Field Flash.

ARMY TM 9-6115-645-24 AIR FORCE TO 35C2-3-444-12 MARINE CORPS TM 09244A109245A-24/2 1-12.8.1.5 The batteries are charged by the battery charging alternator that is belt driven by the engine. The BATTERY CHARGE ammeter indicates the charge/discharge rate of the batteries, from -10 Amps to + 20 amps. A shunt provides a DC voltage signal, which is directly proportional to the actual battery current flow, to the BATTERY CHARGE ammeter. Normal operating indication on the BATTERY CHARGE ammeter depends on the state of the charge in the batteries. A low charge, which may exist immediately after engine starting, will cause a high reading (needle moves toward CHARGE area). When the charge in the batteries has been restored, the indicator moves near zero. The battery charging system is protected from reverse polarity in the battery connections by a fuse and diode. 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 close 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 Operation. Placing the MASTER SWITCH in the 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 position. 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 shut down. 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 REACTIVE 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 tha AC circuit interrupter when one of the sets fail to reproduce 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 dosing when the units are not properly synchronized. The voltage sensing relay senses the operating voltage range, 120/208 volts or 240/416 volts, and switches an additional resistor to each of the SYNCHRONIZATION LIGHT circuits during 240/416 volts operation to protect the lights. Change 2 1-21