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  • Question
  • The characteristics of which device has peak point and valley point


  • Options
  • A. SCR
  • B. PUT
  • C. SCS
  • D. Shockley diode

  • Correct Answer
  • PUT 


  • Power Electronics problems


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    • 1. In a thyristor the gate lead is connected to the n layer near the p layer to which anode is connected.

    • Options
    • A. True
    • B. False
    • Discuss
    • 2. If a step down chopper is fed by a dc voltage V with Ton and Toff are on and off periods then is

    • Options
    • A. average output voltage
    • B. rms output voltage
    • C. average or rms output voltage depending on load
    • D. neither of the above
    • Discuss
    • 3. In a single phase full wave regulator feeding an R-L load, the power factor angle of load is ?. The range of control of firing angle a is

    • Options
    • A. 0 ? a ? p
    • B. ? ? a ? p
    • C. 0 ? a ? (p - ?)
    • D. ? ? a ? (p + ?)
    • Discuss
    • 4. McMurray Bedford full bridge inverter uses

    • Options
    • A. natural commutation
    • B. auxiliary commutation
    • C. complementary commutation
    • D. any of the above
    • Discuss
    • 5. In a stud mounted SCR, the stud is

    • Options
    • A. in thermal contact with heat sink
    • B. insulated from heat sink
    • C. in electrical and thermal contact with heat sink
    • D. in either electrical or thermal contact with heat sink
    • Discuss
    • 6. The two-transistor model of a thyristor consists of two transistors :

    • Options
    • A. one n-p-n and other p-n-p
    • B. both p-n-p
    • C. both n-p-n
    • D. one n-p-n and other UJT
    • Discuss
    • 7. Which of these commutation methods uses an external pulse for commutation?

    • Options
    • A. Class A
    • B. Class C
    • C. Class E
    • D. Class F
    • Discuss
    • 8. In a half bridge inverter each thyristor is gated at a frequency f. The output frequency is

    • Options
    • A. 2 f
    • B. f
    • C. 0.5 f
    • D. 0.25 f
    • Discuss
    • 9. Assertion (A): The turn on time of SCR is about 1 to 4 ms.

      Reason (R): The turn off time of SCR is about 10 to 300 ms.


    • 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
    • 10. In the circuit of figure, the load current when thyristor is off

    • Options
    • A. is constant
    • B. increases exponentially
    • C. decreases exponentially
    • D. zero
    • Discuss


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