Electrical Machines – Multiple Choice Questions (MCQs)

1. 49. Transformer oil provides:

   • A. Insulation
   • B. Cooling
   • C. Both insulation and cooling
   • D. Lubrication

2. 50. Harmonics in transformer magnetizing current are caused by:

   • A. Non-linear magnetization characteristic of core
   • B. Linear magnetization characteristic of core
   • C. Load variations
   • D. Temperature changes

3. 51. The efficiency of a small transformer is generally ________ than a large transformer.

   • A. Higher
   • B. Lower
   • C. Same as
   • D. Independent of

4. 52. The power factor of a synchronous generator at no-load is:

   • A. Leading
   • B. Lagging
   • C. Unity
   • D. Zero

5. 53. Hunting in a synchronous machine can be prevented by:

   • A. Damper windings
   • B. Increasing inertia
   • C. Reducing excitation
   • D. Increasing load

6. 54. An overexcited synchronous motor operates at:

   • A. Leading power factor
   • B. Lagging power factor
   • C. Unity power factor
   • D. Zero power factor

7. 55. The field winding of an alternator is excited by:

   • A. AC supply
   • B. DC supply
   • C. Rectified AC
   • D. Battery

8. 56. What is the significance of "voltage regulation" in an alternator?

   • A. Ability to maintain constant voltage under varying load
   • B. Ability to withstand short circuits
   • C. Efficiency of the alternator
   • D. Speed control

9. 57. A universal motor can be controlled by:

   • A. Changing field winding
   • B. Changing armature voltage
   • C. Both field winding and armature voltage
   • D. Neither field winding nor armature voltage

10. 58. Which of the following is a fractional horsepower motor?

    • A. DC series motor
    • B. Three-phase induction motor
    • C. Shaded pole motor
    • D. Synchronous motor

11. 59. The rotor of a three-phase synchronous motor has:

    • A. Slip rings
    • B. Commutator
    • C. Both slip rings and commutator
    • D. No slip rings or commutator

12. 60. What is the main function of carbon brushes in a DC motor?

    • A. To provide lubrication
    • B. To conduct current to the armature
    • C. To cool the armature
    • D. To reduce friction