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ECE :: Power Electronics

  1. The commutation method in an inverter, is

  2. A.
    line commutation
    B.
    forced commutation
    C.
    either (a) or (b)
    D.
    none of the above

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  3. Inverters find applications in

  4. A.
    HVDC transmission
    B.
    UPS
    C.
    variable speed ac drives
    D.
    all of the above

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  5. When a thyristor is conducting, the voltage drop across it is about

  6. A.
    1 V
    B.
    10 V
    C.
    100 V
    D.
    0.1 V

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  7. The use of free wheeling diode in controlled rectifier improves the waveshape of load current.

  8. A.
    True
    B.
    False

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  9. As the firing of a thyristor is delayed, the output voltage of a controlled rectifier decreases.

  10. A.
    True
    B.
    False

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  11. Assertion (A): A GTO can be turned on and turned off by gate pulses

    Reason (R): A GTO can be turned off by negative gate pulse.

  12. 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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  13. In a half bridge inverter circuit fed by a battery of voltage V, the rms value of fundamental component of output voltage is

  14. A.
    2 V
    B.
    C.
    D.

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  15. In a full bridge single phase inverter feeding RLC load

  16. A.
    one thyristor and one diode conduct simultaneously
    B.
    two thyristors conduct simultaneously
    C.
    two thyristors or two diodes conduct simultaneously
    D.
    four thyristors conduct simultaneously

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  17. It is possible to use a freewheeling diode in

  18. A.
    single phase half wave controlled rectifier as well as in single phase full wave controlled rectifier (M - 2 connection)
    B.
    single phase half wave controlled rectifier but not in single phase full wave controlled rectifier (M - 2 connection)
    C.
    single phase full wave controlled rectifier (M - 2 connection) but not in single phase half wave controlled rectifier
    D.
    all controlled rectifier circuits

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  19. Assertion (A): When the anode current of an SCR starts increasing during turn on process, the anode cathode voltage drop starts decreasing.

    Reason (R): During turn on the reverse biased junction in SCR breaksdown.

  20. 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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