ML18037A321

LER 80-033/03L-0:on 801224,auxiliary Power Feed Experienced Loss to Emergency Power Bus.Caused by Feeder Breaker Trip Due to Setpoint on Over Frequency Protective Relay Being Set Too Close to Nominal Frequency.Relay Recalibr

ML18037A321
Person / Time
Site:	Nine Mile Point
Issue date:	01/23/1981
From:	Harrison P NIAGARA MOHAWK POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML17053C298	List: ML17053C297 ML18037A321
References
LER-80-033-03L, LER-80-33-3L, NUDOCS 8102100629
Download: ML18037A321 (2)

Text

CONTROL BLOCK:

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-,I 80 Qe 50 61 QQCKcT NUhl8ER BVCNT DESCRIPTION ANO PROB*BL= CONSBQUBNC-S IQ During normal operation, the loss of a 115'IlV auxiliarv Dolker feed to an

~os emergency power bus was experienced. The Emergency Diesel Generator

~o automatically came into service as required. This had no adverse affect on safe operation since these components operated as designed.

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7 8 9 SYSTEM CAUSE CAUSE CQSIP. VALVE CQOE COOK SUECQQE COMPONENT COOK SU8CCOE SUKCOOE

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3 34 3S 36 37 40 41 42 43 44 47 CAUSc DESCRIPTION ANO CORRECTIVE AC i IONS 27 o >k calibration check of the over-fre uencv nrotective relav for the feeder breaker revealed that the trip aetpoint vaa found too conaervativelv close to the nominal frequency, thus causing a spurious trio of the breaker. The relay was properly recalibrated to prevent recurrence. This type of relay will be calibrated on refuel cycle frequency for future preventative action.

8 9 80 FACILI > f POWER OTHER STATUS METHQO OF OISCQVERY OISCOVKRY OESCRIPTION STATUS ~~

e i ~EPa ~os s Qe v/a Event troubleshootin 7 8 9 10 12 13 44 80 ACTIVITY CQNTcNT RELEASEO QF RELEASE AMOUNTOF ACTIVITY I.OCATION OF RELc~K 36 a ~Z Pz ~lpz> iv/A iM/A 7 8 9 10 44 80 PcRSONNEL. EXPOSURES uUMKER TYPE OESCRIPTION 8

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~vQ 9 IO q/a 68 69 80 c ~ p-~ . ~oPwop PREPARER ~'AME Paul Harrison PHDNE 515-345-21 10 ext. 1212