1 0 - 1 .
PURPOSE AND FUNCTION OF ENGINE
AND GENERATOR CONTROLS AND INSTRU-
b. Functional Theory of operation.
to be an overspeed condition, the
overspeed acknowledge line is enabled.
If the fault is an overtemperature, the
Knowledge is passed through
overspeed signal to one input of a set
of eight latches.
The ENGINE OVERTEMP
line is connected directly to one of
the other latch inputs.
microprocessor at the same time that
the signals on these lines are buffered
and applied to two other latch inputs
on the switch card.
fault signal from the microprocessor to
the latches enables any signal present
on a latch input to be passed to the
latch output unchanged.
a fault is sensed, fault changes logic
status and latches whatever signals are
on the latch inputs into the latch.
Changes on the latch input lines no
longer affect the latch outputs; they
are now locked in the logic status they
were in when fault changed logic
Each latch output is applied
to a lamp driver, buffered, and routed
to the control panel. Only that line
signifying a malfunction will be in a
different logic state from the others.
Whichever line carries the fault status
signal causes the appropriate lamp on
the control panel to come on and
indicate the source of trouble to the
As the fault is being
indicated on the control panel, the
automatic engine shutdown routine is
shutting off the fuel pump drive and
closing the engine fuel valve via the
MARINE CORPS TM 6115-34/8
fuel pump drive and fuel valve signal
lines from the EECM to the engine.
Generator faults consist of overload,
sensed by the EECM microprocessor as it
monitors the overload, undervoltage,
and generator overtemp
lines from the generator electronic
control module (GECM).
Each line is
routed to the EECM switch card and
placed on a latch input. Each line is
also an input to a generator fault
Any fault, with one
The one exception
is a simultaneous
which is not treated as a
fault because it is instead detected by
the GECM and appropriate steps taken by
circuits in the GECM.
If any other
fault is sensed,
the output of the
generator fault gating is enabled to
send a fault signal
to the micro-
processor on the generator fault line.
Reception of generator fault causes the
fault signal to latch the latches, shut
off the fuel supply to the engine, and
reenergize the contactor relay.
Manual contactor disabling is different
from automatic contactor disabling in
that this is an operator-controlled
process initiated because of a mal-
To disable the contactor and
stop power from flowing to the load,
switch on the control panel momentarily
in the OPEN position.
then releases it back to the center
As the switch moves to the
OPEN position, +24 Vdc from the switch