Electrical Machines
In a DC machine the armature mmf is

  stationary with respect to armature.
  stationary with respect to field poles.
 rotating with respect to field poles.
  rotating with respect to field poles as well as armature.

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Electrical Machines
A bipolar dc machine with interpoles has a main-pole flux of ф per pole and an interpole flux of Фᵢ per pole. The yoke of the machine is devide into four quadrants by the main-pole axis and The commutation axis. The flux-distribution in the quadrants will be

 ½ ( ф + фᵢ ) in two adjacent quadrants and ½ ( ф - фᵢ ) in the remaining two quadrants
 ½ ( ф + фᵢ ) in all the four quadrants
 ½ ( ф - фᵢ ) in all the four quadrants
 ½ ( ф + фᵢ ) in two diametrically opposite quadrants and ½ ( ф - фᵢ ) in the remaining two Quadrants

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