Electrical Machines – Multiple Choice Questions (MCQs)

1. 13. Which type of induction motor has a higher starting torque?

   • A. Squirrel cage
   • B. Slip ring
   • C. Both have same
   • D. Depends on winding

2. 14. Cogging in an induction motor occurs when:

   • A. Number of rotor slots is equal to number of stator slots
   • B. Motor is overloaded
   • C. Voltage is too low
   • D. Motor is lightly loaded

3. 15. Crawling in an induction motor is caused by:

   • A. Harmonics in the supply voltage
   • B. Under-voltage
   • C. Over-current
   • D. Loose connections

4. 16. A synchronous motor can operate at:

   • A. Lagging power factor
   • B. Leading power factor
   • C. Unity power factor
   • D. All of the above

5. 17. The speed of a synchronous motor is:

   • A. Dependent on load
   • B. Independent of load
   • C. Proportional to load
   • D. Inversely proportional to load

6. 18. Synchronous motors are not self-starting because:

   • A. They have no starting winding
   • B. The stator field and rotor poles are locked at zero speed
   • C. They need DC excitation
   • D. Their starting torque is zero

7. 19. What is the main application of a synchronous condenser?

   • A. To improve power factor
   • B. To regulate voltage
   • C. To generate active power
   • D. To provide mechanical power

8. 20. The V-curves of a synchronous motor show the relationship between:

   • A. Armature current and field current at constant power
   • B. Armature current and power factor
   • C. Field current and power factor
   • D. Speed and torque

9. 21. Which test is used to determine the regulation of an alternator?

   • A. Open-circuit test
   • B. Short-circuit test
   • C. Zero power factor test
   • D. All of the above

10. 22. Alternators usually have salient poles on the:

    • A. Stator
    • B. Rotor
    • C. Both stator and rotor
    • D. Neither stator nor rotor

11. 23. The frequency of the generated EMF in an alternator depends on:

    • A. Number of poles and speed
    • B. Number of turns
    • C. Flux per pole
    • D. Armature current

12. 24. Parallel operation of alternators is advantageous for:

    • A. Increased reliability
    • B. Increased capacity
    • C. Improved efficiency
    • D. All of the above