC DISTLRBhNCE CYCLESOntheaverage,solaractivity. asmeasuredbyt."enuroer".monthlysunspots. followsan11yearcvcl'e.he"esen!sunsootcycle22haditsminimumtnSeoten.oer 1986.a."cisexoectedtooeakin1990-1991. Geomagnetic 'elao5~tvrbancecyclesdonothavethesameshaoeas:nesunscotnumbercycles.eventhOughtheyarecyclical. FSure1snowsthenatureofthesunspotnumbersandgeomagnetic 3C!i"".v~.alseOperation of:."eprotection system.suchashav-ingOCCurreOrOrSVC.CabaCitar andlinerelayOpera-tionswhere:te!towofharmoniccurrentsaremisin-:erpreter2 OVthereiaVaSaraultOrOVerlOadCOnditicn. Thisisthemostcommonfailuremode.~FailuretoOperatewhenanoperation isdesirable, thishasshowntobeaproblemfortransformer differential protection schemesandforsituations inwhich;heoutputofthecurrenttransformer isdistorted. ~SlowerthanDesiredOperation. thepresenceofGlCcaneasilybuilduphighlevelsofoffsetorremanentttuxinacurrenttransformer. ThehighGICinducedoff-setcansignificantly reducetheCTtime.to.saturation foroffsetfaultcurrents. 4uit'ocrorC(rtworts Cctrsrrrrapr25SurtsIre4 i431~1444Cyclei7CyclelaCycleiaCyote20Cyci~21iIr~)40;120lirumoereliOlslureetd OdyVyear150tISuitspoiHumber~00IIiiIii)IrIIl00j50j,~~d0Iidei40I~20~~.~014540uiII\!40035eecSMostoftherelayandprotective systemmisoperations thatareattributed toGICaredirectlycausedbysomemalfunc-tionouetotheharshharmonicenvironment resulting fromlargepowertransformer half-cycle saturation. Currenttrans-formerresponseerrorsaremoredifficult todirectlyassociate withtheGICevent.ForexampfeinthecaseotCTremen-encc.theCTresponseerrormaynotoccuruntilseveraldaysaftertheGlCeventthatproducedtheremanence. Therefore. thesetypesoffaituresaremoredifficult tosubstantiate. 50554045707540Figure1.Vaitstfons oftheYearty-Averaeed SunspotNumberenidQetsmaenettealty Olsturbed Oaysfrom'1932-1SBB. cyclesfrom1932to1988i2,3l.Notethatthegeomagnetic dleturbanCe CyCleeCanhaVeadOublepeak,OneOfWhiChCanlagthesunspotcyclepeak.Whilegeomagnetic activityinthepresentcycleisexpectedtomaximizeinapproximately 1993-1994, severegeomagnetic stormscanoccuratanytimeduringthecycle;theK-9stormofMarch13,1989wasastrikingexample.CONCLUSIONS AsevidentbytheMarch13thblackoutintheHydroQuebecsystemandtransformer heatingfailuresintheeasternUS,thepowerindustryisfacinganimmediate andseriouschal-lenge.Thepowerindustryismoresusceptible thanevertotheinfluence ofgeomagnetic disturbances. Andtheindustrywillcontinuetobecomemoresusceptible tothisphenome-nonuntessconcenedeffortsaremadetodevelopmitigation techniques. EhRTHQURFhCE.POTENTIhL hNDGEOMhGNETIChLLY.INDUCEDWURREVTS Theauroralelectrojete producetransient fluctuations intheeanh'5magnettcfieldduringmagneticstorms.Theearthisaconducting sphereandportionsofftexperience thistime-varyingmagneticfield,resulting inaninducedearth-surface-potentlal lfSP)thatcanhavevetueeof1.2to8volta/kmt2to10volte/mile) duringseveregeomagnetfc stormsinre-gionsoflowearthconductivity l4),Geomagnetic Disturbance CausesAndPowerSystemEEectsflectricpowersystemsbecomeexposedtothe8SPthroughthegroundedneutralsofwye-connected transformers attheoppositeendsoflongtransmission lines,aeshowninFigure2.ThefSPactaaeantdealvoltagesourceimpressed be.tweenthegroundedneutrateendhasafrequency ofonetoafewmittfhene. Thegsomagnetlcally-fnduced currentslGIC}arethendetermined bydividingtheESPbytheequivalent dcresistance oftheparalleled transformer windingsandlineconductors. TheGIClssques%tract current,andvaluesinexcseeof100empersehavebeenrrNaeured intransformer

neutrals, VernonD.Albettsw2 University ofiiIJnaaota POWERSYSTEMEFFECTSOFGICThepsr.phses GlCinpowertransformer windingscanbeIEEEPowerEngineering Review.October1989SOLhRORIGINSOPGEOMhGNETIC STORMSThesolarwindiesrsrffiedplasmaofprotonsandelectrons emittedfromthesun.Thesolarwindfsaffectedbysolarflares,coronalholes,anddisappearing filaments, andtheso-larwindpanicleeinteractwiththeeenh'emagneticfieldtoproduceauroralcurrents, orauroraletectrojste, thatfoltowgenerally circularpathsaroundthegeomagnetic pate!atal-titudeeof100kilometers ormorel1).Theauroraborealisievisualevidenceoftheauroralelectrojets inthenorthernl6 1~

44~Inaia.sat~tat.ah n-richI:.tarsgr~ersauseclaymisoperat ontet~44Al=.sr~ti.RFACS~I~9T-SARvii-SuRFACS <T5hti41. ~t'igui~2.Induced5aich.Surtact-Poitntial ISSP)Producing Qtamtg.htticaliy InducedCunehisIQICIinPowerSytttmt.io.aimanytimeslargerthan:heRMSacmagnetizing current,re-sultinginadcbiasaftransformer coreflux,asinFigure3.IIlo,plI~REFEHENCES1.Akasatu.S.I"TheOyhtmiCAurcra,'ciehutCAme":~Mageziht. May1989.pp.90972.Jactlyh.J.A.."Reel-Time Ptedicuch otGfcbalGoonagrtiActivny,SaltrWindMagnetosphere Cauphi'g, "p.141.TarrtSciehuflc Publishing Company.oxvo.'986.3Thompsah. R.J.,"TheAmplitude atSaiarC.cie22,RiidiaehdSpaceSewiciisTtchhiCal ReportTR8703,ctcbti1987.4V.O.Albertgan ehdJ.A.VthBatten,"Utcuicphdhlaghe.;i FieldsatthtStnh'sSurfacedutioAurartlCunenls." i55iTcahaaCIiohs ahPowerApparatus andSystems.Val.PAS39hia.2.April1970.pp.578-584.5.J.Q.Kappehmtn, V.O.Albtrtaon. 9.Mohan."CurserTrahatarmtr ahdRelayPtrtolmtnCt ihthePresenceotGtcmagnetically InducedCurrents." ISEETriiheactians ahPawe~Apparatus ahdSystems,Vai.PAS.100.No.3,pp.1078-1088.March1981.TheHydro-Quebec SystemBlackoutOfMarch31,l989<<ICI<<r~Rgurt3.OCBtt!afTrtntfarmtr CartRulcOuttoQIC.Thehalf.cycle saturation oftransformers onepowersystemisthesourceofnearlyalloperating andequipment problemscausedbyGIC'sduringmagneticstorms.Thedirectconse-quencesafthehalf-cycle transformer saturation ere:~Thetransformer becomesarichsourceofevenandoddharmonics ~Agreatincreaseininducttve versdrawnbythetrans-former~Possibledrasticstrayleakagefiuxeffectsinthetrans-formerwithresulting excessive localized heating.Thereareanumberofeffectsduotathogeneration ofhighlevelsofharmonics bysyatimpowertransformers. includ-ing,Overloading otcapacitor banda~Possiblerntsaperottan ofrelays~Sustained overvoltogos onlang.lineenergizattan Highersocondory arccurrentsduringsingle.poleswitching .~HighercfratffCMakerrecoveryvoltage~Ovorlaadtno ofharmonicfttfyrsofHVOCconverter ter-minals,anddtotantan intfioacvoltagewaveshapethatmayresultinlossotdcpowertransmission. Theincreased tnductfvo voradrawnbysystemtransformers duringhalfwycl~soturat)an aresufficient tocauseintoler-abtosystemvoltagedepression, unusualswingsinMWandMVARflowontransmission linea.andproblemswithgener-atorvarlimitsinsomeinstances. Inadditiontothehalt-cyclo saturation otpowertrans-formers,highlevelsofGICcanproduceadlstarted responseIEEEPowerEngiaeerintf Review,Octoberf989DanielSaulier,Hydro-Quebec OnMarch13.1989.anexceptionally intensemagneticstormcausedsevenStaticVarCarnpensators ISYC)onthe735-kYnetworktotriporshutdown.Thesecompensetors arees-sentialforvoltagecontrolandsystemstability. Withtheirloss.voltagedroppedandfrequency increased. Thistedtosystarttinstability andthetrippingofalltheLaGrandetrans-missionlinestherebydepriving theHQsystemof9500MWofgeneration. Thoremaining powersystemcallapsed withinsecondsoftholossoftheLaGrandenetwork.Thesystemblackoutaffected~itbutafewsubstations isolatedantolo-calgene~sting stations. Pawerwasgradually restoredoveraninehoursperiod.Oe-leyainrestoring powerworeencounterea becauseofdam-agedequipment onthoLaGranden>>twarkandproblemswithcaidloadpickup.SYSTEMCONDITION PRIORTOTHEEVENTSTatalsystemgoneratfon priortotheeventswas21500MW.mastofitcomingfromremotepower-generating stationsatLaGrande,Mantcouagon andChurchf8Felts.Exportstoneighboring Systemstotalled1848MWofwhich1352MWwereonOCinterconnections. The735-kVtransmission net-warkwasladedat90%ofttsstability limft.SEQUENCEOFEVENTSAt2:45o,m.onMarch13,averyintensemagneticstormtedtotheconaequortttal trtporshutdownofsevenSVC's,Contafnlng thoimpactofthoeventthroughoporatarinter-yentionwasimpassible attSVC'ahavingtrippedatcaaaodtofunctionwithinoanominuteperiod.Afowsecondsl8-8s.)aftertholossaftholastSVC,~IIfive735.kVlinesoftheLoGrandetransmission netwarktrippedduotoanoutofstepcondition. TheseItnetripsdeprivedthesystemot9500MWotgeneration andsubsequently tedtoacamptetosystemcattapao.17 1\ iO~:ecuonancere~airir9'curSVC'ssnotsownovcaoactor~oitageuncaiance prctec::o." >>aivsisotvootageanocur.rentosc:itograms taxenat:neCtioougamau sitebeforetneSVCtnpssnowedtne'.oitowing narmoniccontents. .wC,hCCurrentarl6kyHarnaiiic VcliageOrderat.35kyTCABraccheTSCBrasche100'"o1OO3'ioa~Iifo3~o'Ã"9ofIOof5OofI~3~oI00~o36~o24~}6~o5%16ifoaffQuasiDCcurrentsgenerated by:hemagneticdisturbance, saturating intneSVCcouplingtransformers arethoughttobethecauseforsuchatargesecondharmoniccomponent ofcurrantintheTSCbranch.DIsturoances OnPoiyerTransformers HooertJHingjceJamesB.StewartPowerTechttoloip'es Inc.Thisdiscussion addresses theeffectsofgeomagnet:c cistii"oancesonpowertransformers. Theprimarveffect:scuetccoresaturation resulting!rom geomagneticaltv incuceacr~rents.GICs.Coresaturation canimooseseveretemoerature problemsinwindings. ieads,tankplateanastructurai mer.-barsoftransformers andplaceheavyvarandharmonicoi.r~densonthepowersystemandvoltagesupportequiprriant. GIC'sof10to100amperesaremore:henmerenuisances inthaoperation ofpowertransformers, thernanr.erof!Iowcanresultinsaturation ofthecoreandconsequent changesinsystemvarrequirements. increases inharmoniccurren.magnituctes. increased transformer strayanaeadytosses.andproblemswithsystemvoltagecontrol.GENEAhLOBSEAVhTIONS ONTHESYSTEMBEHhVIOAThesystemblackoutwascausedbylossofallSVConI.aGrandeNetwork.SevenSVCtrippedorstoppedfunctioning. PriortoandduringtheeventalltheOCinterconnections be-havedproperly. Norelayfalsetripsormisoperation ofspecialprotection systemswereobserved. Telecommunications warenotaffected. Noequipment damagewasdirectlyattrib-utabletoGICbutoncethesystemsplit,someequipment waadamagedduetoloadrejection overvoltagea. RF'VIEDIhL hCTIONSThKEViSincetheevent.thefollowing actionswereimplemented: ~SVCprotection circuitshavebeenreadjusted onfourSVC'ssoastorendertheiroperation reliableduringmagneticstormssimilarworkisbeingperformed onthefourremaining SVC's,~Energy,MinesandResourceCanadanowprovidesHy-dro.Quebec withupdatedforecasts ontheprobability ofmagneticdisturbances. Thaaoforecasts areusedbytheSystemControlCenterdispatcher topositionthetransmission systemwithinsecurelimits.~A.C.voltageasymmetry iamonitored atfourkoylo-cationsonthesystem(Bouchorvitto, Amaud,LG2,Chhtgeaguay). Upondetection ofo3%voltageaaym-rnetryatanyonalocation, theayotomcontrolcenterdispatcher iaalarmedandwillimmediately ta'koactiontopositionsystemtranaforlevelswithinsecurelimitsifthishaan'talreadybeendanebecauseofforecasted magneticactivity. OPERhTING LIMNIDURINGMhGNETICDISTURShNCES (hNDhLERTSITUhTIONS) Thefallowing operating limitsarenowbeingappliedt~10%safetymarginshallbeappliedonmaximumtrans-ferlimits.'Maximumtransferlimitsshellnottakeintoaccountthoavailability ofstaticcomponaators deemedunreliable. ~AdjusttheloadingonHVOCcircuitstobewithintho40%to90%,orloaa.ofthonormalfullloadrating.l8CICEFFECTSVERSUSCOREhNDWIIOoDINC COiVFIGURhTIONS Principal concernsinthisdiscussion areforEHVsystemswithgroundedYtransformer banksproviding conducting pathsforGICandzerosequencecurrents. Coraandwindingconfigurations responddifferently tozerosequenceopen.cir-cuitcurrentsendtoGICa.Note:aausedhere.theterm"opencircuit"refers totestsperformed withalldeltaconnections openedor"broken." Forexample,thethree.phasethreelegcoreformtransformers arolesspronetoGICinducedsatu-rationthanthree-phase shallformtransformers. But.bothcoreformandshellformsinglephasetransformers aresus.ceptibl~toGICinducedsaturation. Windingandleadarrangemanta responddifferently toGICinducedcoresaturation aawell.Forexample,thecurrentdis-tribution withinpareil~Iwindingpathsandwithinlowvoltageloadsdependsupontheleakagefluxpathsandmutualcou-pling.Loaaeawithinwindingaandleadsmaychangesignifi-cantlyunderGICinducedsaturation owingtothechangeinmagneticfieldintensity. H,andtheresultant changesintheboundaryconditions fortheleakagefieldpath.EDDYLOSSESINSTEELMEMBERSThechangesinthemagneticintensity. H,andthemagneticboundaryconditiona resulting fromtheGICexcttation biascanincreasetholoaaoainsteelplate,thelossesforfieldsparalleltotheplaneoftheplatoincreasenearlyaathesquareofH.Notealsothattheleveloflossesincreaseapproxi~matelyaathesquarerootofthefrequency otH.owingtotheeffectofdepthofpenetration. Thomagneticfieldalongyokeclampsandlegplatesincoreformtransformers andinTeebeamsandtankplateInahoNformtransformers closelymatchesthomagneticgradientlnthocore.Areasofthetankandcoreclampsaresubjected tothowindingleakagefield.Ifthecorosaturates, themagneticfieldimpressed uponthesteelmembersmayrisetontoonehundredtimesnormalduotothesaturation andtheoffoctooftheleakagefield.Theloaaoointhestoolmomborowillriaohundredsoftimesnor-mal,evenunderhalf-cycle saturation. Onthosteelsurfaces. eddylosedensitymoyrisetontothirtywattsparsquareinch,approaching thethermalfluxdensityotan~lactricrangeele.ment.Surfacetemperatures riaorapidlywiththisthermalfluxandcanresultindegradation ofinsulation touchingtnesteelIEEEPowerEatpaeeriag Review.Octoberl989 r DestgnOcftcfencyOcllrlentvendoraafma1UPShaSnobatterytestCII'CUItVendornaINIa1naintenancesectloAdocsAOIQCAtIOAbatteries. DesignDeficiency Battefies havenotbeenreplacedin6ycafsDesignDeficiency ACinputtologicpoucrsaltyisnaihtchahcc preferred Backupbatteries degradedordeadk.Srelaycharactertst-ICSPfCveAtStransfertoinverteroutput.BreakerffcIctionperdesignGroundfaultoccursonBphaseofaaintransfofncr Voltagctraflicnt oAstatloflACpouersteeplyACpouertologicnoduleforUPStA.D,G cspcrIchccs thetransient outpu'IvoltagegoestoulogictripsOApoucrSISIPtyfailure.2VSSUPStA,S,C,O,GtripBreakersCS-I,23open;Ch-Cdoesnotcloseupsloadsdohotautotransfertomint.supplylossofallloadsonUPS1AD,riFault1$clcafcdin6cycles;transfercocptetcd in12cyclesPernisstves prohibItCSCbreakerfrozeclo>IngCS'4ncsvh<toIfunsfernaIntsullplytolnvcltcfoutput r 1.StaticDCtestingwasperformed onindividual chipsfromtheeffectedcircuitsinordertocharacterize Latch-upsusceptibility. Statictestingisperformed withfixedvoltagesettings. Thetestingwasperformed onthe4049,4011,4044and4068devices.Thetestschemeincluded: A.OutputvoltagebelowVss(Vssisthegroundornegativepowersupply).B.OutputvoltageaboveVdd(Vddinthepositivevoltagepowersupply).C.InputvoltageaboveVdd.D.Powersupplyovervoltage. Vss>>VddThetestingrevealedthatpermanent physicaldamagewasinducedbytestsCandD.TestBdidnotinducelatch-upbuttestAconsistently inducedlatch-uponthe4049andathighervoltagedifferentials ontheotherdevices-The4049wasquitesensitive tothistest.2.VoltageDropouttesting,wheretheVddwascutoutandrestoredduringtimeperiodsrangingfrom20mSto2secondsdidnotresultinlatch-upbehaviorontheindividual components. A"breadboard" testcircuitwasfabricated tosimulateatypicalcircuitpath,i.e.a4044latchdrivinga4049invertordrivinga4068gatedrivinga4011gatedrivinganMC1615lampdriver.Slowratedropouttestingofthetestcircuitdidnotresultinlatch-uporotheranomalous behavior. 3.Boardleveltestinghasbeenperformed ontheA13A21cardsf'romUPSunitsA,BandG.Astockcardhasalsobeentested.Atestfixturewasfabricated toholdthecardsandsupplypaverandinputselection andoutputmonitoring. AnMC1615lampdriverchipwithLED's(lightemittingdiodes)wasconnected tothecardoutputs.Staticboaeftestingrevealednoanomalies ontheAcard,adamagedU104049oNtheBcard,Noanomalies ontheCcardandafailuretoset,anyofthe4044latchesontheGcard.(Notethatlatchingofthe4044chipsisnormalwhilelatch-upisanabnormalcondition.) The.functional failureoftheGboardhasbeentracedtotheKlrelayand/ortheSW1resetsvitchonthecircuitboard.Failuresimulation testingonthefunctional Aboardhasrevealedthatthelightingpatternreportedduringtheincident, wherothelampsonthecardwereextinguished and"downstream" lampsremainede

illuminated, hasbeenduplicated bysettingthePSF-notlatch,loweringtheDCvoltagetoapproximately 4VDCandlifting(floating) theDCgroundforseveralseconds.IftheDCvoltageremainslowafterthegroundfaultthelampsontheboardwillresetandtheexternallamps(UPSfail,LogicfailandtheSSTRlines)willremainilluminated. Thesimulation conditions areunlikelytobethoseofthefailureevent,however,ithasbeendemonstrated thattheboardcanoperateinanthisillogical state.Amorecomplicated failuresimulation (approximating theactualevent)mayproducethesameresults.4.HighSpeedtransient. testingonthepowerlinesisplannedanddelayedpendinglaboratory analysisofthedegradedsamplesdiscussed inthefollowing section.MC0A.NEGATIVEVOLTAGEONTHEOUTPUTOFTHE4049MILLINVARIABLY CAUSELATCH-UP-INJECTING NEGATIVEVOLTAGEINTOTHEOUTPUTISIDENTICAL TORAISINGTHEGROUNDVssABOVETHEOUTPUT.B.THEINITIALFAILURECONDITION INTERMSOFTHELAMPSETTINGSCANBEDUPLICATED UNDERUNLIKELYCONDITIONS ANDMAYBEPOSSIBLEUNDERMOREPLAUSIBLE CIRCUITCONDITIONS. Thefollowing sampleshavebeensubmitted forlaboratory analysis: 1.Onebatterypack.Batterypack1fromUPS1C.n'.Two(2)integrated circuitsfromafailedA20card.A4049anda4011.3.AfailedU104049fromtheA13121,UPSBcard.4.TheU104049fromtheA13A21cardsfromUPS'sAandG5.TheUPS6KlrelayandSWlswitch.Thefollowing resultshavebeenobtained. 1.Two(2)oftheThree(3)batteries fromUPS1Cweredriedout.Waterwasaddedandchargingdidnotresultinrecoveryofthecell.Itisconcluded thatthecellfaileddueoldagewearout.Analysisiscontinuing ontheothertwo(2)cells.2.The4011fromtheA20cardiselectrically good.Internal IJ~~I ~~~lj~.inspection oftheDierevealednoanomalies. The4049is'electrically bad.Acatastrophic failure.Internalinspection ofthedierevealedseveredamagecenteredontheVssandVddpowerlinesandseveralinput/outputs. Theinitiating overstress wasintroduced ontheVddorVsslinesasindicated byarc-overdamageacosstheoxidebetweenthetwopowerlines.3.Electrical testingoftheU104049fromA13A21,UPSBrevealedthatitwasnotfunctional. Internalinspection ofthedierevealedafusedaluminummetallization linetoonepartoftheinternalcircuitry. Probingrevealedno)unctiondamageoneithersideofthefusesite.Thisdamageischaracteristic ofclassicSCRlatch-up. 4.Electrical testingofthetwo(2)additional 4049'swasperformed duringcircuitboardtest.Thedeviceswerefunctional. Internaldieexamination revealednodamageoneitherdevice.5.Electrical testingoftheA13A21circuitboardfromUPSGrevealedthatSW1wasintermittently opencircuited inthenormallyclosedposition. Thiscondition wouldprovidecontinuous resetsignalstothe4044latchesthroughtheK1relay.TheswitchwasisolatedandagoodswitchwasplacedacrosstheKlrelay.Thecircuitboardinputsstillwouldnolatchthelamps.TheKlrelaywasremovedandtestingrevealedthatitwaselectrically good.ThefindingsrevealthateithertheKlrelayiseitherintermittently badorthereareotherproblemcomponents onthecircuitboard.Analysisiscontinuing. R0U0A.THEDAMAGENOTEDONTHE4049FAILEDINTEGRATED CIRCUITFROMUPSBWASINDUCEDONTHEVss(GROUND)SIDEANDSUGGESTSAGROUNDTRANSIENT MAYHAVEOCCURRED. THEDAMAGEONTHE4049FROMTHEA20.BOARDINDICATES THATTHEDAMAGEWASINITIATED BYATRANSIENT ONEITHERTHEVddORVssLINE,BUTITMAYALSOHAVEBEENINITIATED BYLATCH"UP. B.ATLEASTONEOFTHEBATTERIES FAILEDDUETOOLDAGEWEAROUT.C.THECAQNEOFTHEFAILUREOFTHEUPSGTOSETTHELATCHESZSUNKNOWNATTHISTIME.THESWSWITCHHASBEENFOUNDTOBEDEFECTIVE ANDANALYST'S WILLDETERMINE IFTHECOMPONENT ISRELIABILITY RISK. I -UPSlA1B1GTESTSUMMARYpage1Purpose:ToprovethattheDClogicpowerfortheExideUPSispoweredfromtheB-phasemaintenance supply.TheK-5pickupanddropoutvoltagesandtheDCtrip-point o=theDClogicwillberecordedforUPSlA,notforUPS13andUPS1G.Theinternalbatteries willbetestedandreplaced. ResultsSummary:1.)OnUPS1A,UPS1BandUPS1G,itwasverifiedthattheDClogicpowersuppliesarefedfromtheB-phasemaintenance supply.2.)TheK-5relaydropoutandpickupvoltageswererecordedforUPS1AandtheywerefoundtobebelowthetrippointoftheDClogicpower.3.)OnUPS1A,UPS1B,UPS1G,themaintenance supplywasopenedwiththeUPSfeedingtheloadsandnoUPStripsoccuzredo 4.)OnUPSlA,UPS1BandUPS1G,thebatteries werereplaced. CONCUThistestprovesthattheDClogicpowerisfedbytheByhaaemaintenance power.ItprovesthattheinternalbatCOries wereeffectively dead.ForUPS1Aitprovesthatonaslowtransient that.theDClogicpowerwilldropoutbeforetheK-5relaywilltransfertoUPSpower.

Numerical Results:page21.)TheUPS1ADClogictripsat<16.7VDC.(with.75.6 VAConinput).2.)UPS1A:K-5relaydropout-47VDCK-5relaypickup-52VDC4.)Theinternalbatteryvoltagewasmeasured: UPS1A:UPS1B:UPS16:Positive-Negative-Positive-Negative-Positive-Negative-0.546.218.30.69 )J 2VBB-UPS1C TESTSUMMARYpage1Purpose:ToprovethattheDClogicpowerfortheExideUPSispoweredfromtheB-phasemaintenance supplyandthatifatransient occursonthemaintenance supplyitcaneffecttheDClogicsuchthatitwilltriptheunit.Thistestisdonewiththeoldinternallogicbatteries andthenrepeatedwithnewones.EachoftheinvertertripswillbetestedtoverifythateachcircuitisstillintactexceptDCOV.,AnACinputtransient toUPSwillbesimulated toverifythattheunitcan"rideout"anormalACinputtransient withouttripping. TheK-5relaypickupanddropoutvoltagesandtheDCtrip-point oftheDClogicwillberecorded. ResultsSummary:1.)ZtwasverifiedthattheDClogicpowersuppliesarefedfromtheB-phasemaintenance supply.2.)ArapidopenandclosingoftheupstreamnormalACinputbreakertotheUPSwasdoneandtheunitdidnottriporgoonbattery.Nonoticeable effectwasseenontheUPSoutput.3.)EachinvertertripcircuitexceptDCOVwastestedandeachfunctioned asdesigned. 4.)Fasttransient tests:Withtheoldbatteries stillinstalled avoltageinterruption of100-150msecdurationwasgiventotheACinputtotheDClogicofUPS1C.TheDClogicwasinitially at19.86VDC.Theunittripped3outof4times.Thiswasdonefirstwiththeloadson.xaintenance supplyandthenalsowiththeloadsonUPSpower~Withthenewbatteries installed therewasnotripwhenthefasttransient testwasperformed 25successive times.TherewerenotripsbutarepeatedSCRshortalarmoccurredwhichisindicative ofnoisespikeswithintheunit.

page25.)TheK-5relaydropoutwasrecordedandwasfoundtobebelowthetrippointoftheDClogicpower.6.)Normaltransfers weredone,UPStomaintenance andmaintenance toUPS,withdeadbatteries andtherewerenotripsoftheUPS.Themaintenance supplywasopenedwiththeUPSfeedingtheloadsandnoUPStripsoccurred. CONCLUSZON ThistestprovesthattheDClogicpowerisfedbytheBphasemaintenance powerandthatitissusceptible tovoltagetransients onthemaintenance supply.Ztmaybesusceptible toothertransients aswellbecauseitisdirectlytiedtomaintenance supply.ThetestDOESNOTprovethelevelofsusceptibility, thatis,itdoesnotprovethatthetransient wasofanysetvoltageorduration. Thetestimpliesthatthebatteries mayhavemitigated thetripbutisnotconclusive. Eachtripcircuitwastestedsuccessfully sonofailuretoanyoftheseoccurredthatcausedthetrip.Thefastopen/close ofthenormalACinputbreakerprovesthattheunitwouldwithstand anACinputtransient withoutfailureorwithoutgoingonbatterypower. I'5~ Numerical Results:1.)FastTransient Tests-a.)W'texistinbatteries page31.)Withloadsonmaintenance: At19.86VDC(90.0VAC)-~tri(150msec.)At19.86VDC(120VAC)-~t'150msec.)2.)WithloadsonUPSpower:2Tries,1~ti(200msec.)b.)W'tnewbatter'es-1.)Approx.20.0VDC-25times,~notri.(100msec.)2.)TheDClogictripsat<16.9VDC.(with84.59VAConinput).3.)K-5relaydropout-45VACK-5relaypickup-**notrecorded4.)Thefollowing tripstestsweredone:a.)b.)c.)d.)e.)f.)g)h.).OV/UVACUVACOVDCUVFrequency failLogicFailurePowersupplyfailureClockfailure5.)Theinternalbatteryvoltagewasmeasured: Positive-+0.6Negative-+0.04 l~45 5.)Xndividual cellvoltages: page41.)2.)3.)4.)5.)6.)BatteVoltae1.192.482.240.170.791.78NewBatteVoltae6.106.076.106.096.106.12

V-UPDSSpagePurpose:ToprovethattheDClogicpowerfortheExideUPSispoweredfromtheB-phasemaintenance supplyandthatifatransient occursonthemaintenance supplyitcaneffecttheDClogicsuchthatitwilltriptheunit.Thistestisdonewiththeoldinternallogicbatteries andthenrepeatedwithnewones.TheK-5pickupanddropoutvoltagesandtheDCtrip-point oftheDClogicwillberecorded. ResultsSummary:1.)Itwasverifiedthatthe'ClogicpowersuppliesarefedfromtheB-phasemaintenance supply.2.)Fasttransient tests;Withtheoldbatteries stillinstalled avoltageinterruption of100-150msecdurationwasgiventotheACinputtotheDClogicofUPS1D.TheDClogicwasat20.9VDC.Theunitwouldnottrip.TheACinputvoltagetotheDClogicwasthenreducedsuchthattheDClogicwasat20.0volts.Whenthetestwasperformed withtheDClogicpowerat20.0VDCtheunittripped.Thiswasdonefirstwiththeloadsonmaintenance supplyandthenalsowiththeloadsonUPSpower.Withthenewbatteries installed therewasnotripwhenthefasttransient testwasperformed thoughtherewassignificant hitsshownontheDClogicpowerbusasseenbytheoscilloscope. 3.)TheK-5relaydropoutandpickupvoltageswererecordedandtheywerefoundtobebelowthetrippoint.oftheDClogicpower.4.)Normaltransfers weredone,UPStomaintenance andmaintenance toUPS,withdeadbatteries andtherewerenotripsoftheUPS.Themaintenance supplywasopenedwiththeUPSfeedingtheloadsandnoUPStripsoccurred. Ia pllt4iV1i,~CONCpage2ThistestprovesthattheDClogicpowerisfedbytheBphasemaintenance powerandthatitissusceptible tovoltagetransients onthemaintenance supply.Itmaybesusceptible toothertransients aswellbecauseitisdirectlytiedtomaintenance supply.ThetestDOESNOTprovethelevelofsusceptibility, thatis,itdoesnot,provethatthetransient wasofanysetvoltageorduration. Thetestimpliesthatthebatteries mayhavemitigated thetripbutthatisnotconclusive. ta0 Numerical Results:1.)FastTransient Testsa.)W'teistinbatteries page3Withloadsonmaintenance: At20.9VDC-fivetries,notrips.At20.7VDC-onetry,one~tri.(150msec.)2.)WithloadsonUPSpower:At20.06VDC-one~t'(100msec.)b.)W'tnewbatteries 1.)At20.05VDC-Fivetries,~sotris.-noticeable DChitoneachtransient. 2.)TheDClogictripsat<17.3VDC.(with84.5VAConinput).3.)K-5relaydropout-42VDCK-5relaypickup-55VDC4.)Theinternalbatteryvoltagewasmeasured: Positive-Negative- +0.6+0.14(thenegativebatterysetwasactuallyslightlypositive). 5.)individual cellvoltages: tVtaewBatteVotae2.)3.)4~)5.).254.5701.03.071~176'06'66~106'06'3 t0 It6.)1.396'9, 1 resulteduntilsuchtimethepowertotheseUPS'swasrestored. However,oneormoreoftheotherlightingsystemsnamely,emergency, normaland8hourbatterypackwereavailable inthesea'reasduringthisevent.Thestairwells areprovidedwithessential lightingonlyexceptwhere8hourbatterypacklightingisaddedforAppendixRcompliance. Illumination tothesestairwells wasnotavailable duetolossofnormalUPS.The8hourbatterypacklightingdidnotenergizebecausetherewasnolossofnormalpower.EventEvaluation TherootcauseoflossofpowerfromnormalUPSisevaluated separately inanotherreport.Duringtheevent,someareasoftheplantlostpartialilluminations providedbyessential lightingforsometime. Areascriticalforsafeshutdownwherethislightingareidentified areprovidedinAttachment 7.Duringthiseventtheplantwassafelyshutdownfromthecontrolroom.Becausethecontrolroomisprovidedwithadequatelightingwithouttheessential

lighting, lossofessential lightingdidnotadversely affecttheoperatoractionsneededtobringtheplanttosafeshutdown.

Theaccessrouteusedbytheoperators duringthiseventforrestoration ofthenormalUPSpower(Attachment 8)supplieswasilluminated fromnormallightingexceptforthestairwell whereportablehandheldlightswereused.(FSARSec.9.5.3.3allowstheuseofportablelightingintheformofhandheldflashlights forshortexcursions intotheplant).ThenormalUPSlocations wereilluminated bynormallighting. Therefore, restoration ofUPSpowerwasunaffected bylossofessential lighting. Eventhoughtheessential andegresslightingarepoweredbythreenormalUPS's,during,thiseventduetomultiple'ailuresofallnormalUPS's,essential andegresslightingsystemswerenotavailable. Theexistingessential andegresslightingdesignisadequate, however,therootcauseofthemultiplefailuresofthenormalUPS'swillbedetermined/evaluated andappropriate corrective actiontakenifrequiredtoensurethatmultiplenormalUPS'sfailurewillnotreoccur.Theproposedplantmodification 89-042willenhancethereliability ofstairwell lightingwhere8hourbatterypacklightingisprovided. NSK214

StatusofNormalReactorBuildinLihtinDuringtheeventonAugust13,1991,itwasreportedbytheoperators inthereactorbuildingthatsomeareasofthereactorbuildinglostlightingmomentarily. EventEvaluation Normallightingforreactorbuildinggeneralareas,workarea'sandelectrical equipment areasisprovidedwithlowwattagehighpressuresodiumvaporlights.Intheeventofpowerinterruptions orvoltagediplastingformorethanonecycle,thesefixturesextinguish anddonotrestartuntilthelampcoolsandpressuredecreases. Whenapowersupplytocontinuously energized sodiumvaporlightisinterrupted, ithasacooldownperiodbeforearestrikeofthelightingcanoccur.Thecooldownperioddependsupontheratingofthelightbulbs.Duringtheevent,theemergency distribution systemexperienced a,transient duetothefaultonthePhaseBmaintransformer. Duringtheevent,theReactorsBuildingnormallightingincertainareaswherethesehighpressuresodiumvaporfixturesareprovided, wasinterrupted forapproximately 30seconds.Thismomentary lossoflightingwasduetotheinherentdesignoflowwattagehighpressuresodiumvaporlightingwhichrequirescooldownperiodpriortorestrikewheneverpowerisinterrupted. Thesamescenariocouldoccurintheplantwhereverpowersupplytohighpressuresodiumvaporfixtureisinterrupted momentarily, however,thereisnoindication ofsuchalossinotherareasoftheplant.Therefore, itisconsistent withNMP2lightingdesignandUSARSection9.5.3.h)Grou9Isolation ValvesClosureThegroup9primarycontainment isolation valvesarepartofcontainment purgesystem.ThesevalvesarelistedinTechnical Specification Table3.6.3-1,Page3/46-24andUSARTable6.2.56,Pagellof24.Thefunctionofgroup9isolation valvesistolimitthepotential releaseofradioactive materials fromprimarycontainment. Theseisolation valvesareopenedduringpoweroperation onlyatinfrequent intervals toallowinjection ofnitrogenintoprimarycontainment toinertorde-inerttheprimarycontainment atadesiredpressure. Thesevalves,ifopen,receivesignaltocloseifanyofthefollowing happen:NSK215

a)Highradiation throughstandbygastreatment system(SGTS).TheSGTSradiation monitorlocatedinthemainstackisdesignedtocontinuously monitoroffsitereleaseandprovideisolation signalstotheseisolation valves.b)Highdrywellpressure. c)Reactorlowwaterlevel.d)Manualisolation ofmainsteamisolation valves.EventEvaluation Duringthisevent,thegroup9primarycontainment isolation valvesclosed.Thisisolation isthesafemodeofoperation limitingpotential releasesofradioactive materialfromprimarycontainment. Theinitiating condition forthesevalvesoccurredasaresultoflossofpowertoradiation monitor2GTS-RE105 whenUPSpowertotheDRMScomputerwasinterrupted. Theactualisolation occurredwhenthelogicwasreenergized uponrestoration oftheUPSpowersupplytothemonitor's auxiliary relaycircuit.Therefore, group9isolation valvesclosedasdesignedandisconsistent withUSARSection6.2.5.2.4, Page6.2-77.j)ReactorManualControlSstemThereactormanualcontrolsystem(RMCS)providestheoperatorwithmeanstomakechangesinnuclearreactivity viathemanipulation ofcontrolrodssothatreactorpowerlevelandcorepowerdistribution canbecontrolled. Thissystemisapowergeneration systemandisnotclassified assafetyrelated.TheRMCSreceiveselectrical powerfromthe120VACnormalUPS.TheRMCSdoesnotincludeanyofthecircuitry ordevicesusedtoautomatically ormanuallyscramthereactor.TheRMCScontrolandpositionindication circuitry isnotrequiredforanyplantsafetyfunctionnorisitrequiredtooperateduringanyassociated DBAortransient occurrence. Thereactormanualcontrolcircuitry isrequiredtooperateonlyinthenormalplantenvironment duringnormalpowergeneration operations. Thediscussion ofRMCSisconsistent withUSARSections7.7.1.1,Pages7.7-1,2,14.NSK216

EventAnalsisTheRMCSwaslostduringthiseventbecauseitspowersource,thenormalnonsafety relatedUPS,waslost.ThelossofRMCSisnotaconcernduringthisevent.Sincetheplantwasautomatically scrammedduringthisevent,theRMCSneednotperformanyfunctionafterthescram.ThisRMCSisusedbyoperatoronlyduringnormalplantoperations. Therefore, iftheplanthadnotautomatically scrammedduringtheevent,lossofRMCSwouldnothavecausedasafetyconcernbaseduponthefollowing: 2)EOP'sprovideguidancetotheoperatorundersituations involving failuretoscram,andvariousATWSmitigating designaspectsoftheplantwerefullyoperablethroughout theevent.Althoughthissystemwaslost'during thisevent,itsimportance diminished oncetheautomatic scramoccurred. Therefore itisconcluded thattheRMCSfunctionwasconsistent withUSARSection7.7.1.1.k)Feedwater ControlSstemThefeedwater controlsystemcontrolstheflowoffeedwater intothereactorvesseltomaintainthevesselwaterlevelwithinpredetermined limitsduringallnormalplantoperating modes.Duringnormalplantoperation, thefeedwater controlsystemautomatically regulates feedwater flowintothereactorvessel.Thesystemcanbemanuallyoperated. Thefeedwater flowcontrolinstrumentation measuresthewaterlevelinthereactorvessel,thefeedwater flowrateintothereactorvesselandthesteamflowratefromthereactorvessel.Duringautomatic operation, thesethreemeasurements areusedforcontrolling feedwater flow.Thefeedwater controlsystemreceivesitsnormalpowersupplyfromthenormalUPS.Thefeedwater controlsystemisdesignedtolockinitslastpositionuponalossofpowertoitscontrolelectronics. Thefeedwater controlsystemisdiscussed inUSARSection7.7.-1.3, Page7.7-23.EventAnalsisDuringthisevent,uponlossofthenormalUPS's,thefeedwater controlsystemperformed asdesignedandfailedinitslastposition. Therefore, itisconcluded thatthefeedwater controlsystemfunctionwasconsistent withUSARSection7.7.1.3.NSK217 h'1 l)Feedwater PumTriFeedwater isprovidedtotheReactorPressureVessel(RPV)viatheCondensate Pumps',Condensate BoosterPumpsandtheReactorFeedPumpsshowninAttachment 9.TheCondensate Pumpdrawscondensate waterfromtheCondenser andprovidesthenecessary NetPositiveSuctionHead(NPSH)fortheBoosterPumps.TheCondensate BoosterPumpsprovidethenecessary NPSHfortheReactorFeedPumps.Aminimumflowcontrolheaderisprovidedoffthedischarge headerofeachpumptoensurethattheminimumflowismaintained throughtheassociated pump.Theminimumflowcontrolvalvesandassociated instrumentation actuatestomaintainthisminimumflow.Themainfeedwater controlvalves(LV10),locatedonthedischarge headeroftheReactorFeedPumps,modulatetocontrolreactorwaterlevel.Thefeedwater controlsystemispoweredbynormalUPSpowersupplies. Theabovediscussion isconsistent withUSARSection10.4.7.EventEvaluation Itwasreportedduringthiseventthatfeedwater pumpstripped.Anevaluation ofthiscondition revealsthatreportedhappenings areconsistent withthesystemasdesignedandisinconsistence withUSARSection10.4.7.Theinstrumentation controlling theminimumflowrecirculation valvesonthecondensate, condensate boosterandthefeedwater pumpsispoweredfromthenormalUPS's.Theseinstruments arealsodesignedtoopenthevalveuponlossofpowerinordertoprotectthepumps.UponlossofnormalUPS,thefeedwater controlvalvesfaillockedintheirlastposition. Following theturbinetrip,anATWSsignalwouldattempttodrivethefeedwater controlvalvesclosed,howeversinceanATWSsignalwasnotpresent,thisdidnotoccur.Withthefeedwater controlvalvesfailedlockedandtheminimumflowcontrolvalves(FV2)drivenfullopen,feedwater flowincreases andapproaches pumprun-out.TheReactorFeedPumpNPSHdecreases tothelow-lowpressuretrippoint,trippingtheFeedwater Pumps.TheFeedwater pumpcontrolcircuitdoesnotutilizeanautotransferlogictostandbyFeedwater Pump;therefore, feedwater flowislost.Theinstrumentation circuitsforallotherminimumflowcontrolvalvesarealsopoweredbynormalUPSpowersupplies. ThesevalvesallfailintheopenpositionwiththelossofUPSandcontribute tothelossofFeedwater pumpandcondensate boosterpump.Thisisconsistent withUSARSection10.4.7.NSK218 'II m)Annunciators andComutersTheplantannunciator systemprovidesinformation totheplantoperators bywindowslocatedonthemainoperatorpanelboards andonbackpanelswithinthePowerGeneration ControlComplex(PGCC).Thissystemdoesnotincludeannunciators onlocalpanelsthroughout theplantandonspecialpanels,e.g.,fireprotection, withinthePGCC.Theplantannunciator systemisnon-safetyrelatedandisconnected tothenormalpowerdistribution systemthroughnormalUPS's.Theplantannunciator systemisnotdiscussed intheUSAR.Severalcomputerdisplays, withinter-active keyboards, arelocatedinthePGCC.Thesedisplaysarefromthefollowing computersystems.PMS-PlantProcessComputerLWS-LiquidRadwasteComputer, whichhasthefollowing subsystems: LWS-LiquidRadwasteControlGENTEMP-Generator Temperature Monitoring ERF-Emergency Parameter DisplaySystemSPDS-SafetyParameter DisplaySystemDRMS-DigitalRadiation Monitoring System3DMonicore-Asystemusedprimarily forcorecalculations andmonitoring Inaddition, noblegasinformation isprovidedtotheplantoperators fromtheGEMS(GaseousEffluentMonitoring System)computerbychartrecorders onabackpanel;andtheoperators haveaccesstotheGETARS(GeneralElectricTransient Analysis&Recording System)computer. Alloftheabovecomputersystemsarenon-safety relatedandareconnected tothenormalpowerdistribution systemsthroughnormalUPS's.Therearesomesafetyrelatedradiation monitoring skidsthatprovideinputtotheDRMScomputer. However,theseskidsalsoprovidesafetyrelatedindication inthePGCCthatisindependent oftheDRMScomputer. NSK219

ThePlantProcessComputerisdiscussed inSection7.7.1.6oftheUSAR,whereitismentioned thatthecomputerisnon-safety related.USARSection11.2.1.2coverstheLiquidRadwasteSystemdesignbasisandstatesthatthepowersupplyforallRadwasteSystemcomponents isprovidedfromnon-Class 1Epowersources.Thisiscompatible withtheSafety-Parameter Displayrequirements sinceNUREG-0737, Supplement 1statesthattheSPDSneednotbequalified toClass1Erequirements. Theprocessandeffluentradiological monitoring andsamplingsystems,whichincludetheDRMSandGEMScomputers, arediscussed inUSARSection11.5.Thissectiondefineswhichmonitorsaresafetyrelatedandwhicharenon-safety related.TheDRMSandGEMSdesigncomplieswiththisUSARsection.Arearadiation andairborneradioactivity monitoring instrumentation, whichincludetheDRMSandGEMScomputers, arediscussed inUSARSection12.3.4.1. Thissectiondefineswhichmonitorsaresafetyrelatedandwhicharenon-safety related.TheDRMSandGEMSdesigncomplieswiththisUSARsection.Adescription ofthe3DMonicorecomputersystemwasaddedtoUSARSection7.7.1.6byLDCNU-1235.ThisLDCNstatesthatthe3DMonicoresystemisnon-safety related.Thedesignation ofthecomputersystemsmentioned aboveasnon-safety relatedisconsistent withtheexplanation oftheUninterruptible PowerSupplySysteminUSARSection8.3.1.1.2. Inthissectionitisstatedthat2VBB-UPS1A feedstheradwastecomputerhardware, 2VBB-UPS1B feedslocalnon-safety relatedradiation monitoring microprocessors, and2VBB-UPS1G feedsplantcomputerloads.EventEvaluation WiththelossofthenormalUPS's,theplantannunciation systemandthecomputersystemslistedabovebecameinoperative duetothelossofpower.Thisisconsistent withtheplantdesignandthedescription oftheplantintheUSAR.Thesesystemsarenon-safety relatedand,hence,arenotrequiredtoshutdowntheplantfollowing adesignbasisevent.NSK220

CONCLUSION Basedontheaboveevaluation, itcanbeconcluded thattheplantresponses duringtheeventon8/13/91isconsistent withUSARdescriptions.. RECOMMENDATIONS Basedontheaboveevaluation, thefollowing longtermrecommendations areprovided. 1)PlantOscillograph -Thein-plantoscillograph shouldbereplacedwithamorereliableandfunctional unit.Ifthisoscillograph wasfunctional duringtheeventon8/13/91,adequatedatacouldhavebeenavailable toaccurately evaluatethecauseofthedisturbance. 2)Essential Lighting-Theproposedmodification 89-042shouldbeimplemented assoonaspossibletoenhancetherel'iability ofstairwell lightingwhere8hourbatterypacklightingisprovided. 3)ControlPowerSupplies-DuringtheElectrical Distribution Systemevaluation, itwasrevealedthatmostofthesystemsimportant toplantoperations suchasfeedwater system,annunciation system,etc,receivetheircontrolpowerfromeithernormalUPS1A,1Borboth.Itisrecommended thatcontrolpowersuppliesforthesesystemsbeevaluated andreconfigured toavoidplanttransient duetolossofsinglenormalUPS.4)MainGenerator -Itisrecommended thatathoroughvisualinspection beperformed ofthegenerator statorandwindingsupportsystemduringthenextrefueling outage(seeAttachment 10).NSK2

345KVTOSl"ASTATIONLINE23)ATTACHMENT'-1 115KVSOURCE'A'LINE5)345/25KVUNITTRANSF.498HVAEACHSPARE115KVSOURCE'8'LINE6)115KVSOURCE'B'OR'A'2/56/78HVA RESERVEBANK'A'WJGKVUNIT25KV~~NORMALSTA.TRANSF.24.')KV/13.8KV 199-59/59HVA 42/56/79MVA RESERVEBANK'8'UXBOILERNOCUBONLY2NPS-SWG991 13.BKVNORHALAUX.TRANSF.CUB.ONLY2NPS-SWG993 AUX.TRANSF.NC.~13.BKVAUX.BOILERBUS2NPS-SWG892 NONORHAL4J69KV2NNS-6WG914 2NNS-SWG91 52NNS-SWGBII 2NNS-SWG812 2NNS-SWG913 4J6KV0.16KVNOSTUBBUSSTUBBUSWJGKV~CUILONLYNC2ENSiSWGIB) iJ69KVOIV.I>EHERGENCY BUSEGIOIV.14489KW2ENS~SWGI92 ~4.169KVDIV.3EHERGENCY BUSEG2DIVE2688KW2ENS~SWG193 4.168KVOIV.2EMERGENCY EG3BID4489KWONSITEA.C.POWERSUPPLY 5 BIIKLELQKFORNN-IEtPSIAIILICJOol(LI)L3(L38 2NPS-SWGB8) ONV)2NPS-SWG883 03.8KV)2NPS-SWGBBI a@SKY)2NPS-SWGM3 (688V)2NJS-US4(688V)2NJS-US3BUS82NJS-US3BUSA2VBB-TRSI AUTOHATIC TRANSFERSWITCH(688Vl(688V)(6MV)2LAT-PN.388 2VBB-PNL381 2NHS-NCC996 BUSANNNUPSUPSBAT-IC(688V)A(6BSV)A(688V)2NJS-US62NJS-USS2NJS-US6ASUPSUPSBATIBIOBAT-IAICBAT-IAIABAT-IC2NJS-USIBUSC2NJS-US4BUS8UPSIN~BAT-ICUPS3ABAT-18UPS3BN(6MV)(688V)(688V)2NJS-PNL')81 2NJS-PNL5M 2NJS-PNL688 (688V)(688V)~INTERNALBATTERYNO2LAT-PNL188 2NJS-PIL482 ALTERNATE 2%S-SWGBIS HJGKV)2NNS-SWG914 HJ6KV)(4JSKV)2NNS-SWG815 (6MV)(688V)2NHS-HCCB)6 2NJS-USSBUSB(6MV)2NJS-US603J)KV)2tfS-SWGM3 2NPS-SWGBBI 03.8KV)2NPS-SWG883 0XSKV)(689V)(4J6KV)HJ6KV)2NJ6-US') 2NNS-SWG814 2NNS-SWG915 BUS8SINGLELINEFORCLASSIELES-2(L2BOXSKV)03J)KV)2NPS-SWMBI 2NPS-SWG883 HJSKV)HJQOO2ENSiSWGIBI 2ENS+SWG)83 (688V)2EJSiUSI(6MV)2EJSiUS3(6MV)2EJS+PNLIBBA 2EJSiPNL38BA BAT-2AUPS2ABAT-28UPS28(6MV)(688V)2LACiPNLIMA 2LACiPNL3M 8(688V)2EJSiUSI(688V)2EJSiUS3(4J6KV)HJGKV)2ENSiSWGI91 2ENSiSWGI93

3889.5A2SPUY823889-5A2SPMXBI2HTX-HIAHAINXFHR292KV-24~KV 498/457MVA OA/FOA&89-SACOREGAP2SPHXBI63-163-1pe65HGA25989-5A39-139-1HAA3898-SA3898-SA2MTX-HIB63-63-pe65HGA258M-SA39-39-3BM-SA2MTX-HIC63-63-pe65HGA25889-5A8-2SPUZBI1289-SA2SPMZBIpe662HTX-MIDSPARE5951IAC22-2YXCNBI 63-463-4pe65HGA8787PB65BDD39-439-cP864BDOHAA86-1P866HEAI[6Ipe66~HEAIP866HFAI86-1IP864~HEAIP864~HEAPSa<~MFAI86-1IPBSS~HEA IPBSS~HEAP865HFA-15889-SA2SPGZB245989-5ACOREGAP2SPUY922GHS-GlGEN.13<e.iMvn BPFFIELD25K'BBRpM 75PSIGH23PH6BNZIpe67pscz2-2YxcNBI Ir-86-1P867~HEAI6-P867~HEAIP867~MFA45988-5A2SPUY822STX-XNSI AwhcHeemgPACjpg~gATTACHHENT Q

LISTOFPROTECTIVE RELAYACTUATEDONAUGUST131991UnitProtection Alt1Protective RelaLockoutRelaActionRef.Dwg,87-2SPMX01 MainTransformer Differential Protection Relay86-1-2SPUX01 86-2-2SPUX02 ~InitiateTurbineTripESK-8SPU01 ~InitiateFastTransferESK-8SPU02 toReserveStationESK-5NPS13 Transformer ESK-5NPS14 UnitProtection Alt2Protective Rela87-2SPUY02 UnitDifferential Protection RelayLockoutRela86-1-2SPUY01 86-2-2SPUY01 Action~InitiateTurbineTrip~InitiateFastTransfertoReserveStationTransformer ESK-8SPU01 ESK-8SPU03 ESK-5NPS13 ESK-5NPS14 63-2SPMY01 FaultPressureTransformer UnitProtection BackuProtective Rela86-1-2SPUY01 86-2-2SPUY01 LockoutRela~InitiateTurbineTripESK-8SPU03 ~InitiateFastTransferSh.2toReserveStationESK-8SPU03 Transformer Sh.1ESK-5NPS13 ESK-5NPS14 Action50/51N2SPMZ01Protection Relay86-1-2SPUZ01 86-2-2SPUZ01 ~InitiateTurbineTripESK-8SPU04 ~InitiateSlowTransferESK-5NPS13 After30Sec.ESK-5NPS14 BlockFastTransferAfter6CyclesGenerator Protection Protective RelaGen.PhaseOCDuringStartup50-2SPGZ02 LockoutRela86-1-2SPGZ01 86-3-2SPGZ01 Action~InitiateTurbineTrip~InitiateSlowTransferAfter30Sec.BlockFastTransfer~ThisRelayPicksUpOnlyWhenUnitisOffLineRef,D~ESK-8SPG01 ESK-8SPG04 ESK-5NPS13 ESK-5NPS14 HSKl II AXTACEKNT 3PAGE3of3Switchear2ENS*SWG103 DegradedVoltageLockoutRela27BA-2ENSB24 27BB-2ENSB24 27BC-2ENSB24 ActionNoActionTookPlaceDegradedVoltageStaysDuringFaultConditions Ref.DwESK-5ENS18 ESK-8ENS02 2ENS*SWG101 27BA-2ENSA24 27BB-2ENSA24 27BC-2ENSA24 NoActionTookPlaceDegradedVoltageStaysDuringFaultConditions ESK-5ENS14 ESK-8ENS01 2ENS*SWG102 27BA-2ENSC08 27BB-2ENSC08 27BC-2ENSC08 NoActionTookPlaceDegradedVoltageStaysDuringFaultConditions 807E183TY Sh7NSK1 J' 4~aAgeeF,-+0c~pgLc~ePi2~Le~z)K&~a>tF<.lg1vXPrPV~4UPVv>>'PiJN;x~,:'NfV,i'lgl/lj/>VL~~~xs83lLgveg./4/g[Q}l~eZ0fle~-reSfCJtNC,/'(,<3gA

Mkiiw:~.~~~00()I'&~gr=--E~-AlE-nkcp==3QsVtle)IP(trFCbHDN~g>tll~'F9Itll3)9'Y3ClfJUytgg"l1~r.Y!W~~0~e0U<)

/s~t3n9Ee.<ep4XII8FoIgglPAAVLt~eGJgg~g6Cg.AI'tvV-)(1()iiQ(:)i)~')g)VU~, 4 A~7ACLW64 '$VOLTAGEPROF[LEFORTHENORMALSUPPLYPPCE4opyTOUPSDURINGFl-"[ULTEO CONDITION 345/,Qi23,85K7345KV2MTX-XMIA4 BoC2GMSG1FOULTEOCol;OITION [Qi[88KVN,232KVx82.5KV2232KVKvi[6<V21.55KY[6KV03i3.sKv24.9/2NPS~2STX.XNSI7,5%SMG8830316KV21.55KV16KV8.9KV[II[[.9KV8.9KVQ3i3.53/4.16KV~2ATX-XS3~ii5.57.0'.9KV11.9KVN2,8KY04688V2NJS12VQROP688/~288.128VUS6A2NJS-X3E5.75%~2VBB-XQ688 5.540>>38.9KY2.58KV23.46KV2.58KV2.58KV368V482V368VREGULATING05348V478V89V[[4V!UPS2VBB-UPS10 348V65V114V45V154VFROMSCRIBASUBSTATION OSCILLOGRAPH RECORO12VQROPALLO[[iIEO INTHECABLEFROMTHELOAOCENTERTOTHEUPS

~I/ZC(CPgI'gQQLJLIIWPiZBTECTION QL~IJA+21.Q,E.HI3-P84'4FiA.(OIirl:CrrrQAI(r(~popXPIRR.8~X-XKl5DiFFERE(vT(AI-p~TEcAQLJl~uT%~LA'(pg,~~owI~~unR<~'(I/ZC~-PNL.8L+-u<n><oTET(o< ALTa<Nhr~ Z~.Q.HIP-PS45LA(5I(~('.(DL(v(TP((ALE7.L((FFcRoLT'IIAI-VV(T7(r((OEgrLFrFSR'OV(T*L ~9Uun7aeTEcaou Lcc.Kb~~~E~YLluW'7(OOTS'T( oNLOLLOvFfTELA.YZ.@SABA(NSrEPL(pXPA(E..H'TX-Xg((3FAO(-TPr<<<E(LO3)(Z)>(b3'/2.)ZCE(.-'PNL globo-UNIT%fTKCT(QiU pAL(rgpc.e.His-PRt'"'r(VlA(L( ~PL'PXPPIR.HFX-XM(345KYLIGuT.('ROOLIQC(.C.((~~T)5c~'.C.EcPdL-.Ffo7-"&E(vERATc(I2PR.oreczog (@pc(LuP) '15-Pg47ML&lrv:~i(rr~((ORATOR STAILFVPP((AOEP(LCrfKCWo(v (h((OILSkpicItlPiAOIS)CQ(oEoEILATAR DAcJvPP<'-o<ELofoLI LoeKovTgE~j8~vPEe~M0<W<~v'cR&-4-Y2p~P"f~5P&POf4OFZ.

2E,k/5~SvJcto~Z~t'3.RlNX,Fphg,.FOR..ZCSS-rom-(u~bMAo~&CCRE.MYF'~5ixou')27SAZEUSSZQ~)zqipsez.c+5g)~grgb2.EU&5M&[G[xF~<.FaR.2EZ'5XIA[Q(-lQU~b~VsaAC.E, RE~A'tPc4<5i.)zqi&+zealp~<2)Zjpl@Z.~ggpZg2.EACHA>'6plows~s~~i.~uncsQs~~i~cC.ursic~~V~bcR.vo~<Ac a'Sm9SFLA(5la;l.)21BAz.)z,zzs~)z~eczavs-s~~ccz.p.vy.SetL.BIZ.<)ppg-+I+SuJ&.OQ2- %i-2.-ZA6+55l(j.EST;)F~+~p~~p+~~spP6Kz.iA

lNTHINAl. CONIRSfONDSHCI NON11154%~I$41MOPROgh.R.-.LAk~ToDistrQT~kCHei~ PREi~FWgv>~~~NineMilePointNuclearstationOATL15August91FfLXCOalNineMilePointFireprotection ProgramPostEventXnterviews Afterinterviews conducted todaywithFireChiefBernieHarvey,andFiremenFatBrennanandNarkLocurcio, andconcurrence withTerryVermilyea, SystemExpertPireDetection andJohnPavlickoofCautionEquipment Enc.,Xhavereachedthefollowing conclusions. 1~Ofthe20firepanelsatUnit2,18maintained anormalpowersupplyo2a.TwoCirepanelsLFCP113and123transferred tointernalbatterybackup.'b. Thesetwopanelswb'ileonbatterywillstillfunctionnormallyaslongasthe120VACisavailable intheLPCF,whichitwas.Therewasnointerruption ordecreaseoffireproteotioni detection/suppression atthelocalfirepanels.FirePanels849and200/1beingfedfromQNdidhaveapowerinterruption. ThiswouldhaveleftthecontrolswitchesoperableatPanel849,(astheyarefedfromLPCP),butcontrolRoomwithnoCireannunciation. Anyfiresuppression/indication couldalsohavebeeninitiated locally.ABA:dlcT,Tomlinson A.Julka(FAX7225-SN)D.Pringle

QJQ15'9115'ttttKTNaÃCSs~DTSINTSHNALCOhllSNKNDRNCK INN'tMAeSNpg4gyLoen~ToFiISUSJCCT+~AD-+8'~ 4CLopfg7P.3NineM5.1ePointNuclearStation15'AugustQlRLRCOOINin<<MilePoint,Unit2FireProtection ProgramFeetRvent8/13/91Interviews ?ireDept.Personnel Interviews( PoetIveatofaugust13(1901BernieHarvey-Chieflnearlyfoxcoverage, interviewed forlosscfpowerinContxolBuilding. Lightsblinked,loudnoise(louderthaneverheardinplant),wasinFireDept.office(toldshifttogetoutintoplant.PatWilsonwasinRxBldg>switchedradiostoChannel10,standardFireDept.practiceifsuspectloseofrepeator. PatBxennanwasintheFoamRoomandproceeded totheChief(sdesk.ChiefHarveyheardfirepanelalarmingwhenhegottoControlBuilding. WentpastFir~Panel114inTurbinebuildf.ng passageway( noaudiblealarms(seemednormal.Mar}cLocurclowenttoPanel12d-214elev.whileChiefHarveywenttoPanel127>>244elev.ttheseweresoundingtroublealarmandD&wasclear.WentpastPanels120(121(128ftheywerenormal-noaudible.PxiortoSiteAeaEmergency (SAE)messageandevacuation beingannounced -PatbrennanreportedPanelsR.B.normal,calledcnGaitronics -hadtosilencePanels113onI,B.250andthansilencedallFaneleinR.Be(Panels101,103(104(105(10d(10>andXQ8.ChierHarveywaeCofnptotri~eetagewetlnRh.a.ndhaveaaninR.s.cnardeLynnRoon,accocpanled hyLarrycchaner,calledhfasupervisor, whentheysawtransformer blow.ChiefHarveywou14havelikedtOgettotransfcrmer quf.okerfor".ireevaluation. Hefeelsitwasatleastonehourbefore,'OV41QLCiOt1 ech'fHarveyfeelsFireDept.shouldhavebeenpartof'nlinvestigation/inspection teamwithOperationse

QJQf5'9t15~41tt%JKTl%WT&CCttlDTS19911'nterviev (Cont'4)P.45'ff'Acp-m~y-gp~r-ggpgPatPatminfoamRoomapproximately 0550>heardloudnoise,venttoChief"'sofficeandaskedwhatnoisewas.Lightingdimmed,onestringoflightsoff(NOTE:thesefeedframEmergency -UPSshouldhavegoneoff)Thenheventonrover-heardalarms-whichvereonvatertreatment systempanel,thenventtoPanel123.TherewerenodisplaysonDAXpanel,vasblanknolightsvereon.Powerlightsvoreoff.TrouhleLightblinking. RenttoT.S,261NN,eignedsheet,stairtower dark'noproblem,knewvayaround),TurbineTraokBay4imlylighted.WonttoT.S.306-OK,sign>>4sheetTBSvgr277OK)signedsheetT.Q.250byFeedpumps -notednotrunningbyPanel113-noLightson,noaudibleortroublealarmestimat>>s timeapproximately 0605Continued raverroundstoPanel106SouthStairtover R.S.249vasalarmingdisplaysai4"oninternalclock"hadtvotroublesdisplayed WenttoQ.B.215tirepanel103alarming-silencedR.B.190Fir~panel101alarmingsilencedbothpanelswereintrouble-unknovnR.B.175SignedsheetR.B.261SBCTS-OXPanel105-silencedtroublesCQ2Room,aboutt?)istime,evacuation alarmsoundedwenttoUnit2ControlRoomassemblypointWalkedaroundwithPatBrennanon8-15-91taPanel123andPanel113,poweronlightvasburnedoutonPanel123."Poweron"Lightwason,onPanel113~

.AJG15'9115:41N1leMGKIScCOPFlDTSP.5Aff~Alm8Ng gP08+opppostI+gtkuy.13,1991Xnterview (Cont'4)CMarkZcNtok,o(Calle4athome)HaslocatedintheFireDept.Officewhenlightsflickered andnoisewasheard.Radiocommunication wasgone,HearHerewasout.ChiefHarveydirectedpersonnel tocovervitalareas.PatwilsonwasinRXBldg.PatBrennanwasrovingT.B.BerniefHarkweretccoverControlBldg.TriptoC.B.uneventful PanelsPassedinroute)Panel114Elect.BayElv.261'anel120C.5~Elv.261'anel128C.5.Elv.261~Panel121C.B.Elv,261'anel125C.B.Zlv.261'anel127C.B.Elv.2i4'anel126C.B.Elv.214'ormal NormalNormalNormalNormalTrouble,Hornsounding-SU,enaodTroubleHornsounding-

lilenoed, alsoanamberlightwaslitonpanelCheckedvalveroomonC.b.elv.2ii'ightwasoninroom.Noindication ofsystemactuation.

stairwells weredark,Elv,261'.B.wasdark.s.A.E.announcement andreportedtoControlRoom. I A<7~mgur7pt)c,pk~NMP2LIGHTINGSYSTEMPOWERSOURCEANDMINIM)StILLUHINATION AVAILABLE -CRIT]CALAREASMODESOFOPERATION PAGEILOCAStSEISMICWITHLOOPTRANSIENT WITHOUTLOOPILLIILSIXRCE6PROVIDEDBYPOWERSIXRCEMIN.AVAIL(FOOTCAN)LE)XMIN.POWERAVAIL.SDUIKES~~~<FOOTBYPOWERCANDLE)SIXRCEPOWERSIXRCESXHIN.AVAIIPOWERBYPOWERCANDLE)PROVIDED)FOOT~ESSOURCEXOFPROVIDEDCANDLE)(FOOTSOURCEXOFPOWERSOURCESPROVIDEDSOURCEMIN.ESSENTIAL AVAIL.LIGHTING(FOOTUPSPAtELCANDLE)ILCIXITROLROOHIDPERATING AREA5RELAYPANELAREA)CONTROLBLDLEL.336'E-65E N)RMAL58ESSENTIAL )9EHEROE498NXRBAT.PACK~ESSENTIAL 188NXRBAT.PACK159NORMALESSENTIAL EMERGE8NXRBAT+PACKESSENTIAL 8NXRBAToPACKNORHAL58ESSENTIAL 18EHERGENC48SNXRBAT.PACKNONESNXRBATT.PACKHANXACTIRER-EXIDI (TYPICAL) CONTROLROONMRTM-SOUTH CDRMDORS) CONTROLBLDLEL3P&'E-&5E CONTROLROOM(SHIFTSLPERVISOR OFFICE)CINTROLBLDLELo3P&'E-65E RELAYANDCO)4'UTER ROOMRELAYPAMPAS)CONTROLBLDLEL28F-6'E~RELAYANDCOtPUZERCQ4%6EAIKXNOCONTROLBLDG.EL288'-6'E-650 HORHAL189BAT.PAtxNONE8NXRNRHAL58BAT.PA)XNONESNXRSNXRBAT+PACKSNXRBATPACK8NXRBAT.PACKNORHAL58ESSENTIAL 18SNXRBAT.PACKNORHAL58ESSENTIAL 18EMERGENC49SNXRBAT.PACKNORHAL'QESSENTIAL 188NXRBAT.PACKSNXRBAT.PACKNORHALESSENTIEMERGENCSNXRBAT+PACKNORHALESSENTIAL SNXRBAT.PACKESSENTIA. SNXRBATePACKYES16SNXRBAT+PACKNORHALEHERGESNXRBAT.PACKESSENTIAL EHERGESNXRBAT.PACKSNXRBAT+PACKYES16SNXRBAT.PA)XNORMAL58ESSENTIAL 18EMERGENCi8SNXRBAT.PACKESSENTIAL 18EMERGENC<9SNXRBAT.PACKESSENTIAL 188'NXRBAT+PACK2VBB-UPSID 2VBB-UPSID 2VBB-UPSID NTHELIGHTINGWINGS,CIRCUITSTARTINGWITHAN'NICATENRMALPOWIWITHA%'H)ICATE ESSENTIAL POWER,WIT)AN'E'INDICATE EMERGEN:Y POWER.

AtrocmC~r 7PAcEX,~<<'MP2LIGHTINGSYSTEMPOWERSOURCEANDMINIMUMILLUMINATION AVAILABLE HOOESOFOPERATIDN PAGE2LOCAttSEIS)GCWITHLOOPTRANSIENT WITHOUTLOOPItOF~RILLLSLSOURCESPRDVIOEDBYPOWERSOLSCEMIN.AVAIL.LFOOTCQOLE)ILLLSL2DFPRLMDEDAVAILBYPOWERC~E)LFOOTSOURCEPOWERSDLRCES2OFAVAIL.POWERBYPOWERCAN)LE)LFOOTSOURCESSOURCEHl)L/OFILLLSLAVAILPOWERILLUMPROVIDEDLFDOTSOURCESPROVIDEDBYPOWERCANDLE)SOURCEBYPOWERSOURCEMIN.AVAIL.LFOOTCANDLE)ESSENTIAL LIGHTINGUPSPANELIILRELAYAN)CQ%'UTERROOMLCLXLRIDLRS) CONTROLBLDG.EL288'-6'E-65D DIESELGEtKRATOR BUILDINGtWORKINGAREA)EL261'E-6BC DIESELGEtKMORBLBLDINGLELECTRICAL EQ)IPMENT AREA)EL.261'E-6BC DIESELGENERATOR BUILDINGLGENERALAREA)EL261'E-68C ESSENTIAL 18SNXRBAT.PAIXN)RMAL78SNXRBAT.PA)X~NORHAL78ESSENTIAL 18EMERGE28SNOLRBAT.PAtxNNORHAL98ESSENTIAL 18SNXRBAT.PALX~BAT.PACKSNOLRNORHAL78ESSENTIAL 18SNXRBAT.PACKNORMAL78ESSENTIAL 18EMERGENC28SNXRBAT.PACKNORMAL98ESSENT)AL 18SNXRBAT.PACKNORMALESSENTIAL SNXRBAT.PACKNORHALESSENTIAL EHERGESNOLRBAT.PACKNORHALESSENTIAL SNOIRBAT.PACKNORHALESSENTIAL SNOLRBAT.PACKYESYESSNXRBAT.PACKNORHALSNXRBAT.PACKNORHALESSENTIAL SHOLRBAT,PACKNORMALESSENTIAL SNXRBAT.PACKYESYESNORHAL98ESSENTIAL 18BAT.PACKSHOLRNORMAL78ESSENTlAL 18EMEROENC28SHOLRBAT.PACKNORMAL78ESSENTIAL 18EHERGENC28SHOLRBAT.PACKNORHAL98ESSENTIAL 18SNOtRBAT.PaX382VBB-ASS2VBB-UPSID 2VBB-UPSID 2VBB"UPSIO 11 HHP2LIGHTINGSYSTEHPOWERSOURCEANDHINIHJHILLUHINATION AVAILABLE .HXKSOFOPERATION PAGE3LOCA8SEISHICWITHLOOPTRANSIENT WITHOUTLOOPPOWERSO(SCES2OFPROVIDEDBYPOWERCA)b)LE)(FOOTSOURCEPOWERSOURCESHl)L2IROY)GEOAVAIL.BYPOWER(FOOTSOURCEPOWERSOURCES2OFILLUH.PROVIDEDBYPOWERSOURCEHIlL2AVAIL+POWERPROVIDEDCANDLE)BYPOWERSO(SCEHIN.IOFAVAIL.POWER(FOOTS~ESPROVIDEDCANDLE)BYPOWERSOURCEHIN.ESSENTIAL AVAIL.LIGHTIW(FOOTUPSPAtKLCANDLE)IILREHARKSREHOTESHUTDOWNROOHCONTROLBLDLEL261'E-&5C EE-165CEHERGE88XRBAT.PACKYES16.58HOLRBAT.PACKYESEHERGE8HOLABAT.PACKYESIL5EHERGENCYESBAT.PACK8HOLRNORHALYESEHERGENCYESBAT.PoxNE8dnaSTANDBYSWITCHGEAR ROOHa)SWG.PANELS(2)HCCFRONTSCONTROLBLDG.EL261'E-65C EE-165CEPICSSWITCtSEAR RQOHCONTROLBLDG.EL261'E-65C EE-165CSTANDBYSWITCH%EAR ROOH(CORRIDORS) CONTROLBLDLEL+26)'E-65C EE-16SCN(RHALESSENTIAL EHERGE8BXRBAT.PACK8BXRBAT+PACK8NXRBAT.PACKESSENTIAL 8HOLRBAT.PACKNORHALESSENTIAL EHERGENCaexaBAT.PACKNORHALESSENTIAL 8NQLRBAT.PACKNORHALESSENTIAL EHERGE8N(XRBAT.PACKNORHALESSENTIAL EHERGE8(XXRBAT.PACKESSENTIAL 8HRRBAT.PACKYES3515ESSENTIAL YESEHERGEYESBAT.PACK8HXRNORHALNONEESSENTIAL YESEHERGENCYESBAT,PACK8IRLRESSENTI(V. YESBAT.PA(X8NXR15NORHALYESESSENTIAL YESEHERGENCYES8HOLRBAT.PACKNORHALYESESSENTIAL YESEHERGENCYES8(K)LHBAT.PA(XNORHALYESESSENTIAL YESBATPACKNONE8N(na2VBB-UPSID 2VBB-UPSID 2VBB-UPSID

NHP2LIGHTINGSTSTEHPO)fERSOURCEANDMINIHUHILL'NfINATION AVAILABLE HODESOFOPERATION PAGELOCA8SEISMIC))ITHLOOPTRANSIENT NITHOUTLOOPSTAHDBTS)fITCHGEAR RDOHIEASTCABLECHASEAREA)COHTRCLBUXLELÃl'E~EE-)at)cPDVERAVAILHIM.SOURCESfFDDTBYPOVERC~E)SRSCENORHAL199ESSENTIAL YESPOVERAVAILHIN.SOURCESfFOOTBYPOVERCAtOLOSOLACENORHALIBBESSENTIAL YESPom'"LU)LPROVIDEDBYPOVERSm)RCEESSENTIAL NONEHI)LAVAIL.POVERfFOOTSOURCESCANDLE)NORHALESSENTIAL ILLlHHINKPROVIDEDAVAILBYPDVERC~E)fFDOTSOURCEYESPOVERSOURCESILLUHPROV)DEDBTPOVERSOURCEHI)LESSENTIAL AVAIL.LIGHT1tOlFOOTUPSPANELCANDLE)ID.2VBB-UPS)0 REMARKSCOMHONINSIDEAREASESSENTIILI99ISTAIR)fATS)fALLIRI)VDOS) ESSENTIAL 198ESSENTIAL IBB1992VBB-UPSIC 2VBB-UPS10 NOTEaHOURBATTERYPACKPROVIDEDIt4.TOHSAFESHUTOOVHPATHS.COHMCNINSIDEAREASfEGRESSPAT)afALLNhtfltCS) 8tKXABAT.PACKNORHALYESESSE)fl)AL YES8HOLABAT+PACKESSENTIAL YES8)NURBAT+pAcK8HDtABAT+PACKNORHALESSENTIAL YES8)K)URBAT+PACK2YBB-UPSIC 2VBB-UPSID HDTE8HOURBATTERYPACKPROV)DEOCN.TOHSAFESHUIDOVNPATHS.BAT.PACK8talACOtafDNESSENTIAL 199EXITSIGNSOV.LDRIVI)OS)BAT.PACK8H)XAESSENTIAL 199BATPACKYESatK)URESSENTIAL tONE8HOtABAT.PACKESSENTIAL YESIBBatK)URBAT.PACKESSENTIAL IBB2VBB-UPSIC 2VBB-UPSID

Af'fnareevV 7IAAFgNMP2LIGMTINGSYSTEMPOWERSOURCEANDMINIH)MILLUMINATION AVAILABLE M(K)ESOFOPERATION PAGELOCAhSEISMICWITHLOOPTRANSIENT WITHOUTLOOPSTA)4)BYSWITCNGEAR RMM(GENERALAREAS)(XNTROLBLD(LE(2GI'E-65C EE-)65CCtÃNNIHSIDEAREAS(STAIRWAYS) (ALLDRAWINGS) POWERAVAILMIN.SOURCES(FOOTBYPOWERCA)NLE)SOURCEESSEHTIAL YESESSENTIAL IBQPOWERSOURCESNORMALESSEHTIAL ESSENTIAL /MIH.AVAIL.POWERPROVIDED(FOOTQ)URCESBYPOWERC~E)SDLRCENORMALESSEHTIAL ESSENTIAL XILLUM.PROVIDEDBYPOWERSOURCEAVAIL.POWERMl)L(FOOT'ESPROVIDEDCA)K)LE)BYPOWERSOURCEESSEHTIAL YESESSENTIA. 188MIN.AVAIL.POWER(FOOTSOURCESCANDLE)NORMALESSENTIAL ESSENTIAL 2PROVIDEDAVA'L-BYPOWERCNXE)(FOOTSOURCEYESIBBESSENTIAL LIGHTINGUPSPANELID.2VBB-lFSlO 2VBB-lPSIC 2VBB-UPSID CROCKINSIDEAREAS(EGRESSPATH)(ALLDRA)O(GS) bNOIRBAT+PACKESSENTIAL YESS)K)LRBAT.PACKNORMALESSEHTIAL YESYESS)K)LRBAT.PACKNORMALESSENTIAL SHOLABATPACKESSEHTIAL YESSHOLABATPACKHORMALESSENTIAL YES2VBB-UPSIC )NTESHOLR2VBB-UPSID BATTERYPACKPROVIDEDONLYONSAFESWTOOWNPATHS.bHSLRBAT,PACKSHOLRBAT.PACKSHOLRBAT.PACKYESSHOLRBATsPACKYESSHGLRBAT.PACKC&tQNIHSIDEAREASEKITSIGNS(ALLDf(AWINGS) ESSENTIAL IBBESSENTIAL ESSEHTIAL ESSENTIAL IBBESSENTIAL IBB2VBB-UPSIC 2VBB-IfSIO l'll ISIP2LIGHTINGSYSTEMPOWERSPLRCEANDMINIINMILLUMINATION AVAILABLE MOPESOFOPERATION ATf4~6nlT' P~~gongPAGE5TRANSIENT LOCAdcSEISMICWITHLOOPWITHOUTLOOPCLXITRPLRXNLEAST-WEST CORRIDONCONTROLBLDGEL.386EE-65EQ)RTfKAST STAIRSCONTROLBLDG.EE-65EEE-650EE-165CEE~ILLLH.SDLRCESPROVIDEDBYPOWERSXRCEESSENTIAL 33@bHXRBAT.PACKESSENTIAL 198SWXRBAToPACKMIN.AVAILPOWERLFppTSOURCESPROVIDEDCA)6)LE)BYPOWERSOURCESHXRBAT.PACKESSENTIAL 189SBXRBAT.PACKMIN.AVAIL.LFOOTCANDLE)POWERAVAIL.MIN.SDLRCE$LFOOTBYPOWERCAINLE)SOURCEESSENTIAL NONE$HXRBAT.PACKESSENTIAL NONE$HXRBAT.PACKPOWERSDLRCESM)R)LALESSENTIAL SHXRBATPACKbHOLRBAT.PACKILLLSL/pROVIDEDAVAILeBYPOWERCANDLE)(FOOTSOURCEPOWERSOURCESESSENTIAL SNXRBAT.PACKESSENTIAL SHNRBAT.PACKMIN.ESSENTIAL (FOOTUPSPAHELAVAIL.LIGHTINGBY~RCANDLE)10SOURCE2VBB-L$%$333VBB-iX%10 SOUTHWEST STAIRSCMfRPLBLDGEE-66BEE-650EE-66FEE-65CEE-165CINTERBAYRA)4EL258TpEL261EE-7%ESSDITIAL 189SIXXRBAT.PACKYESESSENTIN.YESSIKXRBAToPACKESSENTIAL 188SHOLRBAT.PACKNORHALYESESSENTIAL YESSHXRBAT+PACKESSENTIAL NONESHOLABAT.PACK'YESESSENTIAL NONESINLRSATPACKSHOLRBAT.PACKNORMALESSENTIAL bNXRBAT+PACKESSENTIAL SHOLRBAT.PACKESSENTIAL SHOLRBATsPACK1892VBB-UPS10 2VBB-UPS10 1 %%>2I.IGHTING SYStEHPOwERSOURCEANOHINI)K)HILLUHINAtlON AVAILABLE HOOESOFOPERATION PAGE6LQC4LOCA5SEISHICWITHLQIPTRANSIENT WITHOUTLOOPXIF~RILL)M.PROVIDEDBYPOWERSOURCEHt)L4VAIL)FOOTCANOLE)ILLU)LXOFPRQVIOEOAV41BYPOWERCANOLE)<FOOTSQRCEPOWERSOURCESXHIN.4V4ILPOWER<FOOTSQRCESBYPOWERSOURCEtu~BYPOWER~E)PROVIOEOFOOT'V4IL, PQWERSQRCE%OFILLIH.PROVIOEOBYPOWERSOURCEHIN.ESSENtIAL 4VAILL[GHTINO(FOOTUPSPANE)CANIXE)10.REACTIRIXOO.EL353'-N'EET JNQRHAI.YESSSENTIALYES'ftALYESN)'IALNQRHALESSENTIAL YESNQRH41.SSENTIALYESYESZVBB~IOREACTORKOG.AUX84YSNQ)THEL215'~EE&TL8HOIRBATPACKNORHALYESSSENTIALYES8NXRBAT.PACKNTIALYES8HOURBATPACKNORHALSSENTIAL8HQRBATPACKNQRHALESSENTIAL YESYES8HQRBATPACKNORHALSSENTIALYESYESZYBB~ICREACfORM)O.AUXBAYSSQ))HEL2)5'448'- EE&7L8NXRBAT.PACKNQRHALYESTIALYES8HOURBAT.PACK'IIALYES8HOURBAT.PACKNORHAIENTIAL8HQRBAT.PACKNORMALSEN'flALYESYES8HQRBAT.PACKNORHAISSENTIALYESYESZVBB~IOAUXSERVICEBLOG.SOUTHEL261'E&7P8HQ)RBAT.PACKNQRHALYESSSENTIALYES8NOIRBAT.PAOCNQRHALYESTIALYES8HQ)RBAT.PACKNORMALYES8HQRBA'f.PACKNQRHALSENrtALYESYES8NQRBAT.PACKNORHALSSEN)'IAL YESYESZVBB~IOSCREENWEIL SLOG.EL261'E-728 8NXRltATPACKHORHALYESSSENTW.YES8NXRBAT.PACKTIALYES8HQRBAT.PACKfIAL8HQR84T.PACKSENTIALYESYES8HQRBAT.PACKNQRHALSSEN'ftA). YESYES2VBB-UPSIC 8)KXRBAT.PACK8HQRBAT.PACK8HOURBAY.)AC'YES8NXR84T.PACKYES8HQRBATPACK~LGHTIl4INREACTORBUILOINGISPOWEREOFR(HPLANTEHERGENCT POWEROISTRIBUTIQI STSTEH.OURINGLOC4,'fHISNQI-IELIGHttNGSYSTEHPOwERISTRIPPEOBYANACCIENtSIGNAL

J8%'2LIGHTINGSYSTEMPOVERSOURCEANOMINI%HtLLUHINAI'ION AVAILABLE PAGE7HQQESQF6%JIATION LOCA8SEISHIC'VITHLOOPTRANSIENTVITHIXJTLOOPTIRBLDG.Et2I5EEOCSPENTRKLCQm.DKIAREA8OFSIXRCESTLLI84.BTneCRSCXJRCEHJRHALYESS%NTIALYES8NXRBAT,PACKHIM.AVAILIFOOTCAHJLEJ8HXRBAT,PACKYESHIJL8OFPRQVIOEQAVA~BYPOVERIFOOTMIRCENORHALNt&SSEMTIAL'IESPOVERSmRCESNORHAI.SSEMTIAL8HXRBAT,PACKYESESSENTIAL 8NXRBAT,PACKHIILILL~AVAILPOVERBYPOVER(FOOTSIXRCESSOURCE7OFILLUH.PROV!OEDBYPOVERSOURCEYESHBLAV40POVERCANm.E)BYPOVERSOURCENORHALYFSESSEM'fIALYES8NOIRBAT.PACKHIILESSENTIAL AVAIL.LIGHTINGIFOOTUPSPAWLCANQLEIIL2VBB~ICREMARKSTORBLDG.EL.2<8MEE+7D%7ITIALYES8HXJR,BAT.PAI7(NORMALYES8HXIRBAT,PACKYESNORHALHOKEDESSENTIAL YES8NXRBAT,PACKYESSSEMTIM.8NXRBAT,PACKYESYESYESSSEMTIALTES8HXRBAT.PACKVBB~SICNORHALYESSIJITIALYES8HXJRBATePACK8HXRBAT,PACKYESNORHALNO%'TIAL'YES8NXRBATPACKYESHORHALSSEMTIAL8NXRBAT,PACKYESYESHJRHALYESSSDITIALYES8MmRBAT,PACK2VBB~SICACCESSP4THt74.YQRHALYESSDITIALYES8HXRBAT,PACK8HXRBAT.IACKYESYES8NXRBAT,PACKYESMORHALSSEMTIM.8NXRBATPACKYESYESHJRHALYES$%MTIALYES8IKXRBAT,PACK2VBB-ITIC TORBLQd.Et328'-l8'%7M WeeLYESSEJITIALYES8HXRBar.IACX8HXRBAT.PACKYESESSOITIYESNDIHALSSEMTW.8HXRBAT.PACKYESESSENTIAL 8NOIRBAT.PACKYESYESNORMALYESSSBITIAL'YES8NXRBAT.PACK2VBB-IPSIQ iNIXBIALLIGHTINGIMREACTORBUILDINGISPOVEREDFROMPLANTEHERGEMCY PQVEROISTRIIXJTION SYSTEH.OIRIMGLOCA,THISNON-IELIGHTII4) SYSTEHPQVERISTRIPPEOBZANACCIDEMI'IGNAL~

avTmH>~f7presg'+%(PZLIGHTINGSYSTEHPOwERSOURCEANOHINIHUHILLUHINATIQN AVAILABLE PAGE8HOOESOFOPERATION LOCA8SEISMICWITHLRPTRANSIENT WITHOUTLOQPACT6IBLOC.ST4IRSEE-67EEE-67FE'E-67OEE%7HEEWTJPROVIOEDPOWERBYPQWERS(X)RCESDITIALIBBHIN.4V4ll(FOOTC(WE)LE)POWERILL~AvAIL.HIM.SOURCES(FOOTBYPOWERS(mRCESENTIAL188POWERSOURCESILUHHIN,PROVIOEO4"4'"-8'IPOWER~E)(FOOTSOURCEPOWERSOURCESILLUH.AVAIL~ERHIN.YPOWERC~E)PROvtOEO(~TSOURCEILLUILPROvtOEOBYPOWERSQLIICEte8HIN.ESSENTtAL 4V4ILLIGHTINO(FOOTUPSP~CAIZILEI[O.ZVBB~LBREHARKST&BLOC.AUX.BAYSN(XITHST4IRSEE<7L8)CURBAT,PACKTIALIBB8HOURBAT,PACKYESi8IXXXIBAT,PACKSENTIA(.8IKXXIBATPACK8H(XXIBATePACKSSENTI4LZVBB~LCACTUIBLOG.AUX.BAYSSOUTHST4IRSEE.67L8HERBAT,PACKSENTIALIBB8Ie)R9AT.PAO(ESSENTIAL YES08IKNXIBAT,PACK8IXXXIBATPACKIBB8H(X)RBAT,PACKZVBB-UPSLO 8IOLXI84T,PACK8HOURBAT+PAO(YES'IKWXIBATPACKYES8IKX)RBAT,PACK8IKXXIBAT+PACKHORHALLIGHTINGINREACTORBUILOINGISPOWEREDFROMPLANTEHERGENCY POWERDISTRIBUTION SYSTEH.IXNINGLOCA.THISNON-IELIGHTINGSYSTEHPOVERISTRIPPEOBYAHACCIDENTSIGNAL.

NMP2LIGHTINGSYSTEHPOWERSOURCEANDMIHINJMILLUMINATION AVAILABLE MODESOFDPERATIDN PAGELOCA4SEISHICWITHLOOPTRANSIENT WITHOUTLOOPTLRB.BLDG.GRMM)FLOORCORfODORELe258'E-66B POWERSOURCESESSEHTIAL XILLLÃ.PROVIDEDBYPOWERSOLRCEMIN.IAVAIL.POWERILL(FOOTSOURCESPROVIDEDCA)K)LE)BYPOWERSDLRCENORMALYESESSEHTIAL YESMIH.AVAIL.IFOOTCANDLE)POWERAVAIL.SOURCESIFOOTBYPOWERC~E)SOURCEHORMALNONEESSENTIAL NONEPOWERSOURCESNORMALESSENTIAL OFPROVIOEOBYPOWERC~E)(FOOTSOURCEYESPOWERSOURCESESSENTIAL ILLU)LXOFpRovloEoAVAIL.BYPOWERC~E)(FOOTSOURCEYESYESESSENTIAL LIGHTINGO'SPANELID.2VBB-LPS1D SAFES)IJTDOWN PATHO)l.YNoELXJIPPKNT TURLBLDLCLEANACCESSAREAEL.2QYEL2Q'L.288'-8'L. 396'E-66H TtSLBLOLCLEANACCESSAREASTAIRSEL+258'L2Q'L288'-8'L386'E-66H 8NXRBAT+PACKNORMALESSENTIAL 8)KXRBAT.PACKbHOLRBAToPACK8HLXRBAT+PACKNORMALYESESSENTIAL YES8HL)LRBAT.PACKESSEHTI)V. YES8HOLRBAT.PACK8HOLABATsPACKYESSHXRBATPACKYESESSENTIAL NONE8HXRBATPACKNORHALNONEESSENTIAL NONE8NXRBAT+PACKNORMALESSENTIAL S)NLRBAT.PACKSHOLRBAToPACKYESYES8HOLRBATePACKNORMALESSENTIAL SHOLRBAT.PACKESSENTIAL 8HOLRBAT.PACKYESYESYES2VBB-UPSIO 2VBB-UPSIC 2VBB-UPSIC SAFESHUTDOWNPATHD)LYNOEOUIPMENT SAFESWTDOWNPATHM.YNDEIXJIPPKNT IU ACCESSROUTETAKENBYOPERATORFROMCONTROLROOMTOUPSROOMINNORMALSWITCHGEAR BUILDINGON8-13-91Thefollowing routewastakenbyoperatorfromcontrolroomtogotoUPSroominswitchgear buildingtotransferalternate powersourcetoUPSunits,Operator leftthecontrolroomEL306throughsouthdoorandproceeded towest.Thenheturnednorthalongthecorridoronthewestsideofthecontrolroom.ThenheexitedthecontrolroombuildingthroughnorthwestdoorEL306toAuxiliary building. HethentookthestairwayjustsouthoftheelevatortogotoEL261.ThenatEL261ofAuxiliary

building, heproceeded tosouthandenteredthecorridor(Electrical equipment Tunnel).Fromthecorridorheenteredthenormalswitchgear buildingEL261andproceeded tostairwaylocatedinthecenterofthebuilding(Westhalf)downtoEL237wheretheUPSunits2VBB-UPS1A, 1B,1Cand1Darelocated.Hethentransferred theUPSpowertomaintenance powersource.Afterrestoring powertotheaboveUPSunits,theoperatorproceeded toUPS2VBB-UPS1G viathedoorontheeastendoftheroom,wentsouthdownthehall,throughthedooronhisleft(eastside) andenteredthecontrolbuilding.

HethentookthestairsdowntoEL214whereUPS2VBB-UPS1G islocatedandtransferred thepowertothemaintenance power.

CONDENSATE/FEEOMATER SIMPLIFIED SKETCHlCQOCMJEANSFEll4IIIIIIQlZEMSATE BOOSTERIIFVRi)FOI)MFlOPAWLIIIIIIIIIIIiFEEOvATER COMlROLLOO)C)II)IILVIBFLFVgPRESS)I)RED REAC)TX)VESSELO'RVIC(ÃH6ATEPAPHIM.FLOMIEgKRICQI+QNCOMPENSATE )MISTERPNTPHDLFLOMTEAOERFEEOPUH'lM. FLOVTRACERFOXBOROPANELTRAINA-2CEC-PNL825 TRAINB-2CEC-PNL826 TRAINC-2CEC-PNL827 FEEDWATER CONTROLPANEL2CEC-PNL6I2 (TYPICALTRAINA,8,8,CCROSSOVER HEADERSBETWEENTRAINSPROVIDECROSSOVER FLOW

OeGEIndustrial A,TrAQftttl+IIf'/QapowerSystemsPROPomrGeneration ServicesDepartment GeneralElectricCompany3532JamesSt..PO.Bott484t,Syraorse. Nyt322tNIAGARAMOHAWKPOWERCORPORATION NINEMILEPOINTNUCLEARSTATIONUNITg2rGENERATOR g180X632GENERATOR INSPECTION -POSSIBLEPHASE-TO-PHASE FAULTcc:NIAGARAMOHAWKPOWERCORP.R.AbbottN.KabarwalM.McCormick GENERALELECTRICCOMPANYAugust28,1991L.Jordan(37-3)W.JuddS.KolbR.SmithW.TurkMr.AnilK.JulkaNIAGARAMOHAWKPOWERCORPORATION 301Plainfield RoadNorthSyracuse, NewYork13212

DearMr.Julka:

DuetotheAugust13,1991failureofthephaseBstep-uptransformer onNineMilePointUnitg2,GeneralElectricGenerator Engineering recommends performing athoroughvisualinspection ofthegenerator statorendwindingsupportsystematthenextconvenient opportunity. Theinspection shouldincludeallaccessible components ofthestatorendwindingsupportsystem,including statorbarendarms,blocks,tiesnoserings,andouteraxialsupports. Thisinspection shouldbeaccomplished byaGEGenerator Specialist trainedtodetectthepotentially subtleindications ofdamage.Theaboverecommendation isbaseduponthepossibility ofphase-to-phase generator shortcircuitcurrentsthroughthefailedtransformer ashighas5pu.Theinitialrecommendation fortheimmediate generator inspection considered thepossibility ofhighercurrents, resulting inseveraltimesgreaterendwindingforces.Physicalevidenceofhighcurrentforcesatthetransformer .lowsidewastheprimarydriverforthisrecommendation, sincemeasurements ofgenerator currentswerenotavailable. Ourengineers continued toreviewthelimiteddataavailable andsubsequently concluded thatcurrentshighenoughtodoprobabledamagetothegenerator werenotlikely.Thisconclusion wasreachedprimarily byconsidering ameasurement ofdepressed generator voltageduringtheincident, inferring generator

currents, andspecificcapabilities ofthegenerator design.

'k PageIIMr.,AnilK.JulkaAugust28,1991Shouldyouhaveanyquestions regarding thisrecommendation, pleasecontactme.VeryrulyyoursJeph.KirchMaagerEngineringServicesPowrGeneratio Services"SYRACUSE OFFICEJAK/bsJAK-059 .rI~T}}

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