Discussion
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- Question
From which instant is the turn off time of a thyristor defined
Options- A. when anode voltage becomes zero
- B. when anode current becomes zero
- C. when both anode voltage and current become zero
- D. none of the above
- Correct Answer
- when anode current becomes zero
- 1. When an SCR is reverse biased
Options- A. two junctions are reverse biased and one junction is forward biased.
- B. all the three junctions are reverse biased.
- C. one junction is reverse biased and two junctions are forward biased.
- D. any of the above depending on the magnitude of reverse bias. Discuss
- 2. The duty cycle of a step down chopper is
Options- A.
- B.
- C.
- D.
Discuss
- 3. A class B chopper operates in third quadrant.
Options- A. True
- B. False Discuss
- 4. A single phase cycloconverter with centre tapped input transformer requires
Options- A. 2 thyristors
- B. 4 thyristors
- C. 8 thyristors
- D. either 2 or 4 thyristors Discuss
- 5. In a modified series inverter
Options- A. the maximum output frequency is less than frequency of damped oscillations
- B. the output frequency can be even higher than the frequency of damped oscillations
- C. the output frequency cannot exceed the frequency of damped oscillations
- D. any of the above Discuss
- 6. The number of thyristors in a single phase fully controlled bridge rectifier is
Options- A. 16
- B. 8
- C. 4
- D. 2 Discuss
- 7. In a 3 phase bridge inverter with 120° mode of operation the. number of thyristors conducting at one time are
Options- A. 1
- B. 2
- C. 3
- D. 4 Discuss
- 8. The snubber circuit consists of
Options- A. a capacitor connected in series with thyristor
- B. a capacitor connected in parallel with thyristor
- C. a resistor and capacitor in series connected across thyristor
- D. none of the above Discuss
- 9. In a dual converter operated in circulating current mode, the circulating current flows
Options- A. when load current is zero
- B. when load current is non-zero
- C. even when load current is zero
- D. none of the above Discuss
- 10. Assertion (A): Light triggering is very suitable for HVDC transmission.
Reason (R): Light triggering has the advantage of complete electrical isolation of gate circuit.
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 Discuss
Power Electronics problems
Search Results
Correct Answer: two junctions are reverse biased and one junction is forward biased.
Correct Answer:
Correct Answer: False
Correct Answer: 4 thyristors
Correct Answer: the output frequency can be even higher than the frequency of damped oscillations
Correct Answer: 4
Correct Answer: 2
Correct Answer: a resistor and capacitor in series connected across thyristor
Correct Answer: even when load current is zero
Correct Answer: Both A and R are correct and R is correct explanation of A
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