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rewiring 380 2speed motor for 220v


Jul 17, 2022
Hey there,

I bought a new lathe which is the newer model of my old lathe. The old lathe has a 380/220V motor that could be made to run on the desire voltage by switching from star/delta. I ran it with a VFD. On my new lathe, i was surprised to find the motor was high/low speed 380V, and inside the motor cover, the star/delta configuration indicated the speed at which the motor ran. Can it run on 220v with a VFD? Can I tried the same configuration on my old lathe's motor to test it? Both motors are 3kw. The VFD I have on hand is 220V AC input 1 phase output 3 phase 220v
Can you post a pic of the diagram inside the motor cover?
There are two ways of getting two speeds, completely separate windings for each speed (costly, larger motor) or a "Dahlander" winding which swaps connections - picture a delta winding triangle, with centre taps in each phase - by moving the applied power from "corners" of the triangle to the centre taps then grounding the corners you double the number of effective windings and so poles, halving the motor speed. The Dahlander winding is by design only single-voltage and not at all easy to change!
As above, it's not likely you can change the voltage.

Feeding 220V into windings intended for 380V will deliver you about 58% power, and full rated torque up to about 58% speed.