Swapping out a 3-phase motor for a 1-phase motor

[Jason White]

I'm sure this question has been asked a-thousand times, but how hard is it to swap out a 3-phase motor for a 1-phase on a Unisaw or Powermatic 66? Are the NEMA mounts on the motors different? And do I have to change the switches as well? I assume everything mechanically is the same.

And PLEASE don't tell me to buy a phase convertor! Ain't gonna happen. ;)

[Charles Taylor]

Just make sure to get a 1-phase motor with the same frame type and tilt direction as the original.

You can use a 3-phase switch/starter for a 1-phase motor. One of the three sets of contacts will be unused. You'll want to ensure that the overload protection in the switch/starter is sized properly for the replacement motor.

[Mike Schuch]

A Powermatic 66 takes a standard NEMA C-Face motor. Available from a lot of manufactures. Usually a 56C if it has a 5/8" shaft or a 143TC with a 7/8" shaft.

A Unisaw requires a motor with a special mount welded to it so you are limited to a few pretty expensive replacement motors.

I have several machines that I run with VFD's. Not a very difficult addition but not a solution for everyone.

[Kenneth Love]

I am a new subscriber to the community. I recently purchased a Delta Rockwell Model 34-395 12" - 14" table saw. I has a 7.5 HP 3 Phase 230 Volt motor which I will have to convert to single phase for use in my workshop. I am looking at using a Grizzly H3473 Static Phase Converter (6 - 10 HP) for the conversion. The table saw will be the only 3 phase piece of equipment I will be utilizing in the shop. My question is....Does anyone have any history with this Static Phase Converter that they can share?

I also apologize if this question "highjacks" this thread. If it is inappropriate, I am sorry. Please forgive the intrusion. Any posting advise will be appreciated.

[Kim Gardner]

I'm looking at the same situation, a nice piece of equipment but a 3-phase motor. I was given the following link to consider using a VFD that will convert the single phase input into a 3-phase output to run the existing motor. And you get variable speed control as a bonus. I haven't tried it yet, but it does look promising. Anyone else looked at these?

http://www.automationdirect.com/adc/Shopping/Catalog/Drives/GS1_(120_-z-_230_VAC_V-z-Hz_Control)/GS1_Drive_Units_(120_-z-_230_VAC)

[Mike Henderson]

I know you said you didn't want suggestions for converting single phase to 3-phase, but it may be cheaper to use a VFD and the 3-phase motor than to buy a new single phase motor. If it gets the job done, why not consider it?

Mike

[Gregory King]

Hi Jason: I guess phase convertors were not for me either. I swapped out a 3 ph. for a single phase motor for my planer. 2HP single phase motor is very heavy. Ordering the right T frame cost me about $225.00 Can. I had an electrician change the wiring to 220V and the proper rotation as well. Still don't have it fired up yet but will soon when I get time. Greg

[Don Jarvie]

I convert my 66 over for about 300 bucks. Most important item as mentioned above is using a C-frame motor. Everything else can be swapped out.

I got a 3 hp single phase motor from AO Smith and since it had no overload protection switch the starter to account for the single phase. The motor shaft was smaller so I swapped the pulley on the motor and arbor so they matched.

I got the motor and starter off EBay and the pulleys from Surplus Center. Saw runs great.

[Kenneth Love]

I have looked at those units, but they are too small for my motor size (7.5 HP).

[Rich Riddle]

It's a pretty straight-forward swap. You might even be able to use the same magnetic switch, but show us a diagram/picture of your existing switch. I did a 5 HP swap for a friend for about $350. Good luck.

[Robert Parent]

I'm looking at the same situation, a nice piece of equipment but a 3-phase motor. I was given the following link to consider using a VFD that will convert the single phase input into a 3-phase output to run the existing motor. And you get variable speed control as a bonus. I haven't tried it yet, but it does look promising. Anyone else looked at these?

http://www.automationdirect.com/adc/Shopping/Catalog/Drives/GS1_(120_-z-_230_VAC_V-z-Hz_Control)/GS1_Drive_Units_(120_-z-_230_VAC)


I have the Automation Direct GS2 series VFD on my lathe and it works very well. The GS2 has capability to add external braking resistors, not sure if that is available on the GS1 series. I would recommend a VFD over a static converter as you get variable speed control, electronic braking etc.....

Robert

[Allan Speers]

It's a pretty straight-forward swap. You might even be able to use the same magnetic switch, but show us a diagram/picture of your existing switch. I did a 5 HP swap for a friend for about $350. Good luck.


This. But make sure you upgrade the heaters. Also the wiring might need to be replaced with something heavier.

Guys like Mike H can probably talk you through this, better than me.

[jack forsberg]

I"m often surprised how far people go to avoid 3 phase conversion with a VDF .

Changing out 3hp motors be it C frame or Uni mount is straight forward with a bit the knuckle skin in payment. The motor controls on the other hand can be a problem in the 3hp range when converting . Most of the better older saws had NEMA size 0 Mag starters that are just fine for 3Hp 3 phase motors But:::::::::::::::::::::::::: the smallest size Nema starter for single phase 3HP is Size 1 Mag starter. So its not a matter of changing the heaters(overload). Single phase motors draw more Amps than 3 phase motors of the same HP as they only have 2 wires not 3. they draw 1.732 times more amps.

Often people ringing off costs for motor conversion fail to include proper motor control costs , pulley and new plug costs in the conversion total.

The VFD is so easy to wire a monkey could do it and no knuckle skin for payment or pulleys, starters or plug. and its got a proper motor control and overload with features that add safety like breaking.