ML19262B030

Responds to IE Bulletin 79-23.Will Perform 24 Load Tests During Preoperational Testing of Emergency Load Generators. Problem Described in Item 1 Not Applicable

ML19262B030
Person / Time
Site:	Zimmer
Issue date:	10/25/1979
From:	Borgmann E CINCINNATI GAS & ELECTRIC CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
IEB-79-23, NUDOCS 7912110439
Download: ML19262B030 (1)

Text

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THE CINCINNATI GAS & ELECTRIC COMPANY ~

CIN CIN N ATI OHIO 4 5201 October 25, 1979 E. A. BO RG M AN N wc t *=r s'or NY 4

U.S. Nuclear Regulatory Cc:,.ission Region III 799 Roosevelt Road Glen Ellyn, Illinu _ 60137 ATIN: Mr. James C Ecp"ler Regional Director RE: hM. H. ZIMIER NUCLF>R PoliER STATION - UNIT 1 IE BULLETIN 79-23, POTENTIAL FAILURE OF DIERGENCY DIESEL GENERATORS FIELD EXCITER TRANSFORMERS DOCKET 50-358, W.O. 57322, JOB E-5590, ITBI # 2676 Gentlemen:

This Ictter is in response to I.E. Bulletin #79-23 concerning potential failure of emergency diesel generator field exciter tnnsfomers.

First, in response to item 1 of the referenced I.E. Bulletin, we have re-viewed this problem with the diesel generator vendor. The problem described by the bulletin does not exist at the Wm. H. Zimmer Nuclear Power Station - Unit 1.

He excitation power transfomer primary winding does not have a neutral connection.

The winding is connected phase to phase. In addition, 3 potential transfomer primary windings arc connected in wye with the neutral grounded. However, the generator neutral is grounded through a high resistance which provides adequate limitation on the flow of circulating currents induced by hamonic voltages.

In response to item 2, the 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> load test described in the bulletin and in Regulatory Guide 1.108, revision 1 will be perfemed during preoperational testing of the emergency diesel generators. He test is tentatively scheduled for the first quarter of 1980.

We believe this information provides a complete response to the subject I.E.

Bulletin.

Very truly yours, THE CINCINNATI GAS S ELECTRIC CCTIPANY

(( pW-E.A. BORGbteN, SENI0IVICE PRESIDENT WPC/kjd cc: U.S. Regulatory Commission Office of ISE R.F. Scheibel C.W. Beringhaus ) 32 030 R.E. Cotta B.K. Culver i:E:j$il " C 8'i" * ""

0CT 2 91979 J.R. Schott J.D. Flynn 7912110 )