TM 9-6115-604-34NAVFAC P-8-633-34SECTION VII. AC CIRCUIT BREAKERS5-42. GENERAL. Switchgear circuit breaker CB123 (73, Figure 5-9) connects and disconnects station power to loadcircuit breaker CB101. MAINTENANCE LOCKOUT circuit breaker S100 connects and disconnects station power to thearray of circuit breakers on distribution panel DP2.5-43. SWITCHGEAR CIRCUIT BREAKER CB123 MAINTENANCE (73, Figure 5-9).a.Inspection. Check switchgear circuit breaker CB123 (73, Figure 5-9) for security of mounting, signs of burning orscoring, and security of electrical connections.b.Remove.(1)Tag and disconnect wires to switchgear circuit breaker CB1 23 (73, Figure 5-9).(2)Remove hexagonal head screws (75) and lockwashers (76) to remove circuit breaker bracket (74) andswitchgear circuit breaker (73).c.Test.(1)With circuit breaker set to OFF position, use a multimeter set to RX1 scale to check continuity across thebreaker. Meter should indicate infinite ohms (contacts open).(2)Set circuit breaker to ON position. Use multimeter to check continuity across breaker. Meter shouldindicate zero ohms (contacts closed).(3)If circuit breaker fails this test, it must be replaced.d.Installation.(1)Position switchgear circuit breaker CB123 (73, Figure 5-9) and secure with circuit breaker bracket (74),hexagonal head screws (75), and lockwashers (76).(2)Connect wires as tagged and discard tags.5-44. MAINTENANCE OF MAINTENANCE LOCKOUT CIRCUIT BREAKER S100 (77, Figure 5-9).a.Inspect. Check MAINTENANCE LOCKOUT circuit breaker S100 (77, Figure 5-9) for security of mounting, signsof burning or scorching, and security of electrical connections.b.Remove.(1)Tag and disconnect wires to MAINTENANCE LOCKOUT circuit breaker S100 (77, Figure 5-9).(2)Remove screws (78), flatwashers (79), and nut and captive washer assemblies (80) to removeMAINTENANCE LOCKOUT circuit breaker S100.c.Test.(1)With circuit breaker set to OFF position, use a multimeter set to RX1 scale to check for continuity acrossthe breaker. Meter should indicate infinite ohms (contacts open).(2)Set circuit breaker to ON position. Use multimeter to check for continuity across breaker. Meter shouldindicate zero ohms (contacts closed).(3)If circuit breaker fails to meet this test, it must be replaced.d.Install.(1)Install MAINTENANCE LOCKOUT circuit breaker S100 (77, Figure 5-9) with screws (78), flat washers (79),and nut and captive washer assemblies (80).(2)Connect wires to MAINTENANCE LOCKOUT circuit breaker S100 as tagged and discard tags.5-84
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