Assertion (A): Inverters and choppers use fast switching thyristors Reason (R):

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Question
Assertion (A): Inverters and choppers use fast switching thyristors
Reason (R): Fast switching SCR has low turn off time.
Options
A. Both A and R are correct and R is correct explanation of A
B. Both A and R correct but R is not correct explanation of A
C. A is correct but R is wrong
D. A is wrong but R is correct

Correct Answer

Both A and R are correct and R is correct explanation of A

Explanation

Low turn off time enables fast switching.

Power Electronics problems

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1. A semiconverter feeding an RLE load operates in
Options
A. first quadrant only
B. first and second quadrants
C. first and fourth quadrants
D. first and third quadrants

2. A single phase semiconverter is feeding a highly inductive load and has freewheeling diode across the load. The waveshapes of output voltage and output current
Options
A. are similar
B. are not similar
C. may be similar or dissimilar
D. are similar only if firing angle is zero

3. The phenomenon of overlap in converter operation due to
Options
A. source resistance
B. source inductance
C. both source resistance and source inductance
D. high value of firing angle

4. Assertion (A): A transistor requires a continuous base signal for conduction but a thyristor requires a gate pulse.
Reason (R): Transistor find widespread application in power electronic circuits.
Options
A. Both A and R are correct and R is correct explanation of A
B. Both A and R correct but R is not correct explanation of A
C. A is correct but R is wrong
D. A is wrong but R is correct

5. Current derating may be necessary when thyristors are operating in
Options
A. series
B. parallel
C. series or parallel
D. none of the above

7. The terminals of a power BJT are called
Options
A. emitter, base, collector
B. emitter, base, drain
C. source, base, drain
D. source, base, collector

8. In a single phase full wave converter (M - 2 connection) feeding a highly inductive load, the firing angle for each thyristor is a in the respective half cycle. The period of conduction of each thyristor is
Options
A. p - a
B. p
C. p + a
D. p - 2a

10. Figure shows a chopper feeding RLE load, The free wheeling diode conducts when
Options
A. thyristor is on
B. thyristor is off
C. both when thyristor is on and thyristor is off
D. partly when thyristor is off and partly when thyristor is on

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