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Electronics Engineering Objective Questions { Power Semiconductor Devices and Their Applications }



190. Which semiconductor power device out of the following is not a current triggered device?
A. Thyristor
B. GT.O.
C. Triac
D.MOSFET
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191. The Triac can be used only in
A. inverter
B. rectifier
C. multiquadrant chopper
D. cycloconverter
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192. Which of the following does permanent damage of an SCR?
A. High current
B. High rate of rise of current
C. High temperature rise
D. High rate of rise of voltage .
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193. In a thyristor dc chopper, which type of commutation results in best performance?
A. Voltage commutation
B. Current commutation
C. Load commutation
D. Supply commutation
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194. In a 3-phase controlled bridge rectifier, with an increase of overlap angle, the output dc voltage
A. decreases
B. increases
C. does not change
D. depends upon load inductance
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195. A single phase diode bridge rectifier supplies a highly inductive load. The load current can be assumed to be ripple free. The ac supply side current waveform will be
A. sinusoidal
B. constant dc
C. square
D. triangular
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196. A dc to dc transistor chopper supplied from a fixed voltage dc source feeds a fixed resistive-inductive load and a freewheeling diode. The chopper operates at 1 KHz and 50% duty cycle. Without changing the value of the average dc current through the load, if it is desired to reduce the ripple content of load current, the control action needed will
A. increase the chopper frequency keeping the duty cycle constant
B. increases th chopper frequency and duty cycle in equal ratio
C. decrease only the chopper frequency
D. decrease only the duty cycle
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