ceiling fan buzzing

A 120vac ceiling fan motor uses a pancake induction motor which can't be used with DC. I have seen wall rehostats for sale at hardware stores to be used with ceiling fans. Some of them have two controls, one for the ceiling fan lamp light and another for the fan. These can be installed inside a 2x4 box. The ones I have seen are manufactured by Ace Hardware.

Good luck!

Are you sure it's the speed controller that's causing the problem. I wonder if you ran it at full speed without the blades and the 'whoosh' they cause you might still hear the buzz/hum.

Perhaps as an experiment power it off a resistor for a couple of sec> We have a ceiling fan in our bedroom that we sometimes like to run at

Is the speed controler made for induction motors?

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It's easy to think outside the box, when you have a cutting torch.

How would a speed controller made for induction motors differ from say an ordinary lamp dimmer?

Lamp dimmers are simple phase controllers. They aren't designed for inductive loads. That's why most light dimmers can't be used on Florescent lights. They can cause the motor to overheat at some speeds, and cause it to be noisy or erratic at low speeds.

Leviton makes variable speed fan controls with a slider to set the speed. You can get them at HD, Lowes or a lot of other building supply stores.

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It's easy to think outside the box, when you have a cutting torch.

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Thanks Michael for sending me those dimmer links. They are pricey though... Lenny

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I did find the Leviton but it may not be a continuously variable unit. I'll have to go look at them. Lenny

I had a fan that was noisy like that, and stuck a 5-10 uF capacitor in series with the motor. You can't use the dimmer - so you need a switch to hook the fan either to the controller or the series cap. It runs quite slowly, and no buzzing. Make sure the capacitor is designed for line use ..... 250vac or 600vdc should be OK. If it fails, the fan will just run at full speed. The only worry would be if it were to get hot say from internal arcing or something wierd like that. To be one the safe side use a U/L approved or type Z capacitor. You can cause the cap and inductance of the fan to resonate.... That will cause voltages greater than the line voltage to appear across the fan motor, and it go fast, and overheat. Try a few capacitors, starting at 1uf, and increase until you get the speed you want. Some fans have a switch that gives 3-4 speeds, with a series cap, you can effectively get a much slower range of speeds, and thereby not need to use a dimmer type speed controller.

Paul G.

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That should be a "X" type capacitor, not a "Z" type. It's questionable that you need either X or Y types.

From an Illinois Capacitor blurb on capacitors: " These capacitors are divided into 2 classifications, X and Y. X class capacitors are capacitors that are connected line to line and in the event of failure of the capacitor the potential for electrical shock is not present. X capacitors are further subdivided into three subcategories X1, X2 and X3. X1 capacitors are used where the peak voltage the capacitors will be greater than 2500 volts and less than

4000V. Class X2 capacitors are in applications where the peak voltage is equal to below 2500 volts. X3 capacitors are used where the peak voltage is less than or equal to 1200 volts. X2 capacitors are the most common. Y capacitors on the other hand are connected from line to ground. They are typically a very low capacitance value. In the event a Y capacitor fails the potential for electrical shock is present. Y capacitors are also subdivided into four subcategories, Y1, Y2, Y3 and Y4. Y1 capacitors are used with voltages up 500Vac, Y2 are used with voltages up to 300Vac,Y3 are used with voltages up to 250Vac and Y4 capacitors are used up to 150Vac. X class capacitors are rated up to 660Vac and Y capacitors are manufactured with voltage ratings up to 440Vac. X class capacitors are manufactured with a variety of dielectric materials. This includes polyester, polypropylene, ceramic and paper while Y capacitors are typically produced out of ceramic and paper dielectrics. With the exception of ceramics the capacitors are produced using metallized materials and may be impregnated with epoxy or mineral oils."

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I'm thinking that the fan draws about 1.0 amp. Therefore that current would be passing through the capacitor. I do have lots of capacitors as well as a 5 position tapped transformer type speed control from another fan. The problem with that control though is that slow speed is not slow enough. Perhaps I could put the capacitor in series with slow position and see what that will do. I never thought of doing this. Lenny

Much depends upon what type of motor is in the ceiling fan. There are more than one type of AC motors without brushes.

Klem/Lenny hasn't revealed what type of AC motor he's referring to.. nor anything specific regarding the "generic" controller that wasn't supplied with the fan.

-- Cheers, WB .............

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Well I don't really know what kind of a motor this is. I purchased the fan as new surplus and it never came with a controller. It looks like my other fans I use in the house but from a different manufacturer. There are three metal blades, very plain looking "airplane propeller" style, hangs from the ceiling about 1 foot down. The controller for the other fans looks like a tapped autoformer with a 5 position switch. Lenny

Ceiling fans sold in Australia, typically switch between a couple of non polar mains rated capacitors in series with the motor. a few UF from memory. can look later at one if you really want to know. (note here is 50hz, you might need different values for 60hz).

The other type of speed control that is used here - but not as common is the same as a light dimmer except there is a resistor in series with the pot to ensure a minimum speed to prevent the motor from stalling and overheating due to insufficient speed setting for it to start rotating from a dead stop.

Here in PY there are lots of ceiling fans from Wahson/China.

230V/50Hz

They use a separate autotransformer in an aluminium housing (15x9x4 cm) as controller.

It is in series with the motor and has 7 taps and a turning switch with weird numbered positions from 0 = off and 1=max ... 7=slowest speed! The motor so gets between 230V and down to some 80V.

My 5 Wahsons did not buzzing, even in slowest speed.

However I have 2 fans (also made in china) with no external controller but a small hanging line which switches between 3 different speeds by taping different positions in the motor winding. They both are buzzing in speeds below max. I think thats in the remaining active sectors of the winding.

None of these motors have brushes.

Saludos Wolfgang

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I would like to try the trick with the capacitor in series with the slowest tap on the speed control however I am a bit unclear as to how to "size" the capacitor. By "size" I mean that it seems like if the motor draws one amp for example, (and I will confirm that first), I will need a capacitor that can handle more than that amount of current flowing through it. I remember dealing with this sort of thing in electronics school, but admittedly that was a very long time ago and I've forgotten how to work this out.

For instance, I have a 4uf 250V AC capacitor that I would like to try. This part is designed for motor starting. This is a fairly large capacitor. The control box measures approximately 8" x 6" X 3". Most of that space is taken up by the switch and transformer. There would not be room inside for anything this large. Or do I need to use anything this large? Thanks, Lenny

Try if it works and the Motor starts in this position. If not, it might become very hot after it stops at a PWR out and return of PWR.

In the worst case, you will see firefigters at your home after you return from a party :)

Saludos Wolfgang

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Meine 7 Sinne:
Unsinn, Schwachsinn, Blödsinn, Wahnsinn, Stumpfsinn, Irrsinn, Lötzinn.
Wolfgang Allinger   Paraguay             reply Adresse gesetzt !
ca. 15h00..21h00 MEZ  SKYPE:wolfgang.allinger

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Why don't I just burn my house down before I leave for the party. That way at least there won't be any surprises when I return.....Lenny

The above should give you some ideas of the speed control methods used for ceiling fans. Most of the infinately variable ones will end up with noise. Changing the caps will get you a lower speed. Notice that there are different methods and not one size fits all. Also at

the spped switches are quite pecular.