ARMY TM 9-6115-60412
NAVY NAVFAC P-8-633-12
4-137. SET/UTILITY CIRCUIT BREAKERS (SET STATION POWER CIRCUIT BREAKER CB124 AND UTILITY
STATION POWER CIRCUIT BREAKER CB125). SET/UTILITY circuit breakers are used to select set power or utility
power for the generator set 120 Vac circuits.
a.
Remove. See Figure 4-79
To avoid death or injury to personnel, no electrical component will be worked on
while energized. Ensure equipment Is "tagged out" in accordance with Chapter 1,
Section III, of this manual and equipment is NOT energized. Residual voltage Is
present at the generator leads with the regulator turned off, reaching SEVERAL
HUNDRED VOLTS on the generator set. Proper insulation and isolation of
metering equipment must be observed when testing this generator. USE PROPER
TEST EQUIPMENT TO CHECK FOR VOLTAGE before proceeding with work.
(1)
Set switchgear circuit breaker CB123 to OFF.
(2)
Remove hexagon head capscrews (1) and lockwashers (2) to remove the circuit breaker enclosure
cover (3).
(3)
Remove hexagon head capscrews (4) and lockwashers (5) to remove circuit breaker support (6).
Remove circuit breakers and support from enclosure. Tag and disconnect wires from circuit
breakers.
(4)
Remove pan head screws (7), flat washers (8), and nut and captive washer assemblies (9) to
remove circuit breaker CB125 or CB124 (10 or 11).
(5)
If necessary, remove screw and captive washer assemblies (12), flat washers (13), spacers (14),
and nut and captive washer assemblies (15) to remove circuit breaker locking beam (16).
Dangerous voltage levels may be present at components located within cabinet C.
Observe all applicable safety precautions as outlined in Chapter 1, Section III, of
this manual.
b.
Test. SET STATION POWER circuit breaker CB124 and UTILITY STATION POWER circuit breaker
CB125 are identical and rated at 240 V, 100 amperes each.
(1)
Test circuit breakers CB124 and CB125 using MSIA test set.
(2)
Replace circuit breaker CB124 or CB125 that falls circuit breaker test.
c.
Install. See Figure 4-79.
(1)
If removed, install circuit breaker locking beam (16) and secure with screw and captive washer
assemblies (12), flat washers (13), spacers (14), and nut and captive washer assemblies (15).
(2)
Install circuit breaker CB125 and/or CB124 (10 or 11) on circuit breaker support (6) and secure with
pan head screws (7), flat washer (8), and nut and captive washer assemblies (9).
(3)
Connect wires to circuit breaker and remove tags. Install circuit breaker support (6) and secure with
hexagon head capscrews (4) and lockwashers (5).
(4)
Install circuit breaker enclosure cover (3) and secure with hexagon head capscrews (1) and
lockwashers(2).
(5)
Set MAINTENANCE LOCKOUT switch S100 to OPERATE.
4-198
