Q. In brushless excitation system of modern alternators, the main exciter is

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Q. The two-transistor model of a thyristor consists of two transistors :

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Q. In a thyristor, the forward breakover voltage

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Q. The gate lead, in a thyristor is welded to :

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Q. In a 3 phase full converter, the firing angle is less than 60°. The instantaneous output voltage

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Q. Which converter is used in HVDC transmission?

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Q. Assertion (A): The turn on time of SCR is about 1 to 4 ms.

Reason (R): The turn off time of SCR is about 10 to 300 ms.

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Q. Which chopper circuit operates in all the 4 quadrants?

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Q. A single phase cycloconverter feeds a resistance heating load. The heating power is provided by

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Q. A voltage VBB is applied across the terminals of a UJT. The emitter voltage at peak point is

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Q. A single phase bridge type cycloconverter uses eight thyristors.

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Q. In the basic series inverter circuit, the source supplies load

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Q. In a 3 phase bridge inverter with 180° mode of operation the numbers of thyristors conducting at one time are

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Q. A single phase full converter can operate in

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Q. In a 3 phase semiconverter, the freewheeling diode comes into operation only if firing angle

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Q. A full bridge inverter is fed by a battery of 30 V. The rms value of output voltage is

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Q. The total number of leads in SUS, SBS and SCS respectively are

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Q. Which of these devices can conduct in both directions?

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Q. Assertion (A): A half wave controlled rectifier has poorer efficiency and higher ripple factor than a full wave controlled rectifier.

Reason (R): The use of a freewheeling diode in half wave controlled rectifier circuit improves the waveform of load current and circuit power factor.

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Q. A 3 phase dual converter consists of

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