MARINE CORPS TM 6115-34/8
MAINTENANCE OF DC ELECTRICAL AND CONTROL SYSTEM
PURPOSE AND FUNCTION OF DC
ELECTRICAL AND CONTROL SYSTEM. This
section gives a functional description
and maintenance procedures for the DC
electrical and control system.
system consists of the battery cable,
control module (GECM), circuit breaker,
starter, and 20 amp current shunt.
The DC electrical and
output control and sensing, generator
protection, and battery charging.
b. Functional Description.
following is a simplified functional
description of the DC electrical and
The description is
keyed to the schematic in FO-5, TM
begun, 24 volts from the battery are
applied through the DC CIRCUIT BREAKER
(CB1) to the MASTER SWITCH. When the
MASTER SWITCH is placed in the RUN
position, the transfer pump will come
on and fill fuel filters.
switch is placed in the START position,
the 24V signal is connected to the
engine electronic control module (EECM)
on the start circuit.
If the EECM has
it outputs the start
enable signal to the starter solenoid.
The solenoid energizes, supplies 24
the actuator. As
starter motor begins
to turn, the
actuator causes the starter gear to
Turbine speed is sensed by the digital
speed sensor and relayed to the EECM.
When turbine speed reaches 60 percent
the EECM interrupts the
removes power from the starter and
retracts the starter gear from the
(2) Generator Output Control and
These functions are controlled and
monitored by the GECM and the EECM. If
the EECM does not sense a fault in the
it enables the GECM via
the enable circuit on J4 pin F to the
GECM J2 pin L.
The GECM senses the
of the generator field
winding at J1 pin F.
If the temp-
erature is normal or below, field
is switched onto the
field positive (+) and negative (-)
lines (J1 pins C and B) to the gen-
The amount of field winding
power is adjusted by the GECM to main-
tain the output voltage level set by
the VOLTAGE ADJUST knob. The GECM
compares the output voltage setting at
J2 pin R with the remote voltage sense
at J2 pins E and F. If the two inputs
circuitry in the GECM
adjusts the field power until the
output voltage is correct.
generator is protected
condition exceeds programmed limits,
the GECM interrupts the field current
and sends a fault signal to the EECM.
When the EECM detects a fault, it turns
The EECM will not permit
startup until the malfunction has been
is described below.