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.
Page Last Reviewed/Updated Tuesday, March 09, 2021