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ceiling fan speed control

Discussion in 'Electronic Basics' started by Fritz Oppliger, Jan 23, 2004.

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  1. I installed a pleasantaire brand fan in my kitchen. It runs rather fast,
    the calendar wants to leap off the wall.
    It has a four wire connection, it is made to be reversible.
    White and Black always neutral and hot.
    Blue and Red join neutral and hot respectively but are reversed to change
    direction.

    I tried halving the power (?) by inserting a 4006 diode into the hot
    supply.
    I have seen this trick with other "adjustable" appliances .
    That slowed it down too much.. it barely moves and hums loudly.
    So before I cause the thing to burn up I figure I'd ask... what is the
    bestest way to tame this hurricane?
    Thanks in advance
    Fritz
     
  2. This fan is a strictly AC operation. You may be able to slow it
    without overheating it by lowering the applied voltage. An old
    fashioned fluorescent lamp ballast inductor (the kind you use with a
    starter device) and available at many hardware and electrical supply
    stores) may work. Or you might use a step down transformer or
    autotransformer. Do you have access to a variac (variable
    autotransformer) that you could experiment with to find if this
    solution is functional? If not, you might just wire a lamp socket in
    series and experiment with different wattage lamps as a means of
    temporarily reducing the voltage. After you know the voltage needed,
    and the current the motor draws at that voltage, you are in a much
    better position to select a means of supplying that voltage.
     
  3. bj

    bj Guest

    Hi
    What's wrong with using a light dimmer switch-without all the
    messing
    about above-and you get total controll?
    Several years ago a friend of mine had a similar problem with a chimney
    extractor fan and I got him a dimmer switch and it's been working for
    5+years. Seem to remember that there was a problem with dimmer switches
    and inductive loads and/or current consumption but I'm sure you can get one
    that will do the job

    BJ
     
  4. There are speed controls for ceiling fans. They are not made as light
    dimmers, even though they may look like one. Any place that sells the
    ceiling fans should have the controls. The chimney extractor fan your
    friend had may have been a "Universal", or in other words, used brushes
    and didn't care if it ran on AC, or DC pulses.
     
  5. bj

    bj Guest

    Hi
    It was that bit at the bottom that prompted this post

    you're quite right that the motor my friend has is brushed and I don't
    really
    have a clue how modern motors work.However I just dug out my 1977
    electronics book and I see (from the phase angle waveforms for a
    triac) that with a little bit of smoothing, your normal
    dimmer switch could maybe controll one of these motors
    Any ideas?

    BJ
     
  6. JeB

    JeB Guest

    I've got the type of dimmer promoted as a motor speed controller. Starts
    at highest output after switched on vs lowest of a dimmer. With my
    fan/controller combo there's loud ac hum once you get below about 2/3
    speed and before hitting about 1/3 speed. (ie ... hum at mid speeds). I
    just use one side or the other of hum and still find it useful. Don't
    recall where I bought it but probably an online electronics outfit. I
    suppose a normal dimmer might work as well ... i don't know that the
    motor controller does anything different as far as waveform. And I'd
    imagine the manufacturer offers some sort of speed control too ... but
    likely expensive.

    (Wouldn't an approach that chopped up the waveform more be less likely
    to cause hum? or it might just be higher frequency)
     
  7. It might work, but since dimmers are made specifically to control
    resistive loads and ceiling fans are very low power factor motors
    (very inductive loads) there can be all sorts of problems with dimmer
    control from producing DC output (which will quickly burn the motor
    up) to jumping from very low speed to full speed (losing control).
    These problems are all addressable, but I didn't want to suggest
    method that was problematic to a beginner.
     
  8. Dan Akers

    Dan Akers Guest

    Fritz wrote;
    "I have seen this trick with other "adjustable" appliances . That slowed
    it down too much.. it barely moves and hums loudly. So before I cause
    the thing to burn up I figure I'd ask... what is the bestest way to tame
    this hurricane?"
    ______________________________________
    Re;
    For U.S., 120V/60Hz ceiling fans, the typical scheme for speed control
    is a four-position, pull-chain switch on the units I've tinkered with.
    The switch positions are "off", "L to 1", "L to 1&2", and "L to 3",
    where "L" is the line side voltage input. The motors are capacitor run
    devices; meaning they have two coils; in switch pos. #3 (hi speed) one
    winding is tied directly across the line supply and the other tied in
    the same fashion EXCEPT there is a 4 to 6 uF run cap. in series to
    accomplish the necessary phase displacement for a rotating field. Speed
    reduction is accomplished with two other capacitors; usually 4 and 5uF,
    used as "zero power" voltage dropping devices. Thus, in switch position
    1, both motor coils are powered through the 4uF series cap; in position
    2, the 4 and 5uF cap are paralleled for 9uF total series dropping
    capacitance. Note that the run cap above is always in the circuitry,
    regardless of speed selected. I'm surprised the motor ran at all with
    the series diode!!
    In some fans there are two distinct capacitor devices; one, the "motor
    run cap" and the other a dual capacitor device in one package for the
    series dropping caps. Some even have all three caps in one unitized
    package.
    Having said all of that, these caps can be purchased at department
    stores and hardware stores in the ceiling fan section. So, you might
    try installing one of these in series with the motor power supply lead
    to reduce the speed.

    -Dan Akers
     
  9. Mark Monson

    Mark Monson Guest

    There are two types of ceiling fan speed controls. The cheap ones make the
    motor hum at reduced speeds. The expensive ones don't. Buy a control made
    by Hunter or Casablanca. They work quietly on even cheap fans.

    MM
     
  10. And if I add into the mix the fact that is this all running on inverter
    power, i.e. modified sinewave / glorified squarewave (take your pick)...
    what do I get?
     
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