Use of Dimmer switch as Fan regulator

Why not?

Is it a solid state dimmer?

can anyone explain how 3 votes go to Good Answer for this post when he did not even read the question correctly?! the post stated:

"this particular dimmer can even handle up to 1000W, but fan capacity is only 75W..." yet the response treats it as tho the DIMMER is rated 75watts?

yeah --- the basic info, otherwise, is ok. But (imho) posts like this one, over and over again deserve nothing more than a pointer to one of the dozens of identical threads already posted, with the suggestion of using that fine "Search" tool that CR4 provides.

beans

I agree, with one note to add. The main difference between light dimmers and fan speed controls for shaded pole motors is the "Minimum Speed" setting. If the fan does not actually start turning when turned on, it will overheat and cause serious problems. The minimum speed is set to be sure that at the lowest setting, the fan actually starts turning. Light dimmers do not have that capability, thus serious danger of overheating problems, as mentioned, up to burning the house down. -- JHF

Regards

To your answer I like to add:

Most of the dimmers come in Full/speed or light start & by varying the control goes to lower speed or light.

However may be the types you refer to. But in consumers market the sophisticated devices are not on sale about which the poster of the question is talking about.

So my my answer will be in the context of question.

However one of the friends' view about the bigger fans is valid, that for those special

speed control is required.

sorry, but i don't think that the fan will start if you use a dimmer switch. the voltage on fan it will be less than it should be because the rest will be on the dimmer.the current it will be changed too in the circuit. this fan cannot change it's speed unless you make some changes in the coil. i think you can use the dimmer switch on a dc engine but connected on the mobile coil.

I thought that all dimmers use full voltage, but they chop out parts of the cycles so less power comes through, and thats why they are so noisy in RF/ all the square wave chopps.

the lower the setting the more the percentage of the cycle is chopped out.

and if i remember correctly a motor doesn't like square waves either

Joe

hi aindatissa. you have no problem in using the dimmer switch as a fan voltage regulator. infact it uses the same principle of cutting down the pwm of voltage source as that was done in the triac which was using in modern day fan regulators.

Everyone is correct. Dimmers should not be used as fan controllers, the engineering is wrong. Why do you think we came up will variable frequency drives for motors, if all we had to do is put a large dimmer to control the speed. I have seen dimmers used for small fans before but everyone of them developed problems in the life of the fan. So go ahead and use a proper fan speed controller for the fan and save yourself some headache.

Don't do it!

I had someone who wanted me to fit a ceiling fan on a dimmer once.

when it ran the fan hummed like a good'un and the lights flickered.

Yes you can !! . If you can limit the underspeed not to block in some way. you can use a dimmer. Otherwise the motor burns.

Even applications are available, it is not a good idea to use a dimmer as a fan speed regulator.

Fan motors are Induction motors, with cage type rotors. Theoretically their speed cannot be externally adjustible. They have a narrow interval of slipping range, and later they fall under turning moment, they blocked and burn.

Some manufacturers use dimmers for those types of fan motors. Dimmers are only make some little speed regulations until the bottom level of the permissible slipping range. More regulation causes the motor shaft to block and burn.

(Some special induction motors are built with magnetic leakage in their iron cores. Those motors can stand blocking more than others. Some special servo adjustment motors remain blocked for many hours without burning. Those are all exceptions )

The output of the dimmers are not sinuswave. Dimmer will feed your motor not smoothly but in pulses. You will hear the humming sound when you run the motor.

The safe way to control the speed for such an induction motor like yours is driving it over an frequency inverter (or converter). Voltage and frequency increases relatively to speed up the motor and decreases in the same manner. Pls note that frequency inverters are expensive products, to evaluate if it is worth to buy.

Note : For the Universal motors with carbon brushes, dimmers are used succesfully for any motor. But obviously your fan is not an universal motor.

Regards

Did it work?

How about not a dimmer. but a true Variac. where it is still a pure sinewave, just lower voltages?