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Home ‣ Electronics and Communication Engineering ‣ Power Electronics Comments
  • Question

  • A crowbar circuit is generally needed for protection under fault conditions.


  • Options
  • A. True
  • B. False

  • Correct Answer
  • True 

    • Power Electronics problems

    Search Results

    • 1. A single phase semiconverter is feeding a highly inductive load and has a freewheeling diode across the load. The waveshape of input current is

    • Options
    • A. sinusoidal
    • B. rectangular
    • C. sinusoidal or rectangular
    • D. triangular
      • Discuss
    • 2. In the below figure, the load is highly inductive. The firing angle is a for each of the thyristors. The periods of conduction of Th1 and Th2 respectively are

    • Options
    • A. 0 to p and p to 2p
    • B. a to p and p + a to 2p
    • C. a to p + a and p + p to 2p + a
    • D. a to p - a and p + a to 2p - a
      • Discuss
    • 3. A rectifier is fed by a transformer. The rms voltage and current at secondary of transformer are Vs and Is. Output dc power is Vdc Idc and output ac power is (Vrms ) (Irms), Transformer utilisation factor TUF is

    • Options
    • A.
    • B.
    • C.
    • D.
      • Discuss
    • 4. A single phase full wave regulator feeds a resistive load. The firing angle of thyristors is 90°. The input power factor is

    • Options
    • A. 1
    • B. 0.707 lagging
    • C. 0.5 lagging
    • D. 0.2 lagging
      • Discuss
    • 5. In a parallel inverter the turn off time tq of thyristor and values of commutating elements L and C are related as

    • Options
    • A. tq = pLC
    • B. tq = LC
    • C. tq = LC
    • D. tq = LC
      • Discuss
    • 6. A single phase fully controlled bridge converter is fed by a voltage Vm sin ?t. The average and rms values of output voltage are

    • Options
    • A.
    • B.
    • C. cos a and Vm
    • D. cos a and 2 Vm
      • Discuss
    • 7. In a bridge inverter

    • Options
    • A. an output transformer is essential
    • B. an output transformer is not essential
    • C. an output transformer cannot be connected
    • D. an output transformer, if used, can improve the efficiency of the circuit
      • Discuss
    • 8. In a modified series inverter with two inductors and two capacitors, the load current

    • Options
    • A. has 2 parallel paths
    • B. has only one parallel path
    • C. can have three parallel paths
    • D. has four parallel paths
      • Discuss
    • 9. The number of leads in a DIAC are

    • Options
    • A. 2
    • B. 3
    • C. 4
    • D. 6
      • Discuss
    • 10. An ideal rectifier should have

    • Options
    • A. 100% efficiency, zero ripple factor, zero harmonic factor and unity displacement factor
    • B. 100% efficiency, zero tipple factor, zero harmonic factor and zero displacement factor
    • C. 100% efficiency, zero ripple factor, unity harmonic factor and unity displacement factor
    • D. 100% efficiency, unity ripple factor, zero harmonic factor and unity displacement factor
      • Discuss

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