113. In dc choppers, the waveform for input and output voltages are respectively
A. discontiuous, continuous
B. continuous, discontinuous
C. both continuous
D. both discontinuous

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114. In dc choppers, per unit ripple is maximum when duty cycle a is
A.0.2
B.0.5
C.0.7
D.0.8

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115. A step.up chopper has Vs as the source voltage and a as the duty cycle. The output voltage for this chopper is given by
A. Vs (1 + a)
B. V5/(1 ? a)
C. V5(1 ? a)
D. V5/(1 + a)

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116. In dc choppers if T is the chopping period, then the output voltage can be controlled by PWM by varying
A. T keeping Ton constant
B. Ton keeping T constant
C. T keeping Toff constant
D. Toff keeping T constant

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117. In dc choppers, for periodic time T, the output voltage can be controlled by FM by varying
A. T keeping Ton constant
B. Ton keeping T constant
C. Toff keeping T constant
D. T keeping Toff constant

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118. A motor armature supplied through phase controlled SCR receives a smoother voltage shape at
A. high motor speed
B. low motor speed
C. rated motor speed
D. very low motor speed

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119. An SCR is used to control the speed of a dc motor. At full speed, the motor is taking 1 A at 75 V. The maximum forward surge current rating and maximum forward breakover voltage rating respectively are of the order of
A. 3A, 225V
B. 1A, 300V
C. 6A, 150V
D. 5A, 200V

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