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  • Question

  • Thyristors connected in series need :


  • Options
  • A. static equalizing circuit
  • B. dynamic equalizing circuit
  • C. both static and dynamic equalizing circuits
  • D. none of the above

  • Correct Answer
  • both static and dynamic equalizing circuits 

    • Power Electronics problems

    Search Results

    • 1. In the circuit of figure, the load current when thyristor is off

    • Options
    • A. is constant
    • B. increases exponentially
    • C. decreases exponentially
    • D. zero
      • Discuss
    • 2. Assertion (A): The turn on time of SCR is about 1 to 4 ms.

      Reason (R): The turn off time of SCR is about 10 to 300 ms.


    • Options
    • A. Both A and R are correct and R is correct explanation of A
    • B. Both A and R correct but R is not correct explanation of A
    • C. A is correct but R is wrong
    • D. A is wrong but R is correct
      • Discuss
    • 3. In a half bridge inverter each thyristor is gated at a frequency f. The output frequency is

    • Options
    • A. 2 f
    • B. f
    • C. 0.5 f
    • D. 0.25 f
      • Discuss
    • 4. Which of these commutation methods uses an external pulse for commutation?

    • Options
    • A. Class A
    • B. Class C
    • C. Class E
    • D. Class F
      • Discuss
    • 5. The two-transistor model of a thyristor consists of two transistors :

    • Options
    • A. one n-p-n and other p-n-p
    • B. both p-n-p
    • C. both n-p-n
    • D. one n-p-n and other UJT
      • Discuss
    • 6. A single phase bridge type cycloconverter uses eight thyristors.

    • Options
    • A. True
    • B. False
      • Discuss
    • 7. A single phase full converter can operate in

    • Options
    • A. 4 quadrants
    • B. 3 quadrants
    • C. 2 quadrants
    • D. 1 quadrant
      • Discuss
    • 8. In a thyristor, the forward breakover voltage

    • Options
    • A. is constant
    • B. may be constant or may depend on gate current
    • C. decreases as gate current is increased
    • D. increases as gate current is increased
      • Discuss
    • 9. A single phase half wave converter is feeding a resistive load. Output dc power is Pdc and total power delivered to load is Pac then

    • Options
    • A. Pdc = Pac for all values of firing angles
    • B. Pdc = Pac if firing angle is less than 180°
    • C. Pdc < Pac for all values of firing angles
    • D. Pdc < Pac if firing angle is less than 180°
      • Discuss
    • 10. A relaxation oscillator uses

    • Options
    • A. tunnel diode
    • B. UJT
    • C. both tunnel diode and UJT
    • D. PIN diode
      • Discuss

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