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61. How can we protect SCR from thermal conditions _____________?
A. Use of snubber circuit.
B. Using heat sink.
C. Using CB and fuse.
D. Using equalizing circuit
62. Which of the following is used in heat sink_____________?
A. Iron
B. Aluminium
C. Carbon
D Silver
63. A thyristor can termed as__________?
A. AC switch
B. DC switch
C. Both a and B
D. Square wave switch
64. Materials used in heat sink should have_____________?
A. high thermal conductivity
B. large surface area
C. high melting point
D. All of these
65. Compared to transistor, _________ have lower on state conduction losses and higher power handling capability?
A. TRIACs
B. Semi conductor diodes
C. MOSFETs
D. Thyristor
66. The capacitance of reversed bised junction J2 in a thyristor is CJ2 = 20 pF and can be assumed to be independant of the off state voltage. The limiting value of the charging current to turn on the thyristor is 16 mA. What is the critical value of dv/dt?
A. 600 V/µs
B. 800 V/µs
C. 1200 V/µs
D. 1000 V/µs
67. SCR will be turned off when anode current is_______________?
A. < latching current but greater than holding current and gate signal is 0.
B. less than holding current.
C. < latching current but greater than holding current and gate signal is present.
D. both (A) and (B).
68. After proper turn on of thyristor____________?
A. gate signal is always present
B. gate signal must be removed
C. gate signal should present but can be removed
D. none of the above.
69. Gate circuit or triggering circuit of a thyristor is
A. lower power circuit.
B. high power circuit.
C. magnetic circuit.
D. may be low power or high power circuit
70. Thyristor is nothing but a____________?
A. Controlled transistor
B. Controlled switch
C. Amplifier with higher gain
D. Amplifier with large current gain