Electrical Machines Multiple Choice Questions and Answers

11. Which of the following motors has a high starting torque?

1. AC series motor
2. DC series motor
3. Induction motor
4. Synchronous motor

12. The starting winding of a single-phase motor is placed in

1. Rotor
2. Stator
3. Armature
4. Field

13. In a DC series motor increase in load current results in

1. Decrease in speed
2. Increase in speed
3. Better commutation
4. Increase in the back emf

14. Which DC motors has approximately constant speed?

1. Series motor
2. Shunt motor
3. Cumulatively compound motor
4. All of the above.

15. An electric machine will have high efficiency when

1. input/output ratio is low
2. Reactive power is more
3. kWh consumption is low
4. losses are low

16. Inter poles in DC machines are provided to reduce

1. Sparking
2. Armature reaction
3. Iron loss
4. Efficiency

17. DC motor yoke is generally made of

1. Wood
2. Copper
3. Aluminum
4. Steel

18. The output of a rotating electrical machine is limited by

1. Size of the machine
2. Peripheral velocity
3. Temperature rise
4. None of the above

19. The dimensions of a dc machine primarily depend on

1. kW output
2. Work done per revolution
3. Exposed surface
4. None of the above

20. Skewing of rotor slots helps in

1. Improving beat transfer
2. Reducing noise
3. Suppressing undesirable harmonics
4. all of the above