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Universal generators

  1. Jun 12, 2012 #1
    Hello to anyone out there. I am new to this board and I would like to have clarifications on some electrical engineering concepts that i've been confused about.

    The first question i have is in regards to universal motors. I'm confused about how it works?? I realize that if you replace a stationary magnet with an electromagnet and connect either a DC or AC source, it will work. My question is mainly how it works? Maybe I'm just missing something. Thanks.
  2. jcsd
  3. Jun 12, 2012 #2
    Imagine two bar magnets mounted, one above the other, on a vertical axle so that they can spin around but remain separated (poles spinning in horizontal circle). At a given angle between magnets there will be a torque due to opposite poles attracting and like poles repelling. Now imagine reversing the poles on *one* of the magnets. The torque will be reversed right? Now imagine reversing poles on both magnets. The torque will remain unchanged. In a universal motor, both the stator and the rotor are electromagnets, and when the AC current reverses it simply reverses both stator and rotor poles leaving the torque in the same direction.
    Actually an ordinary DC motor (with stator and rotor electromagnets) will work with AC as well, just not very efficiently (eddy currents and stuff). The universal motor is really just a DC motor that has been enhanced to work efficiently with AC.
  4. Jun 12, 2012 #3
    Yes!! Thank you so much for that.
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