ML20085E463

LER ER-76-033:on 761020,dc Bus 2 Voltage Dropped to 60 Volts,Dropping Associated Ac Preferred Bus Voltage to 90 Volts.Caused by Improper Coordination of Battery Charger Current Limiter & Charger Output Breaker

ML20085E463
Person / Time
Site:	Palisades
Issue date:	11/03/1976
From:	Bixel D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
LER-ER-76-033, LER-ER-76-33, NUDOCS 8308120088
Download: ML20085E463 (3)

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. U UCENSEE EVENT REPORT CONTRot 8toCx:I I II I I I cetrass naar au neaviaan meonmarmu3 1 6 YuY UCENsE NUMBER P Y a lul rlPl AlLl1l l 0l0 l-l 0 l 0 l 0l 0 l 0l-l 25 0l 0l28 lhl1l1l1l1l l 0 l1 l 14 30 31 32 7 69 15 Ype NN DOCKET NUMBER EVENT DATE REPORT DATE j 0 CONT l l l [T_j [LJ l 0l 5 l 0 l-l 0 l 2 l 5 l685 l69l 11012101716 74 l 75l1l110l317161 80 i

7 8 57 58 59 60 81 EVENT DESCRIPTION _

95 l During shutdown of the plant, d-c bus No 2 voltage dropped to about 60 volts. Thisl 80 7 89 l

@ l in turn dropped the voltage on the two associated a-c treferred buses to about 40 eo 7 89 l

3[ l volts. The control room versonnel were alerted to the troblem by dim annunciator 80 7 89 = l

@ l panel lights. The undervoltare relav Th-D2 vas not observed to onerate althonek 60 7 89 I

@ l performance test conducted later showed its overation (Contd on Attached Sheet i 80 7 89 p=E (ER-76-33)

VIOLATON DE CODE COMPONENT CODE

@ lElCl [_E_j lClK lT lBIR lK I 12 17 W 43 44 l Wll 12IOI 47

[,,N_j 48 7 89 10 11 CAUSE DESCRIPTIOrt UE l The apparent cause was due to improper coordination of the battery charger current80l 7 89 UE l limiter and the cb9rger outrut brantear setti v . Tt has been ccelueled that tha l 80 7 89 l

Q l starting of an . oil lift pump earlier in the day was the most (Contd on Line 18)

% POWER OTHER STATI.;S OrSCOVERY OISCOVERY DESCR:PTON Status

@ W l0l0l0l12 l13 NA l 44

( a_l 45 l

46 NA 80 l

7 8 9 10 AMOUNT OF ACTMTV LOCATON OF RELEASE R LE OF REL ASE na l I NA l 35 L2LJ L2LJ l 44 45 80 ,

7 8 9 10 11 PERSONNEL EXPOSURES NLIMBER TYPE DESCRIPTON NA l

@ 1010101 [ 12ZJ l13 7 89 11

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80 PERSONNEL INJUAIES NUMBER DESCRIPTON NA gg l 0l 0 l 0 l l 80 l

7 89 11 12 PROBABLE CONSEQUENCES .

l

@l None. Other safety systems were available. 80 7 89 i LOSS OR DAMAGE TO FAC!LITY

' TYPE DESCRaPTON 3 [Z_j l NA 30 l

7 89 10 PUBUCITY

@l 7 89 None. 80 l

ADDITIONAL FACTORS DE l (Contd from Line 10) likely cause of the outout breaker trin. 80 l

7 89 l

19 l

• 8308120088 761103 PDR ADOCK 05000255 S PDR

I Event Description, continued from Line 06 (ER-76-33) to be satisfactory. In an ' effort to isolate the problem, preferred a-c bus Y20 was isolated. The redundant charger (No 2) was energized and the bus returned to normal. The original charger was also reconnected to the bus to share the charging load. Additional corrective action taken or planned included (1) review of the charger output breaker settings and the charger current limiter settings to assure that they are properly coordinated, (2) a visual inspection of all a-c relays associated with the Y20 and Yh0 buses (required to be energized to trip), and (3) provide a separate annunciator light to alarm battery under voltage.

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Company a.ner.i ome..: m2 west Wchigan Avenue, Jackson, wchigan 49201 e Area Code S17 788-05S0 i November 3, 1976

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Mr James G Keppler S ,,g Office of Inspection & Enforcement  ?,'7e',,gfge Region III US Nuclear Regulatory Comission T99 Roosevelt Road Glen Ellyn, IL 60137 DOCKET 50-255, LICENSE DPR PALISADES PIANT - LOW D-C VOLTAGE - ER-76-33 Attached is an event report which relates to the Palisades Plant. This event relates to one of two redundant d-c buses which provide power, through an in-verter, to preferred a-c buses. This event occurred during a routine shutdown of the plant.

David A Bixel (Signed)

David A Bixel Assistant Nuclear Licensing Administrator

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