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,

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

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
Torque angle of a synchorous machine operating from a constant voltage bus is usually defined as the space angle between

 Stator mmf wave and resultant mmf wave.
 Rotor mmf wave and resultant flux density wave.
  Rotor mmf wave and stator mmf wave.
 Stator mmf wave and resultant flux density.

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
In a synchronous motor when the rotor speed exceeds the synchronous speed during hunting

  the damper bars develop induction motor torque.
  the damper bars develop synchronous motor torque.
  negative sequence currents are generated.
  the damper bars develop induction generator torque.

ANSWER DOWNLOAD EXAMIANS APP
MORE MCQ ON Electrical Machines