Electrical Machines
In a DC machine the armature mmf is

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

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Electrical Machines
Ward-Leonard system for controlling the speed of a DC motor is used where

 Very fine speed control over the whole range from zero to normal speed is required.
 The accuracy in speed control is required.
 The speed in both the direction is required.
 All of above.

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