Re: [CAD_CAM_EDM_DRO] Home shop power for a big machine

vrsculptor wrote:

> I was lusting over a big VMC that would never fit in my home shop and
> got to wondering about power. The machine's data plate says 230 volts
> 3PH @ 80 AMP's, 18KVA. It has a 15 HP spindle.
>
> I could use a rotary phase converter to generate the three phase but
> don't have anywhere near 80 AMP's available. 18KVA/750 watts equals a
> 24 HP phase converter.
>
> If you where using this machine in a hobby environment and not trying
> to get production feeds and loads how small of a phase converter could
> you get by with?
>

I think even with 200 A service in a typical home, you are really
pushing it! The line current into a typical rotaty phase converter is
going to be REALLY high with a machine like this. If you trip the
breaker out on the transformer, the power company is going to get QUITE
nosy about what you are doing. If you have your own dedicated pole
transformer, you might get away with it. Especially if the local setup
has a 50 KVA transformer on the pole. If you have a 25 KVA transformer
shared between 4 residences, you will NEVER get away with it, and you'll
have a bunch of angry neighbors, too.

It is possible that the machine really doesn't need 3-phase at all. If
the servo drives are PWM (not phase-controlled SCR) they may run fine on
single-phaee power. If a VFD is used for spindle speed control, it may
be able to run off single phase at reduced output.

Jon