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Armature Diameter formula question

  1. Jun 20, 2010 #1
    so, i'm taking up a course on electrical machine design and our professor gave us the equations for computing the different values required for a given specification.

    here is my problem:

    given these two equations:

    laD^2 = (W/N)(6.079x10^8)/(Byqr) --> eq. 1


    la = pi(D)(r)/(pK) --> eq. 2

    where la = length of armature core (inches)
    D = diameter of armature core (inches)
    r = ratio of pole arc to pole face
    By = air gap density
    W = output of armature (watts)
    N = speed
    p = number of poles
    K = some constant ranging from 0.667 to 1

    equation 1 came from

    W = Z*Ec*Ic

    where Z = total number of armature conductors
    Ec and Ic = voltage and current on the conductor

    Ec = 6.45(Bg)(la)(pi)(D)(r)(N)/60x10^8

    where Bg = average flux density in the air gap under each pole (gauss)


    Ic = q(pi)(D)/Z

    where q = specific loading

    substituting all Ec and Ic in W you can get equation 1.

    and then you can solve for D by combining the two equations.

    my question is where does the second equation came from??
  2. jcsd
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