A single phase semiconverter is feeding a highly inductive load. The circuit has a freewheeling diode across the load and firing angle is a. During one cycle of input voltage, the total duration of conduction of freewheeling diode is
Answer: B
Freewheeling diode conducts for a° in each half cycle.
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The number of leads in an SCR are :
Answer: B
Anode, cathode and gate.
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In a thyristor the gate current is increased, then
Answer: C
Gate current does not affect the magnitude of anode current.
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A cycloconverter can be
Answer: C
The output frequency can be more or less than input frequency.
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When the core of a saturable reactor is saturated, the inductance is high.
Answer: B
Since core is saturated, change of flux is small and inductance is low.
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A single phase series converter is used for
Answer: A
Series connection increases the voltage.
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In a multiphase chopper, all choppers operate together.
Answer: B
They operate in a sequence.
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Assertion (A): Snubber circuit has an RC series circuit in parallel with SCR
Reason (R): Voltage across a capacitor can not change instantaneously.
Answer: A
Since voltage across capacitor cannot change instantaneously it protects SCR .
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To protect an SCR against high di/dt we connect
Answer: D
current through inductance cannot change instantaneously.
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In a 3 phase full wave regulator feeding resistance load connected in star, the possible range of firing angle a is
Answer: B
Since output voltage is zero if a ≥ 150°, the possible range of firing angles is 0 ≤ a ≤ 150°.
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