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AC 1 Phase Induction Speed Control


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Hey Guys,


I'm sorta new to motor control, and have a question.


I have a 1/2 HP 1 Phase compressor motor (capacitor start) that runs at 1740 RPM. I need this motor to slow down a lot, so I was trying a few things.


I bought a rotary switch thinking that less voltage would slow it down, but it just appeared to lessen the torque, it still spun at the same speed. After some research, I guess I need to modify the input frequency of the power from 60hz to less.


I'm more into DC theory, so this AC stuff is a little confusing for me. Is there a simple way to modify the frequency of the power but keep the same voltage (or close to it)? Will modifying the power frequency change things the way I want? Or do I have to do some modifications to the internals of the motor?


Thanks in advance for any help.


- Travis

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  • 3 weeks later...

Hello Lizard,


The best advice I can give you is to replace the existing motor with a 3 phase unit and utilise a single phase input, three phase output variable speed drive to control motor speed.


Under this arrangement you will achieve the speed control you require without the need to upgrade your supply to 3-phase.




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