I also read somewhere that if you have multiple tools in your shop run off of one rotary phase converter, i.e.: lathe, mill, table saw, etc and have one large item like a welder for instance, you can turn all the other tools on and they will all work together as rotary converters to power the large tool. Please note, they have to be free-idling though to act as additional converter capacity.
BUT, all that said, I WOULD NOT recommend buying a 3 phase welder unless you already had the phase conversion capacity in place already, as it's cheaper to just get a good single phase machine... Unless you have one of those new digital rotary converters, your power balance will never be quite right when you're running a welder (do to the constantly fluctuating load current) and poor arc stability is the result..... This is all things I've learned when thinking of buying a 3 phase welder..... Also, from my research, the average 300 amp 3 phase welder is going to need a 25hp phase converter! :O
Just something for you guys to think about....
Personally, when the day comes that I get a mill, lathe, etc, they will all be run off of VFD's...... Quiet, no waste power when machinery is turned off, etc........
