# 3-phase motor on single phase supply

• posted
I want to use a 3-phase 400V AC motor an a 230V single phase supply.
It says 230/400V and 73.6W on the motor and I know it's possible but that
you need a capacitor connected to the motor windings.
My question:
How to calculate the size of the capacitor, and where to put it ?
(the motor has 3 windings, U, V and W)
• posted
I have heard the number 4mfd per HP tossed around but I don't know. Use a clamp on amp meter to tune it in with the normal load.
• posted
No matter what you do with a capacitor - you will not get a true balanced 3 phase. You will get a capacitor run single phase motor for which the current/HP will be higher than for 3 phase operation. This may not be important depending on the load that you actually have. (by the way 73.6 watts is a very strange rating -particularly for a 3 phase motor. What is the full nameplate data?)
• posted
"Don Kelly" skrev i meddelandet news:ML5gf.557262\$tl2.79939@pd7tw3no...
I just want it to run on single phase, if it draws a few amp's more isn't a problem.
The full spec's:
380V 50Hz 0.1 Hp 660rpm Y/D 380/220V 0.4/0.7A
• posted
Thank you- try it.
• posted
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That's just a small motor. If you find you need real 3-phase, there are many companies that can be googled that provide converters.
Probably you will want the smallest one possible. Is there a special reason that a motor this small needs to run on 3-phase? Beachcomber
• posted

My problem as well. I have a 2HP 3 phase motor in my table saw that I want to run from my home. It's 208-220/440 also. It's a question of whether to use a static or rotary phase converter. A static converter will allow the motor to run at @ 2/3 it's rating. A rotary converter is more efficient but you need a second 3 phase motor at the same or greater HP rating to act as the "generator" Here's a link for you to look at when you have the time.