Ya, and explaining the Why constitutes in a "crash course" in advanced theory, plus physics, along with semiconductor devices, for the person that wants to know "Why" [Linked Image]

In some cases, where the loads are very light, the mixmatch of the two different types will not create major problems or hazards - favoring more towards the motor speed controller being used for Incandescent lamps.

The Primary Thyristor [The actual Triac that the load current flows through and is controlled through] is similar in both applications on low end and small power devices, such as the ones used in the typical house and purchased at Do-It-Yourself type homecenters.
There triggering methods and control techniques are the main difference between the two.

Large power devices are specifically made and designed to that particular application. Mixmatching of these would cause odd operation and possibly quick failure to the control device [???].

What sucks about an Incandescent lamp dimmer [Resistive Only] used for a motor, is it was designed to trigger the True Power parts of a wave, rather than the Volt-Amps [Apparent Power], so the Lag of either current or voltage messes with the control circuit and the Triac - most likely creating rude harmonics.
Another thing is that type of control can set a speed that is at a multiple of the synch frequency. That makes the Induction Motor slow down to below that speed, at which point it can produce torque, which makes it speed up again to once again stall at the synch Hz - over and over and over! Might even jump above the synch speed, then down, then up - due to unstable voltages.

I kind of shy away from explaining the exact Why to someone that mismatched a control device, mainly because you almost certainly have to carry 20 tech books to explain stuff, along with the fore mentioned crash course! But after all is said and done, everything gets shot to heck with the infamous phrase:
"The Guy at The Home Center Said It's OK",
or:
"My nextdoor neighbor said it's OK! He's an Electrical Engineer! I know this because he can run a computer, has a real cool website and rewired his car"
I mean no insult to anyone that is reading this message, whom can use a computer, has a website - cool or lame, or has rewired their own car. This is just something that I hear alot from people and it's kind of funny!

I'll go back to my room now [Linked Image]

Scott SET

Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!