Stepdown Transformer T103. Stepdown transformer T103 is mounted in the rear section of cabinet C, on the
floor. When UTILITY POWER circuit breaker CB1 25 is set to ON and the station power cable assembly is
connected to bring in UTILITY POWER at J101, one or both windings of transformer T103 will be hot. Hence,
the transformer must be isolated before it can be safely worked on.
Station power cable assembly must be disconnected from UTIUTY POWER receptacle J101
and UTILUTY POWER circuit breaker CB125 must be set to OFF before working on stepdown
transformer T103. Failure to do so may result In death by electrocution.
Hazardous voltages appear at terminals In rear section of Cabinet C when generator set Is
running. Do not touch any terminals Inside Cabinet C unless specifically Instructed by the
following procedure. Failure to comply with this warning may result In death by
Disconnect station power cable assembly from UTILITY POWER receptacle J101.
Go into the control room. Set UTILITY POWER circuit breaker CB1 25 to OFF and set circuit breaker
locking beam such that the circuit breaker cannot be set back to ON.
Go into the generator compartment and remove cabinet C rear access panel in accordance with the
Operator and Organizational Maintenance Manual.
See Figure 10-7. Remove hexagon head capscrews (11), flat washers (12), wire terminal shields (13), <
lockwashers(14), spacers (15), flatwashers (16), and hexagonal nuts (17)to gain accesstotransformerTi03
Tag and disconnect wires from transformer T1 03 terminals.
Remove hexagon head capscrews (18) and lockwashers (19) to remove stepdown transformer T103 (20).
Install stepdown transformer T103 (20) and secure with lock-washers (19) and hexagon head capscrews (1
Make wiring connections to T103 terminals as tagged. Remove and discard tags.
Install hexagonal nuts (15), flat washers (16), spacers (15), lockwashers (14), wire terminal shields (13), flat
washers (12), and hexagon head capscrews (11).
Reinstall cabinet C rear access panel in accordance with the Operator and Organizational Maintenance
Go into control room and set circuit breaker locking beam, SET POWER circuit breaker CB1 24, and
UTILITY POWER circuit breaker CB125 as desired.
Transformers T104 and T106 through T110. These six transformers are vertically mounted in the upper rear
section of Cabinet A. All of them have their primaries tied to generator load lines T1 through T3 or LI through L3.
Therefore, the generator set must be shut down, the output power cables must be disconnected, and the load
lines must be discharged before the transformers can be safely worked on.