3 phase to single phase

[Trivo]

Hi all I have bought a Lathe and it has a 3 phase 1 hp 4 pole motor can i convert it to single phase or do i just buy a new motor

Thanks Trivo

[Bill Kichman]

You have several options.  A 1 hp single phase motor is a simple and fairly cheap replacement.  Just match pulley diameters and get the same rpm motor.  Or, you can make or buy a rotary phase converter, consisting of a larger 3 phase motor (thaN that which you are driving), some motor run caps, switches, and a housing for it all.  Look at other areas to find oodles of info on such a design.  If the 1hp motor is the only 3 phase motor you plan to drive, I would recommend just to change out the motor.  The so called static phase converters I wouldn't recommend.  All they are is a pseudo-rotary phase converter, by adding caps to YOUR driven motor.  You only get about 66% of the motor's output due to driving only 2 phases from the grid.  Good luck, it's an easy task.  You can find some f airly cheap motors at harborfreight.com, but note that they are often under-rated.  Seems many motor and vacuum cleaner manufacturers get away with lying these days.  Figure an amp draw of ABOUT 1000 watts, or 8 amps, at 120v, per horsepower, and that should tell you how much they are lying.  Good luck.

[Drives]

You could run the 3 phase motor with a variable frequency drive (VFD).  You will need to purchase a drive that is rated to accept single phase input.  Typically most modern small horsepower (up to 10HP) VFD's will run off single phase.  

Because in single phase only two conductors are carrying all the power that 3 wires carry in 3 phase, you need to derate a standard VFD by a factor of 1.5 for use on single phase.  For your 1 HP motor you need a 1.5 HP (or greater) drive at your rated voltage.  Check Ebay, good luck.