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Motor Poles

  1. Oct 3, 2007 #1
    Motor "Poles"

    Hi, I am currently studying induction motors and I am little confused about 1 concept. I know it is probably a really basic question.

    What is meant by "2-pole", "3-pole" or a "4pole" motor?
  2. jcsd
  3. Oct 4, 2007 #2

    A magnet as 2 poles, so a 2-pole motor is like a magnet spinning on a shaft perpendicular to the poles. A 4-pole motor is like 2 magnets
  4. Oct 4, 2007 #3
    That was my guess but I got confused when I saw this article:


    "Almost always, however, the rotor will have three poles rather than the two poles"
  5. Oct 4, 2007 #4
    A motor with three poles would have three windings in which you would excite the winding in a sequence to get the motor to turn. I am not sure what the best analogy to use is but a stepper motor would be a good chose in my mind. The armature is made up of teeth and depending on which winding in energized is where the teeth line up to. Successively energizing the motor windings will line up the teeth progressively with the windings causing the rotor to turn. It is more complicated with induction motors but essentially you are inducing a current into the armature which will constantly oppose or attract (I can’t specifically remember which) the action of the energized winding or "pole" and will be virtually the same thing.
  6. Oct 5, 2007 #5
    There are 3-PHASE induction motors. I never heard of a magnet with 3 poles
  7. Oct 5, 2007 #6
    There are also 4-pole (Quadrupole) magnets used in focusing ion beams. There are also sextupole magnets (6-poles). (I would post a picture but I dont have permission to post it) a quadrupole magnet is actually 4 magnets with their poles radialy placed about an axis with the other sides of the magnets connected with an iron core. Here is a link to a DC motor with three poles on its armature. http://www.ztrains.com/pages/tech/3_pole/3pole_1.html [Broken]
    As you can see it is similar to my description of the quadupole magnet accept the magnets have their poles facing outward and joined in the center. This is how that terminology applies to motors and magnetic assemblies.
    Last edited by a moderator: May 3, 2017
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