Paul,
For the most part, you are probably talking about the Edison generator I expect. No problem, this is where the brou-ha-ha began over grounding, they weren't. Remember the code was implemented by the Insurance Underwriters in those days, they rarely, if ever, insured lives, only buildings. We did not want those burning down, we had to pay for them. You can still see the same basic system in AC if you check out the Scott or "T" connection. The only place I've ever seen one is in coal mines. It is also the true "2 phase" system with each being 90 deg opposed instead of 120. A machine that can run on DC (such as most battery operated mining equipment) will also run just fine on this, with the help of a rectifier. Real pain to wire, and if you aren't familiar with it, Lord help you on troubleshooting.
