BOLT 1M1081 - Caterpillar

DANGER: Shock/Electrocution Hazard-Do not operate this equipment or work on this equipment unless you have read and understand the instructions and warnings in the Operation and Maintenance Manual. Failure to follow the instructions or heed the warnings will result in serious injury or death.
Personal injury or death can result from high voltage.When power generation equipment must be in operation to make tests and/or adjustments, high voltage and current are present.Improper test equipment can fail and present a high voltage shock hazard to its user.Make sure the testing equipment is designed for and correctly operated for high voltage and current tests being made.When servicing or repairing electric power generation equipment:
Make sure the unit is off-line (disconnected from utility and/or other generators power service) , and either locked out or tagged DO NOT OPERATE.
Remove all fuses.
Make sure the generator engine is stopped.
Make sure all batteries are disconnected.
Make sure all capacitors are discharged.Failure to do so could result in personal injury or death. Make sure residual voltage in the rotor, stator and the generator is discharged.
Accidental engine starting can cause injury or death to personnel working on the equipment.To avoid accidental engine starting, disconnect the battery cable from the negative (−) battery terminal. Completely tape all metal surfaces of the disconnected battery cable end in order to prevent contact with other metal surfaces which could activate the engine electrical system.Place a Do Not Operate tag at the Start/Stop switch location to inform personnel that the equipment is being worked on.
The voltage regulator is located in the enclosure for the control panel or in the terminal box on the generator.The Automatic Voltage Regulator (AVR) may control any of the following excitation systems: AREP, PMG and SHUNT. The AVR monitors and corrects the alternator output voltage by adjusting the excitation current.
Illustration 1 g03368326
The voltage regulator is located in the terminal box on the generator or in the enclosure for the control panel.
(1) Terminal Box on the Generator
(2) Enclosure for the Control Panel The generator set may include one of the following voltage regulators.SHUNT excitation system
The generator with SHUNT excitation is auto-excited with an R220, R250, or R251 voltage regulator. The regulator monitors the exciter excitation current as a function of the alternator output voltage.AREP excitation system
For both AREP and PMG excitation systems, the AVR is the R438. With AREP excitation, the R438 electronic AVR is powered by two auxiliary windings which are independent of the voltage match circuit.The first winding has a voltage in proportion to that of the generator (characteristic SHUNT), the second has a voltage in proportion to the stator current (compound characteristic: Booster effect).The power supply voltage is rectified and filtered before being used by the AVR monitoring transistor. This principle ensures that regulation is not affected by distortions generated by the load.R250 Adjustments
Table 1
R250 and Regulator
Voltage regulation 0.5%
Voltage detection range 85 to 139 V (50/60 Hz)
Rapid response time for a transient voltage variation amplitude of 20% 500 ms
Voltage setting "P1"
Stability setting "P2"
8 Amp Fuse for protection of the power