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Power Electronics problems

  • 1. A class D chopper

  • Options
  • A. can operate in first quadrant only
  • B. can operate in second quadrant only
  • C. can operate in either first or fourth quadrant
  • D. can operate in all the quadrants
    • Discuss
  • 2. In sinusoidal PWM for inverters the width of different pulses are not the same.

  • Options
  • A. True
  • B. False
    • Discuss
  • 3. When an SCR is in forward blocking mode, the applied voltage

  • Options
  • A. appears across only one junction
  • B. is equally shared by two junctions
  • C. is equally shared by three junctions
  • D. may appear across one or more junctions
    • Discuss
  • 4. In figure, thyristor Th is in off state. When thyristor is turned on, the peak thyristor current can be
    Electronics and Communication Engineering Power Electronics: In figure, thyristor Th is in off state. When thyristor is turned on, the peak thyristor current can

  • Options
  • A. 5 A
  • B. 10 A
  • C. 15 A
  • D. 20 A
    • Discuss
  • 5. A 3 phase bridge inverter is fed by 400 V battery. The load is star connected and has a resistance of 10 ? per phase. The peak value of thyristor current is

  • Options
  • A.
  • B.
  • C.
  • D.
    • Discuss
  • 6. The specified maximum junction temperature of thyristors is about

  • Options
  • A. 50°C
  • B. 80°C
  • C. 120°C
  • D. 200°C
    • Discuss
  • 7. In a 3 phase full wave regulator feeding a star connected resistance load, firing angle is 75°. Then the number of thyristors conducting at one time is

  • Options
  • A. 1
  • B. 2
  • C. 3
  • D. 4
    • Discuss
  • 8. The output frequency of a cycloconverter can be changed by changing the firing angle.

  • Options
  • A. True
  • B. False
    • Discuss
  • 9. The minimum gate current which can turn on SCR is called :

  • Options
  • A. trigger current
  • B. holding current
  • C. junction current
  • D. breakover current
    • Discuss
  • 10. In a parallel inverter

  • Options
  • A. each thyristor is turned on twice during each cycle
  • B. each thyristor is turned on once during each cycle
  • C. each thyristor is turned on either once or twice in each load cycle
  • D. each thyristor may be turned on upto four times in each load cycle
    • Discuss

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