- Power for the exciter field is provided by either the permanent magnet pilot excited (PMPE) method or the self-excited (SE) method.
- The location of the bearing can be inboard or outboard from the exciter rotor. The following factors determine the location of the bearing: vibration characteristics of the engine, vibration characteristics of the generator, the size of the engine and the size of the generator.
Note: Some larger generators have two bearings. When a generator has two bearings, there is a bearing at each end of the generator shaft.
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| Illustration 1 | g00611851 |
SE Type Components with Outboard Bearing (1) Bearing (2) Exciter Armature (Rotor) (3) Exciter Field (Stator) (4) Rotating Rectifiers (5) Main Field (Rotor) (6) Main Armature (Stator) (7) Rotor Shaft (8) Fan | |
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| Illustration 2 | g00611845 |
SE Type Components with Inboard Bearing (1) Rotating Rectifiers (2) Exciter Field (Stator) (3) Exciter Armature (Rotor) (4) Bearing (5) Main Armature (Stator) (6) Main Field (Rotor) (7) Rotor Shaft (8) Fan | |
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| Illustration 3 | g00851614 |
PMPE Type Components with Inboard Bearing (1) Rotating Rectifiers (2) Exciter Field (Stator) (3) Exciter Armature (Rotor) (4) Bearing (5) Main Armature (Stator) (6) Main Field (Rotor) (7) Rotor Assembly (8) Fan (9) Heat sink Assembly (10) Pilot Exciter Armature (PM Armature) (11) Pilot Exciter Field (Permanent Magnet (PM)) (12) Seal (13) Seal | |
Rotating Field Assembly (RFA)
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| Illustration 4 | g00851687 |
Rotating Field Assembly (RFA) Components (SE Inboard Bearing Type Shown) (1) Heat Sink and Rotating Rectifier Block (2) Exciter Armature (Rotor) (3) Bearing (4) Main Field (Rotor) (5) Rotor Assembly | |
The RFA components attach to rotor assembly (5), which is supported by the engine flywheel and bearing (3). The pilot exciter field (permanent magnet (PM)) is also an RFA component on PMPE generators.
Main Armature (Stator)
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| Illustration 5 | g00637295 |
Main Armature (Stator) | |
The generator main armature is stationary and the generator main armature contains the stator windings.
Main Field (Rotor)
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| Illustration 6 | g00851688 |
(1) Main Field (Rotor) | |
Generator Main Field (1) is part of the rotating field assembly. The generator main field rotates with the rotating field assembly.
Exciter
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| Illustration 7 | g00637298 |
Exciter Armature (Rotor) | |
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| Illustration 8 | g00637297 |
Exciter Field (Stator) | |
Pilot Exciter
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| Illustration 9 | g00851689 |
Pilot Exciter Armature | |
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| Illustration 10 | g00851690 |
Pilot Exciter Field (Permanent Magnet (PM)) | |
A pilot exciter is used on permanent magnet pilot excited (PMPE) type generators. The pilot exciter consists of the stationary pilot exciter armature. Refer to Illustration 9. The pilot exciter also consists of the rotating pilot exciter field. Refer to Illustration 10. The pilot exciter field is also referred to as the permanent magnet (PM).
Rotating Rectifier Blocks
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| Illustration 11 | g00610186 |
Two Diode Rectifier Block | |
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| Illustration 12 | g00611973 |
6 Diode Rectifier Block | |
The rotating rectifier blocks are part of the rotating field assembly (RFA). There are two types of rotating rectifier blocks that are used. The size of the generator determines the size of the rotating rectifier block that is used.
- The two diode rectifier block contains two diodes. Three identical blocks are required.
- The six diode rectifier block contains six diodes. One block is required.
Note: For additional information, refer to "Rectifier Circuits" within the Systems Operation Section, "Generator Operation".
Note: Early SR4 generators were provided with six individual diodes. Three diodes on a positive heat sink, and three diodes on a negative heat sink.
Voltage Regulators
VR3 Voltage Regulator
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| Illustration 13 | g00626329 |
Adjustment Controls of the VR3 Regulator (1) Voltage Droop Potentiometer (2) Voltage Level Potentiometer (3) Voltage Gain Potentiometer (4) Fuse(s) | |
VR3F Voltage Regulator
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| Illustration 14 | g00626331 |
Adjustment Controls of the VR3F Regulator (1) Voltage Droop Potentiometer (2) Voltage Level Potentiometer (4) Fuse(s) | |
VR4 Voltage Regulator
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| Illustration 15 | g00626398 |
Adjustment Controls of the VR4 Regulator (2) Voltage Level Potentiometer (3) Voltage Gain Potentiometer (4) Fuse(s) | |
Digital Voltage Regulator (DVR)
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| Illustration 16 | g00626333 |
Digital Voltage Regulator (DVR) (5) Display (6) Function Key (7) Scroll Down Key (8) Scroll Up Key (9) Keypad (10) "J1" Connector (11) Screw Terminals | |
All Caterpillar SR4 generators, except the oilfield generators, are provided with voltage regulators. The voltage regulator controls the generator output voltage. Several types of voltage regulators are available. Refer to Illustrations 13, 14, 15, and 16.
The VR3 regulators and all of the VR3F regulators have voltage droop adjustment (1). The VR4 regulator does not have a voltage droop adjustment. The VR4 regulator is not designed for parallel applications.
The VR3, VR3F and VR4 regulators have voltage level control (2) .
The VR3 and VR4 regulators have voltage gain adjustment (3). The VR3F regulator does not have a voltage gain adjustment.
Voltage level and voltage gain are controlled by multiturn potentiometers. The adjusting screws on the potentiometers do not have a fixed stop. When the potentiometer reaches the end of adjustment, a ratchet action begins. The beginning of a ratchet action can be felt with the adjusting tool. The adjusting screw can be turned past the potentiometer stop (ratchet action) without further changing the potentiometer setting.
The DVR is a microprocessor based voltage regulator. All the parameters are preset at the factory. The parameters can be modified in order to meet the specific requirements on the site. Certain system parameters can also be monitored on display (5) of the DVR. Keypad (9) is used to change the information that is shown on display (5). J1 connector (10) is used to join the DVR to a personal computer. Screw terminals (11) are used to join the DVR to the generator and various customer options.