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51. Leakage current flows through the thyristor in_________?

A. forward blocking mode
B. reverse blocking mode
C. both forward and reverse blocking mode
D. forward conduction mode

52. Which triggering is the most reliable____________?

A. Forward voltage triggering
B. Gate triggering
C. dV / dt triggering
D. Thermal triggering

53. Which of the following devices has the highest di/dt and dv/dt capability?

A. SIT
B. SITH
C. GTO
D. SCR

54. Let of a thyristor Vc1, Vc2, Vc3 are forward break over voltage for gate current Ig1, Ig2, Ig3 respectively. Then________________?

A. Vc1 > Vc2 > Vc3 when Ig1 > Ig2 > Ig3.
B. Vc1 > Vc2 > Vc3 when Ig1 < Ig2 < Ig3.
C. Vc1 = Vc2 = Vc3 any value of Ig.
D. Vc1 > Vc2 > Vc3 when Ig1 ≥ Ig2 &Atil

55. BCT is used for____________?

A. High power phase control
B. High power current control
C. Low power current control
D. Low power phase control

56. If the anode current is 800 A, then the amount of current required to turn off the GTO is about____________?

A. 20 A
B. 200 A
C. 600 A
D. 400 A

57. CB used for over current protection of thyristor operates when the fault current is__________?

A. of a long period
B. of short duration
C. both (A) and (B)
D. neither (A) nor (B)

58. A power semiconductor may undergo damage due to____________?

A. High di/dt
B. High dv/dt
C. Low di/dt
D. Low dv/dt

59. When a large surge current of very short duration flows through a thyristor then which one of the following devices will operate to protect the thyristor ___________?

A. CB
B. Snubber circuit
C. Voltage clamping device
D. Fast-acting current limiting device (FACL fuse)

60. Which of the following is the disadvantage of fast recovery diodes?

A. Recovery is only 5 µs
B. Recovery is only 50 µs
C. Doping is carried out
D. None of these