ML19312C927
| ML19312C927 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 05/19/1976 |
| From: | DUKE POWER CO. |
| To: | |
| Shared Package | |
| ML19312C919 | List: |
| References | |
| RO-287-76-03, RO-287-76-3, NUDOCS 8001140586 | |
| Download: ML19312C927 (1) | |
Text
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Duke Power Company O
Oconee Unit 3 Report No.:
R0-287/76-3 Report Date:
May 19, 1976 Occurrence Date: April 19, 1976 Facility:
Oconee Unit 3, Seneca, South Carolina Identification of Occurrence:
Inadvertent isolation of 230 KV yellow bus during electrical breaker maintenance.
Conditions Prior to Occurrence: Unit at 807. full power.
Description of Occurrence:
I On April 19, 1976, maintenance was being performed on electrical switchyard breakers PCB23 and 24 which had been isolated from the 230 KV yellow bus.
At this time, Unit 2 was shutdown, and it was necessary to reset generator lockout relays prior to closing PCB24. These relays were not closed and when breaker PCB24 was closed, a trip signal was generated, causing all breakers connected to the 230 KV yellow bus to trip, isolating the bus.
Apparent Cause of Occurrence:
This incident was apparently caused by an incorrect assumption that the generator lockout relays were reset immediately prior to closing electrical breaker PCB24, t
b Analysis of Occurrence:
This occurrence did not result in the loss of any emergency sources to Oconee units. Additionally, the 230 KV red bus was still available to supply power from all transmission lines to the startup transformers for all the Oconee units.
It is concluded, therefore, that this incident did not affect the health and safety of the public.
Corrective Action:
t Maintenance procedures have been revised to assure that generator lockout relays are properly reset prior to the performance of breaker maintenance.
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8001140f((
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