Part 21 Report - 1996-293

ACCESSION #: 9605200148 MKW POWER SYSTEMS, Inc. Report No. 10CFR21-0073 FEBRUARY 27, 1996 10CFR21 REPORTING OF DEFECTS AND NOR-COMPLIANCE COMPONENT: Chicago Telephone Supply (CTS), p/n 115R251A Voltage Adjust Potentiometer SYSTEM: Diesel Generator control systems with NEI Peebles (Portec) Voltage Regulators CONCLUSION: Defect is Reportable in Accordance with 10CFR21 PREPARED BY: DATE: Donald D. Galeazzi Engineering Manager REVIEWED BY: DATE: Michael Nuding General Manager, Quality Assurance Post Office Box 1928 o Rocky Mount. North Carolina 27802-1928 o Phone:(919) 977-2720 TWX: (510) 929-0725 o FAX (919) 445-3830 REPORT NO. 10CFR21-0073 PAGE: 1 OF 5 SUMMARY MKW Power Systems witnessed repair and testing of a voltage regulator for FPL Turkey Point at NEI Peebles an 2/10/96 and 2/11/96. NEI a manufactured many of the voltage regulators utilized in MKW's safety related diesel generators. Voltage instability was observed and was determined to be caused by foreign material on the stationary wiper portion of the R4 voltage adjust potentiometer. The potentiometer in 250 ohm, 2w, manufactured by Chicago Telephone supply (CTS), p/n 115R251A and had been used by NEI for over twenty years for this application. Because of availability problems, NEI replaced the CTS potentiometer with Maury Instrument Corporation p/n 50-M123-251 in 8/94). This is an enclosed precision wirewound potentiometer, 250 ohm, 1.5w, with a shaft locking nut. According to NEI applied burden is 0.06w. When compared to the CTS component, the Maury is an upgrade in quality and appears to be less susceptible to contamination on the wiper surface. The FP&L regulator had the R4 potentiometer replaced with the Maury part while at NEI and the voltage instability was corrected. The purpose of the R4 potentiometer is to adjust generator voltage to rated value after installation of the remote voltage adjust motor operated potentiometer. This is normally a one-time adjustment which occurs during initial installation/startup of the EDG and is applicable to the automatic and manual (if used) voltage regulators. MKW has been supplying NEI voltage regulators for safety related EDG control systems since 1972. This incident and one prior in 1994 (FP&L EDG 4A and 4B respectively) are the only reported problems of this type; therefore, it in difficult to interpret this occurrence an a defect. In addition, because R4 is normally a one-time adjustment, any foreign material which develops/ accumulates on the wiper surface will not affect voltage regulator operation because it will not interfere with the wiper surface to wiper arm interface. It is recognized that this could cause problems if field adjustment of R4 is required; therefore, MKW Power Systems will notify all customers with NEI voltage regulators about this potential condition. COMPONENT Chicago Telephone Supply (CTS) p/n 115R251A (NEI p/n 01068). REPORT NO. 10CFR21-0073 PAGE: 2 OF 5 CUSTOMERS AFFECTED AUTO VOLT REG MANUAL VOLT REG U. S. Duke Power - Oconee #72-13000-100 FP&L - St. Lucie #2 #72-05000-100 #72-05100-100 FP&L - Turkey Point #72-13000-100 #72-13200-100 Grand Gulf #72-03200-100 #72-03100-100 Knolls Atomic - Kesselring #72-05000-100 #72-05100-100 Portland G.E. - Trogan #72-00101-100 PP&L - Susquehanna #72-06300-100 #72-08400-100 SMUD #72-05000-100 #72-05100-100 TVA - Watts Bar #72-06204-100 #72-05100-100 TVA - Watts Bar-/Sequoyah #72-06204-100 #72-05100-100 Wisconsin Elec - Ft Beach #72-05000-100 #72-05100-100 Foreign Almaraz - Spain #72-05000-100 #72-05100-100 CNV/G.E. - Spain #72-05000-100 #72-05100-100 Cofrentes/G.E. - Spain #72-05000-100 #72-05100-100 Korea Elec - Kori II #72-05000-100 #72-05100-100 KRSKO - Slovenia #72-05000-100 Kuo Shang/G.E. #72-05000-100 #72-05100-100 Laguna Verde (HPCS) #72-01200-201S #72-01200-101 Laguna, Verde Units 1&2 #72-05000-100 #72-05100-100 Phillippines #72-05000-100 #72-05100-100 Zorita - Spain #72-05000-100 #72-05100-100 DEFECT Microscopic examination of the potentiometer showed foreign material on the surface and edge of the stationary slip-ring under the wiper arm collar. The material on the edge was translucent/white-ish and appeared to be a lubricant. The material an the surface wan blackish with some white flakes. It is postulated that the lubricate accumulated contaminants and/or dried on the surface. The total amount of foreign material is very small. REPORT NO. 10CFR21-0073 PAGE: 3 OF 5 CORRECTIVE ACTION 1) FP&L is in the process of updating their voice regulators with the Maury potentiometer. Other users should be aware of this possible problem and monitor their EDG output voltage for unstable output during routine testing. Replacement of the potentiometer is dependent upon monitoring/testing. Immediate response to this notification does not appear to be necessary as the majority of the in-service voltage regulators have been operating without incident. for approximately 15-20 years. 2) The potentiometer is soldered to a circuit board within the voltage regulator assembly; therefore, field modification is not recommended. For replacement of the potentiometer, it is recommended that the regulator be returned to NEI (either directly or through MKW Power Systems) where proper testing can be performed before the regulator is returned to the customer. Contact MKW Parts Department for assistance. If a regulator is to upgraded, we would also recommend replacement of the R5 (stability) potentiometer which is the same type as the R4 potentiometer except it is 100 ohms. This is strictly optional, no voltage regulator operability problems exist with R5 potentiometer. The R5 potentiometer is CTS p/n 115R101A (NEI p/n 01070) and its replacement is Maury p/n 50-M123-101. REPORT NO. 10CFR21-0073 PAGE: 4 OF 5 EXHIBIT 1 (1 page attached) VOLTAGE ADJUST POTENTIOMETER "R4" NEI DRAWING A-01068 CHICAGO TELEPHONE COMPANY POTENTIOMETER #115R251A Figure omitted. REPORT NO. 10CFR21-0073 PAGE: 5 OF 5 EXHIBIT 2 (1 page attached) "R4" REPLACEMENT MAURY #50-M-123-251 Figure "50-M123 MIL-TRIMMER WIREWOUND WT=0.2 OUNCE" omitted. *** END OF DOCUMENT ***

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