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Old 01-28-2013, 08:22 PM   #1
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Generator output

I'm confused. This is a plate from my Phasor generator. It is a 6.5KW powered by a Kuboto diesel. My confusion is in the base AMPs. I was under the impression that with a 6.5kw generator there would be 54 amps available. Is that not correct? Having a hard time wrapping my head around this and would appreciate any help. Thanks
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Old 01-28-2013, 08:25 PM   #2
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Ohm's law. The plate says 240volts. 54 amps would be if it were 120v.
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Old 01-28-2013, 09:17 PM   #3
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Watts = volts * amps. As the previous poster noted, your generator can prduce 6.5 KW, either 240 V at 27 amps or 120 V at 54 amps. It can be wired internally to produce either.

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Old 01-29-2013, 06:04 AM   #4
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Quote:
Originally Posted by swampu View Post
Ohm's law. The plate says 240volts. 54 amps would be if it were 120v.
Yes I understand that I forgot to mention that it is producing 120volts the way it is connected.
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Old 01-29-2013, 06:26 AM   #5
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Originally Posted by djmarchand View Post
Watts = volts * amps. As the previous poster noted, your generator can prduce 6.5 KW, either 240 V at 27 amps or 120 V at 54 amps. It can be wired internally to produce either.

David
That was my understanding. The unit is producing 120volts but I think Im only getting 27amps. The problem is I cant run my AC off the generator. Specifications on the AC unit state 27amps is needed for compressor start up. It tries but just cant quite do it.
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Old 01-29-2013, 07:31 AM   #6
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That was my understanding. The unit is producing 120volts but I think Im only getting 27amps. The problem is I cant run my AC off the generator. Specifications on the AC unit state 27amps is needed for compressor start up. It tries but just cant quite do it.
Is your AC 120v ?

Anyway, you only have a max of 27 amps available, 27 at 240 or two 120 legs at 27 each. The 24 volts is what the generator consider full constant load capacity. You could look at getting a "soft start" circuit for your AC, but you are still pushing the capacity of your genset with all those amps on one leg (if indeed 120v). you could also see about having your AC rebuilt to run on 240, then you would be well within the genset's capacity. (going to 240 cutting the amps needed in half)
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Old 01-29-2013, 07:40 AM   #7
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It is possible that your generator is wired to produce 240 V but you are using one leg of 120 V for the generator. The generator has two coils. If they are wired in parallel you get 120V at 54 amps. If they are wired in series with a center tap neutral you get 240 V at 27 amps across both coils and 120V across one coil and the center tap but at only 27 amps. That may be your problem.

Get an electrician to look at your generator. You might have to rewire it to produce 120V at 54 amps to feed the A/C.

Having said all of that I am surprised that even wired with one coil producing 27 amps you can't start an A/C. Have an electrician investigate that problem first.

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Old 01-29-2013, 07:53 AM   #8
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When you say the generator can be wired fro 240V or 120V, that can mean two different things, and I think the difference is the source of your problem.

A typical 240V power source (like a generator) set up for North America is wired in what's know as a split phase 120V/240V configuration. It is two 120V circuits stacked together to make 240V. It's actually a 240V center tapped winding or transformer if you want to be specific. This is most likely how your generator is set up. In this case, you can pull 240V @27A. Or you can pull a total of 120V @54A, but (and it's an important but), you needs to be equally balanced across the two 120V circuits, i.e. neither can exceed 27A. If this is confusing you, that's because it is indeed confusing until you understand it, and most people don't completely understand it. After all, why should they? If you want to know more, google about AC power systems, and in particular north american power systems. This arrangement is unique to NA and the areas that have copied us.

The other way the generator might be wired up, but it would be unusual, is for the two 120V circuits to be wired in parallel rather than stacked in series. Many generators can be wired up this way, but typically are not, and you need to really know what you are doing to make the change, if it's even possible. In such a configuration, instead of having two 120V, 27A circuits, it has one 120V, 54A circuit and no 240V capability. The sad thing is that for smaller generators like yours, and assuming you have no need for 240V service, having a single 120V circuit is much preferable because you can run these higher loads. But almost nobody sets them up that way. I have an old 4KW Onan RV generator that is set up this way and will produce 33A at 120V. I also rewired a 5KW portable cheapie generator like this a long time ago so it could more easily run larger power tools.
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Old 01-29-2013, 07:54 AM   #9
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One possible clue would be to understand how many electrical panels you have. Do you have two, each with a volt and amp meter? I'd agree, if you are having to ask all this here, get a qualified marine electrician to look at your exact set up. messing with this uneducated can kill you or burn down your boat or both.
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Old 01-29-2013, 10:14 AM   #10
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Thank you everyone for your input. I am not nor do I intend to do any work myself, I simply am trying to gain of basic understanding of what this unit is capable of. My panel has 2 sides. 2 30amp breakers for shore power and 2 50amp breakers for the generator. There is 70amp breaker at the generator with a single leg that feeds the left side breaker on the panel. there is a jumper between the 2 50amp breakers. I guess what I am really after is can I get 54amps to the panel with the equipment I have? If so how much work would it be for an electrician? Just trying to be a more educated consumer.

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Old 01-29-2013, 11:31 AM   #11
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The best way to accomplish your goal is to contact Stamford Newage directly with the dataplate information. They will be able to tell you exactly what you have and what kind of perfomance to expect.
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Old 01-29-2013, 11:54 AM   #12
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Phasor is over in Pompano, maybe they know who installed it or other details. In looking at their site, their current 6.5kw is shown as 120 only. Your description sounds like something is wired wrong at the generator, as the circuits as you describe them indeed are those of a 50 amp 120 system. But I don't know what exactly is going on, not being there to see for myself. You have enough to describe to the manufacturers and an electrician to shorten the diagnoses time required on their part.
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Old 01-29-2013, 06:46 PM   #13
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It is possible that your generator is wired to produce 240 V but you are using one leg of 120 V for the generator. The generator has two coils. If they are wired in parallel you get 120V at 54 amps. If they are wired in series with a center tap neutral you get 240 V at 27 amps across both coils and 120V across one coil and the center tap but at only 27 amps. That may be your problem.

Get an electrician to look at your generator. You might have to rewire it to produce 120V at 54 amps to feed the A/C.

Having said all of that I am surprised that even wired with one coil producing 27 amps you can't start an A/C. Have an electrician investigate that problem first.

David
David's correct. I think the stopper here is the starting current for the ac which may be two or three times the running current of the compressor. The ac can likely be wired for 240. In any case you should get an electrician to rewire your generator if that's what you wish to do because if you do it yourself and hook it up wrong it could smoke.
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Old 01-30-2013, 07:11 AM   #14
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On many boats , in order to operate from ONE 30A shore cable , everything will be on one leg of the power supply.

A 50A 240 cable is much preferred, but is heavy , and not at all marinas.

In your case the air cond needs to be on one leg of the noisemaker and the rest of the house loads on the other.

This is simply a wiring setup.
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Old 01-31-2013, 01:18 PM   #15
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I would not be too concerned about the brand name of the total gen set but the name of the engine which is what really matters. Most boats only need 50 amps or 7 KW. When our Kohler, Perkins engine dies, I will be looking for the gen set with the larger engine HP that will fit the space which drives the hydraulic get home and bow thruster. The Eagle is wired for 75 amps but I installed as 50 amp breaker.
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