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GATE 2020 || Power Electronics || Quiz 3 (App update required to attempt this test)

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Question 1

The given commutation circuit has C = 15 Mf and L = 4 MF. the initial voltage across capacitor = 230 V for a constant load current 325 A. The time required to turn off the main thyristor after the auxiliary thyristor is switched on is


Question 2

In resonant pulse commutation, C = 30 μF and L = 6 μH, initial voltage across capacitor Vs = Vc = 260 V. If the constant load current is 280 A, then the circuit turn off time of main thyristor is ____  μsec.

Question 3

For the class 'C' commutation circuit the dc source voltage Edc = 220 V and current through R1 and R2 is 25A. The turn off time of both the SCRs is 50 μs, calculate the value (in μF) of commutating capacitor 'C' for successful commutation.

Question 4

In the circuit shown below.


If Vs = 230 V, L = 20 μH, C = 40 μF and a constant load of 120 A then the circuit turn off time of auxiliary thyristor (TA) is

Question 5

A voltage commutated chopper operating at 1 kHz is used to control the speed of dc motor as shown in figure. The load current is assumed to be constant at 10 A.

The minimum time in uses for which the SCR M should be ON is

Question 6

A circuit employing parallel resonance turn off (or class B commutation) circuit has C = 50 µs, L= 20µH, VS=200 V, and initial voltage across capacitor is 200 V. Determine the circuit turn-off time for main thyristor for load R= 1.5 Ω.
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Jul 2ESE & GATE EE