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Air gap flux density in DC machine

  1. Dec 15, 2012 #1
    Why is it that the air gap flux density is flat topped at no load. What happens to it's shape when machine is loaded?
  2. jcsd
  3. Dec 16, 2012 #2

    jim hardy

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    Is flux = mmf/reluctance? Is air gap constant under pole piece?

    Have you looked up "Armature Reaction" ?

    Unloaded, the only MMF is that from the field current. When armature current begins to flow, armature mmf changes shape flux .

    Surely your textbook shows diagrams...
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