GASKET-WATER REGULATOR 4W0549 - 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.
Illustration 1 g00959580
The voltage regulator is located in the electrical box that is mounted on top of the generator. Remove bolts (1) and cover (2) in order to access the voltage regulator.The voltage regulator is powered by two auxiliary windings. These windings are independent from the circuit for detection of voltage. The first winding is Labeled as "X1" and "X2". This winding has a voltage that is proportional with the output voltage of the generator. The second winding is Labeled as "Z1" and "Z2". This winding has a voltage that is proportional to the current of the stator. The voltage from the power supply is rectified and filtered before being used by the regulator monitoring transistor. This principle ensures that regulation is not affected by interference that is generated by the load. These voltage regulators may have an optional remote potentiometer for voltage adjustment. This potentiometer is 450 ohms 0.5 W minimum. The adjustment range is 5%. The voltage range is limited by the internal potentiometer "P2". Remove "ST4" in order to connect the potentiometer. A 1000 ohm potentiometer can also be used to extend the adjustment range.R438 Adjustments
Table 1
R438 Regulator    
Maximum current for short circuit     3 x In for 10 seconds    
Standard power supply     Two auxiliary windings    
Supply for shunt     max 48 VAC at 50/60 Hz    
Rated overload current     8 amperes for 10 seconds    
Electronic protection for overload and short circuit opening on voltage sensing     Excitation ceiling current for 10 seconds and