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Posted By: Frank Cinker Kohler Generator 120V, 7.5KW - 11/29/07 09:42 PM
We have a 40 year old, 120 volt, 7.5 KW, (62.5A) Kohler transfer switch at one of our facilites. The generator operates fine but the automatic transfer switch needs replaced. Are 7.5 KW (62.5A) 120 volt transfer switches manufactured now days?

Frank
Posted By: HotLine1 Re: Kohler Generator 120V, 7.5KW - 11/30/07 12:51 AM
Frank:
Did you try Kohler.com, or look for a local Kohler Gen dealer/service shop & inquire.

Posted By: sparkyinak Re: Kohler Generator 120V, 7.5KW - 11/30/07 12:51 AM
there are several models

http://www.kohlerpower.com/industri...1&filter_1=Standard&viewAll=true
Posted By: Frank Cinker Kohler Generator 120V, 7.5KW - 11/30/07 11:20 AM
Thank you for the link,however I couldn't find any 120V rated automatic transfer switches listed. Could I use a 120/240V rated switch for my 120V application?
Posted By: JValdes Re: Kohler Generator 120V, 7.5KW - 11/30/07 05:04 PM
If you cannot find one, build one. Do you have someone in your company that can do this? It's a simple project.
Posted By: gfretwell Re: Kohler Generator 120V, 7.5KW - 11/30/07 06:17 PM
JV
Wouldn't the lack of a U/L evaluation (or other NRTL) be a problem?

It might be cheaper/easier to fix the one he has. What's wrong with it? Are the parts available?
It is possible a "120v" version is just a 240 with some contacts removed. For that matter I am not really sure why you couldn't just use the 240v version and not hook up one phase. The function is the same.
Posted By: Frank Cinker Re: Kohler Generator 120V, 7.5KW - 11/30/07 09:23 PM
Greg,

Considering it is 40 years old, our plan is to replace it. My initial thought was, why wouldn't a 120/240V switch work. But just to be sure I called the Kohler generater local distributer in my region. I expect a return call when I get to my office on Monday.

Frank
Posted By: JValdes Re: Kohler Generator 120V, 7.5KW - 12/01/07 06:38 PM
gfretwell,
I guess I am just so used to building my own stuff. Working primarily in industry for the last 18 years, I just always built my own control panels and rewired many machines. Once I learned to draw my own schematics and implementing them, I just never purchased factory built equipment in most cases. And when your company knows you can do it, you are doing it.
You are right about the 240 volt, same thing. I also, wonder what is wrong with the old one. Maybe the 40 year old enclosure is the issue. Who knows.
As far as UL approved I am not sure how that plays out in a plant. We kinda always figured if it was on our side, we could do pretty much anything we wanted. Of course we always put safety first. Mechanical, electrical interlocks, Emergency controls etc....
Posted By: gfretwell Re: Kohler Generator 120V, 7.5KW - 12/01/07 07:52 PM
I am not a code cop, I just play one on the internet wink

To be honest, I have built a lot of stuff around my house too but I do try to make it as code compliant as possible, just to make it easy when I am gone.
I was just trying not to say he would be "fine" cobbling something up in the shop.
I agree if you used listed components within their parameters it should be safe.
Posted By: gfretwell Re: Kohler Generator 120V, 7.5KW - 12/01/07 08:03 PM
Frank, if they faxed you a page of "instructions" on company stationary saying you could hook up one phase (120v) to the switch you should be OK, no matter how pedantic an inspector was.
Posted By: JoeTestingEngr Re: Kohler Generator 120V, 7.5KW - 12/02/07 12:22 AM
Just about any ATS should have NCHO generator start contacts. Whether or not you can use a higher voltage or multiple pole unit depends on being able to set the normal and emergency voltage sensing for 120 single phase. The emergency side sensing should also check that the frequency is within acceptable limits before switching. I almost forgot to mention that the coil that is pulsed to actually perform the transfer would probably need to be changed. It is extremely easy to smoke the coil with its low duty cycle. If it doesn't fire across and open the contact on the other side, that coil won't get a second chance.
Joe
Posted By: Frank Cinker Re: Kohler Generator 120V, 7.5KW - 12/02/07 11:34 AM
I guess it's not as easy as using any 120/240V ATS to replace an existing 120V automatic transfer switch. It will be interesting to see what the people at Kohler Generator will recommend as a replacement.
Posted By: Frank Cinker Re: Kohler Generator 120V, 7.5KW - 12/02/07 11:59 AM
I don't think there are many 120V only transfer switches available. I certainly can't locate any online. It will be interesting to find out what the people from Kohler Generator recommend. For future jobs, I'd really like to find out if a 120/240 switch could be use for a 120 volt only generator.
Posted By: JoeTestingEngr Re: Kohler Generator 120V, 7.5KW - 12/02/07 03:45 PM
I wish I could help you there Frank but I never ordered an ATS. I've diagnosed and helped repair quite a few over 14 years, but we never needed to change the input voltages. I would imagine that the folks at ASCo or Zenith would be able to provide one.
Joe
Posted By: SteveFehr Re: Kohler Generator 120V, 7.5KW - 12/03/07 12:50 PM
A stock 240V ATS wired up for 120V would likely detect incoming power as either a failed phase or improper voltage (depending on how you wired it) and fail to operate properly. Would be a trivial thing for the manufacturer to correct with software- and who knows, maybe they did? It might be as easy as flipping a DIP switch on the controller board. A lot of transfer switches are good at a variety of voltages, with the "acceptable" voltages easily adjustible through a wide range, so a higher voltage single-phase ATS might be adjustable down to 120V.

If you can't tell from online documentation of the commercially availible switches whether it will operate at 120V, you'd have to contact the manufacturer(s). Usually, when ordering an ATS or generator, I'll simply give the manufacturer's sales rep my specs and let them figure out what parts I need. Half the time, they come up with other parts & options I'd never have thought of, or point out flaws in my plan, like "oh, by the way, those 200kW generators you asked for are the budget model and don't parallel. Want us to quote you one that does?"
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