In article ,
"Tom Biasi" wrote:

The operator's manual states that the fan must not be used with a solid
state speed control device. I understand that to mean that I must not
simply attempt to vary the voltage, i.e. from 120VAC to 90VAC for
example. I understand that this may cause the amperage to rise, and all
sorts of nasty things may occur after that.

I don't know the details. It would be mighty peculiar controller that
would change frequency without changing voltage. As a general rule, you
should be able to run typical induction motors below synchronous speed
by changing the frequency to less than line frequency. BUT you have to
lower the voltage in proportion to the frequency so as not to get
excessive no load current.

If you do that, the only consequence is lower maximum torque. For a fan,
that should not be a problem.

This assumes that between your own controller and the actual motor
itself there is no other controller or circuitry that does not like
yours.

--

Sam

Conservatives are against Darwinism but for natural selection.
Liberals are for Darwinism but totally against any selection.