05000220/LER-1980-033-03, /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

/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: 05000220/LER-1980-033, Forwards LER 80-033/03L-0 05000220/LER-1980-033-03, /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 ML17053C297 ML18037A321
References
LER-80-033-03L, LER-80-33-3L, NUDOCS 8102100629
Download: ML18037A321 (2)

LER-1980-033, /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

Event date:
Report date:
2201980033R03 - NRC Website

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The Emergency Diesel Generator automatically came into service as required.

This had no adverse affect on safe operation since these components operated as designed.

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>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.

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~'AME op PREPARER Paul Harrison PHDNE 515-345-21 10 ext.

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