LEVER 2V0055 - Caterpillar

In order to form a bridge rectifier circuit, two similar three-diode rectifier blocks are connected. Each of the three-diode rectifier blocks contain three diodes. Positive rectifier block (1) contains diodes "CR1", "CR2", and "CR3". Negative rectifier block (2) contains diodes "CR4", "CR5", and "CR6". Three-diode rectifier blocks must be wired correctly. Refer to Illustration 10. Each "AC" terminal connects to an "L2" wire from the exciter armature (6). The "+" terminals connect together. The "+" terminals also connect to one "L3" wire (3) of the main field. The "-" terminals connect together. The "-" terminals also connect to the other "L3" wire (3) of the main field.The positive rectifier block (1) and the negative rectifier block (2) are mounted to heat sink assembly (4). The heat sink assembly is on the end of the generator shaft. Heat sink assembly (4) also contains a varistor (7) and resistor (5). The varistor and the resistor are used to protect the generator circuit. Refer to Generator Operation, "Generator Circuit Protection".Six-Diode Rectifier Block
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Six-Diode Rectifier Block
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Six-Diode Rectifier Block Location (Inboard Bearing)
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Six-Diode Rectifier Block Location (Outboard Bearing) (1) Exciter (2) Six-Diode Rectifier Block (3) Disc (4) Main FieldThe six-diode rectifier block contains the six diodes of the bridge rectifier circuit. Each "AC" terminal connects to an exciter armature wire. The "+" terminal and the "-" terminal connect to main field (4) .On inboard bearing type generators, the six-diode rectifier block is on the end of the generator shaft. On outboard bearing type generators, six-diode rectifier block (2) is mounted on disc (3). Disc (3) is between exciter (1) and main field (4) .The six -diode rectifier block also contains varistor (CR7) which is used to protect the generator circuit. Refer to Generator Operation, "Generator Circuit Protection". Generator Circuit Protection
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PMPE Generator Wiring Diagram (CR1 - CR6) Diodes (CR7) Varistor (L1) Exciter field (stator) (L2) Exciter armature (rotor) (L3) Main field (rotor) (L4) Main armature (stator) (L5) Pilot exciter armature (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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Varistor (CR7) Varistor (CR7) protects the following diodes by suppressing any abnormal transient peak voltages: CR1, CR2, CR3, CR4, CR5 and CR6. On generators that use the two-diode rectifier blocks or the three-diode rectifier blocks, varistor (CR7) is a separate component and mounts on the heat sink assembly. On generators that use the six-diode rectifier block, varistor (CR7) is contained within the six-diode rectifier block.Note: Some generators are provided with another varistor (CR8) for additional protection.Resistor (R5) is a separate component and mounts on the heat sink assembly. This resistor is only used on some of the larger generators. Resistor (R5) provides a low resistance circuit from the insulated windings to the shaft and cores of revolving field assembly (RFA). Resistor (R5) is a 27000 ohm resistor. Air friction on the windings can cause an electrostatic charge. If this resistor is not installed, these