SEAL-U-CUP 4392697 - Caterpillar

Auxiliary Winding Regulation Excitation Principle ( AREP)
The AREP excited generators use the AVR for regulation of the exciter field.
Illustration 3 g02999698
AREP Generator Wiring Diagram Example (CR1 - CR6) Diodes (CR7) Varistor (L1) Exciter Stator (L2) Exciter Rotor (L3) Main Rotor (L4) Main Stator (R5) Resistor (RFA) Rotating Field Assembly (TR1) STD Voltage Droop Transformer (T0, T1, T2, T3) Generator Terminals and/or Generator Leads (Auxiliary Windings) Internal Excitation Windings
Illustration 4 g01321903
(10) Main stator windings (11) Auxiliary windings (12) Core stackAREP excitation consists of two special sets of coils that are wound to fit in carefully selected slots of the main stator. The wire coils provide total separation and isolation from the stator main winding. The coils can only be fitted to the main stator while the main stator is being wound.The two auxiliary windings are designed in order to provide power to the voltage regulator. The two coils are connected in series and the two coils are connected to the three phase power input of the voltage regulator.One auxiliary winding produces a voltage proportional to the output voltage of the generator. The other auxiliary winding acts like a current transformer and produces a voltage that is proportional to the output current of the generator.The outputs from the two coils are combined inside of the voltage regulator and provide a constant power source.When the engine starts turning the "Rotating Field Assembly" (RFA), the residual magnetism that is in the exciter stator (L1) and the embedded permanent magnets that are in the exciter cause a small amount of AC voltage to be generated in the exciter rotor (L2) . Induced voltage causes current to flow. The current that is caused by the induced voltage is present in the exciter rotor.The AC voltage is then rectified by a three-phase full-wave bridge rectifier circuit. Like the PMPE generators, flashing of the field is not required in order to start the generator.The rectified direct current then flows through the main rotor windings (L3) . The flow of DC through the main rotor windings creates a magnetic field. This magnetic field adds to the existing residual magnetism of the main rotor windings.As the main rotor windings rotate, an AC voltage is induced into main stator (L4) which appears as a three phase AC voltage at the following output terminals: T0, T1, T2 and T3.The voltage regulator senses the output as a low voltage output condition. Therefore, the voltage regulator output to the exciter stator is increased so that the generator output will continue to increase up to the rated voltage.The amount of current which flows through the exciter directly affects the generator output voltage. The voltage regulator maintains a constant generator output voltage with changing loads.The voltage regulator controls the DC voltage and the DC current. The DC voltage and the DC current are supplied to the exciter which produces the generator output voltage.The voltage regulator senses the generator output voltage at wires that are connected to the generator phase leads. The voltage regulator then supplies a