Q. A single phase half wave rectifier is feeding a resistive load. When α = 0, dc output voltage is 127 V. When α = 30°, the dc output voltage will be about

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Q. A two winding transformer is feeding a single phase half wave rectifier circuit. The load is purely resistive. The rms value of transformer secondary current is Is and rms value of load current in Irms. Then

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Q. The terminals of a power BJT are called

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Q. In single phase half wave regulator, the average current over one full cycle

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Q. The dynamic equalising circuit consists of a series combination of capacitor C and resistor RC across each thyristor. This resistance RC (along with parallel connected diode)

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Q. A single phase semiconverter is feeding a highly inductive load and has freewheeling diode across the load. The waveshapes of output voltage and output current

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Q. An SCR is triggered at 40° in the positive half cycle only. The average anode current is 50 A. If the firing angle is changed to 80°, the average anode current is likely to be

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Q. The characteristics of a non-linear resistance is i = kv⁴. If i becomes 100 times, v becomes

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Q. In a step down chopper using pulse width modulation, Ton = 3 x 10¯³ and Toff = 1 x 10¯³ s. The chopping frequency is

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Q. Thyristors are suitable for dc circuit breakers but not for ac circuit breakers.

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Q. Assertion (A): Inverters and choppers use fast switching thyristors

Reason (R): Fast switching SCR has low turn off time.

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Q. The number of leads in an SCR are :

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Q. A thyristor has a turn on time of 6 μs. If the anode circuit is inductive, the turn on time will be

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Q. The total number of leads in reverse conducting thyristor is

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Q. Assertion (A): A TRIAC is a bidirectional SCR.

Reason (R): A TRIAC is a four layers 3 terminal device and can conduct in both directions.

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Q. The value of capacitor C for dynamic equalising circuit of series connected thyristors is determined by

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Q. A chopper

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Q. Assertion (A): If the duty cycle of chopper is low the current would not become discontinuous

Reason (R): If the time constant L/R of the load in chopper is low the current may become discontinuous.

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Q. In a single phase full wave regulator, the firing angles in the positive and negative half cycles are generally

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Q. An electric heater is controlled by thyristors through on-off control. If α = 0.4, the heating is

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