Q. A single phase semiconverter has a freewheeling diode. If the firing angle is α and the load is purely resistive, the periods of conduction and freewheeling respectively are

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Q. HVDC transmission systems generally use

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Q. A single phase semiconverter is feeding a highly inductive load. The circuit has a freewheeling diode across the load and firing angle is α. During one cycle of input voltage, the total duration of conduction of freewheeling diode is

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Q. During forward blocking state of SCR, the voltage and current respectively are

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Q. In a 3 phase full converter the average load current is 150 A. The average thyristor current is

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Q. The two modes of operation of three phase bridge inverters are known as

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Q. To protect an SCR against high di/dt we connect

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Q. In a parallel inverter

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Q. A silicon controlled switch has :

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Q. A dc chopper V = 500 V feeds an electric fraction dc series motor. The chopping frequency is 400 Hz. The series inductance required to limit the maximum current swing to 10 A is

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Q. A single phase fully controlled bridge rectifier is fed by a source having inductance. The output voltage during overlap period is

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Q. A single phase half wave converter is used to charge a battery of 50 V. The thyristor is continuously fired by dc signal. Input voltage is v = Vm sin ωt. The thyristor will conduct

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Q. In a 3 phase semiconverter, the firing frequency is

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Q. Present day HVDC converters are all

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Q. A single phase full converter gives maximum and minimum output voltage at firing angles of

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Q. A thyristor has its gate current zero. To start conduction the forward voltage must exceed

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Q. Assertion (A): Snubber circuit has an RC series circuit in parallel with SCR

Reason (R): Voltage across a capacitor can not change instantaneously.

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Q. In dielectric heating, the thyristor circuits consist of

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Q. On load tap changer using thyristors can have a maximum of two taps.

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Q. Assertion (A): A cycloconverter may be line commutated or forced commutated

Reason (R): A step up cycloconverter requires forced commutation.

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