A Best Way To Crack Gorenment Job Exams

ECE Objective Questions { Power Semiconductor Devices and Their Applications }

71. In a full converter, 6 SCRs are fired at an interval of
A. 0?
B. 60?
C. 120?
D. 180?.

72. The function of connecting a zener diode in a UJT circuit used for triggering of SCRs is to
A. expedite the generation of triggering pulses
B. delay the generation of triggering pulses
C. provide a constant voltage to UJT to prevent erratic firing
D. provide a variable voltage to UJT as the source voltage changes.

73. The metal oxide variator (MOV) is used for protecting
A. gate circuit against overcurrents
B. gate circuit against overvoltages
C. anode circuit overcurrents
D. anode circuit against overvoltage

74.  In a GTO, anode current begins to fall when gate current
A. is negative peak at time t = 0
B. is negative peak at time t = storage time ts
C. just begins to become negative at t = 0
D. none of these

75. Thyrisor A has rated gate carrent of 2 A while thyristor B has rated gate current of 200 mA. Then
A. thyristor A is a GTO conventional SCR
B. thyristor B is a GTO conventional SCR
C. thyristor B may operate as a transistor
D. none of these

76.  The anode current through a conducting SCK is 10 A. If its gate current is made one-fourth, the anode current will become
B. 5A
C. 2.5A
D. 10A

77. As compared to UJT, an SUS
A. triggers only in one direction
B. does not have negative resistance property
C. needs definite polarity of the applied voltage
D. triggers only at one particular voltage

Page 11 of 36

« 9 10  11  1213 »