Ceiling fan motor speed controller efficiency?


Old 01-24-20, 04:16 PM
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Ceiling fan motor speed controller efficiency?

This is a question just out of curiosity.

I have a old ceiling fan / light with built in controller. This fan is old so it doesn't support LED bulb (old Triac circuit). I bypassed light control circuit and also bypassed fan control circuit and permanently connect to high setting. Motor capacitor was built into the controller, so I had to keep the controller, but just cut power feeding rest of the circuit.
Now the ceiling fan is running with this external controller.

In the process of modification, I learned that the speed was controlled by varying capacitor value. Fan controller was just 2 relays emulating pull chain switch.

I am not so sure how fan speed controller on new controller work.
Is there any disadvantage of fan controller in terms of efficiency?
Old 01-25-20, 04:23 PM
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I believe newer fan controllers use triacs, which cut off part of the AC waveform. Other controllers use capacitors to cut the voltage. Both solutions work pretty much the same way, and both are quite efficient. In theory, there's no wasted electricity in both technologies (though in reality, there's always a bit of loss).

Old old controllers used to be resistive, which would reduce the voltage and the waste would be converted into heat. I've never seen one of these, even in old houses... so I'd imagine they haven't been around for a looong time

So long story short, there's pretty much no loss in fan controllers.

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