Standby Generator Only Outputting 24V

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Old 07-08-16, 08:16 AM
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Standby Generator Only Outputting 24V

I have an older Lombardini Diesel motor with a Getech generator on it. It is a self regulating capacitor set. I do not know much more than that and Im not sure what size it is. The label is worn off, but it is assumed to be at least 18kw, with the potential to be up to 25kw. At any rate, it has recently stopped outputting power. A while back, it stopped working and the generator repair tech put on two new 25uF capacitors and its been working fine. However, the other day, the transfer switch would not kick over and it does not indicate that backup power is available. I measured both legs directly on the genset and I get 24V. I also took off the capacitors and tested those and they check OK. The repair tech came out and stared at it for an hour, called his boss and sent pictures and then called me and told me he was instructed to stop working on it because its too old and they can't get parts and its dangerous or some BS. Don't know about that, nor do I care. I pretty much think he didnt want to mess with it, and thats fine, but im stuck without a functional unit and very few people in my area know anything about generators unless its a Generac that they sold. So....I need some assistance.

Is there anything I can DO to get this thing running? I am comfortable around electricity but aside from capacitors, have no idea how this one works or what causes low output on something with so few components.
 
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Old 07-08-16, 05:23 PM
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I assume that the diesel motor works fine it just does not output any voltage at the genset? Have your tried putting a load directly off the generator bypassing the transfer switch?

Looking online it appears that Gentech are most hydraulically driven generators, so perhaps this has been cobbled together?

I am a little confused about what the capacitors are doing there, power factor correction?
 
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Old 07-12-16, 06:12 AM
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No idea what capacitors are for. Apparently no one around my house knows how generators work unless they are specifically made by Generac, either. LOL. They must me magic. All I know is that when the capacitors were KNOWN to be bad the last time, no power was output at all. They are crucial to the supply of power somehow.
 
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Old 07-12-16, 07:19 AM
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If the capacitors and everything else checks out OK the only other thing that I can think of might be that it needs "flashing".
 
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Old 07-12-16, 07:28 AM
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Yes, but I dont know how to do that with a drill considering all of the outlets are not connected because the auto transfer switch will not kick over to emergency power.
 
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Old 07-12-16, 12:12 PM
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You've got to get creative and bypass the transfer switch. And, using a drill is not the only method.
 
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Old 07-13-16, 07:34 AM
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You are making power so you don't need to flash the generator.

Replace the caps. You are describing a common failure. Yes they can still test well but not work in your application.

The caps help regulate the voltage.
 
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Old 07-13-16, 05:20 PM
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Are there any model/serial number you can find?
Any circuit diagram inside?

Finding a circuit diagram for your generator will really be helpful in trouble shooting.
 
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Old 07-14-16, 03:18 PM
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Can I use one of those 'universal capacitors' for this application? Its one that was used for an AC system. I have a good one laying around. I could swap each of the 'bad' ones out with the universal one to test. I doubt BOTH capacitors are bad since they were both installed as new a couple of years ago.

The unit, as far as I can guess is a GeTech GS140 unit. It runs at 3600RPM. Thats all I know.
 
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Old 07-14-16, 03:21 PM
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If one of the combinations match the necessary MFD, yes.
 
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Old 07-15-16, 07:35 AM
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How can a 2 year old capacitor test OK but not be OK? Its a 25uF and 440VAC. Its a sturdy one.
 
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Old 07-15-16, 08:24 AM
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Testing is almost always not a duplicate of actual conditions under load. Voltage for instance and actual loading are probably less.
 
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Old 07-15-16, 06:23 PM
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I bought ONE capacitor, because I dont think its that. At any rate, I replaced both capacitors one at a time, and the unit is still not working. Its now putting out 11V on each leg. I was told that there are only two things that control voltage on it if its running at 3600RPM - the capacitors and the diode. Im skeptical. That is from the guy that owns the company that makes them.
 
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Old 07-15-16, 06:52 PM
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Replacing both capacitors at the same time is the only way to be sure.
 
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Old 07-16-16, 07:21 PM
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I dont think that's the problem, but I may buy another one. Now, lets go ahead and say that it doesnt fix the issue. Then what? What's the next step? Im pretty much depending on this site because I have had a couple of generator people out and they don't know what to do. For me, its not working now, so why the hell not go ahead and try to fix it. LOL.
 
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Old 08-20-16, 04:12 PM
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Alright, with a bunch of communication with the manufacturer (there are no distributors), I was able to speak to the designer/engineer about it. There are only two things that control the voltage output...the capacitors and a diode on the armature.

The diode on the armature failed. I was sent a new diode and a varistor to go across it. It is installed, hopefully my soldering holds. So far, she is outputting 115v/114v on each leg.

Cross your fingers she stays running. I changed the coolant and oil in the motort too.
 
 

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