United States Nuclear Regulatory Commission - Protecting People and the Environment

Bulletin 74-012: Incorrect Coils in Westinghouse Type SG Relays at Trojan



BL74012 

RO BULLETIN NO. 74-12                                       Date: 10/21/74 

INCORRECT COILS IN WESTINGHOUSE TYPE SG RELAYS AT TROJAN 

We recently received information from the Portland General Electric Company 
describing incorrect relay coils supplied as component parts of the 4kV and 
12kV switchgear that were discovered during preoperational testing at the 
Trojan nuclear power plant.  The information provided is as follows: 

A.   Description of Circumstances 

     Eleven (11) Westinghouse type SG293-B255A20 relays supplied by ITE in 
     the 4kV and 12kV switchgear were determined to have incorrect coils 
     during Trojan field preoperational testing. The relays were found to 
     have 48V dc coils rather than 125V dc coils. The resistance of 48V dc 
     coils is 725 ohms; the resistance of 125V dc coils is 4650 ohms). The 
     relays were found to have been labeled incorrectly as being 125V dc 
     relays by the subvendor, Westinghouse. 

     Five of the 11 incorrect relays are located in engineered safety 
     features (ESF) circuits - three of which (27-A1, 27-D1, 27-D2) are 
     potential monitor relays whose only function is to alarm; the other two
     (162-108X and 162-208X) perform an ESF function. The licensee's 
     evaluation showed that these relays with 48V dc coils could fail in 
     either of two ways - burn open or short to ground when subjected to 
     125V dc. 

B.   Action Requested of Licensees 

     It is requested that you notify this office in writing within 30 days: 
     (1) whether or not similar circumstances or the potential for similar 
     circumstances described above exist at your facility for Class IE 
     equipment, or (2) the date(s) when action to determine whether similar 
     circumstances exist will be completed. If the findings as a result of 
     the action above indicate that similar circumstances exist, the 
     specific findings together with a description of the corrective action 
     taken or planned, including the scheduled completion date of planned 
     corrective action, should be submitted to this office within 30 days of 
     the findings. If there are no such relays at your facility(ies) a 
     negative report is requested. 
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