Anyone converted a Powertech generator to 120 volt?

belfert · October 01, 2008, 07:09:30 AM

Anyone had good luck converting a Powertech generator from 240 volt to 120 volt? I have an Ultimate Series 8 KW generator if that matters.

Ever since doing the conversion to 120 volt I keep blowing one of the breakers on the generator. I have added a jumper between the two breakers as required. Powertech recommended still using the two legs and running them to the transfer switch as before. When one leg is loaded over 35 amps the breaker on the generator blows.

I'm tempted to just go back to 240 volt, but that isn't good for the generator head. Powertech has no answers except that the breaker could be weak.

gumpy · October 01, 2008, 07:19:58 AM

Quote from: belfert on October 01, 2008, 07:09:30 AM
Anyone had good luck converting a Powertech generator from 240 volt to 120 volt? I have an Ultimate Series 8 KW generator if that matters.

Ever since doing the conversion to 120 volt I keep blowing one of the breakers on the generator. I have added a jumper between the two breakers as required. Powertech recommended still using the two legs and running them to the transfer switch as before. When one leg is loaded over 35 amps the breaker on the generator blows.

I'm tempted to just go back to 240 volt, but that isn't good for the generator head. Powertech has no answers except that the breaker could be weak.

Ummm, I think that's what it's supposed to do! Don't you have 2 legs of 120v coming out through a double pole 35 amp breaker now (35 on each leg, as you stated in your previous thread).

8000 watts /120 volts = 66.6 amps. 66.6 amps / 2 legs = 33.3 amps per leg.

If you load up a single leg to 35 amps, you're overloading it. The breaker is doing what it's supposed to do. The operator isn't.

craig

Busted Knuckle · October 01, 2008, 07:23:11 AM

Try replacing the breaker! After all you just said what I was already thinking! If it's the same breaker every time, then it sounds logical to me that it could be bad or weak! FWIW!

BK

belfert · October 01, 2008, 07:30:15 AM

Quote
Ummm, I think that's what it's supposed to do! Don't you have 2 legs of 120v coming out through a double pole 35 amp breaker now (35 on each leg, as you stated in your previous thread).

There are two seperate single pole 35 amp breakers on the generator. One of the steps in converting to 120 volt is to add a jumper wire between the two breakers. According to Powertech that jumper should allow me to use the full 66 amps on one leg.

Busted Knuckle · October 01, 2008, 07:41:13 AM

Brian, I ain't no electrician or even electrically smart. But neither wuz Forrest... Forrest Gump! So I may be wrong but I don't think it works quite like that! I'd say you still need to try and pull off both breakers instead of one! But what do I know?

BK

boogiethecat · October 01, 2008, 08:31:39 AM

From reading your post, I'm thinking that instead of jumpering the two breakers, you need to hook the two circuits together and find yourself a single 65 amp breaker to use.

While hooking two breakers in parallel to get a single circuit with twice the current rating is theoretically possible, and in some situations might work, there are a lot of reasons that it might not work also. To work properly the breakers would have to be electrically identical and the current thru them be absolutely balanced, which is possible to do but truthfully not very practical for a bus.

Most generators I've seen that have two 35 amp circuits wired for 120 mean that you have two individual 120v 35 amp circuits, NOT a single 65 amp circuit. If a jumper were to be used, the jumper is probably supposed to be hooked up PRIOR to the breakers (if at all) and then I'm guessing that's what powertech means when they have you hook the both together- it's probably not supposed to create a 65 amp circuit, and what you're seeing is totally normal. IF they are telling you that you CAN create a 65 amp circuit with those two breakers, I would not hesitate to have a lengthy arguement with one of their engineers, because that's basically not a sound presumption, and it's not necessarily a safe one either.

So bottom line, try jumping the thing and get yourself a 65 or 70 amp breaker, and you'll probably be fine...

belfert · October 01, 2008, 12:29:09 PM

I wanted to see if anyone had actually done this change on a Powertech generator themselves before diving into making changes.

It certainly makes more sense to use a 65 amp breaker, but why would Powertech insist two 35 amp breakers with a jumper would work? I was skeptical, but I did what they said. I am going to see how easy or hard it would be to switch to a single 65 amp breaker. I will still have a double pole 50 amp breaker in the main panel that could limit amperage, but not as much as a 35 amp breaker.

Len Silva · October 01, 2008, 01:19:18 PM

Just to be sure, you did put the jumper on the output side of the breakers, right?

belfert · October 01, 2008, 01:31:04 PM

Quote from: Len Silva on October 01, 2008, 01:19:18 PM
Just to be sure, you did put the jumper on the output side of the breakers, right?

Not really sure. My electrician buddy did the conversion per the diagrams in the owner's manual. Powertech claimed that the jumper could be on either side of the breakers which I am skeptical about.

rdbishop · October 01, 2008, 02:06:18 PM

Brian,

I have a kabota 9 kw and did what your wanting to do. It alows me to use 50 amps on one side of the panel and 15 on the other or whatever combination of ampsa per leg to add up to 65total amps. seems like I had to change some wires around inside the head and then ran a #6 to the transfer switch and looped the wire at the 50 amp contactor. If no one else chimes in I'll open it up and get a good look at it for you.

Richard

belfert · October 01, 2008, 02:13:37 PM

Quote from: rdbishop on October 01, 2008, 02:06:18 PM
Brian,

I have a kabota 9 kw and did what your wanting to do. It alows me to use 50 amps on one side of the panel and 15 on the other or whatever combination of ampsa per leg to add up to 65total amps. seems like I had to change some wires around inside the head and then ran a #6 to the transfer switch and looped the wire at the 50 amp contactor. If no one else chimes in I'll open it up and get a good look at it for you.

I got the generator head itself changed to 120 volt and the power regulator changed to 120 volt just fine.

The issue is there are two single 35 amp circuit breakers each outputting 120 volt seperately. Powertech said to put a jumper across the breakers so one leg can pull more than 35 amps. It doesn't work and the breaker seems to trip once I get above 35 amps.

niles500 · October 01, 2008, 02:20:38 PM

Excuse me for being silly - but I got to ask the obvious - How do you run 66 amps through a 35 amp breaker? Really I am serious -

Len Silva · October 01, 2008, 02:36:50 PM

Quote from: niles500 on October 01, 2008, 02:20:38 PM
Excuse me for being silly - but I got to ask the obvious - How do you run 66 amps through a 35 amp breaker? Really I am serious -

It's supposed to be two breakers in parallel. Doesn't sound like the best way to do it but it should work.

Jerry Liebler · October 01, 2008, 02:43:23 PM

Belfert,
It sounds like you have the jumper on the generator side of the breakers, which is incorrect. The jumper needs to be on the load or output side of the breakers.
Regards
Jerry 4107 1120

rdbishop · October 01, 2008, 02:58:43 PM

OK Brian, I went an looked. I have two bars at the head. one side is the white wire, and the other bar has the black & red wires hooked together that feeds to the breakers seperately. the wires go from the breakers to the transfer as you would run 220v. The breakers are run in parallel and the only jumpper is at the head. I hope this makes sense. That is how the gen people told me to hook it up at the time. It's been working great for about 9 years.

Richard