Operation of three phase motor on single phase supply

[AlanBeckett]

I've never done much with electric motors, is a delta connected three phase motor designed to run on single phase using a run capacitor or is it a frig/compromise?

It's a frig. It works but you never get the full Torque, particularly when starting. On my Chipmaster I swich in an extra 500uF to get it going then switch it out again, like this:-

   

So there's 600uF to get it rolling and 100uF to keep it going. Even so, it's reluctant to start if the Variator is wound up too far.
VFDs are getting cheaper all the time so I might invest one of these days, although 3hp ones are still pretty expensive.
The other problem is that they - Motors - take horrendous Currents when Starting. I run it off a Type C Breaker otherwise it would trip all the time.

Is there a formula for calculating the value of the capacitor or is it a case of try it and see? I'm thinking impedance arms etc.

Lawrence.

Not exactly, although there are rough figures available. You can always measure the Voltages and/or Phases, although they will vary with Load.

Alan