Trivia Questions On Electrical Machines

20 Questions | Total Attempts: 1120

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Trivia Questions On Electrical Machines - Quiz

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Questions and Answers
  • 1. 
    The inductive reactance of a transformer depends on 
    • A. 

      Magnetomotive force

    • B. 

      Electromotive force

    • C. 

      Magnetic flux

  • 2. 
    The inductive reactance of a transformer depends on 
    • A. 

      Magnetomotive force

    • B. 

      Electromotive force

    • C. 

      Magnetic flux

  • 3. 
    The emf induced in the primary
    • A. 

      Is in phase with the flux

    • B. 

      Lags behind the flux by 90degrees

    • C. 

      Leads the flux by 90degrees

  • 4. 
    The flux in transformer core  
    • A. 

      Increases with load

    • B. 

      Decerase with load

    • C. 

      Remain constant irrespective of load

  • 5. 
    The primary ampereturns are counter balanced by
    • A. 

      Secondary ampere turns

    • B. 

      Primary flux

    • C. 

      Increase in mutual flux

  • 6. 
    Power  transformed from primary to secondary depends upon 
    • A. 

      Number of primary turns

    • B. 

      Number of secondary turns

    • C. 

      Magnetic coupling between primary and secondary windings

  • 7. 
    A transformer is supplying pure resistive load.The power factor on primary side will be
    • A. 

      About 0.95(lead)

    • B. 

      About 0.95(lag)

    • C. 

      Zero

    • D. 

      Unity

  • 8. 
    The voltage regulation of a well designed transformer is of the order of
    • A. 

      20 precentage

    • B. 

      10 percentage

    • C. 

      2 percentage

    • D. 

      Zero

  • 9. 
    The various losses occuring in a power transformer are------ losses
    • A. 

      Copper and iron

    • B. 

      Friction and winding

    • C. 

      Iron,friction and windage losses

  • 10. 
    In the transformer circuit mode,the core loss represented as a
    • A. 

      Series resistance

    • B. 

      Series inductance

    • C. 

      Shunt resistance

    • D. 

      Shunt inductance

  • 11. 
    Smooth cylindrical rotors are usually designed for
    • A. 

      2 or 4 poles

    • B. 

      8 poles

    • C. 

      12 poles

    • D. 

      24 poles

  • 12. 
    A coil consists of 
    • A. 

      Two coil-sides

    • B. 

      Two conductors

    • C. 

      Two turns

    • D. 

      One turn

  • 13. 
    The stator of modern alternators are wound for --------- phase groups
    • A. 

      180 degrees

    • B. 

      120 degrees

    • C. 

      60 degrees

    • D. 

      240 degrees

  • 14. 
    Distributed winding is preferred over concentrated winding as it
    • A. 

      Reduces noise

    • B. 

      Reduces the machine size

    • C. 

      Reduces the amount of copper required

    • D. 

      Improves the generated emf wave-form and adds rigidity and mechanical strength to wdg

  • 15. 
    The doubly exicted magnetic systems are
    • A. 

      Solenoids

    • B. 

      Synchronous motors

    • C. 

      Eletromagnetic relays

  • 16. 
    The cooling medium used in large sized synchrounous machines is usually
    • A. 

      Hydrogen

    • B. 

      Air

    • C. 

      Water

    • D. 

      Mineral oil

    • E. 

      Sulphur hexafluoride

  • 17. 
    A polyphase field is
    • A. 

      Pulsating and stationary

    • B. 

      Pulsating and rotating

    • C. 

      Constant in amplitude and roatating at synchronous speed

    • D. 

      Constant in amplitude and sationary in space

  • 18. 
    An alternator with higer value of SCR has.
    • A. 

      Poor voltage regulation and lower stability limit

    • B. 

      Better voltage regulation and higher stability limit

    • C. 

      Poor voltage regulation and higher stability limit

    • D. 

      Better voltage regulation and low stability limit

  • 19. 
    The minimum no of windings required for producing a polyphase field is
    • A. 

      One

    • B. 

      Two

    • C. 

      Three

    • D. 

      None of these

  • 20. 
    Number of slip-rings in a 3-phase synchronous motor will be
    • A. 

      0

    • B. 

      1

    • C. 

      2

    • D. 

      3 or 4

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