ML20084F121

Ro:On 711205,safety Injection Pump Motor C Tripped Automatically When Nearly Up to Speed.Caused by Motor Tripping Out on Starting Current Due to Leakage in Time Delay Dashpot.Replacement Overcurrent Device Installed

ML20084F121
Person / Time
Site:	Ginna
Issue date:	12/14/1971
From:	Amish K ROCHESTER GAS & ELECTRIC CORP.
To:	Morris P US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084F124	List: ML20084F121 ML20084F136
References
NUDOCS 8304200099
Download: ML20084F121 (2)

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q-S u bj ect- Failum of "C Safety Intoction Pump to 5 tart or. Test R. E. Ginna Nuclear Power Plant Unit No. 1

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At about 1100 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.1855e-4 months <br /> on Decer-ber 5, 1971, during the performance

" the routine mcnthly surveillarcr test, No. PT-2.1 Safety Injection System, the "C" Sefety Ir.iection Purg a otor trippari automatically when nearly up to speed. This was a manual start with the electric feed coming from 480 volt Bus No. 16. Tne "A" and ' B" Sa fety Injection Purnps had becn successfully tested p:eceding t he :allJre of the ' C" tt start.

A second attempt prodaced the sarr.e result. The investigation which followea revealed that the 'B"_ phase series overcurrent tripping device, which has a long time delay and instantaneous element, was tripping out the motor on starting current because of leakage in the time delay dashpot.

The electric feed to this pump motor was then transferred to the alter-nate cource , 4 80 volt Bu = 'lo. 14, which also has a three phase protection.

The rnator was turned by nana and the leads from Bus No.14 were meggared hefore th a mater wa s enera! <ed. The "C ' injection nump start was success-

u! an;: t!;e surveidance test was comt.leted.

As a re-heck, the faulty relay was reinstalled and again the injection pump motor tripped a s before. Removal of the "B" phase protection but leav-ing t'r e other twc pilases with overcurrent protection permitted the proper

• unctir n of the breaker during rnctor startup.

' The Pian

• Operati:ns Deview Committee reviewed the occurrence and agreed

/ c, that wrcurrt at protection on two phases of the breaker from Bus No. 16 wa s ll, l l,A '1N 3G L . *"

f,, ^ re* Meerent overcurrent device with the same type long time delay i -

anu ins *ar.taneous overcurrent element was installed on the "C" Injection

,G Parr Wtor prir.ar~ breaker of Bus No.16 on December 10, 1971. The Safety injectier Pur.p was tosted and operated successfully with this new unit.

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