Electrical Machines
The direction of rotation of a 3 - Φ induction motor is clockwise when it is supplied with 3 - Φ sinusoidal voltage having phase sequence A - B - C. For counterclockwise rotation of motor, the phase sequence of the supply should be

 B - C - A or C - A - B.
 C - A - B.
  A - C - B.
 B - C - A.

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,

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

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
Compensating windings are used in DC generators

  to provide path for the circulation of cooling air.
  mainly to reduce the eddy currents by providing local short circuit.
  to neutralize the cross magnetizing effect of the armature reaction.
None of these

ANSWER DOWNLOAD EXAMIANS APP
MORE MCQ ON Electrical Machines