Electrical Machines
What will happen if the the supply terminals are reversed in case of a DC shunt motor?

 The motor will stop.
 The motor will run much faster in the same direction.
 The motor will run at its normal speed in the same direction as before.
 The motor will run in reverse direction.

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Electrical Machines
The introduction of interpoles in between the main poles improves the performance of a dc machine, because

 the inequality of air-gap flux on the top and bottom halves of the armature is removed
 a counter-emf is induced in the coil undergoing commutation
 the flux waveform is improved with reduction in harmonics
 the interpoles produce additional flux to augment the developed torque

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Electrical Machines
Two of supply terminals to a 3 - Φ induction motor get interchanged during re-connection after normal maintenance. When switched on the supply, the motor will

  rotate in the same direction as before maintenance.
  not start at all.
  get heated and damaged.
  rotate in direction opposite to that before maintenance.

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