Three phase motors on single phase service...

lin842 · Nov 12, 2010

Is there any way to change a 3 phase motor so that it can be run on single phase. I mean can you rewire the motor or do you have to go the phase converter route?

I have a 4000 lb lift table and it has a three phase motor on it and I found another power unit that was supposed to have a single phase motor but when it came to the door it was three phase too. Now I have two hydraulic units and can't use either one. I thought about just buying another motor but both these motors are 3500 rpm motors and they are hard to come by from what I have seen. Can they be rewired to run on 220V.

johnoder · Nov 12, 2010

Anything is possible with enough money, but in a practical sense, NO.

By not going "the convertor route" , I take it that you also wish to exclude VFD, a good sense approach for single motors.

J.O.

L Vanice · Nov 12, 2010

A VFD (AC speed control) with 110 or 220 V single phase input and 220 V three phase output can be bought very cheap these days. I have found them for as low as $35 on eBay. That is a much simpler solution, compared to changing a special motor. It is so neat to run an industrial machine off a house 110 V outlet. If you don't need the speed control feature, you just leave it set on 60 HZ all the time.

If you have a 440 V motor, it becomes more difficult, involving an external transformer.

Larry

Hopefuldave · Nov 12, 2010

L Vanice said:
A VFD (AC speed control) with 110 or 220 V single phase input and 220 V three phase output can be bought very cheap these days. I have found them for as low as $35 on eBay. That is a much simpler solution, compared to changing a special motor. It is so neat to run an industrial machine off a house 110 V outlet. If you don't need the speed control feature, you just leave it set on 60 HZ all the time.

If you have a 440 V motor, it becomes more difficult, involving an external transformer.

Larry

====================

If youhave 220V available (stove circuit?) and need 440 you can still go the VFD route, either by using a voltage converting VFD (a fair bit more expensive than straight 220 to 220, even from Ebay) or "hacking" an older 440V VFD to fool it into thinking it has 440 volts in - I say older because they usually had 2 series-connected sets of reservoir capacitors after the mains rectifier, so all you have to do is move one side of the 220V to the point between the capacitor banks and you suddenly have the required voltage. If you were to go this route (with assistance from an electronics tech. if required) you'd have to de-rate the VFD some, 25 or 30% seems to work (does for me, ayway!). I used this method to get 3HP worth of 415V 3-phase (UK standard) from 240V single-phase (also UK standard!) with an old ABB that cost me £20 and a little work fixing up the case and replacing the smashed LCD panel in the programmer (£2 from a gent in China).

Dave H.

Frederick Harvie · Nov 12, 2010

Just buy a single phase motor . 3600 rpm motors are pretty common , Dealers electric has 3 hp 3600 rpm motors right now for $115 listed at the bottom of there home page . They have other sizes as well . I have bought from them on many ocasions and always found them to be good to deal with.

viper · Nov 12, 2010

What kind of Hp are we talking here. You indicate 3500 rpm but really, this has to just be a standard 2 pole motor which means syncronous operation would be 3600 but they all have a slip factor and can run anywere from 3400 to 3550 rpm. If you can find the right frame on the motor, a 1ph, 2 pole might be the answer but as mentioned above, I would reach for a VFD for this one most likely. This would soft start your pump and give you motor protection, etc. I really doubt you will buy one for 35 bucks but they can be found "reasonable". Because you want to operate on 1ph power, you will have to derate by 33% for the missing leg so example would be a 7.5HP VFD for a 5HP load with incomming 1ph power.

Or you can sell both of your 3ph units and just go buy a 1ph assy.

mike_kilroy · Nov 12, 2010

Hitachi's we sell are rated out of the box for 1ph in and upto 3ph out depending on model. No extra charge. Just buy the right one from the start. I would be happy to quote u a price of one of these for reference.

also around here harbor freight is starting to sell 1ph motors for cheap (like $ 100 each). not sure if they sell 2pole (3600rpm but probably

surplusjohn · Nov 12, 2010

FYI on VFDs, I recently set up a 1 hp 220 volt 3 phase motor to use 110 single phase. so 110 is also an option.

S_W_Bausch · Nov 12, 2010

If you consider VFD, the unit can stay with you, on a shelf, when/if you sell the machine it was on.

Not so with purchasing a special frame motor, or paying some shop to make some modification (single to three phase internal modification really doesn't exist).

lin842 · Nov 13, 2010

mike_kilroy said:
Hitachi's we sell are rated out of the box for 1ph in and upto 3ph out depending on model. No extra charge. Just buy the right one from the start. I would be happy to quote u a price of one of these for reference.

also around here harbor freight is starting to sell 1ph motors for cheap (like $ 100 each). not sure if they sell 2pole (3600rpm but probably

Viper above asked about the HP rating on the motor. I haven't been able to get by there to see what the HP of the two motors is but I'll post it when I do. When I find out the Hp maybe you can tell me what I need and give me an idea of what I'm looking at price wise. This is not one of my projects that is on a front burner but I'm getting stuff together so that I can put it together when I get a new shop built. Thanks!

lin842 · Nov 13, 2010

surplusjohn said:
FYI on VFDs, I recently set up a 1 hp 220 volt 3 phase motor to use 110 single phase. so 110 is also an option.

I know one of these motors is a 440/460V 3 phase but not sure of the HP. I was so bombed out when I saw three phase on the motor plate of the other unit I bought I didn't even look any further I just pushed it over in a corner. This unit came off of an old 2 post car screw lift so it could very well be a 208/220 motor. Hopefully I'll be able to get by there to see exactly what it is this weekend sometime.

DaveKamp · Nov 13, 2010

So...

So the motor in question isn't currently mounted in a machine? If it was purpose built for the machine, and you don't have the machine anymore, it'd be a better use of resources is to find a motor most suitable to both your application and available source, and put this old 440 3ph motor on a shelf somewhere, and someday either find a use for it, for it's parts, or for someone who has a good use... perhaps even one in need of a replacement motor for said lift.

mike_kilroy · Nov 13, 2010

220v 3ph motor running on 110v 1ph

surplusjohn said:
FYI on VFDs, I recently set up a 1 hp 220 volt 3 phase motor to use 110 single phase. so 110 is also an option.

John,

Please tell us how you did this. 3ph motor running on 1phase AND 220v rating and running on 110v to boot! sounds like magic! How'd you do it?

lin842 · Nov 16, 2010

Ok, I finally got back down there to see what I had. One of the motors is a 1 hp 460V 3 phase and the other is a 1.25 hp 440 v 3 phase. It looks like from the wiring diagram that is stamped on the motor that the voltage can be changed on both motors to 220 or 208v.

The hydraulic system that is on the lift table now has what looks like a reversing valve attached to the hyd pump to lower the table. This valve looks like it is run by 110v single phase current.

The other one I bought has a manual valve that makes the system work. I'll probably use this one for something else maybe a hydraulic press. So, with this in mind I'm thinking that a small phase converter would be best considering i'll probably be using both these motors sooner or later. Yes///No ??

lin842 · Nov 16, 2010

DaveKamp said:
So the motor in question isn't currently mounted in a machine? If it was purpose built for the machine, and you don't have the machine anymore, it'd be a better use of resources is to find a motor most suitable to both your application and available source, and put this old 440 3ph motor on a shelf somewhere, and someday either find a use for it, for it's parts, or for someone who has a good use... perhaps even one in need of a replacement motor for said lift.

That is why I bought the second unit I thought I could use that motor on the table since it was supposed to be 220 single phase. It turned out to be a 3 phase motor also. The biggest problem I see with looking for another motor is finding one with the same frame/ mounting setup as I have now so that the hyd pump can mount to it. It has a 4 bolt flange at the end for the pump to mount to. I could probably change it to a typical hyd coupler but them I would have to make a bracket for the pump to mount to the frame so one problem leads to another problem. All this because I wanted a welding table that could be used as a lift table too. Nothing is simple anymore. :willy_nilly:

RP Designs · Nov 16, 2010

Go the VFD route.

220 single phase in, 3 phase out.

Here is an example:

General Purpose Drive, IP20<br>Up to 15hp, Single or 3 Phase<br>AC Tech SCM/SM - wolfautomation.com

Frederick Harvie · Nov 17, 2010

mike_kilroy said:
John,

Please tell us how you did this. 3ph motor running on 1phase AND 220v rating and running on 110v to boot! sounds like magic! How'd you do it?

No magic at all. For small motors up to 1.5 hp VFD's are commonly available with 110 single phase in and 230 3 phase out. See the first item catagory on dealerselectric page for a list of 110 VFD's

mike_kilroy · Nov 17, 2010

a-ok. thanks. It did not sound like you bought a voltage doubler drive but found some way to do this simply otherwise. Yes, the Hitachi's we sell have small drives that double 120v 1phase to 240 3 ph also for low cost. We're always looking for new ways to do stuff! Thanks for reply!

Three phase motors on single phase service...

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