Low Output from Generator


Old 06-15-16, 08:36 AM
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Join Date: Aug 2010
Location: USA
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Low Output from Generator

I have a genset that was installed in my home before I moved in. Unfortunately, ALL of the genset information is completely unreadable. But, as I understand it, my generator is a 25-28hp Lombardini Diesel water cooled motor. I have zero information on the genset attached to it, but it runs at 3600 rpm and is hooked up to a GE Zenith Controls automatic transfer switch with a 50A breaker. It probably will handle more, but they put a 50A on it to be safe. It runs all three freezers/fridges and all the lights in a portion of my home as well as the water wells. I have the transfer switch information if needed....so...the problem:

I fired it up yesterday, and the automatic transfer switch would not recognize that emergency power was available. There are two red lights that come on when the generator normally runs. In the past, when this happened, the issue was the capacitors in the genset. Those were replaced wtih two 25uF capacitors and it was working fine until yesterday.

I tested the capacitors, and they both check out OK on my Klein Voltmeter. The voltage output from the generator when it is running is at 21 volts or so on each leg. That is why my ATS is not seeing it.

I had this same problem a while back when they replaced my capacitors. But this time, the capacitors seem to check out OK. What else can cause this?
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Old 06-15-16, 09:44 AM
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Depending on the generators construction it might need "flashing". Many generators rely on residual magnetism when off to be enough to generate enough current to power the electro magnets inside the generator. Sometimes if they sit too long the residual magnetism can be lost. So, even though the motor is running and the generator is turning there is not enough magnetism to generate electricity. Search the web for "flashing a generator" and you'll see instructions and determine if that would be appropriate to try on yours.
Old 06-15-16, 10:09 AM
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Join Date: Aug 2010
Location: USA
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Cool . Ill check that out. And this is appropriate for a 25kw whole house generator?

Also, is there any reason a 'weak' car battery (one used to start the generator) would cause this issue?

Ill have to use a receptacle somewhere close by. I was wondering if it was a voltage regulator, but I have no clue where that would be, because I see nothing like that in the end where the 8ga wires are connected.
Old 06-16-16, 04:22 AM
Join Date: May 2006
Location: upstate New York
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In the future, to prevent loss of residual magnetism, it;s recommended to run the generator, with a good load on it, for a few minutes every month or so.
Old 06-16-16, 05:27 AM
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The easiest method I have found uses an electric drill. Start the generator, plug the drill motor into an outlet on the generator. Pull the trigger on the drill motor and spin the chuck in reverse...it should take off on its own and the generator is now genning.
Old 06-16-16, 08:52 AM
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Join Date: Aug 2010
Location: USA
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My auto transfer switch won't kick over, so I don't know that I have an elecrtical connection to the generator through an outlet. Ill check. Ive just never heard of this happening and the generator does get tested once every few months. Just wierd, but im going to give it a go if I can get access to a plug.

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