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ECE :: Power Electronics

  1. Lead mounting for SCR is used for

  2. A.
    rating less than mA
    B.
    rating about 1 A or less
    C.
    rating of 20 A or less than 20 A
    D.
    rating 100 A or less

  3. A load commutated chopper circuit has

  4. A.
    one thyristor
    B.
    two thyristors
    C.
    four thyristors
    D.
    six thyristors

  5. Assertion (A): The output voltage of an inverter can be controlled by PWM technique

    Reason (R): In a current source inverter the input current is constant.

  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

  7. A TRIAC is equivalent to

  8. A.
    two thyristors in series
    B.
    two thyristors in parallel
    C.
    one thyristor and one diode
    D.
    one thyristor and one transistor

  9. Which of the following commutation methods is the overall circuit under damped?

  10. A.
    Class A
    B.
    Class B
    C.
    Class C
    D.
    Both class A and Class B

  11. In a half bridge inverter, the freewheeling diodes are needed

  12. A.
    even when load is resistive
    B.
    only when load is inductive
    C.
    only when load is inductive or capacitive
    D.
    for all types of loads

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

  14. A.
    is absolutely constant
    B.
    decreases with increase in load current
    C.
    increases slightly with increase in load current
    D.
    none of the above

  15. The advantage of modified series inverter with two inductors and two capacitors is

  16. A.
    the intermittent operation of battery is avoided
    B.
    efficiency of circuit is more
    C.
    the output frequency is low
    D.
    all of the above

  17. An SUS is

  18. A.
    exactly similar to SCR but with higher rating
    B.
    similar to UJT
    C.
    PUT and avalanche diode connected in anti parallel
    D.
    SCR and avalanche diode connected in parallel

  19. Which chopper circuit operates in quadrants 1 and 4?

  20. A.
    A
    B.
    B
    C.
    D
    D.
    E