Speed control for 1ph AC motor w/o drive


Thread Starter


Looking to control the speed for a 1ph AC reversing motor without using a drive. Is this possible to accomplish?

Curt Wuollet

Generally, no, most are synchronous and are best speed controlled by frequency. Simple methods like varying voltage run the motor in modes they don't like, like constant slippage. If the hp needed is very low, this may work, but testing is needed to ensure the motor won't stall or overheat. Some special motors can be controlled this way like some ceiling fans. The good news is that vfds are becoming fairly inexpensive.


What is the HP? Is it designed to run varable speed? Does it have a starter switch ( Click after it's turned on/off) these type can only be lowered to 80% then the starter switch kick on.
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Phillip Wade

forget it. You have a motor and that's all. You need something more because you can not make a variable speed system from nothing.