ML19345G164

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RO:480 Volt Bus 5 Lost Voltage,Causing Momentary Voltage Loss to Motor Control Ctr 5.Caused by Automatic Opening of Breaker 4850 When Station Svc Transformer 485 Faulted. Incident Under Investigation
ML19345G164
Person / Time
Site: Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date: 05/09/1974
From: Hartley F
CONNECTICUT YANKEE ATOMIC POWER CO.
To: James O'Reilly
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
CYH-2655, NUDOCS 8103090786
Download: ML19345G164 (1)


Text

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CQNNECTICUT YANKGE ATOMIC POWER COMPANY C/

HADDAM NECK PLANT RR = 1. BOX 127E. EAST HAMPTON, CONN. o6424 May 9, 1974 CYH-2655

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'Y' Mr. James P. O'Reilly, Director U. S. Atomic Energy Commission

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Dear Mr. O'Reilly; As defined by Technical Specifications for Connecticut Yankee Atomic Power Station Section 5.3, the following information involving the momentary loss of voltage on Motor Control Center #5 is here-by reported.

480V Bus 5 lost voltage when #485 Station Service Transfomer faulted and 4850 breaker opened automatically. Upon loss of voltage on Bus #5 the power supply for MCC #5 shifted over normally to 480V Bus #6.

During the restoratian of affected equipment there occurred a momentary loss of voltage on MCC #5. The plants' operation was unaffected by this momentary loss and continued to operate at full power.

An investigation is being conducted and a written report will be submitted within ten days.

Very truly yours, l

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Plant Superintendent f

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