Electrical Machines
The armature mmf in a dc machine is 1. stationary with respect to field poles 2. stationary with respect to armature 3. rotating with respect to field poles 4. rotating with respect to armature From these, the correct answer is

 1, 4
 2, 4
 1, 3
 2, 3

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Electrical Machines
An inverted V curve of synchronous motor shows variation of

  power factor and DC excitation at constant load.
 supply voltage and field current at constant excitation.
 supply voltage and excitation current at constant load.
 power factor and supply voltage during hunting.

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