ML20086Q580

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Special Rept:On 950705,2B DG Tripped on Loss of Excitation Due to Fluctuations of Var Loading on Grid
ML20086Q580
Person / Time
Site: LaSalle Constellation icon.png
Issue date: 07/24/1995
From: Ray D
COMMONWEALTH EDISON CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9507280104
Download: ML20086Q580 (1)


Text

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, Osmmonwealth Illiwn Osmpany

/ La911e Generating Mation

' 2601 North 2iSt Road Marwilles, II. 613 419757 Td fs15-3574,761 July 24,1995 ,

U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555 This special report is submitted in accordance with LaSalle Unit 2 Operating Ucense NPF-18, Appendix A, and Technical Specifications 4.8.1.1.3 and 6.6.c regarding Unit 2B Diesel Generator (E22,2E22-S001); manufactured by Electro- 3 Motive Division of General Motors Corporation (Model EMD 20645E4).

On July 5,1995, with LaSalle Unit 2 at 100% power, the Unit 2B Diesel Generator (DG) was operating in accordance with LaSalle Operating Surveillance LOS-DG-M3, "1B(2B) Diesel Generator Operability Test". At approximately 0947 hours0.011 days <br />0.263 hours <br />0.00157 weeks <br />3.603335e-4 months <br />, the 2B DG tripped on Loss of Excitation due to fluctuations of VAR loading on the grid.

This failure was not a valid failure in accordance with Regulatory Guide 1.108 and Technical Specification 4.8.1.1.3.

The 2B DG trip due to Loss of Excitation is most likely due to an improper setting on the paralleling circuit of the 28 DG voltage regulator. Further investigation following the 2B DG trip found no problems within the field flash circuitry or any of the associated equipment. Conversations were held with voltage regulator experts within the company, and it was determined that these personnel would adjust the regulator setting associated with the paralleling circuitry during the next monthly DG run. The asynchronous portion of the regulator circuitry remains unaffected by any adjustments to the regulator, therefore, the DG will not require any emergency mode testing following the adjustment. I The 2B DG was operated successfully and declared operable on July 6,1995.

Sincerely, s

D. . Ray Station Manager LaSalle County Station DJR/CTK/lja cc: H. J. Miller, NRC Region ill Administrator P. G. Brochman, NRC Senior Resident inspector, LaSalle R. J. Zuffa, IDNS Resident inspector /

ce INPO - Records Center

' M '-. n-,3 D. L Farrar, Nuclear Regulatory Service Manager, NORS 'b Central File A Unkom Company 9507280104 950724 PDR ADOCK 05000374 S PDR