Section III. TECHNICAL PRINCIPLES OF OPERATION
1-12. GENERATING EQUIPMENT AND CONTROL DEVICES
(1) EXCITER-AUXILIARY GENERATOR.
The auxiliary generator section furnishes current to charge the storage batteries and to operate the electrical
auxiliaries. This generator is controlled by the voltage regulator.
The exciter section furnishes excitation for the main generator and has a four-pole field excited from the battery
and in series with two 20-ohm resistors, and a two-pole field in series with an 8-ohm resistor excited by both a
self-excited winding and a differential exciter, used in conjunction with the diesel engine governor.
(2) VOLTAGE REGULATOR (VR). Regulates at 74 volts the power used for charging batteries and operating devices in
the locomotive control circuitry. The regulator maintains control voltage by varying the average value of auxiliary
generator field current.
(3) GENERATOR STARTING CONTACTOR (GS). Connects the battery to the main generator and its starting field,
when operating the generator as a starting motor.
(4) SHUNT FIELD CONTACTOR (SF). When closed, bypasses a 5-ohm resistor and connects the output of the exciter
directly to the main generator field. It is closed whenever the throttle is in a running notch and the reverser is in
either FORWARD or REVERSE.