ML20034E393

Rev 0 to Summary of Degraded Voltage Study

ML20034E393
Person / Time
Site:	Indian Point
Issue date:	01/22/1993
From:	Chan A, Sullivan R CONSOLIDATED EDISON CO. OF NEW YORK, INC.
To:
Shared Package
ML20034E389	List: ML20034E388 ML20034E391 ML20034E393
References
EGP-00110-00, EGP-00110-00-R00, EGP-110, EGP-110--R, NUDOCS 9302260083
Download: ML20034E393 (40)

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J CON EDISON CALCULATION / ANALYSIS Page 1 of

1. o COVER SHEET Subsection: PLANT PROJECTS (NUCLEAR)

Code: EGP' l Calc.No.: EGP-00110-00 Calc. Type: VOLTAGE _ DROP l

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Pitle:

SUMMARY

OF DEGRADED VOLTAGE STUDY

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Project:

06786-91 MODIFICAT10N:'EGP-91-06786-E

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Document Page Count: 040 Old Calc.Ho.: NONE TAG NUMBERS I

(none) t

.i COMPONENT (S) AFFECTED l

l Equip. Type 038 ELECTRICAL SUPPLY-l l

Structure 08 CONTROL BUILDING l

Structure 25 PRIMARY WATER STORAGE TANK i

System 77 138 KVAC ELECTRICAL System 80 480 VOLT ELECTRICAL l

System 81 6.9 KVAC ELECTRICAL I

Preparer /Date Reviewer /Date Approval /Date Super-Confirm.

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Rev.No.

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i DJGUIEERI!IG OPERATIO!JS'IWJUAL Exhibit E Page 2 of //0 l

COff EDISOli CAICUIXf1Oli/AllALYSIS t

Description of Q1 ant 3e Sheet calculation tio:

EGP-00110 i

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Dascription of Giange Reason for diange f

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Sect. 5.16 June 7, 1991 OP-290-1 All Previous Page 27 of 32 pages

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CON E (H!.ON CALCitt A! ON'ANAty$t$ $UMMARY $Ht fl 1GP 00110 00 0

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PREPAHt RcDAf t RtwawtR DATE Ct. ASS KENNETH CHU 1/4/93 ANDY CHAN 1/22/93 CLASS A,1E SUBJE Citt ait t PROJECT No.

SUMMARY

OF DEGRADED VOLTAGE STUDY 06786-91 MODNo kfy EGP 9106786 E 1

i OBJECilvE OF CALCut ATION See Page 5 CALCu1 AT K)N ME THOD, A55UMPliONS See Page 8 i

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l'fti P Arti is th4 i e nivst wf ft'DA1E ct A E S VE NNElli CHU 1/4/03 At3DY CilAN 1/22/93 Cl ASS A.1E sunitct, te st t t MOJECT No

SUMMARY

Of DEGRADTD VOLT AGE STbDY OG106 91 e.wo u.. an <

(GP 94 011785 E 1

SUMMARY

OF DEGRADED VOLTAGE STUDY I) INTRCDUCTION l

During the 1993 Refueling

Outage, modifications will be implemented in connection with the degraded voltage study.

The enhancement will provide greater margin to insure the safety-related equipment operation.

In addition, as part of

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the Motor Operated Valve Upgrade Program.

MOV(s) will be

upgraded, based on a

MOV analysis that uses a higher degraded voltage serpoint.

Modification Procedure No. EGP-91-06786-E Revision 0 and 1.

I will replace the degraded undervaltage relays and change the setpoint from 403VAC +/-5 volts to 421VAC +/-6 volts; this will increase the margins between the minimum starting vol tage and the minimum voltage due to degraded conditions at the 480VAC safequard motor terminals.

Modification Procedure No. EGP-92-07762-E Revision 0

will enhance the 480VAC Safety Buses 2A, 3A, SA and 6A voltage level through a faster load tap changer response by lowering i

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P c AitutArsou no rce vision sAct Cort FDISOf f cat Clit Af tOrilAf1A1YSIS $1if fI FGP tvil10 00 D

RJf 40 T'fif FAft( R (Pall fil Vli W( R 'DA I L (tA$s KEtJrJElit Cilu 1/4/93 AtJDY CilAf4 1/22/93 Cl ASS A.1E sunn C ]sist((

PHOJf 01 feu StirAMAHY Of DEGilADED VO!1 AGE STUDY DS HIS 91 l

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the 138/6.9kV oftaite supp1v Station Auxiliary Transformer (SAT) load tap changer (LTC) initial time delay from 45 l

l t,econds to 2 seconds and by reducing the transferred AC load to the offsite bus after the unit trip through the automatic tripping of 6.9kV Condensate Pump No. 23 following a

unit trip.

Modification Procedure No.

FEX-92-08169-E will upgrade fiOV(s) based on the new degraded voltage relay setpoints i

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when required.

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11) OLJECTIVE Based on the 1993 enhancements and the new degraded voltage relay setpoints, this analysis will demonstrate the l

fo]Iowing:

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o 11a s i s for new degraded voltaqe relay serpoint i

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With the new degraded voltage rebys setpoint, under the I

normal offsite voltage conditions 136kV to 142kV. the I

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CON CDISOri CAL Cill.ATiotitAtlAl YSIS SHE l T i GP 00110 00 0

g of 40 PRIPAftt.ft (pA IL fit viIw[ R DAIE CLASS j

KE NNIill Clld 1/4/93 ANDY CilAN 1/22/93 CL ASS A,1E SUBJt C1/1114 E PHOJICI No

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SUMMARY

Of DEGRADfD Vol TAGI: STisDv os7po 9:

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1 480VAC buses will not be degraded to a level that would initiate an unnecessary transfer &o the emergency onsite power supply durinq normal plant operation, unit trip or accident conditions.

o For the worst case ]38kV offsite power degradation which i s well beyond the Electric Planning Extreme Contingency Analysis and the New York Power Pool Design Criteria, i

the 480VAC buses will transfer to the emergency onsite power supply, as designed.

l 11I) DEGRADED VOLTAGE MODIFICATION ENilANCEMENTS f

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Due to the higher degraded voltage setpoint, enhancements i

are being made to preclude any unnecessary transfers to the

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onsite emeroency power supply.

These changes are covered i

under modification Procedure EGP-91-06786-E, (IP2 SV Relay Heplacement) and EGP-92-07762-E, (IP2 Degraded Voltage i

l Circuit Modification).

Modification EGP-91-06786-E provides for the replacement of the existing West-inghouse SV relays l

with ABB Type 27N high accuracy relays and for the associated setpoint changes.

Modification EGP-92-07762-E

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CON EOiSOff cat Clit Aunts /AtlAl YSIS SlH f1 IGP 00110 fur a

7 t>F du 5 R( PARI ft<DAIL pf vil WI R'DAlf CLASS KENNEill Clit) 111/93 ANDY CllAN 1/22/03 Cl AS S A.1 E susus cis tetti PRoitti u.

SUMMARY

Of DEGRADED VOL TAGE STUDY DG706 91 5

r. ion no hav icc et estan r t

l provides for the reduction of the tinie delay for the Station Auxiliary Tra n s f ortrie r LTC a nd for the automatic trippino of Condensate Pump No. 23 on a unit trip.

Tripping of the condensate pump uill reduce the load that is transferred

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from the unit supply (tinit Auxiliary Transformer) to the offsite supply (Station Auxilinry Transformer).

This modification provides for the quicker recovery of the 6.9kV and 480V bus voltages following an offsite power grid disturbance and for a reduction of the voltage drop through the Station Auxi.liary Transformer and associated cable and switchgear, thus reducing the voltage drop the LTC must quickly compensate for.

Both modifications will be performed during the 1993 refueling outaqe.

i IV) MOTOR OPERATED VALVES Presently a study is being conducted by B&W Nuclear Services in response to Generic Letter 89-10 to determine the minimum j

required voltage at the MOV terminals.

The minimum acceptable voltage at the MOV terminal will determined by the B&W analysis.

A comparison will be made between the l

required voltage and the degraded voltage relay setpoints to l

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COf a 1:DisOta rAl rif t AIlOfi/ ANAL y5tG Siif [1 iGP nit to LH)

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l determine whether MOV(s) have to be upgraded.

Modifications will be performed for those MOV's identiffed by the B&W analysis which do not have adequate motor terminal voltage l

during starting conditions.

V) BASIS FOR DEGRADED UNDERVOLTAGE SETPOINT To increase the margin of motor starting voltage, the degraded voltage relays setpoints will be changed from the present setpoint value of 403V

+/-5V to 421V +/-6V via modification procedure EGP-91-06786-E. Revision 1.

The setpoint value was chosen with an enhanced margin of safety above the minimum required bus voltage (415VAC, see Calc. EGE-00001-00) to start and run the 480V safeguard 1

motors, with an upper bound to preclude spurious transfers to the diesel generators for system fluctuations and to account for relay drift and tolerances and for the tolerances of the potential transformers.

The setpoint range is based upon the actual operating characteristics of the ABB Type 27N relays which will be used in the degraded voltage protection circuits.

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V1) MINIMUM VOLTAGE REOUIREMENTS FOR CLASS lE 110 TORS v

In order to determine the voltage requirements for Class 1E safety-related motors, an analysis was performed by the Rotating Machinery Subsection of Electrical Engineering.

The analysis consisted of determining the minimum required voltage at the motor terminals to start the motor by using the latest EPitI recommended calculation method and actual motor and pump curves. (See Calculation EGE-00001-00).

In

addition, the calculation also determined the minimum voltage level required at the 480V supply buses (2A, 3A, 5A, 6h), taking into consideration the voltage drop of the power cable.

Based on the results of the above calculation. it was determined that the 250 HP Component Cooling Pump Motors were the bounding motors in terms of maximum required terminal voltage.

This corresponds to 415VAC at the 480V Safety 1(elated Buses (2A, 3A, SA, 6A).

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Vill OFFSITE POWER SYSTEM DISTURBANCE (Offsite Power-138kV)

Under the normal operating conditions.

Con Edison system voltages are maintained within the specified range as

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s ntPAntn uAn ntvirwt n r>An CIA 55 KENNETH CHU 1/4/93 ANDY CilAN 1/22/D3 Cl ASS A,1 E SUB IE C I/1t fi t Phal 101No SUMMAftY Of DEGHADED VOLT AGE STilDY 06788 98 MO(n Ho - 541 V eur.i nns e i described in EO-4000, Rev 04. " System Operati ng Manual

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5" and are as follows:

I Minimum Maximum t

Substation Voltage Voltage l

138-kV 136-kV 142-kV 345-kV 340-kV 359-kV For this range of offsite power grid voltage variations the 480V bus voltages must not he reduced to a level which would 1

initiate an unnecessary transfer to the emergency onsite power during nornial plant operations, unit trip or accident i

condition.

For this

analysis, the voltage used was based on the Electric Planning Department study which simulated the loss at Indian Point No.

2.

In order to simulate the degraded voltage

scenario, pre-contingency voltages for the IP2 offsite supply from the Buchanan 138-kV substation were in&entionally scheduled at their minimum design level (136kV) to achieve the lowest voltage condition resulting

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SUMMARY

Of DEGitADED VOLT AGE STUDY 06706 91 I

s u n..H.. n.iv no mr. a,

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trom this system disturbance.

The 138-kV offsite voltage after the loss of IP2 is 0.958 pu (132.20-kV).

Immediately after this contingency. System Operations at the Energy Control Center is required to restore the 138-kV system to the value 0.985-pu minimum as defined in EO-4000-4 I

and in accordance with the

" Standards For Planning and i

Operating The New York Power Pool Bulk Power System".

0.95 pu minimum.

This can be accomplished by System Operations l

at the Energy Control Center who would control the Buchanan t

North 345/138-kV Transformer TA5's tap changer via the t

supervinory system (System Operntion Computer Control System l

Known as SOCCS).

In addition, the IP2 Stntion Auxiliary Transformer LTC would automatically adiust the voltage on the 6.9kV and 480V buses.

As a result, the amount of time l

that the offsite grid voltage would be degraded to the l

l extent that there would be a transfer to emergency onsite power in minimal.

Offsite power remains the preferred power source by design, and a transfer to emergency onsite power is designed to occur only for sustained degraded conditions I

which would reduce the margin for the 480V safeguard motors i

below the enhanced acceptable levels.

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For offsite grid voltages which fall below the above

rance, the offsite grid voltage is considered to be degraded, and l

if the degraded voltage setpoint is reached and sustained for the Technical Specification time delay, the 480V buses will be transferred to emergency onsite power by design.

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A) LOCA ANALYSIS To evaluate the effects of the degraded voltage on the various safety-related

motors, a case study was performed i

for the plant LOCA scenario mode (when the offsite power is initially at 136kV) using EBASCO's computerized program.

Electrical System Management Software (ESMS),

dated j

12/31/89, with a database updated to reflect the installed 1991 outage modifications.

This model reflects the electrical distribution system of the 6.9kV and 480V buses l

at IP2.

The program was written and QA verified by EBASCO Services Incorporated.

This case scenario assumes no voltage adiustment by the System Operator via the SOCCS supervisory panel.

The proaram is limited in its capability i

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b (JF 40 Phtf AHE N/DAlt (tive(wlR DAIE C4 ASS KENNE Til Clll) 1/4/93 AfJDY CllAN 1/22/93 CLASS A.1E suit st c s eisit t PHolt ti ##o

SUMMARY

OF DIGRADED VOt T AGE STllDY 06700-98 l

1.10D fio - HE V iGP St D6/66 f 1

to fully model the load tap changer.

To compensate for the program's inability to model the LTC for the

43MVA, i

138/6.9kV Station Auxiliary Transformer, the transformer's winding ratio was manually varied to simulate LTC movements.

i The SAT is a

Westinghouse unit with a

URT type LTC.

Modi fi ca ti on EGP-92-07762-E will reduce the time delay for operation of the first tap by lowering the transformer's SVR relav raise and lower time delay from 45 seconds to 2

seconds and will provide for the automatic tripping of the 6.9kV Condensate Pump No.

23 via the auxiliary relays 1

86X-1/P and b6X-1/BU.

(These relays will be actuated by the 86/P and 86/BU relays which also actuate the fast bus transfer)

These moditications will improve the bus voltage levels on the 6.9kV and 480V buses.

After the initial time delay, the time required for the load tap changer to change from one position to the next is one (1) second.

For conservatism, this analysis will use two (2) seconds as the mechanical operation time to change frotri one position to the next as the worst case assumption.

In actual operating circumstances after the system disturbances, the LTC will either automatically ndiust the L_

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PRU #L C I '"

50MMARY Of Df GRADED VOU AGE STUDY OGFDG D1 uon n.. ni v t t.P 91 Hu?M I 1

voltage back to approximately 7.05kV or be operated manually via the Central Control Room.

lu addition the System Operator will rest cre the 138-kV system voltage via the i

l SOCCS supervisory panel manually to maintain the specified operating voltage (136-kV to J42-kV).

l LOCA CONCLUSION The results of the LOCA case scenario with the automatic i

load sequencinq of safety related loads as per Reference 9, are shown in Figures 1 nnd 2.

These figures represent the l

load profiles for the 480V Buses SA and 6A and illustrates that during motor starting transients the voltage on the bus will drop to a level below the proposed degraded voltage setpoint (Bus SA - 403VAC, starting Safety Inlection Pumps Nos. 21, 22, 23.

uus 6A 398VAC.

starting Auxiliary Feedwater Pumps Nos.

21, 23).

lioweve r, the bus voltage after the trictor(s) has started will recover to a

steady state voltage above the reset value of the degraded undervolteqe relays within the acceptable time frame (10 seconds with SI) as designed (Bus SA - 438VAC. Bus 6A -

434VAC).

These figures also demonstrate that the i

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ID or 40 f

rassantn nAir e t v4 Wi ft.nA T E CLASS KEtJNE Til CHU 1/4/93 ANDY CllAN 1/22/93 CLASS A,1 E sunaicunn a enoasci u.

StifAfAARY OF DEGRADED VOL TAGE STUDY 06786 91 uon no r<tv EGP 910EtsG E 1

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safety-related motors will be able to start and continue to operate under the LOCA scenario and not transfer to the j

i emergency onsite power.

After the completion of the SI loading sequence, the steady state voltage on the 480VAC Bun SA and 6A will he 441V and 434V respectively.

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The worst case 480V bus loading occurs on Buses SA and 6A.

Therefore, this analysis does not include the load profiles l

for Buses 2A and 3A since these are not the bounding cases.

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Table 1 lists the safety related equipment, desired terminal starting voltage, deuired voltage at bus and the voltage prior nnd after starting of the nubiect motor per the SI loading sequence.

Table 2 lists the attachments numbers of the EBASCO computer printouts for selected caseu with corresponding SAT LTC secondary winding ratio's and the selected motor (s) to be d t.a r t ed.

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SutJtAAltY OF (IEGIIADFD Vol T AGF STilDy 06706 91 noin no - r<f v i GP 91 Uls/Bfi i 1

Table 3 lists the saf et.y related motor starting sequence and s

their respective starting times from the initiation of bus i

i sequence signal.

FASTBUS TRANSFER ANALYS_I_S We have also evaluated the effects of a Unit trip resulting in a fastbus transfer of loads from the Unit Auxiliary Transformer supply to the Station Auxiliary Transformer suppl y during normal plant conditions.

This case scenario assunies no voltage adiustment by the System Operator via the SOCCS supervisory panel.

During a non SI condition, the P

deqraded undervoltage relays actuate a Aqastat timer (set at 180 seconds) which in turn trips its respective 480V breaker in the event that the degraded voltage relays do not reset within the 180 seconds.

The time delay allows for the voltage fluctuations on the 138-kV offsite system and normal plant load variations to stabilize to prevent an inadvertent transfer to the emergency onsite power supply.

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PAGE l'/ OF 8/O Mod. No. EGP-91-06786-E, Rev 1 Calc. No. EGP-00110-00 1ADLE 1 t

o IP2 in operation, Offsite power at 136kV (0.985pu) o Loss of IP-2, the offsite power drops to 132kV (0.958pu)

SWP 21, 22, 23 assumed to be on essential header 480V DESIRED HOTOR DESIRED DECRADED DUS VOLTAGE SUPPLY TERMINAL VOLTAGE LOCA MODE Mol0R DESCRIPilON BUS STARilNG VOLTAGE AT BUS (V)

Pe!OR AflER I

CONTAINMENT SPRAY PLMP (21) 5A 313 337 443 438 1

CONTAINMENT SPRAY PUMP (22) 6A 313 338 441 435 SAIETY INJECTION PUMP (21) 5A 343 365 442 438 SAFETY lt!JECTION PUMP (22) 24 343 367 442 437 SAFETY INJECTION PUMP (23) 6A 343 365 442 438 CONTAINMENT RECIRCULAllON FAN (21)

SA 313 354 440 435 CONTAINMENT RECIRCULAflON TAN (22) 54 313 356 441 437 CONTAINMENT RECIRCULAllON TAN (23) 2A 313 359 448 443 CONT AINMENT RECIRCUL ATION FAN (24) 3A 313 362 449 445 CONTAINMENT RECIRCULATION FAN (25) 6A 313 370 441 437 r

5 LO HEAD S1 RECIRCULATION PUMP (21) 5A 312 358 LO HEAD SI RECIRCUL A110N PUMP (22) 6A 312 357 SERVICE WATER PUMP (21) 54 440 436 SERVICE WATER PUMP (22) 2A 123 357 444 439 SERVICE WA1ER PUMP (23) 6A 323 358 440 435 SERVICE WATER PUMP (24)

SA 323 361 SERVICE WATER PLMP (25) 3A SERVICE WATER PUMP (26) 6A 323 361 AUKillARY FEEDWATER PUMP (21) 3A 370 397 453 447 i

Auxill ARY f EEDUATER PUHP (23) 6A 370 395 441 434 COMPONENT COOLING PUMP (21) 5A 369 403 440 437 COMPONENT COOLING PUMP (22) 2A 369 415 442 439 COMPONENT COOLING PUMP (23) 6A 369 411 441 439 RESIDUAL NEAT REMOVAL PUMP (21) 3A 333 365 444 441 RESIDUAL llEAT REMOVAL PUMP (22) 6A 333 362 441 438 Note: loss of IP2, f astbus transfer, automatic strirping of the 480V buses, the bus voltage will drop to the following values:

Bus 2A-438V Bus 3A-438V Bus 5A-438V j

Dus 6A-438V

• SWP 21 and 25 are electrically and mechanically interchangeable with the other SWP's rnotors s

• • 140 t required during injection mode I

l l

i cAtcULAIenN No REVISION PAGE Con rosson cALCul AllON/ ANALYSIS SHEH EGP 00110 - ec 0

gr,-,

PRE PAftE R'D A r f HIVir WL R/DAlf f j cLAb5 KENNETH CHU 1/4/93

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//2E/93 CLASS A,1E i

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pumic, u, y

suuMARY OF DEGRADED VOLT AGE S11tDY 0670G 91 Ec"P ""ea."U TABLE 2 SAT WINDING ATTACH #

PAGE #

CASE #

RATIO.

REMARKS LOCA-1 155,156 1

(N) 7073 Normat precontingency condition LOCA-2 155 2

(N) 7073 T=0+, IP2 unit trip coincident with St LOCA-3 155 2

(R1) 7105 LTC changing posabon LOCA-4 155,156,167 2

(R2) 7137 Starting $1-21 (SA), $1-22 (2A), S1-23 (GA)

LOCA-5 155 3

(R3) 7169 Starting CCP-21 (SA)

LOCA-6 155,167 4

(R4) 7202 Starting RHR 21 (3A), RHR-22 (6A) l LOCA-7 167 5

(RS) 7234 Starting CcP-22 (2A)

I LOCA-8 156 6

(R6) 7267 Starting CCP-23 (6A)

LOCA-9 155,156 7

(R7) 7299 Starting CS-21 (SA), CS-22 (6A)

LOCA-10 155,156,167,168 8

(R8) 7331 Starting SWP-21 (SA), SWP-22 (2A),

l LOCA-11 155,156 8

(R9) 7363 LTC changing positen LOCA-12 155,156,168,169 9

(R10) 7395 Starting SWP:23 (6A), CRF-21 (SA), CRF-24 (3A)

LOCA-13 155,156,168 9

(R11) 7428 LTC, changing posihon LOCA-14 155,156,168 9

(R12) 7460 LTC changing posinon

(

LOCA-15 155,156,169 10 (R13) 7493 Starting CRF-22 (SA), CRF 23 (2A), CRF-25 (6A)

LOCA-16 156,157,169 10 (R14) 7525 LTC changing posmon LOCA-17 157,169,170 11 (R15) 7558 Starting ABFP-21 (3A), ABFP-23 (6A)

LOCA-18 155,156,168,169, 11 (R16) 7590 LT C changing posihon i

h I

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=

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PHlPAftENrDAlf RE viEwin'DAIE CLAS5 VENNETH CHU 1/4/93

[, c n #44 //22./J73 CLASS A,1E buBJE CIIIII4 E suuunny or otGnADfD VOLTAGE SfuDY PhDJECI No.

06706 91 Yc*?,% s'l '

TABLE 3, $1 STARTING TIME FROM INITIATION OF BUS SEQUENCE SIGflALS (SECONDS) i MOTOR DESCRIPTION BUSSA BUS 2A BUS 3A BUS 6A l

SAFETY IfJJECTION PUMP (21) 3 SAFETY INJECTION PUMP (22) 3 l

i SAFETY INJECTION PUMP (23) 3 COMPOfJEtC COOLING PUMP (21) 6 RESIDUAL HEAT REMOVAL PUMP (21) 8 i

RESIDUAL HEAT REMOVAL PUMP (22) 8 COMPONEhT COOLING PUMP (22) 9 COMPONENT COOLING PUMP (23) 11 l

i CONTAINMENT SPRAY PUMP (21) 14 CONTAIUMEtJT SPRAY PUMP (22) 14 SERVICE WATER PUMP (21) 15 SERVICE WATER PUMP (22) 15 SFRVICE WATER PUMP (23) 20 CONTAINMENT RECIRCUl ATION FAN (21) 20 COfJT AINMENT RECIRCUt ATION F AN (24) 20 CONTAINMENT REClRCULATION FAN (22) 25 CONTAINMENT RECIRCULATION FAN (23) 25 CONT AlHMENT REClRCUl ATION F AfJ (25) 25 AUX 1LlARY FEEDWATER PUMP (21) 30 AUXILIARY FEEDWATER PUMP (23) 30 NOTES: Time = 3 Seconds, Sequence initiated

( Al COL A 1 ff !f4 fee fil Vf $k Df4 I' h(,1 CO'l I DISOtl CAI Ct H Allot 1/AfiALY515 Siirf 1 f nt' 00110 00 0

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b) FASTBUS THANSPER CONCLUSION For the computer inodel of the fastbus

transfer, the precontingency condition SAT LTC is in the neutral position (N-7073V at no load).

At the T=0+,

the moment when the fastbus transfer

occurs, the voltage on the 480V Bus SA l

drops to 408vAC, below the degraded undervoltage setpoint.

Iloweve r,

the setpoint of the Aqastat timer is 180 seconds l

end during this time the SAT LTC will be changing tap positions from the precontingency LTC position (neutra]) to the upper most tap position (R16-7590V) within 35 seconds.

This takes into consideration the 2 second initial time delay for the first load tap changer operation and the 2

second time delay to change from one tap position to the next due to the sacchanical mechanism of the tap changer.

The load profile for the fastbus transfer is shown in Figure 3.

i i

This load profile of the 480V Bus SA represents the worst case boundinq condition in terms of voltage levels for the safety related buses.

Therefore, this analysis does not j

include the load profiles for the 480V Buses 2A, 3A and 6A i

l 1

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since these are not the bounding cases.

The.EBASCO program was run for the Neutral (7073V) and the R16 (7590V) tap positions.

The bus voltages with the SAT LTC in the neutral (U-7073V) and the upper triost tap position (R16-7590V) are an l

follows:

I

~

CASE Ia: FBT-1. Pace 155. 156, 171 Fastbus Transfer loads supplied from 138kV system immediately after transfer of -loads (Degraded Voltage Scenario - 0.950 pu). SAT LTC position (N-7073V)

Bus 2A - 416V Bus 3A - 414V Bus SA - 408V Bus 6A - 410V l

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{

e.sonu. ntv IGP 91 DG/Sfs E I

S S SII l b i Attachment #FBT-2. Page 155, 166 e

Fastbus Transfer ~ loads supplied from 138kV system 35 seconds after transfer and SAT LTC moving to raise voltage (Degraded Voltage Scenario - 0.958 pu). SAT LTC posi. tion (R16-7590V)

{

I i

Bus 2A - 447V Fuc 3 A -- 445V Bus SA - 440V l

Bus 6A - 442V C) NOltMAL PLAf1T MODE ANALYSIS During normal plant conditions at IP2, the 6.9kV Buses 1 -4 are supplied via the Unit Auxiliary Transf ormer and Buses 5 and 6 are supplied via the Station Auxiliary Transformer.

As part of the normal plant mode scenario, this analysis will assume tne 0.958pu (132.2kV) value that was defined for the loss of IP2 by the Electric Planning Department.

This is a conservative assumption, since the the normal operating range of the 138kV offsite power supply as defined by EO-4000-4 is in the range of 136kV 142kV.

The l

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sonat clis a t t E enOJE Ci no-i SUMMAftY Of DIGilADED VOt.T AGE STUDY 067Dfi 91 J

I lZ7.'l%."!!.

precontingency voltages for the IP2 offsite supply from the i

Buchanan 138kV Substation were intentionally scheduled at l

l their minimum design level (136xV) to achieve the lowest voltage resulting from the above system disturbance.

l l

l Special cases were run for the Component Cooling

Pumps, j

which are the bounding motor cases.

For each special case l

studied. the voltage level at the motor terminals and at the supply 480V safety buses was analyzed

prior, during, and after bounding motors were started.

These cases were run assuming no voltage adiustment by the System Operator via the SOCCS supervisory panel or any adiustment by the 138/6.9kV Station Auxiliary Transformer LTC.

i

)

NORMAL PLANT MODE CONCLUSION For the computer model of the Normal Plant

Mode, the preconti ngency SAT LTC position is neutral (N-7073V).

Our results for the starting or the bounding case motors indicates that the vol tage on the 480V buses will be high i

enough to start and operate the equipment.

nisted below are t.he results of our case scenario.

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j SUMMAHY Of DEGRADID VOL.TAGE STin)y oraes et U$'n'i m,$s'E i i

i CASE _ iia:

Attachment #!JIl-1, Page 88 Normal-Plant loads supplied from 138kV system (Degraded Voltage Scenario - 0.958 pu); Starting 460V Motor on Bus SA I

(Component Cooling Pump #21) l Min. Desired l

Prior During After Voltage i

Bus (V) 463 445 460 403 Motor Terminals (V) 0 407 453 369 i

CASE TIh:

Attachment # fJB-1. Pages 97, 98 Normal-Plant loads supplied from 138kV system (Degraded Voltage Scenario - 0.958 pu); Starting 480V Motor on Bus 6A (Component Cooling Pump #23)

Min. Desired Prior Durino After Voltage i

l l

Bus (V) 465 447 462 411 Motor Terminals (V) 0 400 453 369 I

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Sun #I C1stit t i f

suuunny or DIGRADf D VOLTAGE STllDY OG711G-Di Miin No Iti V I G8' B1 Of.786 I 1

D) PLANT STARTUP MODE During the startup condition, the source of power for the plant auxiliary loads is the 138kV sw.itchyard via the l

Station Auxiliary Transformer.

The 6.9kV Buses 1 and 2 are tied to the 6.9kV Bus 5 and buses 3 and 4 are tied to bus 6 and supplied via the Station huxiliary Transformer.

(See a s suinption under the Norraal Plant Mode pertaining to the 138kV offsite power system disturbance.)

PLANT STARTUP 140DE ANALYSIS For the computer model of the Plan

• Startup

Mode, the precontingency SAT LTC position is R16-7590V.

Our results for the starting of the bounding case motors indicates that the voltage on the 480V buses will be high enouah to start I

and operate the equipment.

Listed below are the results of l

c our caso scenario.

l l

6 e

r

't

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ent ras <r rena t s 844 vir wt n va tt Cte55 KillHE fil CllLJ 1/4/93 ANDY CllAf4 1/22/93 CLASS A,1E 5.H6Jr C 1 e 14 i t I PI4OJE CI N' StifAtAArtV OF DE Gl4ADE D Vol.1 AGE STl>DY 06706 91 i

BAU.D ten

= lit V ec in wn r i CASI: 1 iia:

Attachment #PSil-1. Page 155 Plant Startup

Mode, loa 0s supplied from 138kV system (Degraded Voltage Scenario - 0.956 pu); Starting 480V flotor on Bus SA (Component Cooling Pump #21)

Min. Desired Prior Duri no After Voltage bus (V) 446 427 443 403 Motor Terminals (V) 0 391 435 369 1

CASE IIIh Attachment # PS U-- 1, Page 204 Plant Startup Mode.

loads supplied from 138kV system (Degraded Voltage Scenario - 0.958 pu); Starting 480V Motor on Bus 2A (Component Cooling Pump #22) i i

1 l

Min. Desired Prior During After Voltage Bus (V) 454 436 451 415 Motor Terminals (V) 0 388 441 369

I e

a

• l l

C At ti11 A 160t4 tio lif Vl5tQtd PAGE Cotl I' DfSON cal CIH AllOti/Atl At YSIS $lf! fi FGP 0;1110 en 0

M Of -40 Phi PAfst it DAI[

T4f Vil WIIt'DAlf CLASS KE NNElli CHU 1/4/93 ANDY CllAN 1/22/93 CLASS A 1E blill>f CIdif f t E PHUJE C 3 "

SOfAMARY Of DIGRADED VOLTAGE STODy 06706 91 MOD t&o - DE V l.GP BI DS/85 E 1

l l

CASE IIIc:

Attachment #PSU-1, Page 175 l

Plant Startup

Mode, loads supplied from 138kV system l

(Degraded Voltage Scenario - 0.956 pu); Starting 480V Motor l

on Bua t> A (Component Cooling Pump #23) l l

r Min. Desired l

Prior Durinq After Voltage bus (V) 447 429 444 411 Motor Terminals (V) 0 384 434 369 l

l VIII) WORST CASE DEGRADED VOLTAGE ANALYSIS For the worst case Indian Point degraded voltage study, the voltage used was based on the Electric Planning Department utudy which simulated the worst case possible scenario for transmission degraded voltage conditions.

The Planning I

study was conducted to determine the impact on the IP2 138-kV offsite power sources at the Duchanan Substation 1

during va ri ous system disturbances.

In order to simulate the worst possible degraded voltage

scenario, pre-contingency voltages at the Buchanan Substation were intentionally scheduled at their minimum design level to l

C At(ULAllOff No 64[ Vi$tufi PACE CoH [Dl%Of f C A1 f.lil Allofl/Afl Al Y,15 Y If i I I i.i' 00110 ul O

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$1AfAfA Alf Y Ol' Of:GTt ADI D Vol.T AGE STllDY 0670G 91 MOD fJo - ftE V (GP St 166/06 E 1

i achieve the lowest vol tage condition resulting from various disturbances.

i The worst case 138-kV degradation would result from the loss of Millwood 345/138-kV Transformer TAl and Millwood 345/136-kV Transformer TA2 coincident with the loss of Feeder 96951 and the Peekskill Refuge Generating Unit out of service.

The minimum 138-kV offsite grid voltage for this contingency is 0.912 pu (125.86-kV).

The worst case 138-kV offsite power degradation used for this part of the study are well beyond the Electric Planning Extreme Contingency Analysis, the New York Power Pool Design C ri t e r i.a.

and the System Operation projected extreme con t.i ng enc ie s.

The worst case disturbance is highly unlikely to occur.

The computer raodeli nq of the IP2 electrical distribution sy s t era is based upon the various system configurations at which the IP2 station operates.

The case studies that are l

addressed in the degraded voltage study are as follows:

\\

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SUMMARY

Of Of GRADE D VOLI AGE STlfDY 06706 91 l

t.iOD No - Rf V LGP bl DG76L E I

j 1.

Load supplied from 138/6.9kV System (Normally-Fed from 138/6.9kV SAT).

l II.

Plant startup (Normally-Fed irom 138/6.9kV SAT).

t 1

The voltage analys.is program calculates the voltage profile for the buses and motor terminals before, during and.after selected motors are started.

To evaluate the effects of the worst case degraded voltage on the various safety-related motorr.,

case studies were per f orraed for the normal plant and plant start-up modes.

These cases were run assuming no voltage ad-justment by the System Operator via the SOCCS supervisory panel or any ad ustment by the Station Operator of the 138/6.9kV 7

transformer's LTC.

Special cases were run for the Component Cooling Pumps, which are the bounding motor cases.

For each special case

studied, the voltage level at the motor terminals and at the supply 480V safety buses was analyzed prior, during, and after bounding motors were started.

Our results indicate that the bounding case motors will start and continue to operate under the normal plant and

l l

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StitAMAHV Of DfGHADfD VOI TAGE STllDy DG70G 91 MOD No + hi V i

EGP St MIB6 (

1 l

plant startup modes for the proiected worst case degraded voltage condition (0.912pu).

Ilowever. it should be noted that in the startup mode even though the bounding u.otors can start and

operate, the bus voltages before and after the l

motors have started are below the proposes degraded 4

undervoltage setpoint (421VAC +/-6 volts) and wi)) transfer to the emergency onsite power supply.

Based on values l

\\

obtained in the Plant Startup Mode analysis, we conclude that during a LOCA or Fastbus transfer with the worst case offsite degradation.

the 480V bus voltage will drop below l

the proposed degraded voltage setpoint and the 480V buses will transfer to the emerqcncy onsite power supply.

This will ensure the integrity of the safety related equipment and when called upon to start and continue to operate, they will.

l The bus voltages for the bounding case motors are sununarized below.

l>uring the plant startup it.o d e,

the IP2 Operators are controlling the startup of the plant under controlled conditions.

This nienning that the operatorn are selectively

i a

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1

(' Atr til AIKur rso HiVisluta PAGE Cofl[UlbOIICAlClltAllONIAMAlYfelS SIfifI l ( W Odl10 INI D

Phi PMat inspA lf HE vit w(IvDA T E CLASS KLNNE Hi CHU 1/1/93 ANDY CilAN 1/22/93 CLASS A.1 E Pnonct tea i

surut c lis sin g SufAMAftY OF OfGHADED VOt TAGE STifDY 0670691 i

nou no - nrv IGP 91061st. (

1 starting essential equipment to start in order to support the operation of plant.

In actual operating circumstances i

the IP2 Operators are nionitorino the bus voltage prior to l

utartina of nelected motors.

In the event that the voltage on the buses are below the specified operating

range, the 3

SAT LTC uill adiust the vol taqe eutomatically or manually i

via the Central Control Room to within an acceptable value.

In the event that additional voltage is required, the IP2 Operators will request the operators at the Buchanan Substation to raise the 138kV offsite power supply voltage, i

CASE IVa:

Attachment #NB-2, Page 88 Norma l.-Pl a n t loads supplied from 13BkV system (Degraded Voltage Scenario - 0.912 pu); Starting 480V Motor on Bus SA (Component Cooling Purap #21)

Min. Desired Prior During After Voltage Bus (V) 439 421 436 403 Motor Terminalr. (V) 0 385 426 369

I i

f Cai rut A flOff No f4[VIS10t4 f* ACE CfJil f Ol50fl CAI Cill Aitt)tJ/At4Al YhtS Silf f T I GP 00110110 0

4 f4(PAH(n4sA T(

setystwirt DATE CL A ss Kt,fl110 !!! Cllu 1/4/93 ANDY CHAT 1 1/22/93 CLASS A,1 E M JtClelifti PPOJ1f.? ? s SUMtJIARY Of DECRADID VOI1 AGF S$10Y OG706 91 MOD No MV i t.P St D6785 E 1

CASE IVb:

Attachmen* GNB-2. Pages 101, 102 Normal-Plant loads supplied trom 138kV system (Degraded l

Voltage Scenario - 0.912 pu); Starting 480V Motor on Bus 6A l

(Component Cool i.nq Pump #23) 4 Min. Desired Prior During Atter Voltage Bus (V) 441 423 438 411 Motor Terminals (V) 0 379 428 369 Cf3SE_Va:

Attachment #PSU-2, Pages 155, 156 Plant Startup Mode.

loads supplied from 138kV systeni (Degraded Voltage Scenario - 0.912 pu); Startinq 480V Motor on bus SA (Component Cooling Pump #21)

Min. Desired Prior During After Voltage Dus (V) 415 398 412 403 j

Motor Terminals (V) 0 364 403 369

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Attachment #PSU-2. Page 226 J

Plant Startup

Mode, loads supplied from 138kV system (Degraded Voltage Scenario - 0.912 pu); Starting 480V Motor on Dus 2A (Component Cooling Pump #22) i l

Min.-Desired j

Prior During After Voltage Eus (V) 424 407 421 415 l

Motor Terrainals (V) 0 362 410 369 l

CASE Vc:

Attachment #PSU-2. Pages 184. 385 Plant Startup

Mode, loads supplied from 138kV system (Degraded Voltage Scenario - 0.912 pu); Starting 480V Motor on Bus 6A (Component Cooling Pump #23)

Min. Desired Prior During After Voltage Eus (V) 437 399 413 411 Mc, tor Terminals (V) 0 357 403 369 i

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l IX) Summary, Our analysis of the LOCA (supplied from 138kV offsite power supply), Fastbus

Transfer, Normal Plant Mode and Plant Startup Mode scenarios concludes that Indian Point No. 2 uill not trensfer to the emergency onsite power supply with the projected 0.958 pu (132.2kV) offsite power disturbance resulting in the loss of IP2.

The voltage levels on the i

480V Safety Relnted Buses (2A. 3A, 5A. 6A) will be higher than the pr oposed dearsded undervoltage relay setpoint (421VAC

+/-b volts) for the case scenarios modeled in this analysis.

In addition, the 480V Safety related Buses will be high enough for the safety related lE motors to start and operate prior to any system voltage corrective action by the t

Sr nior S ys tern Operator via the SOCCS supervisory system.

The 138kV offsite power supply remains the preferred source l

hy

design, and a transfer t o the emergency onsite power is l

designed to occur for offuite grid voltages which fall below the acceptable values as defined in EO-4000. Rev 4

and if the degraded voltsqe setpoint in reached and sustained for the Technical Specification time delay.

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Under the worst offsite disturbance, (0.912 pu on the 138kV offsite power system which is well beyond the Electric Planning Extreme Contingency Analysis. the New York Power r

Pool Design Criteria and the System Operating projected extreme contingencies.), the degraded AC voltage is high enough under the Normal Plant and Plant Startup modes for i

the safety-related lE motors to start and continue to

{

operate prior to any system voltage corrective action by the Sasnior System Operator or the automatic 1.TC of the Station Auxiliary Transformer.

In the Plant Startup

Mode, even though the boundinq motors can start and operate, the bus voltage before and after the motors have started are below the proposed degraded voltage setpoint and will transfer the

• 4 480V buses to the emergency onnite power supply.

The proposed degraded undervoltage setpoint. will increase the margin between the required bus voltage and the available bus voltage for the Component Cooling Pumps to ensure the I

integrity of the safety related equipment.

This will ensure l

the operability of safety related equipment when called upon l

to operate.

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In the improbable event that the system disturbance caused AC degraded voltage level lower than our pro 7ections, the degraded undervoltage protection relays will transfer the 480V safety related buses off the 1.38kV c1'faite AC source and reconnect to the emergency onsite power supply at IP2.

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REFERENCES:

1) EBASCO Letter to Mr.

R.

Sullivan. " Verification Of EBASCO Supplied Computer Prooram", dated June 28, 1991

2) Con Edison Calc. No. EGE-00001-00, 480 Volt Motor Undervoltage Starting & Acceleration Times

3) Con Edison Calc. No. SGX-00013-00, Setpoint Change For Undervoltage Relays on 480 Volt Buses 2A. 3A, 5A, And 6A I

4) Indian Point Station Unit 2, System Operating Procedure 27.1.4. Rev.

3.

"6900 Volt System"

5) Con Edison System Opernting Manual No.

5.

EO-4000-4 dated June 1988 i

i

6) indian Point Station Unit 2.

System Description No. 27.1, l

" Electrical Systerns" Rev.

3.

February 1981

7) Planning Study Memo from G.

Jee to R.K.

Sullivan. dated 4/17/91

8) Indian Point Station Unit 2, System Description No. 27.1,

" Electrical Systems" Rev.

3.

February 1981

9) Indian Point Station Unit 2. System Description No. 10.0.

I

" Engineered Safeguards System". Rev.

4, February 1981

10) Planning Study Memo from F.

Elmi to A.

Chan, dated 7/17/92

11) ABB Power T&D Company fax from C.

Librizzi to D.

Brown.

i dated 1/20/93

12) Con Edison H.T.

Oper. Din. 138/345 System Ties. Rev 298.

13) Westinghouse Electric Corporation Calc. No. WCAP-17556, Documentation Book For The Emergency Diesel Generator Loading Study

14) Degraded Voltage Analysis Attachments: LOCA-1, LOCA-2, LOCA-3, LOCA-4. LOCA-5. LOCA-6. LOCA-7. LOCA-8,'LOCA-9, LOCA-10. LOCA-ll.

i l

LOCA-12, LOCA-13. LOCA-14, LOCA-15. LOCA-16, LOCA-17, LOCA-18, FBT-l.'FBT-2. NB-1. PSU-1, NB-2 and PSU-2 i

!