Re: 3 phase motor math

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "rainnea" <yahoo@r...> wrote:

> Can you run a larger motor than a VFD is rated for, ie. run a 5HP
> motor from a 1.5kw VFD ?
> ie. can you limit the voltage / current output from the VFD ?

Probably not... the no load current of an AC induction motor is
about 35% (ranges from 20% to 50%) of the full load current.
So the no-load current of a 5HP motor is likely to be very near
the rating of the small VFD.

> Could a VFD be used to run an AC servo ?

Using a generic VFD to run an AC servo motor _might_ be able
to make it behave like a generic motor - but you certainly
won't get servo-like performance from it. And it's quite
possible it won't work at all (constantly tripping out the
drive, etc.) It would definitely take a lot of tweaking.
Not a project for a VFD newbie. (I have an old AC servo
motor sitting on the shelf, and one of these days I intend
to try it. I'm don't know if I'll succeed, and I design VFDs
for a living!)

John Kasunich