Definitely Kohler. (Did you see the article that I linked to above?) There is a fair amount out there on the electric light plants, and you can still get manuals for them.
Do you have a serial number, and a model number? Some of those units were DC. These days might be useful for LED lights, or directly charging batteries.
They all have a large flywheel, and, I'm told, run very smoothly. They were designed to run for long periods of time. I think that they sound like fun items, but then again, I have a soft spot for Lister diesels, too.
All the best,
Peter