How to change the single phase motor speed

My first choice would be to replace the motor with a 3 phase version and add a variable speed drive.

It is possible, in principle, to modify a single phase, capacitor run motor (remove the capacitor and bring its winding to the outside) to run variable speed on a 3 phase drive, with the addition of a transformer to derive the capacitor winding's phase. I haven't yet done this.

If variable can mean slow, medium or fast, there are motors that do this by switching windings. Perhaps replacing the motor with one of these would be good enough.

We manufacture three roll mills. Our lab model comes with only single phase power supply (750W). Once a while, our customers would ask variable speed. We have variable speed options on other models that use 3-phase power (using Siemens VFD).

Last week we got another order from a customer in UK. Normally we ship our machines to UK with 240V, 50 Hz, 3 Phase motor. To achieve variable speed, we used VFD. It just happens this week they request the power supply to be single phase.

A quick search in Wikipedia shows there is single phase VFD too.

Thanks,

Ken

Opportunities are never lost. The other fellow takes those you miss.

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There are lots of 1 KW, 3 phase VSRs that are powered by single phase input.

For instance:

Universal motor? That runs on AC/DC and you can vary the speed simply by varying the voltage to it using a cheap DC drive.

You must be a shill for Sears-Mart and the over hyped Universal motors used in their products.