POWER ELECTRONICS PART 9
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POWER ELECTRONICS PART 9
communication interval. If the maximum allowable reapplied dv/dt on TM is 50V/μs,what should be the theoretical minimum value of C1? Assume current ripple through L0 to be negligible. [GATE]
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(c) Or else the free wheeling action of the converter will cause shorting of the AC supply
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(a) 0.78
(b) 0.827
(c) 0.866
(d) 0.9
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[8] A three phase fully controlled
thyristor bridge converter is used as line commutated inverter to feed 50KW
power at 420V DC to a three phase 415V(line), 50Hz as mains. Consider DC link
current to be constant. The RMS current of the thyristor is [GATE 2007]
(a) 119.05A
(b) 79.37A
(c) 68.73A
(d) 39.68A
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POWER ELECTRONICS PART 9
(a) a=1, b=2
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[10] The phase of the above lead compensator is maximum at
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[11] A three phase to single phase conversion device employs a 6 pulse bridge cycloconverter. For an input voltage of 200V/phase, the fundamental rms value of output voltage is
(a) 600/π V
(b) 300√3/π V
(c) 300/π V
(d) 600√3 /π V
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[12] A three phase to single phase cycloconverter consists of positive and negative group of converters. In this device one of the two component converters would operate as a
(a) Rectifier if the output voltage VO and output current IO have the same polarity
(b) Inverter if VO and IO have the same polarity
(c) Rectifier if VO and IO are of opposite polarity
(d) Inverter if VO and IO are of opposite polarity
Options:
1) A, D
2) A
3) D
4) C, D
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[13] A 3 phase to 3 phase cycloconverter requires
(a) 18 SCRs for 3-pulse device
(b) 18 SCRs for 6-pulse device
(c) 36 SCRs for 3-pulse device
(d) 36 SCRs for 6-pulse device
Options:
1) A
2) A, D
3) B, D
4) D
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POWER ELECTRONICS PART 9
[14] Which of the following statements are correct for cycloconverter?
(a) Step down cycloconverter works on natural commutation
(b) Step up cycloconverter requires forced commutation
(c) Load commutated cycloconverter works on line commutation
(d) Load commutated cycloconverter requires a generated emf in the load circuit.
Options:
1) B, D
2) A, B, C
3) B, C
4)A, B, D
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[15] The functions of connecting a resistor in series with gate-cathode circuit and a zener diode across gate-cathode circuit are, respectively to protect the gate circuit from
(a) Over voltages, over currents
(b) Over currents, over voltages
(c) Over currents, noise signals
(d) Noise signals, over voltages
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POWER ELECTRONICS PART 9