ARMY TM 9-6115-604-12
NAVY NAVFAC P-8-633-12
Self-latching engine run relay K 15B will deenergize to disconnect battery positive from engine fuel
solenoid L1. Engine fuel solenoid L1 will deenergize; the back-EMf from its collapsing field will be
shorted to ground through diode CR4. Fuel flow to the engine fuel pump will be blocked and the
engine will start slowing down.
DC operating power is removed from synchronizer A105, load sharing panel A104, LUBE OIL
PRESSURE gage M1, LUBE OIL TEMP gage M2, COOLANT TEMP meter M3, FUEL LEVEL
gage M4, and TIME TOTALIZING meter M5.
Engine run relay K1 5A is deenergized. Its normally closed contacts close to apply 240 V ac power
to generator G1 heaters H109 and H110. (K15A contacts are shown on the AC schematic, FO-2.)
Engine run relay K1 5C is deenergized. Its normally closed contacts close to apply 120 V ac power
to the coils of coolant heater contactors K104A and K104B. (K15C contact sets are shown on the AC
schematic, FO-2 )
Engine run relay K15D 5s deenergized. Its normally closed contacts close to energize the trip coil of
load circuit breaker CB101, causing the circuit breaker to open and disconnect generator G1 from
Battery positive is removed from coolant level warning switch S13; coolant level shutdown switch
S14; OVERCURRENT relay K114, crank cycle timer M7; fault by-pass relays K17A and K17B.
When K17A deenergizes, its normally open contacts open to disconnect battery positive from oil
pressure shutdown relay K18, undervoltage annunciator fault relay A1 0K8, low oil pressure fault
relay A10K2, and underfrequency annunciator fault relay A11 K5. This serves to disable automatic
shutdown circuits that would otherwise put the generator set into a fault-shutdown condition as the
engine loses speed.
When engine fuel solenoid L1 loses power (see step (1)(b), above), the engine will be cut off from its fuel
supply and will slow to a halt. During and after this slowing-down period, battery positive will be
unavailable to any of the DC circuits and instruments normally activated when MASTER SWITCH S9 is set
to START and released to RUN. Battery positive will, however, be available to all elements described in
step a, above.
The operator is not expected to restart the generator set until the engine has completely stopped. Note,
however, what will occur after a normal shutdown, if MASTER SWITCH S9 is set to START and released
to RUN under the following speed conditions.
Above 1200 rpm, nothing will happen The normally closed contacts of shutdown relay K14 will be
open to prevent battery positive from reaching DC control circuits
Between 600 and 1200 rpm, engine run solenoid K15B will be energized and latched. Normally
open contacts of relay K15B will close to connect battery positive to engine fuel solenoid L1. The
engine will receive fuel and begin to accelerate.
Below 600 rpm, the engine will crank as described in step c, above
EMERGENCY SHUTDOWN Pushbutton S7. EMERGENCY SHUTDOWN pushbutton S7 is located on cabinet C
door and is used to shut down the generator set in accordance with Chapter 2 of this manual. Pressing pushbutton S7
will disconnect battery positive from generator set DC control circuits, open load circuit breaker CB101, and cut off the
air supply to the engine air Intake manifold. When pushbutton S7 is pressed, the following occur immediately and
Shutdown relay Kl14 will energize (and latch if engine speed is above 1200 rpm). The normally closed
contacts of relay K14 will open to cut off battery positive from generator set DC control circuits.
Additionally, all the events detailed under step g(1), above, will occur.
Relay K30 will be energized. The normally open contacts of relay K30 will close to energize the trip coil in
load circuit breaker CB101 Note that the trip coil will also become connected to battery positive by the
normally closed contacts of engine run relay K15D when K15D is cut off from battery positive by shutdown