Home > NRC Library > Document Collections > Generic Communications > Information Notices > 1983 > IN 83-63
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 . 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. . 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 . 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 .
Page Last Reviewed/Updated Tuesday, November 12, 2013