MOTOR GP-PISTON 5289301 - Caterpillar

Step 1. CHECK THE DROOP CIRCUIT
Turn off the genset.
Connect the droop circuit to the voltage regulator. Verify that connections are correct. Refer to the Testing and Adjusting, "Wiring Diagrams".
Start the genset.
Add a reactive load to the genset.Expected Result:The voltage is within the specified or excepted range.Results:
NO - The voltage is outside of the specified or excepted range. That is, the voltage increases rapidly to a high value then goes to a low value. The rapid change also happens in the case of an over excitation shutdown.Repair: Stop the genset. Switch wires to terminals 5 and 6 for a one A current transformer (CT). Switch wires to terminals 5A and 6 for a five A CT. Start the genset and run the genset at no load.STOP
YES - The voltage is within specified range. Proceed to test step 2.Test Step 2. CHECK THE CURRENT TRANSFORMER (CT)
Check the voltage between terminals 5 and 6 for a 1 A CT. Check the voltage between terminals 5A and 6 for a 5 A CT.Expected Result:There is no voltage between specified terminals.Results:
YES - The voltage between terminals 5 and 6 is less than 100 V for a 1 A CT. The voltage between terminals 5A and 6 is less than 100 V for a 5 A CT.Repair: Replace the CT. Refer to the Testing and Adjusting, "Wiring Diagrams".STOP
NO - The voltage is present. The problem has been eliminated.STOP