HEAD 5597589 - Caterpillar

Procedure A - Check Engine RPM
* If governor operation is unstable: a. Correct engine problem. Reference engine service manual.b. Go to Procedure B.Procedure B - Check for loose connections
* If connections are good: Go to Procedure C.Procedure C - Isolate Regulator
Disconnect leads F1 and F2 from their respective terminals on the regulator. Connect a 12 volt automotive type battery across exciter leads F1 and F2. Operate at half of rated speed and then slowly increase rpm.* If voltage at regulator terminals 20-22 is unstable, shutdown the generator and: a. Check connections to rotating rectifiers CR1-6 (rotating rectifier block), main field poles and other connections on the rotating (revolving) field.b. Check connections to excitor stator L1.c. Check permanent magnet (PM) exciter voltage. Disconnect wires 12 and 13 that go to the PM exciter. Check the PM exciter between wires 11-12-13 for a balanced voltage that increases with speed and is greater than 50VAC at rated speed.* If stable balanced AC voltage between regulator terminals 20-22-24 that increases with rpm: Go to Procedure D.Procedure D - Isolate Attachments
Reconnect leads to regulator terminals F1 and F2. Disconnect all attachments such as manual voltage control, remote voltage control, droop transformer, etc. If remote mounted voltage adjustment is disconnected, connect jumper across terminals 4 and 7.Check all connections to the regulator and regulator fuses.* If generator output voltage is normal: Check attachments.* If voltage at regulator terminals 20-22 is unstable at rated frequency with no load: a. Replace regulator.b. Bench test the regulator; see Bench Test.