05000318/LER-1980-023-03, /03L-0:on 800416,while 21 Diesel Generator Was Being Taken Off 24 4 Kv Bus Following Test,Two 15 Vdc Power Supplies Had No Output.Caused by Tripped Overvoltage Protection Modules: Difference between revisions

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{{Adams
#REDIRECT [[05000318/LER-1980-023-03, Steam Generator Isolation Signal Block B Permitted Steam Generator Isolation Signal B to Be Blocked & Loci Sequencer Alarmed.Caused by Voltage Disturbance in Inverter Output]]
| number = ML19305E820
| issue date = 05/16/1980
| title = /03L-0:on 800416,while 21 Diesel Generator Was Being Taken Off 24 4 Kv Bus Following Test,Two 15 Vdc Power Supplies Had No Output.Caused by Tripped Overvoltage Protection Modules
| author name = Davis S
| author affiliation = BALTIMORE GAS & ELECTRIC CO.
| addressee name =
| addressee affiliation = NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
| docket = 05000318
| license number =
| contact person =
| document report number = LER-80-023-03L, LER-80-23-3L, NUDOCS 8005200473
| package number = ML19305E814
| document type = LICENSEE EVENT REPORT (SEE ALSO AO RO), TEXT-SAFETY REPORT
| page count = 2
}}
{{LER
| Title = /03L-0:on 800416,while 21 Diesel Generator Was Being Taken Off 24 4 Kv Bus Following Test,Two 15 Vdc Power Supplies Had No Output.Caused by Tripped Overvoltage Protection Modules
| Plant =
| Reporting criterion =
| Power level =
| Mode =
| Docket = 05000318
| LER year = 1980
| LER number = 23
| LER revision = 3
| Event date =
| Report date =
| ENS =
| abstract =
}}
 
=text=
{{#Wiki_filter:So a5.2D 0 t(73 (7 77)
LICENSEE EVENT REPORT
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O CONTROL BLOCK: l l
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7 8 9 LICENSEE COOK to 16 UCENSE NUMBER 25 26 LICENSE TYPE JO 57 CAT 58 CON r IoIi1 S$ ice l L l@l015 10 10 10 13 11 18 l@ l 0I 4l 1l 6l RI n @ l nI gI 1 I 6 IeIgl@
7 8
60 61 DOCK ET NUMBER 68 69 EVENT OATE 74 75 REPOR T OATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h I o 12 I l AT 1045 WHILE 21 DIESEL GENERATOR WAS BEING TAKEN 0FF 24 4 KV BUS FOLLOWING A I
Io Ia l l TEST, STEAM GENERATOR ISOLATION SIGNAL (SGIS) B BLOCK PERMITTED. SGIS B BLOCKED I
i o 14 i l AND LOCI SEQUENCER INITI ATED WENT INTO ALARM.
AN INVESTIGATION REVEALED THAT I
I o I s 1 l 'IVO 15 VDC POWER SUPPLIES HAD NO OUTPUT. THEY SUPPLY ESFAS LOGIC B CABINET I
I O ls 1 I SGIS/ RAS /CRS/CSAS, LOCI AND SHUTDOWN SE0VENCER FUNCTIONS.
(T.S. 3.3.2.1) 1 [O l 7 l l THE 15 VDC POWER SUPPLIES WERE RESET AND ESFAS LOGIC B CABINET WAS RETURNED I
ioIai i SERVICE AT 1340.
LER 79-31 (U-1) DESCRIBES A SIMILAR EVENT.
1 OE CODE SUSC E COMPONENT CODE S BCOO'E S
E lolol i Il Bl@ [XJ@ l Z lO il l N l 5 l T I R I U lh l_P_J@ LIJ @
7 8
9 10 11 12 13 18 19 20 VENT YEAR REPORT O COOE N
LE R /RC O Rtg 1810]
l-l 1012l31 l/l 10 13 l lLl l--J l 01 yu
_ 21 22 23 24 26 27 28 29 30 31 32 TAK N ACTO ON PL NT MET HOURS SB if FOR B.
SUPPLI R MANUFACTURER lXl@lXl@
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33 34 JS 36 37 40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS li 101 l BOTH POWER SUPPLIES' OVERV0LTAGE PROTELTION MODULES HAD TRIPPED. REDUCING THFIR I
li t i l ! OUTPUTS TO NEAR 'O' VDC. THE ALARMS DESCRIBED AB0VE WERF RFCFIVFD COTNCTDFNT I
I li i 21 1 WITH THE OPENING OF N0. 21 EMERGENCY DIESEL GENERATOR OUTPUT BREAKER WHICH WAS i,i3i l CARRYING INSIGNIFICANT LOAD AT THE TIME. A PROCEDURE IS BEING DEVELOPED TO I
l ii141 l TROUBLESHOOT THE PROBLEM.
7 8 9
$7A $
% POWER OTHE R ST ATUS SO Y
DISCOVERY DESCRIPTION NA l
l B l@l OPERATOR OBSERVATION l
Ii I 5 l Lfj@ l 1 l 0 l 0 l@l ACTIVITY CO TENT AELE AsEO OF RELE ASE AMOUNT OF ACTIVITY LOCATION OF RELE AsE I1 Is 1 LZ_J @ LZJ@l NA l
l NA I
,EpsONNEt ExPOSMES OESCRiPTiON@
NuveER TvPE l
I t 171 1 01 01 Ol@l Zl@l NA
,ERsONNEoby' lits OEsCRiPTiON@
l NuvsER li la l I 0101 Ol@l NA 20 7
8 9 11 12
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Na 2 o 68 69 23 5 S. M. DAVIS /P. G. RIZZO PsO :E. h01 Wo.a m /am NA.*f. OF PREPARER L
 
LER N0.
80-23/3L DOCKET N0.
50-318 EVENT DATE 04/16/80 REPORT DATE 05/16/80 ATTACHMENT CAUSE DESCRIPTION ArlD CORRECTIVE ACTIONS:
IMMEDI ATELY AFTER RESETTING THE +15 VDC POWER SUPPLIES, THE OVERV0LTAGE PROTECTION TRIP P0INTS WERE MEASURED AT +16.5 VDC. BOTH POWER SUPPLIES WERE FOUND TO BE OPERATING AT +15.1 VDC. AN OSCILLOSCOPE DISPLAYED N0 NOISE OR AC RIPPLE ON EITHER OUTPUT.
THERE IS NO APPARENT REASON FOR A TRANSIENT ON A 4 KV VITAL BUS TO INDUCE A TRANSIENT WITHIN THE ESFAS CIRCUITRY. THE ESFAS IS POWERED BY VITAL INVERTERS, WHICH ARE IN TURN POWERED FROM VITAL BATTERIES; THEREFORE, A PROCEDURE IS BEING DEVELOPED FOR TROUBLESHOOTING THE APPARENT CAUSE AND EFFECT.
SINCE SUBMITTAL OF LER 79-31 (U-1), MEASUREMENTS BY INDUCING 4 KV TRANSIENTS WHILE MONITORING VARIOUS POINTS WITHIN THE VITAL POWER TRAIN MADE ON THE VITAL AC POWER TRAINS IN UNIT 1 HAVE REVEALED N0 UNUSUAL DISTORTIONS NOR COMMON MODE NOISE PATTERNS. BENCH TESTS OF A REPRESENTATIVE ESFAS +15 VDC POWER SUPPLY REVEALED NO REGULATION PROBLEMS IN RESPONSE TO VARIATIONS IN SUPPLIED VOLTAGE OR FREQUENCY WITHIN ITS DESIGN SPECIFICATIONS.
FURTHER TESTING, EMPLOYING A NEWLY PROCURED TRANSIENT-RECORDING DEVICE IS EXPECTED TO BE COMPLETED BY JUNE 30, 1980.
i i
1
}}
 
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