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  • Question

  • In a 3 phase semiconverter, the output voltage becomes discontinuous for


  • Options
  • A. firing angle > 30°
  • B. firing angle > 60°
  • C. firing angle > 90°
  • D. firing angle > 120°

  • Correct Answer
  • firing angle > 60° 

    • Power Electronics problems

    Search Results

    • 1. A single phase fully controlled bridge converter is feeding an RLE load. Input voltage is Vm sin ?t and firing angle is a. If average current is I0, then

    • Options
    • A. cos a = RI0 + E
    • B. cos a = RE0 + E
    • C. cos a = E0 - RI0
    • D. cos a = E - RI0
      • Discuss
    • 2. In integral cycle control of ac regulator, the input power factor is equal to

    • Options
    • A. duty cycle a
    • B. a2
    • C. a
    • D. (a)1/3
      • Discuss
    • 3. Ripple factor RF and form factor FF are related as

    • Options
    • A. RF = FF2 - 1
    • B. RF = (FF2 - 1)0.5
    • C. RF = FF - 1
    • D. RF = (FF - 1)0.5
      • Discuss
    • 4. The application of gate signal decreases the break over voltage of on SCR.

    • Options
    • A. True
    • B. False
      • Discuss
    • 5. A fully controlled bridge converter feeds a highly inductive load such that the load current can be assumed to be constant. The wave shape of input current is

    • Options
    • A. dc
    • B. sinusoidal
    • C. rectangular
    • D. none of the above
      • Discuss
    • 6. A static excitation system uses

    • Options
    • A. transformer and thyristors
    • B. transformer and ac exciter
    • C. dc exciter and ac exciter
    • D. transformer and dc exciter
      • Discuss
    • 7. In a semi converter feeding a resistive load

    • Options
    • A. the waveshapes of output voltage and output current are exactly similar
    • B. the waveshapes of output voltage and output current can not be similar
    • C. the waveshapes of output voltage and output current are similar only for low values of firing angle
    • D. the waveshapes of output voltage and output current may be similar or dissimilar
      • Discuss
    • 8. McMurrary full bridge inverter uses

    • Options
    • A. auxiliary commutation
    • B. complementary commutation
    • C. natural commutation
    • D. any of the above
      • Discuss
    • 9. In an n stage high frequency series inverter having a time period T, each stage is active for a time interval of

    • Options
    • A. T
    • B.
    • C.
    • D.
      • Discuss
    • 10. Assertion (A): Gate triggering is the most commonly used method for triggering of an SCR.

      Reason (R): Even a small gate current is sufficient to turn on an SCR.


    • 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

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