How To Run A 3 Phase 380V Motor On 220V

[Constabulary]

This is a factory wiring diagram from a PFAFF sewing machine clutch motor which shows how to run a 380V 3 phase motor on just 220V. It is in German and English language I hope they translated it correctly.

This diagram was inside the junction box so I took it off and scanned it. I thought this could be very helpful for those who do not have a 3 phase 380V power connection. I did this conversion a couple of times and never had a problem!

How to chose the correct capacitor:

rule of thumb: capacitor = 60µF to 80µF per KW

Assuming the Motor has 370 Watts = 0,370 Kilowatts (KW)

0,370 x 60 = 22.2 µF

0,370 x 70 = 25.9 µF

0,370 x 80 = 29.6 µF

So capacitors between 22µF and 30µF will work.

I always choose a 25µF capacitor as it is just in the middle and works fine.

And you of course have to change the plug!

I will take some pictures later from the junction box of the motor I recently have converted.

WARNING:

Then diagram is for conversion from 380V to 220V - I don´t know if this works in the US with110V but I assume so but don´t know for sure!!! If you know nothing about electricity and you do not understand the diagram - DON'T TRY THIS AT HOME - better ask a qualified electrician.

Edited March 31, 2014 by northmount

[cardinal leather]

Thanks Constabulary,

I will be working on a couple of these machines in the future. Any photos that you have along with these diagrams may be usefull. The big question would be how does the US power system compare to the one you are using? I have a couple of electricians that should be able to do the work or talk me thru it.

Jim

[Constabulary]

To bad I cannot edit the 1st post. Okay, so here are the pictures:

• Picture 1 shows the data plate of a 370Watts PFAFF clutch motor which can be run on 220V and 380V
• Picture 2 shows the original 380V setup of this motor
• Picture 3 shows the setup of the same type motor changed to a 220V + capacitor for clockwise rotation direction

Please compare the pictures with the diagram in post 1.

Please note thats the "earth" is just on a different screw but this does not matter.

One capacitor cable goes on the "free" bridge and the other goes on one of the other bridges depending on which rotation direction you need.

So thats all - it´s a quite easy task!

But again if you know nothing about electricity DON'T TRY THIS AT HOME - ask a qualified electrician!

Edited April 1, 2014 by Constabulary

[Doc Reaper]

I have purchased a saddle stitcher that has a 3 phase motor on it. I was just going to remove everything 3 phase and replace it with a 110 powered motor. I'm also going to add a speed reducer for better control of the machine.

Any thoughts or comments are welcome at this stage, before I remove the 3 phase motor!

[Doc Reaper]

Also need to know - also wouldn't switching over to 220 burn up the motor faster?

[billybopp]

If your motor is designed for dual voltage, it will do no real harm to wire for and run on the lower voltage, however you will get less power from it. How much less depends on the internal design of the motor.

Bill

[Northmount]

If your motor is designed for dual voltage, it will do no real harm to wire for and run on the lower voltage, however you will get less power from it. How much less depends on the internal design of the motor.

Bill

Depends on the motor design. Check the name plate for what the dual ratings really are. The motors I have are 1hp whether run on 220 or 110 VAC. Follow the wiring diagram on the name plate. 220 has an advantage in that there is lower voltage drop in the supply wiring since it is drawing only half the current (amperes) that 110 VAC draws. So it may perform better depending on how long the supply cable is and what size wire the cable is.

Tom

[Parvaiz]

i had this motor, EFka Varistop.

understand the capacitor uf

what about Volt of Capacitor.

seen on Ebay for 450V is that okay.

which wiring diagram should i chose 

Thanks

neet to change Contactor wiring as well 

Putting the PDF file in 2nd post

for AEG Ls07 Contactor how to do that on single phase

[Parvaiz]

Putting the PDF file in 2nd post, file was too big so add screen shots

for AEG Ls07 Contactor how to do that on single phase wiring as it is on 3 phase as well

  

[Gymnast]

You are right, that you can do this wiring change to a 3 phase motor. But this change cause increase of the power losses (to heat) of the motor and in particular when the motor runs with no load. For larger motors and machines that run long hours, this increased power bill can be uacceptable.

[DrmCa]

One thing to remember is that if after wiring a 380V motor to run on 220V it runs at lower RPMs, then it could overheat from the lack of air circulation.

Edited July 15, 2019 by DrmCa

[TonyRV2]

16 hours ago, DrmCa said:

One thing to remember is that if after wiring a 380V motor to run on 220V it runs at lower RPMs, then it could overheat from the lack of air circulation.

Nah....A.C. motors run at an rpm which is determined by the line frequency, not the voltage. More specifically at the line frequency minus the motor's "slip". Now it is possible that the slip is different between running at 380V or 220V, but this would be a minimal difference as slip is usually less than 10%.

[DrmCa]

Depends on the voltage drop. I would not write the above if I did not witness it with my own eyes.

[TonyRV2]

 

34 minutes ago, DrmCa said:

Depends on the voltage drop. I would not write the above if I did not witness it with my own eyes.

Again, an A.C. motors r.p.m is determined by frequency, not voltage. I would not have written the above had I not been an automation engineer and taught electrical engineering for 32 years. If you witnessed that a motor had slowed down under the OP's posted conditions, then it was loaded. However, this would increase the motors slip which then increases the back EMF to the windings which increases the torque which brings the motor back up to speed. However, if the motor is overloaded it cannot recover. This may describe the situation you'd witnessed.

[dikman]

If I had a 3-phase motor I wouldn't mess around with rewiring it I'd buy one of those magic boxes that lets you run a 3-phase on single phase and also acts as a speed controller. Perfect solution, in my opinion.

Edited July 16, 2019 by dikman

[Matt S]

10 hours ago, dikman said:

If I had a 3-phase motor I wouldn't mess around with rewiring it I'd buy one of those magic boxes that lets you run a 3-phase on single phase and also acts as a speed controller. Perfect solution, in my opinion.

I had the same thought when I bought a 3-phase splitter. Turns out those magic boxes release the magic smoke if any switchgear between the motor and the controller changes state while it's running. They also need to be tuned to the load and aren't really recommended for running multiple motors. My machine has 4 motors, all different RPMs and power requirements. I left the electrogubbins in the control cabinet alone and just built a static converter.