05000296/LER-1980-027-03, /03L-0:on 800714,while Performing Surveillance Instruction 4.5.b.1.d,RHR Pump Motor 3D Tripped on Instantaneous Overcurrent on Phase a When Started.No Cause Stated.Relay Setpoint Change Being Investigated

/03L-0:on 800714,while Performing Surveillance Instruction 4.5.b.1.d,RHR Pump Motor 3D Tripped on Instantaneous Overcurrent on Phase a When Started.No Cause Stated.Relay Setpoint Change Being Investigated

ML19344B035
Person / Time
Site:	Browns Ferry
Issue date:	08/18/1980
From:	Calhoun J TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19344B034	List: 05000296/LER-1980-027, Forwards LER 80-027/03L-0 05000296/LER-1980-027-03, /03L-0:on 800714,while Performing Surveillance Instruction 4.5.b.1.d,RHR Pump Motor 3D Tripped on Instantaneous Overcurrent on Phase a When Started.No Cause Stated.Relay Setpoint Change Being Investigated
References
LER-80-027-03L-03, LER-80-27-3L-3, NUDOCS 8008250420
Download: ML19344B035 (2)

LER-1980-027, /03L-0:on 800714,while Performing Surveillance Instruction 4.5.b.1.d,RHR Pump Motor 3D Tripped on Instantaneous Overcurrent on Phase a When Started.No Cause Stated.Relay Setpoint Change Being Investigated

Event date:
Report date:
2961980027R03 - NRC Website

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'S stronT 0 ATE EusT DESCmPTiON AND PAOB A8LE Co*sSECUENCES h [o !: 1 l During nor=al operation while performing SI 4.5.3.1.d 3D RHR pump motor tripped 93g,9jon instantaneous overcurrent on "A" phase when started. Reference T.S. 3.5.B.3.

j g 3 !, j }emair.ing RHR pumps, CSS and diesel generators operable. There was no danger y ] g o health or safety of public. No previous occurrences.

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g j gotted and bridged. Relay setting checked in tolerance. Traces of starting g,j q [ current show DC offset caused by saturation of CT to be higher than anticipated, g,, g l increasing current monitored by relay. Investigation continues ccncerning

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Browns Ferry Nuclear Plant B F 15. 2 1/10/79 LER SUPPLEMENTAL INFORMATION BFRO 296 / S027 Technical Specificat'.on Involved 3.5.B.3 Reported Under Technical Specification

6. 7. 2.b (2)

Date of Occurrence 7/14/80 Time of Occurrence 1855 Unit 3

Identification and Description'of'Occurreng 3D RHR pump motor tripped on instantaneous cyercurrent on "A" phase when started while perf orming SI 4.5.B. l.d.

Conditions Prior to Occurrence:

Unit 1 @ 77%

Unit 2 @ 65%

Unit 3 0 45%

Action specified in the Technical Specificatien Survcilla.ce Requirements met

@te to inoperable equipment.

Describe.

The remaining RHR pumps (LPCI mode), CSS and diesel generators verified

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operable.

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A_pparent Cause of Occurrence:

RHR pump motor tripped out on instantaneous overcurrent.

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l Analysis of Occurrence:

l There was no damage to plant equipment. There was no activity release, no personnel exposure or injury and no danger to the health or safety of the public.

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Corrective Action

Meggered, Hi potted and bridged motor, no problems found. Checked instantaneous ove rcurrent relay setting and f.ound within tolerance. Oscillograph traces of the starting current show that the DC offset caused by the saturation of the CT to be higher than anticipated. This increases the instantaneous current monitored by the relay. Investigation continues concerning change to relay I'. instantaneous overcurrent iilure Data ~ setpoints.

j NA Me_ ten tion : < Period - Lifetime; Reaponsibility - Administrative Supervisor C

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