Electronics > Projects, Designs, and Technical Stuff
Slowing down a pedestal fan
wizard69:
It depends upon the motor in the fan if it is even controllable in a simple manner. Since you mentioned "pedestal fan" and many of those are run via capacitor start, induction run motors there is no simple speed control solution. Induction motors rely upon the AC wave form to set a running speed. The speed being related to the synchronous speed of the motor minus the required slippage to generate torque.
Beyond that many motors are simply not designed to run much slower than rated speed due to cooling issues. You could easily be creating a fire hazard if the motor should over heat. I wouldn't slow down any such fan unless it was known that it was safe to do so, at the very least that means a thermally protected motor no matter what type it is. There are some AC motors that can be varied via voltage control but one can't say what type of motor is in this fan.
Electro Detective:
If you're going to use an external fan speed come dimmer controller, I would suggest running the fan at it's full setting,
and use the controller to vary the speed, to avoid any possible conflict/loss/heat issues
that other members can explain better than me
Similar to this I've run variable speed equipped brush powered power tools on the fastest/highest setting,
and used a variac to slow start and 'fine tune' running the way I need, and ramp down to OFF etc
whilst paying attention to current draw and the load on the motor etc
Drop some photos here of the fan and candidate controller so we can see what the scenario is,
and vote it a go or no go.
amyk:
--- Quote from: wizard69 on April 27, 2020, 01:01:04 am ---It depends upon the motor in the fan if it is even controllable in a simple manner. Since you mentioned "pedestal fan" and many of those are run via capacitor start, induction run motors there is no simple speed control solution. Induction motors rely upon the AC wave form to set a running speed. The speed being related to the synchronous speed of the motor minus the required slippage to generate torque.
--- End quote ---
It depends how big the fan is, but a typical pedestal fan would probably not be using a CSIR motor; or anything that has a starting switch, for that matter. A larger one is likely to be PSC, a smaller one may be shaded pole.
glentek:
I've used a triac controller, and it works perfectly, plus it fits where the buttons were.
https://www.ebay.com.au/itm/1PCS-2000W-220V-SCR-Electric-Voltage-Regulator-Motor-Speed-Control-Controller/301920016934
Whales:
--- Quote from: taydin on April 23, 2020, 12:27:29 pm ---Speed settings for such fans are done by putting extra inductance in series with the motor.
--- End quote ---
Really? I thought they used switchable series capacitors. At least that's what ceiling fan control boxes here seem to use.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version