Thread: VFD for 240V single phase motor

I was of the firm belief that normal 240V single phase motors would not operate from a VFD. Seems I was wrong. This mob make them.

Anacon Systems, Inc.- OPTIDRIVE E2 for Single-Phase AC motors.

If it's true, might be nice way to control your lathe of mill.

Not cheap though at approx $500 for a mid size unit.

Ken

Hi Ken, it looked interesting but there had to be a catch, and it compatible motors.

There is a link to the technical manual on the page you linked to, and on page 8 it has a section on compatible motors. The unit is designed for shaded pole motors, (basicly gutless) and split winding cap run motors, which are not a lot better and certainly don't like starting under heavy load too frequently, and have slow wind up (think bench grinders etc which take 5 seconds plus to get to speed without an imposed load).

Your standard cap start motors use a a start cap tuned to the windings in a switched start circuit. Vary the frequency and you stuff up the tuning and the thing won't survive a lot of starts. The switched start circuit is normally centrifugally switched out once the motor hits about 75% of rated speed, and the motor losses increase dramatically once the frequency exceeds about 60Hz.

If the controller was very smart and the application allowed for the motor to start and run to rated speed before changing to the controlled speed, you could possibly drive a cap start motor and achieve a VF range of +/- 20% i.e 1200 to 1700 RPM for a 1440 RPM motor, but the controller would have to reset to rated speed for every start and hold that for a couple of seconds before reverting to programmed speed. For the limited speed range achievable, it would not be worthwhile.

Thanks Malb,

Thought it was too good to be true.

I don't have a need for one, but just thought it might be the ants pants.

And far too expensive to boot.

Ken