How Well Do You Know About Electrical Machines? Trivia Quiz

44 Questions | Total Attempts: 4646

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How Well Do You Know About Electrical Machines? Trivia Quiz

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Questions and Answers
  • 1. 
    • A. 

      The level of the voltage.

    • B. 

      The power level.

    • C. 

      The power factor.

    • D. 

      The frequency.

  • 2. 
    Transformer is used
    • A. 

      To step up the voltage.

    • B. 

      To step down the voltage.

    • C. 

      On dc.

    • D. 

      To step up or step down the voltage.

  • 3. 
    An infinite bus-bar has
    • A. 

      Constant voltage.

    • B. 

      Constant frequency.

    • C. 

      Infinite voltage.

    • D. 

      Both A and B.

    • E. 

      Both B and C.

  • 4. 
    Tappings of a transformer are provided
    • A. 

      At the phase end of LV side.

    • B. 

      At the phase end of HV side.

    • C. 

      At the neutral end of HV side.

    • D. 

      At the middle of HV side.

  • 5. 
    The auto-transformer is preferably employed in situations where voltage transformation ratio is
    • A. 

      Very low.

    • B. 

      Near unity.

    • C. 

      Very high.

    • D. 

      Unity.

  • 6. 
    An auto-transformer may be used as a/an ___________ transformer.
    • A. 

      Power

    • B. 

      Distribution

    • C. 

      Automatically operated

    • D. 

      Voltage regulating

    • E. 

      Instrument

  • 7. 
    An auto-transformer has
    • A. 

      One winding with taps taken out.

    • B. 

      Two interlaced windings.

    • C. 

      Two windings of same wire.

    • D. 

      Two windings of different materials.

    • E. 

      One winding without taps.

  • 8. 
    The principle of operation of a 3-phase induction motor closely resembles to that of a
    • A. 

      Two winding transformer with its secondary short-circuited.

    • B. 

      Two winding transformer with its secondary open-circuited.

    • C. 

      Synchronous motor.

    • D. 

      Dc shunt motor.

  • 9. 
    • A. 

      Synchronous speed, Ns.

    • B. 

      Rotor speed, N.

    • C. 

      Zero

    • D. 

      Ns-N

  • 10. 
    An induction motor works with
    • A. 

      DC only.

    • B. 

      AC only.

    • C. 

      AC and DC both.

    • D. 

      None of these.

  • 11. 
    The two important parts of an induction motor are
    • A. 

      Stator and rotor.

    • B. 

      Slip rings and brushes.

    • C. 

      Core and winding.

    • D. 

      Shaft and ball bearings.

  • 12. 
    • A. 

      Continue to run as a synchronous motor rotating in the same direction.

    • B. 

      Continue to run as a synchronous motor rotating in opposite direction.

    • C. 

      Stop running.

    • D. 

      Get damaged due to burning of stator and rotor windings.

  • 13. 
    A 3-phase synchronous motor will not start if
    • A. 

      Voltage is too low.

    • B. 

      One phase is open.

    • C. 

      Connections are faulty.

    • D. 

      Any of the above.

  • 14. 
    • A. 

      The direction of instantaneous torque on the rotor reverses after each half cycle.

    • B. 

      There is no slip.

    • C. 

      The stator does not produce revolving magnetic field.

    • D. 

      It has no starting winding.

  • 15. 
    Which of the following electric motors is not inherently self starting motor?
    • A. 

      Synchronous motor.

    • B. 

      3-phase induction motor.

    • C. 

      Reluctance motor.

    • D. 

      DC series motor.

  • 16. 
    In a synchronous motor, squirrel cage winding is provided for making motor
    • A. 

      Noise free.

    • B. 

      Self starting.

    • C. 

      Cheap.

    • D. 

      Quick start.

  • 17. 
    The method that can be used conveniently for speed control of a squirrel cage induction motor is
    • A. 

      Pole changing control.

    • B. 

      Rotor resistance control.

    • C. 

      Cascade operation.

    • D. 

      Secondary foreign voltage control.

  • 18. 
    • A. 

      Stop.

    • B. 

      Continue to run as an alternator.

    • C. 

      Continue to run as a synchronous motor in the reverse direction.

    • D. 

      Continue to run as a synchronous motor in the same direction.

  • 19. 
    • A. 

      Kept open.

    • B. 

      Short-circuited.

    • C. 

      Connected to a DC source.

    • D. 

      None of the above.

  • 20. 
    Synchronous capacitor is
    • A. 

      An ordinary static capacitor bank.

    • B. 

      An over-excited synchronous motor driving mechanical load.

    • C. 

      An over-excited synchronous motor without mechanical load.

    • D. 

      None of the above.

  • 21. 
    When the induction motor is in standstill, the slip is
    • A. 

      Zero.

    • B. 

      1.

    • C. 

      Infinity.

    • D. 

      None of the above.

  • 22. 
    An electric motor gets over-heated. This may be due to
    • A. 

      Over-loading.

    • B. 

      Shorted stator winding.

    • C. 

      Worn-out or dry bearings.

    • D. 

      Low or high voltage.

    • E. 

      Any of the above.

  • 23. 
    A squirrel cage induction motor is not favoured when _______________ is the main consideration.
    • A. 

      Initial cost.

    • B. 

      Maintenance cost.

    • C. 

      High starting torque.

    • D. 

      Higher efficiency and higher power factor.

  • 24. 
    Which of the following ac motor is widely used?
    • A. 

      Squirrel cage induction motor.

    • B. 

      Slip-ring induction motor.

    • C. 

      Double cage induction motor.

    • D. 

      Synchronous motor.

  • 25. 
    A slip-ring induction motor is recommended for applications requiring
    • A. 

      High starting torque.

    • B. 

      Variable speed operation.

    • C. 

      Frequent starting, stopping and reversing operations.

    • D. 

      All of the above features.