ARMY TM 9-6115-644-24
AIR FORCE TO 35C2-3-446-12
MARINE CORPS TM 09249A/09246A-24/2
1-12-8-2 Field Flash. When the engine reaches sufficient speed (900 rpm), the magnetic pickup causes a set of contacts
in the crank disconnect switch to dose and energize the field flash relay. This circuit provides current to the exciter field
windings which sets up an electromagnetic field. The field current is necessary for the set to generate sufficient voltage
for the voltage regulator (FIGURE 1-11) to begin controlling the output voltage of the generator set. The field flash circuit
is maintained until the MASTER SWITCH is released from the START position.
1-12-8-3 Opertion. Placing the MASTER SWITCH in the PRIME& RUN or PRIME & RUN AUX FUEL positions keeps
the electronic governor control (FIGURE 1-10) energized, and fuel will be supplied to the fuel injection pump as long as
no fault condition exists. During operation, the operator should periodically check the set’s instruments to ensure they are
reading in the normal operating ranges. The VOLTAGE and FREQUENCY potentiometers are adjusted as required to
maintain desired frequency and voltage output.
1-12-8-4 Applying the Load. The load is applied by placing the AC CIRCUIT INTERRUPTER switch in the CLOSED posi-
tion. This is a momentary contact switch that returns to the neutral, or center position. The AC circuit interrupter relay is
energized by this momentary contact and a holding circuit keeps it dosed, bringing the load on line.
1-12-8-5 Shutdown.
1-12-8-5-1 The AC circuit interrupter relay is disengaged by placing the AC CIRCUIT INTERRUPTER switch in the OPEN
position. This is a momentary contact switch which will break the AC circuit interrupter relay holding circuit and then return
to the neutral, or center position, disconnecting the load from the line.
1-12-8-5-2 The generator set should remain running for five minutes after disconnecting the load. During this five minute
interval, oil circulates through the turbocharger, cooling it enough to be shutdown.
1-12-8-5-3 When the MASTER SWITCH is placed in the OFF position all power is removed from the control circuit and
the engine will stop.
1-12-8-5-4 The EMERGENCY STOP switch will remove power from the control circuit by energizing the engine fault
relay. This will cause the engine to shut down. The EMERGENCY STOP switch is not to be used as an alternative for
routine shutdown procedures. When the generator set is stopped using the EMERGENCY STOP switch, some circuits
remain energized causing a drain on the batteries until the MASTER SWITCH is placed in the OFF position.
1-12-8-6 Paralleling.
1-12-8-6-1 The generator set is capable of being operated in parallel with one other set of the same model number. This
capability is provided by the PARALLELING RECEPTACLE, paralleling cable, the LOAD SHARING ADJUST and REAC-
TIVE CURRENT ADJUST rheostats, two SYNCHRONIZATION LIGHTS, the UNIT-PARALLEL switch, reverse power
relay, voltage sensing relay, droop current transformer, and the permissive paralleling relay.
1-12 -8-6-2 The paralleling cable is used to interconnect the governor and voltage regulator paralleling circuits of the two
sets. The UNIT-PARALLEL switch is used to select parallel operation. Voltage and frequency of the two generator sets
are synchronized by adjusting each set’s VOLTAGE and FREQUENCY controls. Phase synchronization is indicated by
the SYNCHRONIZATION LIGHTS. The reverse power relay serves as a safety device that opens the AC CIRCUIT INTER-
RUPTER when one of the sets fail to produce power and begins to receive power from the other set. The reverse power
relay operates when the power received exceeds 20% of set rating. The load sharing adjust and reactive current adjust
rheostats, and the droop current transformer are used to adjust power and current for load sharing at the factory or by
maintenance. No adjustment of the rheostats is required for normal operation. The permissive paralleling relay monitors
the voltage phase relationship and prevents the AC circuit interrupter relay from closing when the units are not properly
synchronized. The voltage sensing relay senses the operating voltage range, 120/208 voltsor240/416 volts, and switches
an additional resistor to each of the SYNCHRONIZATION LIGHT circuits during 240/416 volts operation to protect the
lights.
1-12-9
Governor Control System.
1-12-9-1 The Governor Control System (FIGURE 1-10) incudes the electronic governor control, governor actuator, mag-
netic pickup, load measuring unit, frequency transducer, FREQUENCY meter (HERTZ), kilowatt transducer, fuel injection
pump, FREQUENCY SELECT switch, and FREQUENCY adjust potentiometer.
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