ML20040A584

LER 81-029/03L-0:on 811210,during Testing of Bus 16 Undervoltage Relays,Error in Disconnecting Test Equipment Resulted in Blown Fuse for a Phase Relays.Fuses Replaced. Undervoltage Relay Tests Will Be Revised

ML20040A584
Person / Time
Site:	Prairie Island
Issue date:	01/15/1982
From:	Musolf D NORTHERN STATES POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20040A580	List: ML20040A579 ML20040A584
References
LER-81-029-03L, LER-81-29-3L, NUDOCS 8201210265
Download: ML20040A584 (1)

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6 (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) lo l t l l Ml NlP lI lN l 1l@l 0 l 0 l - l 0 l 0 l 0 l 0 ] 0 l - l Q 025l@l 4 l 1 l l j 1l 1]@] l lg 7 8 9 LICENSEE CODE 14 15 LICENSE NUM6hH 26 LICENSE TYPE JO bl LAT bd CON'T lOI1l ER] l Lj@[ 0l 5 l 0 l 0 ] 0 l 2 l 8 l 2 j@l 1l 2 l1 l 0 l 8 l 1 l@l 75 0 ]1 l 1l5 l8l2]@ 80 i H 60 61 DOCKET NUMBER 68 69 EVENT DATE 74 REPORT DATE EVENT DESCRIPTION AND PROB ABLE CONSEQUENCES h lol2l l During routine surveillance test of Bus 16 undervoltage relays, an error in dis- ]

lo l3 l l connecting test equipment resulted in blowing fuse for A-phase relays. C-phase l lo l4 l l fuse was removed as part of test procedure. The voltage restoration and load l 1

loisl l rejection scheme initiated, and since UV condition continued to be senned, closed D2l lO ls l l diesal supply breaker. D2 breaker remained closed with bus deenergized until fuses l l0l7ll replaced and Bus 16 reenergized from its normal offsite source. No effect on l l 0 ls i [ public health and safety. Bus 15, the redundant bus, remained fully operable. l 7 8 9 80 SYSTEM CAUSE CAUSE COMP. VALVE CODE CODE SU8 CODE COMPONENT CODE SUBCODE SUBCODE lOl91 y 8 9 1 ElB lh l Dl@ l Z l@ l Z l Z l Z l Z l Z l Z lh lZ lh 20lZ l h 10 11 12 13 18 19

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40 g g 41 lNlg 42 lZ g 43 lZj9l9l9lg 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS l i l o j [ Fuses were replaced and normal power restored to bus. The undervoltage relay tests, l l

1i 11 I i for all four safeguard buses, will be revised to include two separate steps l i,i;,i l with signoffs when disconnecting test equipment. The existing procedure l j,l3; j uses a single step to disconnect test equipment at the bus cubicle and at the logic l

[ii4 i [ relay cabinet. Two steps will make an error of this type less likely. l 1 8 9 BC ST/  % POWER OTHER STA TUS ISCO E Y DISCOVEHY DESCHIPTtON li15I(,Ej@ l1]Ol0[gl NA l l B [gl Surveillance test l

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