running 3 phase motors from single phase...

From: trash3_at_splab.cas.neu.edu <(trash3_at_splab.cas.neu.edu)>
Date: Tue Mar 30 09:05:15 2004

there are more than a couple of ways to do the conversion.

1) use a solid state 3 phase "inverter". Not my best choice, as they
are usually expensive and a little fragile.

2) get a 3 phase alternator, connect to single phase motor, making an
MG set (motor-generator). straight forward, but 3 phase alternators are
a little expensive also.

3) Use a 3 phase motor with a special starting circuit to create the
third phase. This is what I normally use. the third phase is a little
weak, but it works well. What happens is that you take a 3 phase motor
bigger than what you want to power (for instance, if you have a 1 hp
disk drive, then a 2+ hp motor is required for the "convertor"), and use
a starting capacitor and relay to feed the third leg until the motor
comes up to speed. ( the "mains" go across two of the three input leads,
and the capacitor/relay third wire goes to the last input lead). Then,
once the motor is spinning, you can connect your "load" up to the three
leads of the "convertor" and you get a reasonable 3 phase supply.

joe heck
Received on Tue Mar 30 2004 - 09:05:15 BST