Information Notice No. 83-63: Potential Failures of Westinghouse Electric Corporation Type SA-1 Differential Relays
SSINS No.: 6835
IN 83-63
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
September 26, 1983
Information Notice No. 83-63: POTENTIAL FAILURES OF WESTINGHOUSE
ELECTRIC CORPORATION TYPE SA-1
DIFFERENTIAL RELAYS
Addressees:
All holders of a nuclear power reactor operating license (OL) or
construction permit (CP).
Purpose:
This information notice is provided as notification of a potentially
significant problem pertaining to random trip output of Westinghouse
Electric Corporation type SA-1 differential relays. Addressees are expected
to review the information for applicability to their facilities. No specific
action or response is required at this time.
Description of Circumstances:
On April 13, 1983, Westinghouse Electric Corporation, Bala Cynwyd,
Pennsylvania, notified Brown-Bovery Electric, Inc. of a potential deficiency
in Westinghouse SA-1 differential relays. These relays are used on
safety-related systems and designed to sense a fault within the differential
circuit to protect either a transformer, generator, switchgear, or
distribution system bus. A differential relay trip output will open the
circuit breakers to isolate the differential circuit when a fault occurs.
However, a random differential relay trip output will trip the breakers of
the differential circuit without the presence of a fault, thereby isolating
a transformer, generator, switchgear, or system bus unnecessarily.
The Westinghouse Electric Corporation Relay and Instrument Division in Coral
Springs, Florida, evaluated some field reports of random SA-1 relay tripping
and tested 18 field relay silicon-controlled rectifiers (SCRs) and more than
150 inhouse inventory relay SCRs, concluding that certain SCRs in the relay
trip output circuits can cause the random trip output.
Only some SCRs manufactured by S. T. SEMICON for Westinghouse Electric
Corporation relays since January 10, 1980, have been found to cause the
random trip output. The tendency to provide a random trip is dependent upon
the history of ambient temperature, voltage, and time. The higher any of
these parameters, the more likely an S. T. SEMICON SCR will provide a random
trip.
8308300345
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IN 83-63
September 26, 1983
Page 2 of 3
Westinghouse-Recommended Corrective Action:
Following the Westinghouse Electric Corporation investigation, the
Westinghouse Relay-Instrument Division's Engineering and QA Departments
notified the customers listed on Attachment 1 by individual correspondence
and advised them of the following:
1. A Raytheon SCR (TAG Semiconductors Ltd, type TAG9N600DUX FTS3905-1) has
been chosen as a replacement for the S. T. SEMICON device, in
production and for replacement in relays in the field. The W style
number for this device is S/N 184A614HO5.
2. To prevent recurrence of this type of problem Westinghouse receiving
inspection is continuing its 100% electrical parameter test. In
addition, on a sample basis, a "burn-in" of SCRs from every received
lot is accomplished.
3. Testing indicates that SCRs may be replaced without affecting the
calibration of the relay.
The Westinghouse Electric Corporation Relay and Instrument Division also
asked its customers to take the following corrective action on the relays
listed on Attachment 1.
1. Determine if the relay contains an S. T. SEMICON SCR (identified by a
[s] logo and CR127). If it does, it should be replaced by the SCR
described in item 1 above. A Westinghouse SCR (identified by a W logo
and 2N1850 printed on the barrel) or a SYNTRON (identified by a FMC
logo and 184A614 on the barrel) does not have to be replaced.
2. SCR replacement should be accomplished by an electronics technician
taking special care in the following areas:
a. Tag the wires when disassembling to ensure correct reconnection to
the new SCR.
b. Do not stress the anode and cathode leads of the SCR when
reconnecting the wires.
c. Do not overheat the SCR leads when resoldering. Heat sinks applied
to the SCR terminals during resoldering will help to ensure that
overheating does not occur.
3. Verify correct replacement by following the "Adjustments and
Maintenance" and "Electrical Checkpoints" section of I.L. 41-348-11
"Type SA-1 Generator Differential Relay for Class 1E Applications."
As stated previously, Westinghouse Electric Corporation notified all its
SA-1 relay customers listed in Attachment 1, however, most of these
customers are not the end-users. Therefore, it is suggested that licensees
review the relay serial numbers on Attachment 1 and compare them with the
serial numbers on SA-1 relays in their nuclear facilities to determine if
corrective action is required.
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IN 83-63
September 26, 1983
Page 3 of 3
If you have any questions regarding this matter, please contact the Regional
Administrator of the appropriate NRC Regional Office, or this office.
Edward L. Jordan, Director
Division of Emergency Preparedness
and Engineering Response
Office of Inspection and Enforcement
Technical Contact: W. Laudan, IE
(301) 492-9759
Attachments:
1. List of Customers
2. List of Recently Issued IE Information Notices
.
Attachment 1
IN 33-63
September 26, 1983
Page 1 of 2
WESTINGHOUSE G.O.
SA-1 RELAY CUSTOMER SERIAL NO. NO. & ITEM CUSTOMER ORDER
NO.
Beloit Power Systems 5256A RK43470-NI-9 01507
Beloit, WI 5257A RK43470-NI-9 01507
5258A RK43470-NI-9 01107
5259A RK43470-NI-9 10507
5486 RK43330-NI-25 01401
5487 RK43330-NI-25 01401
7437 RK44202-NI-3 32476
7438 RK44202-NI-3 32476
7439 RK44202-NI-3 32476
7440 RK44202-NI-3 32476
7441 RK44202-NI-3 32476
7442 RK44202-NI-3 32476
7443 RK44202-NI-3 32476
7444 RK442O2-NI-3 32476
7455 RK44202-NI-3 33858
Brown-Bovery Electric, Inc. 4772 PH68-333-NI-H1 J96608-53566
Chalfont, PA 5768A PH69899-NI-D J5253i-53170
6912 PH61036-NI-C J57018-51128
7808 PH61316-NI-I J66315-51128
Brown-Bovery Electric, Inc. 4310 TL70147-NI-36 5-30852
Tulsa, OK 5074 TL69994-NI-36 5-41094
5254 TL71248-NI-37 5-10342
5255 TL71248-NI-37 5-10342
6864 TL72584-NI-36 5-41633
7434 TL70147-NI-36B 5-30852
7435 TL71248-NI-36X 5-20342A
7436 TL71248-NI-36X 5-10342A
7607 TL71249-NI-36 5-10343
Cooper Energy Services 7802 CB64416-NI-1 370941511
Mt. Vernon, OH 7803 CB64416-NI-1 370941511
7804 CB64416-NI-1 370941511
7805 CB64416-NI-1 370941511
7806 CB64416-NI-1 370941511
7897 CB64416-NI-1 37094-1511
Cooper Energy Services 5767 CB63404-NI-1 3609J8150
Mt. Vernon, OH 8060 CB64596-NI-1 360941935
8061 CB64596-NI-1 360941935
Duke Power Company 5778A CHI1784-NI-1 F3527-82
McGuire Nuclear Station
Cornelius, NC
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Attachment 1
IN 83-63
September 26, 1983
Page 2 of 2
WESTINGHOUSE G.O.
SA-1 RELAY CUSTOMER SERIAL NO. NO. & ITEM CUSTOMER ORDER
NO.
Siemens Allis, Inc. 4713 MK20280-NI-P WAH378586V
Raleigh, NC 4714 MK20280-NI-D WAH378586V
5007 MK20280-NI-J1 WAH378586V
Systems Control Corp. 5766A AP42372-NI-1 74178-8
Iron Mountain, MI 5769A AP42372-NI-1 74178-8
Washington Public Power 6996 NA-40038-Y1 01YN085
Supply System 6997 NA-40038-Y1 01YN085
Portland, OR 6903 NA-40038-Y1 01YN086
6904 NA-40038-Y1 01YN086
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Page Last Reviewed/Updated Tuesday, March 09, 2021
Page Last Reviewed/Updated Tuesday, March 09, 2021