5-37. GROUND FAULT RELAY K115

Figure 5-30. Test Setup, Overcurrent Relay K114

Figure 5-31. Ground Fault Relay K115, Time Voltage Curve

TM-9-6115-604-34 Generator Set Diesel Engine Driven Tactical Skid Mtd 5 Kw. 1 Phase-2 Wire 1 Phase -3 Wire 3 Phase -4 Wire 120. 120/240 and 120/208 Volts Manual
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TM 9-6115-604-34 NAVFAC P-8-633-34 (2) Test. (a) Turn on both power sources and increase output of the ac power source to 5.4 amperes. The dc voltmeter should read 24 V dc. Relay K114 should trip in 20 i5 seconds as measured by a stopwatch. This will be indicated by the dc voltmeter reading zero volts. (b) Turn off both power sources and reset relay K114. Connect the ac power source across terminals 3 and 4 of relay K114 and repeat step (a), above. (c) Turn off both power sources and reset relay K114. Connect the ac power source across terminals 1 and 2 of relay K114, and repeat step (a), above. (d) Ensure power sources are turned off and reposition tap on relay K114 to 1 X position. Turn on both power sources and set ac power source output to 4.5 amperes. Relay K114 should trip immediately. (e) Turn off both power sources and reset relay K114. Connect ac power source across terminals 3 and 4 of relay K114. Turn on both power sources and set ac power source output to 4.5 amperes. Relay K114 should trip immediately. (f) Turn off both power sources and reset relay K114. Connect ac power source across terminals 5 and 6 of relay K114, Turn on both power sources and set ac power output to 4.5 amperes. Relay K114 should trip immediately. (g) Ensure power sources are turned off and reposition tap on relay K114 to 3 X 4 position. Turn on both power sources and set ac power output to 13 amperes. Relay K114 should trip immediately. (h) Turn off both power sources and reset relay K114. Connect ac power source to terminals 3 and 4 of relay K114. Turn on both power sources and set ac power source output to 13 amperes. Relay K114 should trip immediately. (i) Turn off both power sources and reset relay K114. Connect ac power source to terminals 1 and 2 of relay K114. Turn on both power sources and set ac power source output to 13 amperes. Relay K114 should trip immediately. (j) Ensure both power sources are turned off. Reset relay K114 and return tap to its original position. Disconnect all test equipment. (3) Replace. Replace overcurrent relay K114 if it fails any portion of this test. d. Install. See Figure 5-9. (1) Slide overcurrent relay K114 (65) through cutout in front of panel and secure with four screws (66) at the rear of panel. (2) Securely reconnect wiring as tagged and discard tags. Ensure that jumper link is restored across terminals 9, 10, and 11 if removed. 5-37. GROUND FAULT RELAY K115 (67, Figure 59). The ground fault relay K115 is an overvoltage relay that has been installed for ground fault detection. It operates by comparing generator set ground with phase neutral of the output of generator G1. Any voltage difference sensed by ground fault relay K115 indicates that current is flowing in the neutral phase. Ground fault relay K115 then trips to open the load circuit breaker CB101. Ground fault relay K115 is mounted on Cabinet A door. Figure 5-31 is a graph of the time voltage curve of ground fault relay K115. a. Inspect. See Figure 5-32. (1) Check that there are no broken or cracked molded parts or other signs of physical damage to ground fault relay K115 (67). (2) Open ground fault relay K115 cover. Endplay of disc should not be so great as to allow the disc to strike the drag magnet. Check that top and bottom pivot screws are tight. There should be no noticeable friction in the rotating structure. 5-76

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