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  • Question
  • A NAND gate has 3 inputs and one output. The number of thyristors required for this gate are


  • Options
  • A. 1
  • B. 2
  • C. 3
  • D. 3 or 4

  • Correct Answer



  • Power Electronics problems


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    • 1. In a single phase semi-converter the number of thyristors is

    • Options
    • A. 16
    • B. 8
    • C. 4
    • D. 2
    • Discuss
    • 2. A 3 phase induction motor is controlled by voltage and frequency control such that the ratio V/f is constant. At 50 Hz, the starting torque is 100 N-m. At 25 Hz, the starting torque

    • Options
    • A. will be less than 100 N-m
    • B. will be more than 100 N-m
    • C. may be more or less than 100 N-m depending on motor parameters
    • D. very small
    • Discuss
    • 3. A UJT exhibits negative resistance characteristics when

    • Options
    • A. Current is less than valley current
    • B. Current is less than peak current
    • C. Current is more than peak current but less than valley current
    • D. None of the above
    • Discuss
    • 4. In a single phase full wave regulator feeding a resistive load, the average current over one full cycle

    • Options
    • A. is always zero
    • B. cannot be zero
    • C. may be sometimes zero
    • D. is always positive
    • Discuss
    • 5. When UJT is used for thyristor gate signal, the output of UJT is

    • Options
    • A. sine wave
    • B. square wave
    • C. saw tooth wave
    • D. either (a) or (c)
    • Discuss
    • 6. In a single phase full wave regulator, the rms current in each thyristors is Ir The run load current is equal to

    • Options
    • A. 2Ir
    • B. 2 Ir
    • C. Ir
    • D.
    • Discuss
    • 7. A class A chopper has an input voltage of 200 V. Ton = 1.5 ms and Toff = 4.5 ms. The duty cycle, average output voltage and ripple factor respectively are

    • Options
    • A. 0.5, 100 V and 1
    • B. 0.25, 50 V and 3
    • C. 0.25, 50 V and 1
    • D. 0.5, 100 V and 3
    • Discuss
    • 8. The symbol in figure is for

    • Options
    • A. SUS
    • B. SBS
    • C. SCS
    • D. Shockley diode
    • Discuss
    • 9. The commutation method in an inverter, is

    • Options
    • A. line commutation
    • B. forced commutation
    • C. either (a) or (b)
    • D. none of the above
    • Discuss
    • 10. The output wave of a cycloconverter consists of a number of segments derived from the input wave.

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


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