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Western Electric 120kw


I have a large diesel gen/set. It's gray and on a very solid trailer. My guess is ex-Navy. The diesel runs like a watch but the gen won't gen. Any ideas, ops manuals available, service persons?

Western Electric set#82114 ks 15622 list 1

G.E 340771 type AT1 frame 954 ?y 230v 3ph

Hercules DFXH 5.75 X 6.00 C377 938

Any ideas are welcome, thanx Bob


Jim Rankin

First inspect the windings and brushes and sliprings or exciter rotor and field if it's a brushless set. Look for burned coils, broken wires, stuck brushes etc. You should be able to lift the brushes and ohm through the fields for continuity and check them for grounds to the frame or shaft. Diodes on the armature of a brushless generator are a common problem. If this all checks out, then the most common problem is loss of the residual magnetic field that is required to excite it. A generator with no/weak residual will show no or very low AC output voltage. If you measure AC voltages on the output with a meter, you should see balanced voltages on the phases even if only a few 10's of volts. The only exception to this would be a delta connected 120/240 3 phase stator. That will show one line-neutral voltage that's 1.73 times the other two lines.

Depending on the configuration, you should be able to flash either the main alternator field through the sliprings/brush leads if it has them, of if it's brushless, flash the exciter field. You need to match Positive and negative so the exciter/regulator doesn't buck the restored field.

The field can be flashed with the engine stopped or with it running. Safer with it stopped! Flashing is usually done using a small battery or using the starting battery through a light bulb or resister to limit current through the field. If it is running and makes voltage when you supply the field with DC, then it may build up to full voltage (quickly disconnect the flashing leads if output voltage begins rising). If voltage builds up, but falls back off immmediately when the flashing connection is broken, there's some problem with the exciter/regulator system, but the main alternator is probably good.

Be careful! It's supposed to make enough voltage to hurt/kill you if it works properly, so don't take for granted it isn't working and touch terminals etc that may have high voltages on them.


Thank you for the exellent instructions. I'll be back at our mine in Baker Ore. to do the tests next week or two. It's a nice set that has enjoyed good maintenance unlike some other military surplus you see. I hope this brings the 'old brute' to life again.