Q. In a half bridge inverter each thyristor is gated at a frequency f. The output frequency is

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Q. Assertion (A): A transistor has lower voltage drop during conduction as compared to thyristor

Reason (R): Transistors are manufactured in very high voltage and current ratings.

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Q. Assertion (A): Typical value of thermal resistance from source to sink of an SCR is about 0.3° C/W

Reason (R): Heat sinks of thyristors are generally made of aluminium.

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Q. In a thyristors are i = kvᵃ. The value of a is

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Q. In an ordinary thyristor

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Q. Thyristors connected in series need :

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Q. If 4 quadrant operation is required we need

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Q. Which of these commutation methods uses an external pulse for commutation?

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Q. In a single phase full wave regulator feeding an R-L load, the power factor angle of load is θ. The range of control of firing angle α is

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Q. A separately excited dc motor is run from a dc source through a chopper. At 600 rpm and rated torque, the duty cycle of chopper is 0.8. At 600 rpm and half the rated torque, the duty cycle is likely to be

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Q. A relaxation oscillator uses

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Q. In a stud mounted SCR, the stud is

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Q. In pulse width modulation of chopper

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Q. In a full bridge inverter, the waveshape of load current depends on

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Q. The characteristics of which device has peak point and valley point

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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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