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Random Voltage (No Common/Neutral reference point)

Posted by prepper2 (My Page) on
Tue, Mar 5, 13 at 17:23

Background: Built a new house in 2011, had a proper sub-panel installed for our "critical" circuits, with a proper double throw disconnect. Sub-panel was designed for a generator. Had a 30 amp. 250 volt plug installed on outside of house, ready to accept a patch cord from my generator.Get big snow, power goes out. Time to fire up the generator. This is a 10Kw, two cyl. Diesel; 1800 Rpm; 41 amp unit of Chinese manufacture that I bought new at a construction company going out of business auction. I had started it up a few times over the last 4 years just to keep it ready but had never put it to use. It has outlet for (2) 120 v and (1) 240 outlet. All three are 3 pronged female plugs with 3 matching male plugs that can be hardwired to feed your load. I made up a 8 gauge cord to mate up to the house and used the 240 male end to plug into the 240 female end.
Problem/Question: I immediately started getting random voltages both high and low, brighter than normal lights, refrig. cycling on and off, dull light on freezer etc. Started taking volt readings at various outlets supplied by the sub-panel. Maybe 49 volts here, maybe 180 there. Crazy readings in the panel. So I quickly disengaged the system but not before high voltage had damaged several devices. Started trouble shooting. Discovered that there is NO NEUTRAL wire on the 3rd prong of the generator plug, there is a space, but no wire feeding it. There is only the two, hot 120 (each) supply. Also discovered there is no ground in the 3rd prong of the 120 volt plugs. One electrician said I have a "floating voltage" generator, designed to supply a straight 240 to construction type machinery that just needs a 240 supply, and that it is/was not designed to feed a house panel with conventional 240 volt supply. He further said that if I could trace the source of the neutral supply, for the 120 outlet, and bring a wire from the source to the 240 outlet, that this would give me a REFERENCE point and the problem would be solved.
A second opinion by another electrician was that providing a neutral would not change anything, that the problem is in the design of the windings or just the way the generator was made to operate.
Can I fix this? Can I bring up a neutral and create a "reference point" or do I give this thing a quick sell and move on?


Follow-Up Postings:

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RE: Random Voltage (No Common/Neutral reference point)

Guess what? The third prong isn't SUPPOSED to be a neutral. It's supposed to be an equipment ground.

What model generator is this? It might well be the case that there is NO center tap 240 that you can turn into two 120V legs. Some of these units make 120V (all on the same leg) and 240V and there's no way to kludge it into a 120/240 service.


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RE: Random Voltage (No Common/Neutral reference point)

I am the student here, so I get to ask the dumb questions. OK so if this is to be an equipment ground, there still is no wire of any kind to the 3rd prong, it is just empty space. So it this a assembly line mistake? What does "kludge" mean?


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RE: Random Voltage (No Common/Neutral reference point)

Had to wait till I got home to get model. This is a Kaiser; the model appears to be: KDE-14-STA. This is a large cabinet style, diesel, two cylinder, large radiator, doors all four sides. I have not been able to locate an importer or any kind of manual. Any ideas would be appreciated.


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RE: Random Voltage (No Common/Neutral reference point)

The link has a little information. Limited Google search turns up very little actual help. I doubt that the generator can be reconfigured internally for 120/240. A transformer between the generator and your panel could provide the 120/240. As far as I know, a suitable autotransformer with center tap would do the job-- but I have not tried that.

Here is a link that might be useful: Link


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RE: Random Voltage (No Common/Neutral reference point)

It's actually a three cylinder. I found the manual for the KDE-12-STA. It seems to be strictly a non-centertapped single phase. Manufacturor is KIPOR.


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RE: Random Voltage (No Common/Neutral reference point)

I believe that the autotransformer would work. Did not find one of your KVA, but three of these 4KVA in parallel would work. Would need ventilated enclosure with fan cooling preferred.
Not low total cost.
http://electricalnotes.wordpress.com/2012/07/17/parallel-operation-of-transformers/

I do not jerry rig-- I fashion solutions from alternative materials.

Here is a link that might be useful: 4KW


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