Q. The use of free wheeling diode in controlled rectifier improves the waveshape of load current.

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Q. As the firing of a thyristor is delayed, the output voltage of a controlled rectifier decreases.

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Q. In a certain inverter circuit each thyristor carries 26.67 A for 60°, 13.33 A for 120° and zero A for 180° of the cycle. The rms current of thyristor is

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Q. The factor η for a UJT is about

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Q. In a single phase full converter fed by a source having inductance, the number of thyristors conducting during overlap is

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Q. The cut in voltages for germanium and silicon diodes respectively as

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Q. Assertion (A): A GTO can be turned on and turned off by gate pulses

Reason (R): A GTO can be turned off by negative gate pulse.

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Q. In a full bridge single phase inverter feeding RLC load

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Q. It is possible to use a freewheeling diode in

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Q. Assertion (A): When the anode current of an SCR starts increasing during turn on process, the anode cathode voltage drop starts decreasing.

Reason (R): During turn on the reverse biased junction in SCR breaksdown.

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Q. An SCR is triggered at 80° in the positive half cycle, only. The rms anode current is 25 A. If the firing angle is changed to 160°, the rms current is likely to be

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Q. The output wave of a cycloconverter consists of a number of segments derived from the input wave.

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Q. A class A chopper has an input voltage of 200 V. Ton = 1.5 ms and Toff = 4.5 ms. The duty cycle, average output voltage and ripple factor respectively are

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Q. A TRIAC can be turned on :

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Q. In a half bridge inverter the gate pulses of the two thyristors have a phase displacement of

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Q. A fully controlled bridge converter can operate in quadrants

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Q. A class E chopper

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Q. A cycloconverter uses

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Q. Assertion (A): A fully controlled bridge converter can operate in first and fourth quadrant.

Reason (R): A semi converter is cheaper than a full converter.

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Q. A fully controlled bridge converter is feeding an RLE load. The load current is I0. The input voltage is Vm sin ωt. The KVL equation to find firing angle a is

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