TRANSFORMERS QUIZ

Which of following is not a power transistor?

TRIAC.

SITS.

COOLMOS.

IGBTs.

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A 200 A thyristor is to be operated in parallel with a 300 A thyristor. The ON state voltage drops are 1.5 V and 1.2 Volts. What is the value of resistance R to be connected in series with each thyristor, so that current through the combination is 500 A and each of them is fully loaded ?

3.0 ohm

0.3 ohm

0.3 ohm

0.03 ohm

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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.

130 ÃŽÂ¼s.

135 ÃŽÂ¼s.

140 ÃŽÂ¼s.

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Which of the following is used in SCR to protect from high dV / dt?

Circuit breaker.

Fuse.

Equalizing circuit.

Snubber circuit.

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A modern power semiconductor device that combines the characteristic of BJT and MOSFET is

GTO.

MCT.

IGBT.

FCT.

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Thyristor can be protected from over voltages by using

heat sink.

fuse.

snubber circuit.

voltage clamping device.

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Light triggering mainly used in

high voltage direct current transmission.

medium voltage direct current transmission.

all of these.

low - voltage direct current transmission.

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The function of snubber circuit connected across the SCR is to

decrease dV / dt.

increase dV / dt.

decrease di / dt.

suppress dV / dt.

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During gate recovery time

charge carriers of J3 junction is removed.

charge carriers of J2 junction is swept out.

charge carrier of J1 junction removed.

charge carriers of J2 junction recombined.

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Typical range of thyristor turn OFF time is

3 - 100 µs.

3 - 50 µs.

3 - 500 µs.

3 - 10 µs.

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