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  • Question
  • 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 load current is


  • Options
  • A. 40 A
  • B. 20 A
  • C. 10 A
  • D. 5 A

  • Correct Answer
  • 20 A 

    Explanation
    Two resistances are in series at any time.

    Power Electronics problems


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    • 1. During forward blocking state of SCR, the voltage and current respectively are

    • Options
    • A. high and high
    • B. low and low
    • C. high and low
    • D. low and high
    • Discuss
    • 2. A cycloconverter is

    • Options
    • A. ac-dc converter
    • B. dc-ac converter
    • C. dc-dc converter
    • D. ac-ac converter
    • Discuss
    • 3. A single phase semiconverter has a freewheeling diode. If the firing angle is a and the load is purely resistive, the periods of conduction and freewheeling respectively are

    • Options
    • A. p - a and 0
    • B. p - a and a
    • C. p + a and 0
    • D. p + a and a
    • Discuss
    • 4. In a 3 phase full wave regulator feeding a star connected resistance load the input voltage is 400 V line to line. The firing angle is 160°. The line to line output voltage would be

    • Options
    • A. 400 V
    • B. about 100 V
    • C. about 20 V
    • D. zero
    • Discuss
    • 5. Two semiconverters are connected in series to form a single phase series converter. The input v = Vm sin ?t and a1 = a2 are the firing angles of the two converters. If a1 = a2 = 0, the dc output voltage is

    • Options
    • A.
    • B.
    • C.
    • D.
    • Discuss
    • 6. A single phase half wave controlled rectifier circuit is feeding on RL load. The circuit has a freewheeling diode. The input voltage is v = Vm sin ?t. If I0 is the load current during the conduction of freewheeling diode, the KVL equation during the conduction of free wheeling diode is

    • Options
    • A.
    • B.
    • C.
    • D.
    • Discuss
    • 7. A 750 A circuit uses thyristor of current rating 175 A. If derating is 25%, the number of thyristors in parallel is

    • Options
    • A. 3
    • B. 4
    • C. 6
    • D. 10
    • Discuss
    • 8. Which of these triggering methods for series connected SCRs use LASCR in the gate circuit?

    • Options
    • A. Resistance triggering
    • B. Simultaneous triggering
    • C. Sequential triggering
    • D. Optical triggering
    • Discuss
    • 9. In a series inverter supplying a load resistance R, the commutating elements L and C should be such that

    • Options
    • A.
    • B.
    • C.
    • D.
    • Discuss
    • 10. An RC snubber circuit is used to protect a thyristor against :

    • Options
    • A. false triggering
    • B. failure to turn on
    • C. switching transients
    • D. failure to commutate
    • Discuss


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