Electrical Machines
The armature mmf of a DC machine has

  trapezoidal space distribution and is stationary in space.
 stepped distribution and rotates at the speed of armature.
  triangular space distribution and is stationary in space.
  triangular space distribution and rotates at the speed of armature.

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
Consider the following statements about commutating poles which are fitted on most large dc Shunt motors: 1. The commutating poles are placed in the geometric neutral plane and their number is usually Equal to the number of main poles 2. The winding on the commutating poles is connected in series with the shunt-field winding on the main poles 3. The polarity of the commutating pole must be that of the next pole further ahead 4. The commutating poles neutralize the reactance voltage produced in the coil undergoing Commutation. Of these statements,

 2, 3 and 4 are correct
 1, 2 and 4 are correct
 1 and 4 are correct
 1, 2 and 3 are correct

ANSWER DOWNLOAD EXAMIANS APP
MORE MCQ ON Electrical Machines