ML19210A205

Abnormal Occurrence 75-23:on 750716,one of Three Auxiliary Relays of Diesel Generator 1B Breaker G11-02 Failed. Remaining Relays Tested Satisfactorily.Cause of Failure Under Investigation

ML19210A205
Person / Time
Site:	Three Mile Island
Issue date:	07/18/1975
From:	Colitz J METROPOLITAN EDISON CO.
To:
Shared Package
ML19210A201	List: ML19210A200 ML19210A205
References
NUDOCS 7910240923
Download: ML19210A205 (1)

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METROPOLITAN EDISON COMPANY sUBSICIARYOFCENERAL PUBLICUTILITIESConP0 NATION ST OFFICE DOX 480 MIDDLETOWN PENNSYLVANIA 1'/057 TELEPHONE 717-944-4041 July 18, 1975 s -

Mr. J.P. O'Reilly, Director _,,

Directorate of Regulatory I Region I hdh g;i 631 Park Avenue King of Prussia Pa. 19406 Operating License DPR-50 Docket 50-289

Subject:

Abnormal Occurrence No. A0 75-23

Dear Mr. O'Reilly:

This telegram is tc confirm the telecon between Lee Spessard (Ragion I-DRO),

and J.J. Colitz (Ttt! Unit 1 Superintendent) at 1930 hours0.0223 days <br />0.536 hours <br />0.00319 weeks <br />7.34365e-4 months <br /> 17 July 1975.

The followino report is submitted in accordance with paragraph 6.7.2.a.4 (page 6-11) of the Technical Specifications.

On July 16, 1975, while performing a post maintenance. auxiliary relay test for a routine work request associated with the Diesel Generator up to frequency and up to voltage relays, it was discovered that one of the three "up to frequency" auxiliary relays, used in the 1B Diesel Breaker G11-02 close circuit logic, failed to energize as required. The auxiliary relay

. which failed is part of the 2 out of 3 loofc matrix which pennits the Diesel Generator output circuit breaker to be closed in on the 4KV ES Bus 1E Once the Diesel Generator is at the proper frequency.

Since the diesel was " operable" and in service at the time the relay failure was discovered, an immediate test of the remaining two frequency auxiliary relays was conducted. Both of the remaining two auxiliary relays in the "up to frequency" logic tested satisfactorily. Based on the above relay logic check and the fact that the B Diesel Generator had been satisfactorily tested six hours prior to the discovered relay failure, it was determined that the B Diesel Generator was operable.

The relay was replaced and testing was successfully completed verifying proper operation of the relay and the 2 out of 3 logic.

An investigation is anderway to determine the cause of the rel failure.

very truiy yours, 14 6 217 a.a. con 7910240 fR3 tisit 1 Superintendent