Discussion
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- Question
In the circuit of figure, the load current when thyristor is off
Options- A. is constant
- B. increases exponentially
- C. decreases exponentially
- D. zero
- Correct Answer
- decreases exponentially
- 1. Assertion (A): The turn on time of SCR is about 1 to 4 ms.
Reason (R): The turn off time of SCR is about 10 to 300 ms.
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
- 2. In a half bridge inverter each thyristor is gated at a frequency f. The output frequency is
Options- A. 2 f
- B. f
- C. 0.5 f
- D. 0.25 f Discuss
- 3. Which of these commutation methods uses an external pulse for commutation?
Options- A. Class A
- B. Class C
- C. Class E
- D. Class F Discuss
- 4. The two-transistor model of a thyristor consists of two transistors :
Options- A. one n-p-n and other p-n-p
- B. both p-n-p
- C. both n-p-n
- D. one n-p-n and other UJT Discuss
- 5. The characteristics of which device has peak point and valley point
Options- A. SCR
- B. PUT
- C. SCS
- D. Shockley diode Discuss
- 6. Thyristors connected in series need :
Options- A. static equalizing circuit
- B. dynamic equalizing circuit
- C. both static and dynamic equalizing circuits
- D. none of the above Discuss
- 7. A single phase bridge type cycloconverter uses eight thyristors.
Options- A. True
- B. False Discuss
- 8. A single phase full converter can operate in
Options- A. 4 quadrants
- B. 3 quadrants
- C. 2 quadrants
- D. 1 quadrant Discuss
- 9. In a thyristor, the forward breakover voltage
Options- A. is constant
- B. may be constant or may depend on gate current
- C. decreases as gate current is increased
- D. increases as gate current is increased Discuss
- 10. A single phase half wave converter is feeding a resistive load. Output dc power is Pdc and total power delivered to load is Pac then
Options- A. Pdc = Pac for all values of firing angles
- B. Pdc = Pac if firing angle is less than 180°
- C. Pdc < Pac for all values of firing angles
- D. Pdc < Pac if firing angle is less than 180° Discuss
Power Electronics problems
Search Results
Correct Answer: Both A and R correct but R is not correct explanation of A
Correct Answer: f
Correct Answer: Class E
Correct Answer: one n-p-n and other p-n-p
Correct Answer: PUT
Correct Answer: both static and dynamic equalizing circuits
Correct Answer: True
Correct Answer: 2 quadrants
Correct Answer: decreases as gate current is increased
Correct Answer: Pdc < Pac if firing angle is less than 180°
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