Electrical Machines – Multiple Choice Questions (MCQs)

1. 61. A transformer is rated at 100 kVA. This rating represents its:

   • A. Active power output
   • B. Reactive power output
   • C. Apparent power output
   • D. Maximum continuous power

2. 62. The maximum voltage induced in a DC generator armature occurs when the coil side is:

   • A. Parallel to the magnetic field
   • B. Perpendicular to the magnetic field
   • C. At 45 degrees to the magnetic field
   • D. Moving along the magnetic field

3. 63. What is the primary reason for using a starter with a DC motor?

   • A. To limit starting current
   • B. To increase starting torque
   • C. To reverse direction
   • D. To improve power factor

4. 64. The power factor of a heavily loaded induction motor is generally:

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

5. 65. A pole shoe in a DC machine is used to:

   • A. Support the field winding
   • B. Spread the flux uniformly
   • C. Reduce reluctance of magnetic path
   • D. All of the above

6. 66. The synchronous reactance of an alternator accounts for:

   • A. Armature reaction
   • B. Leakage reactance
   • C. Both armature reaction and leakage reactance
   • D. Field winding resistance

7. 67. Which of the following is a constant loss in a DC machine?

   • A. Copper loss
   • B. Brush loss
   • C. Iron loss
   • D. Friction loss

8. 68. The 'all-day efficiency' of a transformer is important for:

   • A. Power transformers
   • B. Distribution transformers
   • C. Current transformers
   • D. Potential transformers

9. 69. The main function of a squirrel cage in an induction motor is to:

   • A. Act as a rotor winding
   • B. Provide mechanical support
   • C. Improve cooling
   • D. Reduce noise

10. 70. Which of the following motors is preferred for high starting torque applications with variable speed?

    • A. DC series motor
    • B. DC shunt motor
    • C. Squirrel cage induction motor
    • D. Synchronous motor

11. 71. The no-load test on a transformer is performed to find:

    • A. Copper losses
    • B. Iron losses
    • C. Efficiency at full load
    • D. Regulation

12. 72. A potential transformer (PT) is used to measure:

    • A. High currents
    • B. High voltages
    • C. Low currents
    • D. Low voltages