Q. A 750 A circuit uses thyristor of current rating 175 A. If derating is 25%, the number of thyristors in parallel is

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Q. Assertion (A): An inverter does not require forced commutation

Reason (R): A series inverter is a forced commutation inverter.

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Q. In a single phase full wave converter (M - 2 connection), the rms transformer voltage is 300 V across each half of secondary. The PIV for each thyristor is

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Q. A dc separately excited motor has a constant field current. The armature is fed from a single phase supply through a semi-converter. When α = 0, speed is 600 rpm. If α = 90°, the speed is likely to be

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Q. A static induction thyristor

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Q. A single phase step up cycloconverter changes 50 Hz to 100 Hz. Then one half wave of input will give rise to

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Q. Which of these triggering methods for series connected SCRs use LASCR in the gate circuit?

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Q. A 3 phase ac regulator uses

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Q. A dc circuit breaker must use

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Q. In a single phase full wave regulator feeding R-L load, the minimum firing angle can be zero.

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Q. An RC snubber circuit is used to protect a thyristor against :

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Q. A DIAC has two terminals, anode and cathode.

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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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