Re: [CAD_CAM_EDM_DRO] Phase Converter

On Mon, Mar 25, 2002 at 05:28:10PM -0500, Carlos Guillermo wrote:

> Hi Terry -
>
> I just went through this to get 3 phase from 220VAC @ 60Hz. I
> used a 7.5HP idler motor, and I'm operating a 5HP lathe. I found
> everything I needed at these two links:
>
> http://www.metalwebnews.com/howto/ph-conv/ph-conv.html
> http://www.homemetalshopclub.org/projects/phconv/phconv.html

The Hanrahan article is probably the definitive text on home
built phase converters. It's definitely an article to read.
Just change the Hz and voltages to suit your locale.

> I used the self-starting circuit with a safety relay, and I'm very
> happy with the results. I ended up having to use run capacitors
> to balance the phases, and bypassing the lathe's overload relay,
> but I am able to get 2500 rpm with slow blow fuses.

The converter I built also uses the safety relay, although I opted
for a start push button to engage the start capacitor. I also
used a 7.5 hp motor and run a 5 hp lathe off of it, but if I did
it over, I think I'd go with a 10hp idler. If you're going to
run a CNC machine, I'd go for 2x the largest motor rating, at
a minimum.

After blowing out a start capacitor because a machine what turned on
during startup, I might consider a lockout contactor that engages
only when the start cap is switched out of the circuit and the idler
is up to speed. The smoke they pack into those things stinks to
high heaven.

I am planning on running a 2hp Bridgeport BTC-1 off of it, eventually.
When the new shop gets built I may opt to upgrade to a 10hp motor
though.

Also, running a CNC machine, be sure the control electronics are
tied across the input lines, and not the generated phase.

Feel free to contact me offline as well.

Paul

--
Paul Amaranth | Rochester MI, USA
Aurora Group, Inc. | Systems & Software
paul@... | Unix / Windows / NT