Faking 3 ph power?

[Bud in WV]

I had a 220v Jet 1236 lathe that I traded for a Rockwell 11" lathe. The Rockwell has a 230v 3 ph motor. Part of the trade was an OLD motor that supposed to be 3ph to generate the L3 phase to run this lathe. The guy I traded with had never wired it up so he was no help. Anyone have a wiring diagram or a good link for this?

I also have a box that was an original part of the lathe (from a local high school) that has a transformer, a Polyphase motor starter and a 3ph breaker in it.

The motor has NO markings on it - no name plate, no embossed company logo like GE or Westinghouse and no numbers on the 4 wires coming out of it. (It looks like it"s about 1930"s or 1940"s era.)

How do I test the wires to determine what"s L1, L2 & L3? What do I look for to determine which is the ground/neutral, the start leg and the L2 & L3 run legs? I"ll have to install machine grounds on the motor, box & lathe, too but that should be fairly simple.

I have a good multimeter, a good machining back ground and a good residential wiring back ground but I"m light in 3 phase and theory to figure this out on my own.

Thanks for any info!
 

[David G]

Just put a 3 phase VFD on it and be done. You just have to upsize the VFD by 1/3 to compensate for the lost input phase.
 

[buickanddeere]

For continuous max output, increase the VFD by 1.73 times. A 5HP VFD in this application.
 

[Kirk Grau]

I agree with the guys saying put a VFD on it. Haunt some a woodworking forums, many home shops have 3PH equipment wired through cobbled up phase converters using a variety of methods. Some installations are more "elegant" than others. The VFD is by far the nicest arrangement. Sell the 3PH motor you have to recover some of the VFD cost.

Kirk
 

[JDseller]

Is the motor a special one?? Meaning is it intergal? If it is just an external motor then just replace it with a single phase one. I have also made the factory motor just be a jack shaft and drove it with a single phase motor.If it can't be replaced then go with the newer style inverter. I had one made out of a motor. You had to spine it as you turned it on to make it work. It was a real PIO to use and took up floor space.
 

[timcasbolt]

Here's a link to the area for instruction sheets and whatnot at phaseamatic.com. HTH
 

[timcasbolt]

http://www.phase-a-matic.com/StaticDescription.htm
 

[JMS/.MN]

google home made phase converters. I made mine with a 5hp 3 phase and a 220V half horse spinner motor. Basically hook L1, L2, and L3 to the input side of a 3 phase switchbox. Hook 220V single phase to two of the poles in the switchbox to the motor side, using L1 and L2. On the load side of the switchbox, run L1, L2, and L3 to the motor you want to run. The half horse motor gets hinged to the 3 phase motor, belted to it, and is wired to a little switchbox that is wired to the 220V input of the big box. Start the spinner motor, when the 3 phase is up to speed, turn on the big box, and shut off the little on, flip the hinge so the belt loosens. L3 is generated by the 3 phase motor. No capacitors needed....Voila! 3 phase power.
 

[Bud in WV]

Thanks for the info guys! The VFD sounds like it'd be great but I can't afford $1k for what I'd need. The lathe motor is 3hp so it'd take a 5hp rated VFD.

I have a friend who's an *old* electrician - 85 & still working...he enjoys it. I hope he can determine which lead is which.

I have several 1/2hp & 1hp motors I can use to kick start this one...or use a pull rope. Basically I can build what I need with parts I have on hand or spend $1k to go the easy route.

Thanks for all the info! I never heard of a VFD - I was mechanical - not a sparky....
 

[Jeff NWOH]

You can also use a capacitor to start your inverter motor and eliminate the little pony motor. I've got a small one i built this way and also a larger one that was factory built.

The nice thing about about a rotary converter as opposed to a VFD is that you can also run other 3 phase motors from it. A VFD is set up for only 1 motor.