INSTALLATION GP-RADIO 9U8995 - Caterpillar

shaft. The heat sink assembly (20) also contains a varistor (23) and resistor (21). The varistor and the resistor are used to protect the generator circuit. Refer to Generator Operation, "Generator Circuit Protection".1400 and 1600 Frame Rectifier Circuits
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RFA 12 Diode Configuration (1400 and 1600 Frame Only)
(L2) Exciter Rotor
(L3) Main Rotor The 1400 and 1600 frame generators use 12 discrete diodes.
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(25) Exciter Stator
(26) Exciter Rotor
(27) Positive Diodes (Blue Wire Lead)
(28) Negative Diodes (Red Wire Lead) Generator Circuit Protection
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PMPE Generator Wiring Diagram
(CR1 - CR6) Diodes
(CR7) Varistor
(L1) Exciter Stator
(L2) Exciter Rotor
(L3) Main Rotor
(L4) Main Stator
(L5) PMG Stator
(PM) Permanent Magnet
(R5) Resistor
(RFA) Rotating Field Assembly
(TR1) Optional Voltage Droop Transformer
(T0, T1, T2, T3, T7, T8, T9) Generator terminals and/or Generator Leads
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(30) Varistor for the 1400 and 1600 Frame Generators The varistor protects the diodes by suppressing any abnormal transient peak voltages. The varistor is a separate component that mounts on the heat sink assembly. On generators that use the 12 discrete diodes, the varistor (30) is mounted between the negative and the positive heat sink plates.The varistor is the first component to fail in adverse operating conditions. The adverse conditions include out of phase paralleling and voltage spikes due to unbalanced loads. The varistor must be checked at regular intervals.The resistor is a separate component that mounts on the heat sink assembly. This resistor is only used on some of the larger 1800 framed generators. The resistor provides a low resistance circuit from the insulated windings to the shaft and cores of RFA. The resistor is a 27000 ohm resistor. Air friction on the windings can cause an electrostatic charge. If this resistor is not installed, these charges can cause voltages to become high enough to destroy the winding insulation. The resistor allows charges to dissipate as the charges are generated. This resistor also prevents any build-up of voltage. Because of the resistance value and the power rating of the resistor, a ground failure at any point on the RFA will not prevent the generator from operating normally. A ground failure will not damage resistor.The voltage regulator and related components also protect the generator. Both PMPE and IE exciters utilize fuses that will stop the current flow to the voltage regulators. The fuses open rapidly. If no voltage is applied to the exciter, then the generator output voltage is reduced to a low level.The fuses protect against secondary damage that is caused by other component failures. If any fuse is replaced, use only a fuse of the same type and amperage rating. A larger amperage rating or a fuse which does not open rapidly will not prevent damage to other components.All voltage regulators have built in excessive current protection circuits that also open the excitation circuit.Note: For more information on voltage regulation, see the appropriate voltage regulator service manual.Space Heaters
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Location of the Space Heater
(31) PMG Stator
(32) Diode Assembly
(33) Exciter Stator
(34) Heater Element The space heater is attached to the rear bearing bracket. The space heater is located at the