Q. A dc separately excited motor has constant field current. The armature is fed from a single phase supply through a full converter. When α = 0, speed is 500 rpm. If α = 45°, the speed is likely to be

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Q. In a multiphase chopper, all choppers operate together.

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Q. The terminals of a power MOSFET are called

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Q. Assertion (A): The surge current which an SCR can withstand is much higher than rms on state current.

Reason (R): The duration of surge current is very small.

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Q. Current derating may be necessary when thyristors are operating in

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Q. If duty cycle is a and the load is α resistance R, the rms value of output voltage is

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Q. For a BJT, α = 0.98, then β =

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Q. Assertion (A): Power transistor has lower switching time than SCR

Reason (R): Power transistor has greater switching time than SCR

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Q. A 3 kV circuit uses SCR of 800 V rating. If derating is 25%, the number of SCRs in series is

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Q. The number of doped regions in a SCR is

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Q. All inverters use forced commutation.

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Q. In 180° mode of operation of a 3 phase bridge inverter, two thyristors conduct at one time.

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Q. In a single phase full wave ac regulator the rms value of load current is 20 A load is purely resistive. Then

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Q. A reactor is used in a dual converter operating in non-circulating current mode.

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Q. In a 3 phase full wave regulator feeding resistance load connected in star, the possible range of firing angle α is

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Q. Assertion (A): A dual converter may be circulating current type or non circulating current type.

Reason (R): In circulating current dual converter only one converter can be operated at one time.

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Q. Current chopping leads to

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Q. A 3 phase bridge inverter is fed by 400 V battery. The load is star connected and has a resistance of 10 Ω per phase. The peak value of load current is

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Q. In an SCR, the anode current is controlled by

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Q. The rated current of a thyristor is 40 A. The holding current will be about :

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