Power Electronics Trivia Questions And Answers

20 Questions | Total Attempts: 932

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Power Electronics Quizzes & Trivia

Characteristics of Power Electronic devices, phase control, bridge converters, choppers and inverters, basic concepts of adjustable speed drives.


Questions and Answers
  • 1. 
    Triacs cannot be used in a.c voltage regulator for a
    • A. 

      Resistive load

    • B. 

      Back e.m.f load

    • C. 

      Inductive load

    • D. 

      Resistive inductive load

  • 2. 
    In a step-down cyclo converter commutation required is
    • A. 

      Natural

    • B. 

      Forced

    • C. 

      Depends on power

    • D. 

      None of these

  • 3. 
    Cyclo converter can be considered as a.c-a.c converter with conversion of
    • A. 

      1 stage

    • B. 

      2 stage

    • C. 

      3 stage

    • D. 

      None of these

  • 4. 
    Inverters are used in
    • A. 

      Induction heating

    • B. 

      UPS

    • C. 

      None of these

    • D. 

      Both

  • 5. 
    Commutation overlap in the phase controlled ac to dc converter is due to
    • A. 

      Load inductance

    • B. 

      Harmonic content of load current

    • C. 

      Switching operator in the converter

    • D. 

      Source inductance

  • 6. 
    Which of the following devices should be used as a switch in a low power switched mode power supply(SMPS)
    • A. 

      GTO

    • B. 

      MOSFET

    • C. 

      TRIAC

    • D. 

      THYRISTOR

  • 7. 
    A converter which can operate in both 3-phase and 6-pulse modes is a
    • A. 

      1-phase full converter

    • B. 

      3-phase half wave converter

    • C. 

      3-phase semi converter

    • D. 

      3-phase full converter

  • 8. 
    In d.c choppers per unit ripple is maximum when duty cycle alpha is
    • A. 

      0.1

    • B. 

      0.3

    • C. 

      0.5

    • D. 

      0.7

  • 9. 
    The most suitable device for high frequency inversion in SMPS is
    • A. 

      BJT

    • B. 

      IGBT

    • C. 

      MOSFET

    • D. 

      GTO

  • 10. 
    Which of the following doesnot cause permanent damage of an SCR
    • A. 

      High current

    • B. 

      High rate of rise of current

    • C. 

      High temperature rise

    • D. 

      High rate of raise of voltage

  • 11. 
    A 4-quadrant chopper cannot be operated as
    • A. 

      1-quadrant chopper

    • B. 

      Cyclo converter

    • C. 

      Inverter

    • D. 

      Bi-directional rectifier

  • 12. 
    Power diodes has characteristics of 
    • A. 

      High power,high speed

    • B. 

      Low power,low speed

    • C. 

      Low power,high speed

    • D. 

      High power,low speed

  • 13. 
    IGBT is use for applications in 
    • A. 

      Low power

    • B. 

      Medium power

    • C. 

      High power

    • D. 

      None of these

  • 14. 
    Turn-on and Turn-off times of transistor depend on
    • A. 

      Static characteristics

    • B. 

      Junction capacitance

    • C. 

      Current gain

    • D. 

      None of these

  • 15. 
    Which one of the following is used as the main switching element in a switched mode power supply operating in 20khz to 100khz range?
    • A. 

      Thyristor

    • B. 

      MOSFET

    • C. 

      TRIAC

    • D. 

      UJT

  • 16. 
    When an UJT is used for triggering an SCR, the waveshape of the voltage obtained from UJT  circuit is a
    • A. 

      Sine wave

    • B. 

      Saw-tooth wave

    • C. 

      Trapezoidal wave

    • D. 

      Square wave

  • 17. 
    In a 3-phase semi-converter, for firing angle less than or equal to 60degrees, free wheeling diode conducts for 
    • A. 

      30 degrees

    • B. 

      60 degrees

    • C. 

      90 degrees

    • D. 

      0 degrees

  • 18. 
    In a 1-phase full converter, if load current is I and ripple free, than average thyristor current is
    • A. 

      1/2*I

    • B. 

      1/3*I

    • C. 

      1/4*I

    • D. 

      I

  • 19. 
    Power electronic device with poor turn-off gain is
    • A. 

      A symmetrical thyristor

    • B. 

      A conventioanal thyristor

    • C. 

      Power bipolar junction transistor

    • D. 

      Gate turn-off thyristor

  • 20. 
    Modern ac-dc converters employ self commutated devices like GTOs of IGBTs instead of thyristors inorder to achieve
    • A. 

      Low reactive power loading on the source

    • B. 

      Better efficiency in conversion

    • C. 

      Low switching frequency operation of devices

    • D. 

      Cost reduction in converter realization

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