3-phase power

Paul Koning paulkoning at comcast.net
Tue Jan 4 12:04:47 CST 2022

> 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.


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