Re: [CAD_CAM_EDM_DRO] Re: VFD Selection

george_barr wrote:

>Leslie,
> It appears that I cannot use a VFD or Variac to reduce my router to
>1k rpm. What type of motor can I use with a VFD (input: 120VAC,
>output: 120VAC or DC) without getting too expensive or without using
>servo drives? Is there a specific phase specification. Does the
>motor have to be AC or can it be DC? What I am planning to do is cut
>mild steel (which requires low rpm speed)?
>
>

VFDs are designed to run 3-phase induction motors, ONLY.
There are also DC brush permanent magnet speed controllers
(some can also run wound-field shunt motors, too). Nearly all
VFDs can be run from a single-phase 240 V supply, if you derate
them somewhat. So, a 5 HP VFD should be able to run a 3 Hp
motor from a single-phase supply.

Jon