3 phase motor 1 phase 220

[Art Beisang]

I just had a nice 3 hp 3phase motor given to me. I would like to hook it up to a compressor I have laying around. Anyone know the least expensive (cheap)way to run a 3 phase on a 1 phase circuit?

[Tom Veatch]

Here's a mess of threads talking about Variable Frequency Drives (VFD) and Rotary Converters:

http://www.google.com/search?q=VFD+%22Rotary+Converter%22&sitesearch=www.sawmillcreek.org

[Rick Christopherson]

If you had acquired a 3-phase compressor, it would be a different story, but simply getting a motor and wanting to connect it to an existing compressor is a different story. You will be better off finding another use for this motor. If you don't have a motor for the compressor, then take the time to find the correct motor. It is kind of like a double-negative; the motor is not made for the compressor, and it does not run from the power you have available.

[Art Beisang]

Thanks for the information.

[Chip Lindley]

(You do not give the HP of the motor) MyBAD!

It is 3hp, so costs will begin to be expensive. The least expensive way to run a 3ph motor on 1ph 240V is a static phase converter. The downside of a static converter is, it only provides about 2/3 the rated power of the motor. A SPC may put the motor as risk of burning up under heavy load (such as a compressor)

Rotary phase converters are much more efficient but much more expensive also. An RPC can power more than one 3ph motor running at the same time, up to its rated HP.

The VFDs fall somewhere in between. Not only do they convert 1ph to 3ph current but provide variable speed! (not needed with a compressor) VFDs must be sized to the ONE motor they will power. VFDs for 1 or 2 hp motors are not too expensive. But larger HP causes cost to rise rapidly.

It is hard to justify any of these solutions for just ONE 3ph motor for your compressor. First of all, the motor would have to match the HP and RPM of the original compressor motor to qualify at all. Any of the 3 solutions will probably cost as much as finding a used 1ph motor to fit your needs!