Power Electronics problems
- 1. Natural commutation can be used in :
Options- A. DC circuits only
- B. AC circuits only
- C. both AC and DC circuits
- D. none of the above Discuss
Correct Answer: AC circuits only
- 2. The gate lead, in a thyristor is welded to :
Options- A. p layer to which anode is connected
- B. n layer nearest to the anode terminal
- C. p layer nearest to the cathode terminal
- D. outside n layer Discuss
Correct Answer: n layer nearest to the anode terminal
- 3. Which chopper circuit operates in all the 4 quadrants?
Options- A. A
- B. C
- C. D
- D. E Discuss
Correct Answer: E
- 4. Which converter is used in HVDC transmission?
Options- A. 3 pulse
- B. 6 pulse
- C. 12 pulse
- D. 24 pulse Discuss
Correct Answer: 12 pulse
- 5. A chopper cannot be line commutated.
Options- A. True
- B. False Discuss
Correct Answer: True
- 6. Assertion (A): Typical value of thermal resistance from source to sink of an SCR is about 0.3° C/W
Reason (R): Heat sinks of thyristors are generally made of aluminium.
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
- 7. In integral cycle control of ac regulators, the period of integral cycle control, i.e., (m + n) T should be
Options- A. less than mechanical or thermal time constant of the system
- B. more than the mechanical or thermal time constant of the system
- C. more or less than the mechanical or thermal time constant
- D. very high Discuss
Correct Answer: less than mechanical or thermal time constant of the system
- 8. In load commutated chopper, the commutating element
Options- A. is capacitor
- B. is capacitor and inductor
- C. is capacitor, inductor and auxiliary thyristor
- D. any of the above depending on load Discuss
Correct Answer: is capacitor
- 9. Assertion (A): A transistor has lower voltage drop during conduction as compared to thyristor
Reason (R): Transistors are manufactured in very high voltage and current ratings.
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: A is correct but R is wrong
- 10. The symbol in figure is for
Options- A. SUS
- B. SBS
- C. SCS
- D. None of the above Discuss
Correct Answer: SCS
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