Re: [CAD_CAM_EDM_DRO] high frequency spindle motors

If you're talkin' line freq. (60 hz), IMHO it'd be lots easier, and, in
the long run, cheaper to build a rotary phase converter for
single-to-three phase. Used 3-phase motors (for the dummy leg
generation) are much easier to find, and much more commonly available ,
voltage-wise, than specialty transformers. All you need to add is a bank
of phase shifting capacitors (again, start/run caps are commonly
available), and some kind of timer relay to drop out the phase shift,
after start-up. I ordered a 20 hp package with all the 'guts', inside a
NEMA 6" x 18" x 18" box for, I think it was $285, plus shipping, from a
company in Anderson, S.C. (I highly recommend them) and since this is
now bordering on O.T., anybody wanting particulars, contact me off-list.
(No-affiliation disclaimer applies here.)

RayHex


Bob Simon wrote:

>

snip>

>
> Interesting! I found an example of a 3-2 phase scott-t on the internet. It
> seems that going from 3 to 2 phase the center tap works, but going from 2
> to 3 phase the tap needs to be offset. The example I found was 480v primary
> and 120v secondary. I wonder if I could use 230v primary and 120v secondary
> to reduce the voltage to the windings and still use a 230 volt VFD?
>
> Could both transformers be identical? I though about a pair of used 1KVA
> control transformers, but outside tapped 230v primary gets me only 60
> volts. Looks as though I would need really expensive specialty
> transformers...sigh