If I had a 3-phase RTU exhaust fan controlled by a 120V contactor coil, what are my options as far as speed control of the motor?

What if the control circuit operated at 24 volts?

And finally, does a motor need to be rated for variable speed for a low, medium, and high speed controlling device?

Thanks in advance.

3 phase? Variable Frequency Drive.
Use the 24 VDC control signal(s) to select various pre-programmed speeds.

I do not know if the VFD can be remote mounted close to the fan or if it has to be mounted inside, close to the load center.

Larry C

Nevermind my original post. I'm not even sure what I was thinking when I asked if a control circuit could determine the speed of a motor. I was asked today about installing a speed control in a pizza place to control an exhaust fan. Just nevermind. It's all good.