Re: [CAD_CAM_EDM_DRO] Phase converter circuit

Chris -

This is a great idea, however, I do not have enought money for a VFD to run
my mill with it's 15hp motor. I agree, having to turn on and off the
converter is a pain, and it's noisy, but it was cheap. If I find a big
honkin' converter where I found all my other stuff (at the scrap yard) then
I will be all set! The only ones I ever see are little 2-5hp models.

Thanks -

Mark

>
> > Every time I turn it on, the high-pressure sodium and mercury vapor

lights

> > in my shop go out, then come on a few minutes later. Does anybody know

how

> > to reduce the starting current on one of these things?
>
> Sure, put it on a VFD programmed to slowly ramp up to speed.
>
> What you have done here is used an idler motor as a 'rotary capacitor'
> to supplement the capacitors in the VFD. If you got VFD's with bigger
> capacitors and diodes rated for it, you could simply run them off
> single phase. The capacitors have to supply current between peaks of
> the AC cycle - with single phase these occur 120 (100) times a second,
> but with three phase it's 360(300) times a second, so the caps can be
> smaller.
>
> I had a rotary converter when my 3 phase machines were at home, and I
> hated it. Always have to decide if I was going to use a machine again
> soon, or if it was time to shut it down. I'd much rather have
> electrolytic caps in a VFD.
>
> Chris
>
>
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