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Wires from an AC motor

  1. Aug 7, 2008 #1
    AC motor from washing machine, has 11 wires from it. Aside from earth I have no idea what they are however I have observed:

    If the white+blue OR the red+orange wires are bought into contact then the shaft becomes hard to turn AND I can get a few small sparks by spinning the shaft and quickly touching these wires together.

    So I guess these have something to do with the power. Why four power wires though? Can someone explain AC motors better than what I've read on WIki?

  2. jcsd
  3. Aug 7, 2008 #2


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    Perhaps the reason for 4 power wires is the same as why some transformers have 4 wires: to allow for either 120V or 240V ac input voltage. You wire the line voltage to the input wires one way if it's 120V, and a different way if it's 240.
  4. Aug 7, 2008 #3


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    You have starter windings (to get the rotor spinning in the right direction) and you have running windings. In addition, as Redbelly suggests, you have the option to power the motor at two different voltages, depending on application. Here's an introduction.

  5. Aug 8, 2008 #4


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    Most likely they are for direction and speed. I've noticed that most appliances have a wiring diagram hidden inside a panel for the technicians. Perhaps you have one somewhere too. If not, check out the manufacturer's website. They'll probably have a download for it.

  6. Aug 11, 2008 #5
    The speed of the motor is determined by the number of pole pairs designed into it. AC motors are generally designed for one speed only although multi-speed AC motors are available.

    A 2-pole motor (1 pair of poles) will have a synchronous speed of 3600 rpm when driven by 60 Hz supply [3000rpm when driven by 50Hz]

    1800 rpm when it has 2 pole pairs.

    1200 rpm with 3 pole pairs.

    900 rpm with 4 pole pairs.

    720 rpm with 5 pole pairs.

    600 rpm with 6 pole pairs.

    514.285714286 rpm with 7 pole pairs.

    450 rpm with 8 pole pairs.

    ...and so on.

    The synchronous speeds are those at which a non-synchronous motor produces no torque. The running speeds will be something like...


    depending on the slip the motor.

    Synchronous motors run at full synchronous speeds.
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