Coverting 1.5hp 3-phase motor to single phase AC (capacitor solution?)?

Question

I have a 1.5hp 220v 3 phase motor driven band saw. I need to run it on a 220v single phase system. The original single phase converter consisted of a 550uF capacitor supplying the third phase winding with the contacts of an NC relay in series with the capacitor. The coil of the relay is from the supply through a resistor to the third phase winding and dropped out when the motor came up to speed. A second 40uF capacitor is from the supply to the third phase winding and is the only capacitor that remains active when the relay opens up (motor is up to speed). I'm looking for a simpler and more reliable solution, as the present circuit is temper mental and old. Replacing the motor is a last resort. Is there a simpler capacitor type converter that can be designed? The saw is only operated intermittently for 10-15 minutes on time, 30-60 minutes off for an 8 +hour period, for a few days a month. It is used for a meat cutting band saw. Any sources, help or information would be greatly appreciated. Thank you.

tinkertailorcandlestickmaker · Accepted Answer

Capacitor type converters do tend to be "temperamental", but the circuit you have seems to be about as simple as they come. Rotary phase converters are generally considered much better, but are also much more expensive. Another option that may be practical due to the lowering cost of semiconductors, is a is a VFD inverter drive, while the name includes "variable frequency" you can just as well use it at a fixed speed. 
Just a couple weeks ago I installed 3 conveyors with singe phase to three phase VDF inverters (albeit wit smaller motor than yours) and they work flawlessly.

Coverting 1.5hp 3-phase motor to single phase AC (capacitor solution?)?

1 Answer