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  • Question
  • A single phase fully controlled bridge rectifier is fed by a source having inductance. The output voltage during overlap period is


  • Options
  • A. Vm
  • B. 0.5 Vm
  • C. zero
  • D. 0.5 Vm - voltage drop across inductance

  • Correct Answer
  • zero 

    Explanation
    During the period of overlap all the four thyristors conduct and load is effectively short-circuited. Output voltage is zero.

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    • 1. In a 3 phase semiconverter, the firing frequency is

    • Options
    • A. equal to line frequency
    • B. 3 times the line frequency
    • C. 6 times the line frequency
    • D. 12 times the line frequency
    • Discuss
    • 2. In dielectric heating, the thyristor circuits consist of

    • Options
    • A. rectifier-chopper combination
    • B. controlled rectifier
    • C. ac regulator
    • D. rectifier-inverter combination
    • Discuss
    • 3. In a multiphase chopper, the different choppers operate in

    • Options
    • A. series and all simultaneously
    • B. parallel and one at a time
    • C. parallel and simultaneously
    • D. either (b) or (c)
    • Discuss
    • 4. In the below figure, the average value of load current is 15 A. The load is highly inductive. The peak value of thyristor current is

    • Options
    • A. 15 A
    • B. 152 A
    • C.
    • D. 30 A
    • Discuss
    • 5. When thyristors are connected in series and parallel, it may be necessary to have :

    • Options
    • A. current derating
    • B. voltage derating
    • C. both current and voltage derating
    • D. none of the above
    • Discuss
    • 6. A thyristor has its gate current zero. To start conduction the forward voltage must exceed

    • Options
    • A. about 0.5 V
    • B. forward breakover voltage
    • C. on state voltage
    • D. peak working off state forward voltage
    • Discuss
    • 7. In the below figure the rms voltage across each half of secondary is 200 V. The peak inverse voltage across each of thyristor is

    • Options
    • A. 200 V
    • B. 2(200) V
    • C. 2(400) V
    • D. 800 V
    • Discuss
    • 8. In a dual converter both converters work as rectifiers.

    • Options
    • A. True
    • B. False
    • Discuss
    • 9. The waveshape of output voltage of half bridge inverter is

    • Options
    • A. sinusoidal
    • B. square
    • C. triangular
    • D. either (a) or (b)
    • Discuss
    • 10. In an SCR, the anode current consists of

    • Options
    • A. only holes
    • B. only electrons
    • C. both electrons and holes
    • D. either electrons or holes
    • Discuss


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