TM 9-6115-604-34
NAVFAC P-8-633-34
SECTION VII. AC CIRCUIT BREAKERS
5-42. GENERAL. Switchgear circuit breaker CB123 (73, Figure 5-9) connects and disconnects station power to load
circuit breaker CB101. MAINTENANCE LOCKOUT circuit breaker S100 connects and disconnects station power to the
array 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 or
scoring, 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) and
switchgear circuit breaker (73).
c.
Test.
(1)
With circuit breaker set to OFF position, use a multimeter set to RX1 scale to check continuity across the
breaker. Meter should indicate infinite ohms (contacts open).
(2)
Set circuit breaker to ON position. Use multimeter to check continuity across breaker. Meter should
indicate 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, signs
of 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 remove
MAINTENANCE 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 across
the breaker. Meter should indicate infinite ohms (contacts open).
(2)
Set circuit breaker to ON position. Use multimeter to check for continuity across breaker. Meter should
indicate 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.
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