I feed 240Volts 1ph @ ~60amps. A capacitor helps get the 3ph motor turning. (gets to full speed in less than 1/2 second just like it was powered by normal 3 phase current). Since the motor has 3 phase windings, and is running without load, the 3rd phase is induced. (like a virtual fake) but it will carry current. This output goes into a transformer with a 480 volt primary and 220 volt secondary. (i have it hooked up backwards if you consider there is such a thing in a transformer). My 220volt input gets boosted to 480 volts.. I trade amps so even though the 220v is going in at a max of ~60 amps, the 480volt side is fused at 25 amps. (no getting away from Ohms law)
What is great about it is that a 10 ga wire will run a 10hp motor and still have plenty of capacity left to spare.
The bad news is that a 15hp motor means you either put it outside, or turn up the radio if your shop allows one! LOL
Murphy |