On Tue, 21 Jul 1998 10:22:11 -0400 John Shreffler writes: >You can use 3 phase induction motors on single phase. I have >three industrial quality machines in my shop that do very well. >Put the 240 V across two of the motor leads, and run the >third motor lead back to either of the 240 V supply through >a large (50 mfd or so) oil-filled AC capacitor rated to at least >380V. The motor will begin turning in one direction or the >other depending on what side the cap is connected to. Disconnect >the cap when the motor reaches about 75% speed, it is for >starting only. You will get only about 65% of the torque that >the motor would give on 240V 3 Phase, but usually that is >plenty. For light duty use (and most home uses of industrial machines are quite light duty) this is fine. In industry, motors are often burned out by operating them (at full rating) without knowing that a phase has been lost, so it is essential to keep such operation light and intermittent. A more advanced technique uses another surplus 3-phase induction motor as a converter. The converter motor is started with a capacitor as described and just allowed to idle with no mechanical load. It will act as a "rotating transformer" and generate a fairly good rendition of the third phase. The three wires of the converter motor, two of which are the single phase power, form the 3-phase bus to the load. The converter motor should be considerably larger than the one in the machine tool. The motor(s) in the machine tool can then be used at nearly full rating. The standard controls can be used to start or reverse the load motors just as if they had 3-phase utility power. _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866]