fan control

do other people out there use the dimmer modules for fan speed control? if so, do you have problems with the fan motors being noisey.

regards
grant

 

Yes I tried it once, even though I knew what the results would be.

Triac type controllers are fine for resistive loads but the sharp edges of the modified AC waveform causes harmonics that make the motor windings hum (very loudly in some cases).

Usually sweep fans use a capacitor based switch (3 speed) that lowers the amplitude but keeps the waveform intact, thus eliminating any hum.

I never persisted with the problem, but the answer is to modify one of the capacitive type controllers and replace the switch somehow with a c-bus controlled unit. You will still only be able to select 3 speeds though.

I'm sure one of the more experienced people here will have the answer.

Regards

Rohan

 

I've found that the best way to control a ceiling fan for domestic applications is to take a capacitive-type fan control (the one that comes with the fan in my case), and break off the capacitor block. The capacitor is compact and will fit under the cowl of the fans I have used so far. The capacitor is wired with the common connection to the motor active and then two switched actives can be run back to two relays on a C-Bus relay unit. Crude, but effective. The result is a three speed (plus off) fan. Using 2 keys of a C-Bus key unit will allow the small capacitor element, the big capacitor element, or both capacitors to be connected. The top speed is close, but not quite the full motor speed, but the low speeds are quiet as a hamster on a freshly oiled exercise wheel.

This solution requires two wires to run back to the relay. I've also run a single wire from the fan and mounted the capacitor block at the relay, but that is a little messy in the switchboard.

Downsides: two relays and two keys used.
Upsides: quiet fans and you can tell at a glance what the fan speed setting is from the key LEDs.

Don