TM 55-1520-240-23-7
9-60
LIGHTING SYSTEMS
(Continued)
9-60
Theory of Operation
Power to operate the lamp and motors of each
searchlight assembly comes through a SLT FIL
LIGHTING circuit breaker on the associated 28 vdc
bus. Control of the lamp and motors is through relays
energized by power from the same bus through a SLT
CONT LIGHTING circuit breaker.
NO BREAK - WORK HARDER
With both circuit breakers in, turning the SLT FIL
switch on the thrust lever to ON energizes a lamp
relay to provide 28 vdc to light the lamp. Turning the
control switch on the overhead panel to ON arms the
SEARCHLIGHT control button on the thrust lever. When
it has been armed, moving the spring-loaded button to
EXTEND, RETRACT, L, or A energizes one of four relays
in the searchlight assembly. The energized relay puts
power to one of the two searchlight motors to extend or
retract the light or rotate it left or right.
NO BREAK - WORK HARDER
Moving the switch on the overhead panel to RETR
overrides the switch on the thrust lever. The light
automatically retracts and rotates to point straight down,
regardless of the thrust lever switch position. However,
the light will remain lit until the SLT FIL switch is turned
OFF.
NO BREAK - WORK HARDER
Limit switches in the motor circuits open to cut power to
the relevant motor when the light is fully extended or
retracted with the lamp rotated to face downward.
9-174
