Power Electronics problems
- 1. A TRIAC is equivalent to
Options- A. two thyristors in series
- B. two thyristors in parallel
- C. one thyristor and one diode
- D. one thyristor and one transistor Discuss
Correct Answer: two thyristors in parallel
- 2. Assertion (A): The output voltage of an inverter can be controlled by PWM technique
Reason (R): In a current source inverter the input current is constant.
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
Correct Answer: Both A and R correct but R is not correct explanation of A
- 3. An SUS is
Options- A. exactly similar to SCR but with higher rating
- B. similar to UJT
- C. PUT and avalanche diode connected in anti parallel
- D. SCR and avalanche diode connected in parallel Discuss
Correct Answer: PUT and avalanche diode connected in anti parallel
- 4. In a half bridge inverter the gate pulses of the two thyristors have a phase displacement of
Options- A. 60°
- B. 90°
- C. 120°
- D. 180° Discuss
Correct Answer: 180°
- 5. The cut in voltages for germanium and silicon diodes respectively as
Options- A. 0.3 V and 0.7 V
- B. 0.7 V and 0.3 V
- C. 0.6 V and 0.9 V
- D. 0.5 V and 0.7 V Discuss
Correct Answer: 0.3 V and 0.7 V
- 6. The symbol in figure is for
Options- A. UJT
- B. PUT
- C. Shockley diode
- D. TRIAC Discuss
Correct Answer: UJT
- 7. A cycloconverter is a group of controlled rectifiers.
Options- A. True
- B. False Discuss
Correct Answer: True
- 8. In a certain inverter circuit each thyristor carries 26.67 A for 60°, 13.33 A for 120° and zero A for 180° of the cycle. The rms current of thyristor is
Options- A. 20 A
- B. 13.33 A
- C. 6.67 A
- D. 3.33 A Discuss
Correct Answer: 13.33 A
- 9. Which of the following devices has two gates?
Options- A. SCR
- B. SCS
- C. SUS
- D. SBS Discuss
Correct Answer: SCS
- 10. The factor ? for a UJT is about
Options- A. 0.1
- B. 0.2
- C. 0.6
- D. 0.9 Discuss
Correct Answer: 0.6
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