Need a 4 (or 4) Speed Switch for Blower

Discussion in 'General Electronics Chat' started by downplay, Aug 28, 2016.

  1. downplay

    Thread Starter New Member

    Aug 28, 2016
    3
    0
    I have a 4-speed, 9 amp, 120 volt AC blower. Instead of hard-wiring it to one setting, I'd
    like to have it switchable. Is this unrealistic?

    It does not need to be switched under load. Actually, the
    switch will probably be used very little.

    Please help me with the right terminology and specs.

    Is this a single pole, four throw situation?

    How many amps would be adequate?

    If you could point me to any specific examples that could work well would be really awesome, thanks!
     
  2. KJ6EAD

    Senior Member

    Apr 30, 2011
    1,425
    363
    You can't achieve speed variation with a switch alone. For AC motors, speed control is achieved by modifying phase relationships or frequency. We would need some details on the type of motor to be able to help.
     
  3. AlbertHall

    Well-Known Member

    Jun 4, 2014
    1,951
    387
    You can with some motors. The OP describes it as 4-speed so it would appear this is one of those.
    But you are right we still need details of the present motor wiring and how the 4 speeds are achieved.
     
  4. downplay

    Thread Starter New Member

    Aug 28, 2016
    3
    0
    I'm not sure exactly how it is achieved. There are 4 wires each representing different speeds. I thik they are wired to different windings inside the motor.

    I believe in most situations the installers of these motors just pick one to hard wire and the other speeds are left unused.

    It would seem that inductive motors place high amperage demands on switches. I do not need to switch it under load, but I don't know if this changes the situation much.
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,548
    2,373
    Rather than a Industrial single pole 4 position switch you could use a small equivalent wafer switch and four relays.
    This way you can also use a low voltage circuit to switch in the relays.
    M.
     
  6. downplay

    Thread Starter New Member

    Aug 28, 2016
    3
    0
    Yes, I see what you mean, a relay system is what makes sense considering the equipment I can find in my searches. This puts me well out of my depth though!

    In this case I would then need a low voltage power supply rated for the relay voltage, 4 relays, and just about any 1 pole, 5 throw switch?

    When you say "wafer switch," do you mean like the rotary selector switches on Amazon? This is what pops up when I search for those two key words.

    How about this for a relay: https://www.sparkfun.com/products/10924

    The pins on such a relay are kind of smallish. So, I would need some type of wafer board to hold them so I can solder on the high power leads?
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,548
    2,373
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