3-phase power

[Paul Koning]

> On Jan 4, 2022, at 12:00 PM, Adrian Stoness via cctalk <cctalk at classiccmp.org> wrote:
> 
> you can use a vfd drives to get 3phase power from single u just gotta size
> them bigger then the load u would normally need

I've said that too, and I've been told that this is not a good idea for power supplies.  Something about the waveforms involved in VFDs.  I haven't studied the subject enough to decide whether that's accurate, and the only VFD usage I have is a lathe -- the sort of application VFDs are designed for.

The other option, typically somewhat more expensive but cheaper than an 11/780, is a rotary converter.  Those are 3 phase motors, sometimes modified a bit, driven from single phase power that construct the missing phase somewhat like a dynamotor would.  Those things produce proper sine waves so they are good to use even with things that are picky.  Rotary converters can be found in machine tool supply catalogs.

	paul