POWER ELECTRONICS QUIZ

The reverse recovery time of diode is trr = 3 ÃŽÂ¼s and the rate off all of the diode current is di/dt = 30 A/ÃŽÂ¼s. The storage charge current QRR is

145 ÃŽÂ¼s.

135 ÃŽÂ¼s.

140 ÃŽÂ¼s.

130 ÃŽÂ¼s.

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A step up chopper has input voltage 110 V and output voltage 150 V. The value of duty cycle is

0.27.

0.67.

0.45.

0.32.

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A thyristor will be triggered when Vg = 1.5 volt and Ig = 100 mA in the given figure. Calculate the value of R in ohm is

3.714.

60.

65.

37.14.

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A diac is simply ___________.

A triac without gate terminal

A single junction device

A three junction device

None of these

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If holding current of a thyristor is 2 mA then latching current should be

0.004 A.

0.009 A.

0.01 A.

0.002 A.

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BCT is used for

Low power current control.

High power phase control.

Low power phase control.

High power current control.

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The UJT may be used as ___________.

A rectifier

Am amplifier

None of these

A sawtooth generator

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During gate recovery time

charge carriers of J2 junction is swept out.

charge carriers of J2 junction recombined.

charge carrier of J1 junction removed.

charge carriers of J3 junction is removed.

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A thyristor string is made of a no. of SCR connected in series and parallel. The string have volume and current of 11 KV and 4 KA. The voltage and current rating of available SCRs are 1800 V and 1000 A. For a string efficiency of 90 % let the number of SCRs in series and parallel are a and b respectively. Then the value of a and b will be

4, 6.

6, 4.

5, 7.

7, 5.

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ON state voltage drop across SCR lie between the range

0 - 0.5 V.

0.5 - 1 V.

1 - 1.5 V.

1.5 - 2 V.

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