Re: [CAD_CAM_EDM_DRO] VFD for a 15HP CNC lathe

fuddham wrote:

>I have a CNC lathe that has a 15 HP spindle motor. What size VFD
>would I need if I only fed the VFD single phase power? Would it be
>better to get a 15 hp VFD and use a rotary phase converter to feed
>the VFD? What size VFD and Rotary converter?
>
>

Wow! You really need 15 HP? That is a LOT of current for a single-phase
240 V line. You could probably get by on a 15 Hp VFD, as you are not
real likely to use full power much. Just as a pure resistive load, that is
46 A! If you truly intend to run the spindle near rated power on occasion,
you might want to go to a 20 or 25 Hp VFD. Although people have done
it, the rotary phase converter is unneccesary. Unless the rotary converter
is precisely balanced, it will provide no benefit to the rectifiers in the
VFD. And, if it is badly balanced, it could deliver excessive voltages to
the VFD and burn it out.

Jon