What pot should I use to adjust a 200w fan?

[slikvik]

Hi,

I have a fan that the missus bought that has three settings on a dial:

Off
Fast and Noisey
Really Fast and Really Noisey
Incredibly Fast and Incredibly Noisey

This fan could run far slower and still be effective so I would like put a potentiometer in front of the dial.

Trouble is I'm not sure which spec pot to order.

The fan is a Bionaire Bac-19 which is rated at 200w. It's UK powered. I'm also a bit of a 'noob' so any extra advice on this would be great. The closest I have got to this is using ready made pot's to control the fans in my PC.

Kind Regards

Vic

 

[Nigel Goodwin]

It's a completely different situation, you can't control the fan in that way as it's an AC motor.

 

[audioguru]

The fan is a Bionaire Bac-19 which is rated at 200w. It's UK powered.

It destroys bacteria with most of its power. A small amount of its power is for its fan. I am surprised that it has nuclear power! Hee, hee.

 

[Styx]

you sure the fan is an AC fan and not one of those universal commutator type?

find out what type of fan it is and the method of (crude) speed control can be realised.

IF it can be treated as a DC-machine I would just put in a dimmer-switch that is rated for that power

 

[Hero999]

you sure the fan is an AC fan and not one of those universal commutator type?

All fans I've seen are squirrel cage AC motors, universal motors would be far too noisy.

You can't control the speed of these motors with a lamp dimmer circuit, the built in speed controller simply switches different windings to controll the speed.

 

[audioguru]

My 15" 3-bladed 3-speed fan doesnt have anti-bacterial crap to make it hot, it just draws 54W max. It makes a nice cool strong wind.
Its speeds make it quiet, very quiet and extremely quiet.

EDIT: I looked at your fan. It is a high velocity monster, used to inflate hot air balloons or something. No wonder it is noisy. It doesn't have an anti-bacterial heater.

 

[Styx]

All fans I've seen are squirrel cage AC motors, universal motors would be far too noisy.

You can't control the speed of these motors with a lamp dimmer circuit, the built in speed controller simply switches different windings to controll the speed.

damb, if it was slip-ring could of put a variable resistor to control the slip.
only way to control the speed of a squirral cage is through V/f or vector control.

since they are not an option and there must be winding taps no way then

 

[Analog]

Use a Variac.

 

[zevon8]

Ok, this is kinda reaching, but here goes. Since this fan is basically a big industrial type job akin to a aircraft propeller, how about blipping the throttle like they used to do on piston powered planes. Maybe some form of burst control firing done to keep the thing coasting along at a slower speed?

In-elagant? maybe, but were talkin 19" all steel air re-arranger here, not exactly sublte.

 

[Dr.EM]

I have something that looks similar but is only 90W. It an 18" "power fan" from Homebase, don't seem to sell it anymore but I got it because it looked better built than most (after a previous air cooler started buzzing). It's not too loud on the lowest, but an even lower setting would be nice sometimes.

 

[Hero999]

Use a Variac.

I wouldn't recommend this, undervoltaging an AC motor can actually casue it to overheat as the increased slip would cause excessive current draw.

how about blipping the throttle like they used to do on piston powered planes. Maybe some form of burst control firing done to keep the thing coasting along at a slower speed?

I don't know if that's a good idea either as the motor draws a high curent every time it starts and pulsing it on and off could also cause it to overheat.

 

[Overclocked]

You would need One hell of a Big Resistor to control 200W of Power. You Could use a Dimmer thingy for lights. In Theory It COULD work...Of course, you could always open it up, and modify it to give more power.

 

[zevon8]

...
I don't know if that's a good idea either as the motor draws a high curent every time it starts and pulsing it on and off could also cause it to overheat.

Ya you're probably right, the inrush would likely make it a no go. I was thinking that maybe if the rotor was already spinning it would energize in a "non-stalled" state if you know what I mean.