Run 240 v well pump from 120 v genset w/transformer?

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Old 03-06-13, 08:36 AM
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Run 240 v well pump from 120 v genset w/transformer?

I need to be able to run my 1/2 hp 240 volt submersible pump from my generator, which unfortunately only puts out a 120 volt supply. I have a heavy step-up 120-to-240 transformer. Can I use that to juice it up to 240 volts and run the pump? Or will there be problems with phasing or other things I don't understand too well ?
 
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Old 03-06-13, 09:35 AM
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Welcome to the forums! Before getting into possibilities, is this going to be a permanent connection, or only in an emergency? If the latter, how much trouble are you going to go through to revert it back to 240 volt house current once the emergency is over? Seems like a lot of work. I'd get a larger generator with dual voltage outputs.

A 1/2 hp motor will really tax the generator. What is the wattage output on the genny?
 
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Old 03-06-13, 09:44 AM
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120 v genset for 240 v pump

Thanks for replying.
Yes, it would be only for emergencies, not permanent. I realize I would have to do some adaptor-rigging, etc. in order to get it hooked up. The genset seems adequate, though: 2,000 watt inverter-type, very quiet and economical to run. I also have a big diesel genset (12kw). But it is very noisy, and loves its diesel. I was uncertain, though, about whether or not it could be done at all. I asked one electrician about it, and he didn't think it would run the pump- because only one phase line rather than two were being used, if I understood him properly.
 
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Old 03-06-13, 05:51 PM
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If you have the proper transformer, I believe it could be done, but I have doubts about your little generator being able to start the pump motor.
 
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Old 03-06-13, 08:44 PM
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I have doubts about your little generator being able to start the pump motor.
Maybe I'm missing something obvious here, but it seems to me that if a full horsepower is a little less than 750 watts then a 2 kW generator ought to be able to handle a 1/2 HP load, even if the startup draw is double the run load.
 
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Old 03-06-13, 09:36 PM
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If this is a deep well (submersible) pump the starting draw could be six times the running current. Even though, the little inverter gennie might work as they seem to have quite a bit of overload capacity for a second or two. Since you already have the transformer (at least two kVa in size, I hope) I'd say give it a try.
 
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Old 03-07-13, 04:51 AM
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Thanks for you members' comments, they are helpful. Other than gross capacity issues, I couldn't see why it wouldn't work either. The pump isn't working against much of a head: probably about 40 feet, so I'll give it a try and update this thread when I see what happens.
 
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Old 03-07-13, 04:31 PM
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I'll give it a try and update this thread when I see what happens.
By all means, yes, let us know. I'd like to also know if an inverter generator of that size would start and run a 1/3 HP furnace blower, but without the transformer loss. By the way, what generator do you have? There are several inverter models that are pretty attractive and real fuel sippers.
 
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Old 03-07-13, 06:15 PM
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Mine is a Yamaha, 2 KW. About 5 years old now. I love it. Reliable, starts on the 3rd pull everytime, very quiet. Seems to be easy on gas.
 
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