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Monday, October 26, 2009

Watch Your Speed!

My Emerald (6500-watts) generator has 1220 hours on it and is putting out 160-volts. It has never been decarboned but has had several doses of Onan 4-C. It seems to run okay other than the over-voltage. It ran sporadically at 120-volts but was able to run two air conditioners but now, every time, it ramps up the output to over 160-volts. Any advice will be appreciated.
David, (Livingston, TX)

David, do not allow the generator to power any device in the RV while it is putting out 160-volts AC! It will most assuredly damage the roof air conditioner and all other devices designed for 120-volt AC output at 60-Hertz. 160 is just way too high!

Obviously, the governor, which controls the speed on the generator, is out of adjustment. The generator speed affects the frequency (Hertz) and coupled with the carburetor, affects the output voltage as well. Generator carburetors and governors require a certain amount of expertise to get into synch. It’s vital to understand that RV generators cannot be tuned by ear.

It takes a special piece of equipment called a load bank to correctly tune and set-up an RV generator. Keep in mind that the carburetor adjustments and the governor adjustments, though mechanical in nature, will always have an electrical result or consequence. The load bank must be attached to the output of the generator to safely and correctly monitor the voltage, load and frequency while making any adjustment. Full service RV repair facilities will have a load bank on hand for such service. Do not attempt to do this without one (it appears someone already has). I wish I had better news for you, but I think this one should be left to the pros.


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