Electrical Machines
A 230 volt dc motor has an armature winding resistance of 0.5 ohm. Calculate the emf induced by the motor if the full load armature current is 23 ampere.

  218.5 volt.
 220.4 volt.
  None of these.
  120 volt.

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
Consider the following statements regarding the speed control of dc motors : 1. ward-leonard method is suitable forconstant-torque drives 2. Ward-leonard method is suitable for constant-power drives 3. field-control method facilitates speed control below base speed 4. Armature-resistance control method is more efficient than ward-leanard method 5. Field-control method is suitable for constant-torque drives 6. Armature-resistance control method is suitable for constant-torque drives From these, the correct answer is

 1, 3, 5
 1, 2, 6
 1, 2, 5
 1, 4, 6

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
An ideal synchronous motor has no starting torque because

 rotor is made up of salient poles.
  relative velocity between stator and rotor mmf’s is not zero.
 rotor winding is highly reactive.
 relative velocity between the stator and rotor mmf’s is zero.

ANSWER DOWNLOAD EXAMIANS APP