logo

CuriousTab

CuriousTab

Discussion


Home Electronics and Communication Engineering Power Electronics Comments

  • Question
  • In a step down chopper using pulse width modulation, Ton = 3 x 10-3 and Toff = 1 x 10-3 s. The chopping frequency is


  • Options
  • A. 333.33
  • B. 250
  • C. 500
  • D. 1000

  • Correct Answer
  • 250 

    Explanation
    In a step down chopper using pulse width modulation, Ton = 3 x 10-3 and Toff = 1 x 10-3 s. The chopp .

    Power Electronics problems


    Search Results


    • 1. For a 12 pulse operation, the two 6 pulse units are fed by

    • Options
    • A. Y - Y and Y - Y transformers
    • B. ? - ? and ? - ? transformers
    • C. Y - Y and Y - ? transformers
    • D. Y - ? and Y - ? transformers
    • Discuss
    • 2. A cycloconverter can be

    • Options
    • A. step down
    • B. step up
    • C. step down or step up
    • D. none of the above
    • Discuss
    • 3. Thyristors are not suitable for logic circuits.

    • Options
    • A. True
    • B. False
    • Discuss
    • 4. The number of leads in an SCR are :

    • Options
    • A. 2
    • B. 3
    • C. 4
    • D. 5
    • Discuss
    • 5. The characteristics of a non-linear resistance is i = kv4. If i becomes 100 times, v becomes

    • Options
    • A. about 100 times
    • B. about 10 times
    • C. about 3 times
    • D. about twice
    • Discuss
    • 6. A two winding transformer is feeding a single phase half wave rectifier circuit. The load is purely resistive. The rms value of transformer secondary current is Is and rms value of load current in Irms. Then

    • Options
    • A. Is = Irms irrespective of the value of firing angle
    • B. Is = 0.5 Irms irrespective of the value of firing angle
    • C. Is = Irms if firing angle is less than 30°
    • D. Is = Irms if firing angle is more than 30°
    • Discuss
    • 7. Assertion (A): Power transistor has lower switching time than SCR

      Reason (R): Power transistor has greater switching time than 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
    • 8. In a single phase full wave converter (M-2 connection) feeding on R - L load, the input voltage is v = Vm sin ?t. The expression for dc output voltage is

    • Options
    • A.
    • B.
    • C.
    • D.
    • Discuss
    • 9. An SCR is triggered at 40° in the positive half cycle only. The average anode current is 50 A. If the firing angle is changed to 80°, the average anode current is likely to be

    • Options
    • A. 50 A
    • B. 25 A
    • C. less than 50 A but more than 25 A
    • D. less than 25 A
    • Discuss
    • 10. Assertion (A): The surge current which an SCR can withstand is much higher than rms on state current.

      Reason (R): The duration of surge current is very small.


    • 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


    Comments

    There are no comments.

Enter a new Comment