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ECE :: Power Electronics

  1. The total number of leads in SUS, SBS and SCS respectively are

  2. A.
    3, 3, 4,
    B.
    3, 3, 3
    C.
    2, 3, 3
    D.
    3, 3, 5

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  3. Which of these devices can conduct in both directions?

  4. A.
    SCR
    B.
    SUS
    C.
    SBS
    D.
    UJT

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  5. Assertion (A): A half wave controlled rectifier has poorer efficiency and higher ripple factor than a full wave controlled rectifier.

    Reason (R): The use of a freewheeling diode in half wave controlled rectifier circuit improves the waveform of load current and circuit power factor.

  6. A.
    Both A and R are correct and R is correct explanation of A
    B.
    Both A and R correct but R is not correct explanation of A
    C.
    A is correct but R is wrong
    D.
    A is wrong but R is correct

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  7. A 3 phase dual converter consists of

  8. A.
    two 3 phase semiconverters connected in parallel
    B.
    two 3 phase semiconverters connected in antiparallel
    C.
    two 3 phase full converters connected in antiparallel
    D.
    two 3 phase full converters connected in parallel

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  9. Which inverter circuit uses coupled inductors?

  10. A.
    Modified McMurray full bridge inverter
    B.
    McMurray Bedford half bridge inverter
    C.
    Modified McMurray Bedford half bridge inverter
    D.
    Both (b) and (c)

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  11. When an SCR is in forward blocking mode, the applied voltage

  12. A.
    appears across only one junction
    B.
    is equally shared by two junctions
    C.
    is equally shared by three junctions
    D.
    may appear across one or more junctions

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  13. In sinusoidal PWM for inverters the width of different pulses are not the same.

  14. A.
    True
    B.
    False

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  15. A class D chopper

  16. A.
    can operate in first quadrant only
    B.
    can operate in second quadrant only
    C.
    can operate in either first or fourth quadrant
    D.
    can operate in all the quadrants

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  17. The symbol in figure is for

  18. A.
    UJT
    B.
    PUT
    C.
    SCS
    D.
    SBS

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  19. The efficiency of a chopper circuit is about

  20. A.
    80% or more
    B.
    around 50%
    C.
    around 20%
    D.
    around 5%

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