Home / ECE / Power Electronics :: Section 6

ECE :: Power Electronics

  1. A thyristor circuit is feeding an R-L load. The turn on time can be reduced by

  2. A.
    decreasing R
    B.
    decreasing L
    C.
    increasing L
    D.
    decreasing R and L together

  3. A single phase semiconverter is supplying RLE load and has a freewheeling diode across the load. The firing angle is a. The freewheeling diode conducts for

  4. A.
    a° in each half cycle
    B.
    (p - a)° in each cycle
    C.
    a° in one full cycle
    D.
    (p + a)° in each half cycle

  5. In a full bridge inverter fed by a battery of voltage V, the rms value of fundamental component of output voltage is


  6. In a single phase full wave regulator feeding a resistive load, the average current over one full cycle

  7. A.
    is always zero
    B.
    cannot be zero
    C.
    may be sometimes zero
    D.
    is always positive

  8. Two single phase semi-converters are connected in series to form a series converter. The input is v = Vm sin ωt and a1, a2 are the firing angles. If a1 = 0, the dc output voltage is

  9. A.
    (1 + cos a2)
    B.
    (2 + cos a2)
    C.
    (3 + cos a2)
    D.
    (4 + cos a2)

  10. The total number of leads in MOS controlled thyristor is

  11. A.
    2
    B.
    3
    C.
    4
    D.
    2 or 3

  12. Assertion (A): Chopper always requires forced commutation

    Reason (R): Morgan chopper uses a saturable reactor.

  13. 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

  14. In a power diode the reverse recovery time is the time from the instant the forward current is zero to the instant when reverse recovery current has decayed to

  15. A.
    50% of peak reverse current
    B.
    25% of peak reverse current
    C.
    10% of peak reverse current
    D.
    zero value

  16. Assertion (A): McMurray Bredford half bridge inverter uses complementary commutation

    Reason (R): Three phase inverter can have two modes of operation.

  17. 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

  18. A capacitor C farads is charged to a voltage V. It discharges through a thyristor, a diode and an inductance L. The peak current in the circuit is

  19. A.
    VCL
    B.
    C.
    D.