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

caudlet wrote:

>
> one trick is to use "idler" motors to help generate more 3Phase.

Right, but he was saying he thought a 25 Hp idler motor would be needed.
The idling current on a 25 Hp 3-phase, 230 V motor will be roughly 82 Amps.
This will be at 90 degree lagging power factor, so it won't show up on
your watthour meter, but it IS current on your mains, and will be added
to any current the machine draws. Or, to the rest of the house, you
neighbor's houses, etc. This is why you are really going to hve trouble
running anything this big on a 200 A service. You will almost certainly
need a soft-start system on the idler motor, and if the machine spindle
is a plain 3-phase motor with a run contactor, you will never get away
with starting that once the idler is running. If the machine has a VFD,
then you will be in much better shape, as they can be set for a softer
start.


Jon