Just a quick post to share what I learned about static phase converters while setting up my 3-phase Unisaw.
First off, there are two basic types. Each of them uses some type of capacitor circuit to energize the third phase of the motor just long enough to get the motor up to speed. After the motor is spinning the starting circuit is taken out of the loop and your three-phase motor is running on two phases of power. This was the first type of converter I looked at buying, but after speaking with a technical service representative, he informed that this type of converter is really only suited for powering motors loaded at only a fraction of their rated horsepower (see disussion of idler motors below). Any heavy loading (70 percent or greater) has the potential to cause permanent damage to your motor. (This is all based on information I got from a representative at Enco regarding a Phase-A-Matic converter.)
The second type of converter includes a second “run” capacitor circuit that engages after the starting capacitors are deactivated. This second capacitor is used to provide pulses of power to the third phase of the motor. Its not nearly a sine wave output, but its enough to allow consistent loading of the motor to 70 percent of rated capacity and intermittent loading of 90% of rated power (up to 15 minutes of 90% load with equal no load run time). (This is the type I ended up purchasing. The brand is Autogen and I bought it from Grizzly.)
Another interesting note is that if you run an unloaded 3-phase motor on 220V single phase power, the motor’s third phase will act as a generator and will actually produce the third phase of power for any other motors operating on the same circuit. Each type of static converter above is capable of operating like this and suppliers of both types recommend this configuration as a type of poor-man’s rotary phase converter. The folks who make the Autogen have a pretty good site explaining all types of converters and 3 phase power in general. http://www.gwm4-3phase.com/autogen.html
-- Dylan C ...Seems like all ever I make is sawdust...