ECN Forum Forums General Topics of the Trade General Discussion Area Kohler Generator 120V, 7.5KW

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

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.

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.

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

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?"