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  • Question

  • A 3 phase semiconverter when supplying a certain load has a rectification efficiency of 0.6 and transformer utilisation factor of 0.35. When a 3 phase full converter is supplying the same load


  • Options
  • A. rectification efficiency will be more than 0.6 and TUF will be more than 0.35
  • B. rectification efficiency will be more than 0.6 but TUF will be less than 0.35
  • C. rectification efficiency will be less than 0.6 and TUF will be less than 0.35
  • D. rectification efficiency will be less than 0.6 but TUF will be more than 0.35

  • Correct Answer
  • rectification efficiency will be more than 0.6 and TUF will be more than 0.35 

    • Power Electronics problems

    Search Results

    • 1. An SCR has a turn on time of 4 ?s. The gate pulse should have a duration of about

    • Options
    • A. 2 ?s
    • B. 5 ?s
    • C. 20 ?s
    • D. 50 ?s
      • Discuss
    • 2. In a semi converter feeding a resistive load, the firing angle is a. Each thyristor conducts for

    • Options
    • A. p radians
    • B. (p - a) radians
    • C. (p + a) radians
    • D. (p - 0.5 a) radians
      • Discuss
    • 3. The gate current required to turn on an SCR is

    • Options
    • A. few amperes
    • B. a few mA
    • C. almost equal to anode current
    • D. about 50% of anode current
      • Discuss
    • 4. Between which points does UJT exhibit negative resistance characteristics

    • Options
    • A. between peak and valley points
    • B. before peak point
    • C. after peak point
    • D. after valley point
      • Discuss
    • 5. A dc chopper V = 500 V feeds an electric fraction dc series motor. The chopping frequency is 400 Hz. The series inductance required to limit the maximum current swing to 10 A is

    • Options
    • A. 20 mH
    • B. about 31 mH
    • C. about 51 mH
    • D. about 92 mH
      • Discuss
    • 6. The symbol in figure is for

    • Options
    • A. DIAC
    • B. P-N junction diode
    • C. Schottky diode
    • D. None of the above
      • Discuss
    • 7. When the core of a saturable reactor is saturated, the inductance is high.

    • Options
    • A. True
    • B. False
      • Discuss
    • 8. Assertion (A): When an SCR is conducting, the voltage drop across is about 1 V.

      Reason (R): When an SCR is conducting, the junction temperature is about 200°C.


    • 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
    • 9. A single phase full wave regulator feeds R-L load. The best gating signal is

    • Options
    • A. short duration pulses
    • B. long duration pulses
    • C. pulse train
    • D. either (a) or (b)
      • Discuss
    • 10. A cycloconverter cannot give a frequency higher than input frequency.

    • Options
    • A. True
    • B. False
      • Discuss

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