OPERATOR AR 4885090 - Caterpillar

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.
Make sure the generator engine is stopped.
Make sure all batteries are disconnected.
Make sure all capacitors are discharged.
Table 1
Tools Needed (1)    
Part Number     Part     Quantity    
6V-7070     Digital Multimeter     1    
146-4080     Digital Multimeter     1    
9U7330     Digital Multimeter     1    
( 1 ) Any one of these multimeters may be used.The generator set functional test is a simplified test that can be performed in order to determine if the generator is functional. The generator set functional test should be performed on a generator set that is not under load. The generator set functional test determines if the generator is operating at expected voltage and frequency levels. Perform this test at the regulator and terminal strips. Do not perform this test at the output connections. The generator set functional test consists of the following steps:
Stop the generator. Remove the panels in order to allow access to the regulator and control terminal strips. Determine the part number for the regulator. Record the sensing voltage of the regulator. The sensing voltage is 400 V 3%, or 415 V 3%. If the multimeter has the capability, also record the frequency.
Verify that the generator set is ready to start. Start the generator set and bring the generator set to rated speed. Measure the sensing voltage with the multimeter on terminals 20-22, 22-24, and 20-24. If these voltages match the sensing voltage of the regulator and are nearly equal, then the output of the generator at the bus bar should be the correct value.
If the voltages do not match the sensing voltage of the regulator, see the service manual for the regulator for further troubleshooting instructions.