On Thursday, February 2, 2017 at 1:58:04 PM UTC-6, Electric Comet wrote:

the vfd opens up some possibilities for using 3 phase equipment

3 phase motors can be powered in homes a couple ways. Homes with 220 volt single phase electricity only. As opposed to industrial/commercial space which often has 3 phase electricity into the building from the main electrical system.

You can get 3 phase electricity for motors by using a phase convertor. Rotary or static I think. Rotary is superior. You put 220 volt single phase in and the rotary convertor makes the third leg of the three legs/phases needed to power a 3 phase motor. The other two legs for the 3 phase motor come from the breaker box 220 volt feed. End up with three legs/phases for the 3 phase motor.

The other way to get three phase power is to use a VFD Variable Frequency Drive. Common on lathes that need variable speed from the motor. VFD takes the two legs of the 220 single electricity in and creates the third leg to power the 3 phase lathe motor. Assume the VFD can change the amount of electricity going out to make the motor variable speed. VFD are relatively cheap compared to phase convertors. VFD make three phase power electronically instead of rotary phase convertor which makes the three phase by actually having an additional motor making the third phase. Cheap electronics compared to expensive copper wound motor.