personal

I have a customer who would like their fans on a variable speed fan control. He has 30 of these drawing 3.3amps (4 per circuit) at 240VAC. I'm sure they are a capacitor start type. If I am right these cannot be adjusted with a speed control. What do I need to know. I have little experience with FHP motors.

Thanks

micromind

One effective clue is the nameplate RPM. On a split-phase or capacitor-start motor with a 48 or 56 frame, the RPM will almost always be 1140, 1725, or 3450. This isn't necessarily what the motor runs at, just a NEMA standard for small motors. These motors cannot be speed-controlled.

If the nameplate states something like 1075, or 1625, then it's most likely a PSC (Permanent Split Capacitor) motor. A lot of these have more than one winding, with more than two leads brought out, and are two, three, or even four speed. These can also be speed controlled with an appropriate controller.

Split-phase and capacitor-start motors have start switches in them. You can usually hear the click when it speeds up and slows down.

Rob

John Valdes

If they are not three phase or multi-speed single phase motors your customer is out of luck.