Power Electronics problems
- 1. In auxiliary commutated chopper, the charging and discharging time of capacitor
Options- A. are constant
- B. depend on load current
- C. may be constant or may depend on load current
- D. none of the above Discuss
Correct Answer: depend on load current
- 2. Which of these devices is used in relaxation oscillator?
Options- A. UJT
- B. SCR
- C. DIAC
- D. TRIAC Discuss
Correct Answer: UJT
- 3. The difference between resonant commutation and self commutation is
Options- A. both these methods are based on entirely different principles
- B. in resonant commutation, the commutating elements carry load current but in self commutation, the commutating elements do not carry load current
- C. resonant commutation uses L and C but self commutation uses only capacitor
- D. none of the above Discuss
Correct Answer: both these methods are based on entirely different principles
- 4. A cycloconverter for single phase operation has
Options- A. one positive group and one negative group converters
- B. two positive group and two negative group converters
- C. three positive group and three negative group converters
- D. any of the above Discuss
Correct Answer: one positive group and one negative group converters
- 5. Which of these commutation methods uses two leads?
Options- A. Class A
- B. Class B
- C. Class C
- D. Class D Discuss
Correct Answer: Class D
- 6. In a controlled rectifier a freewheeling diode is necessary if the load is
Options- A. inductive
- B. resistive
- C. capacitive
- D. any of the above Discuss
Correct Answer: inductive
- 7. The total number of leads in MOS controlled thyristor is
Options- A. 2
- B. 3
- C. 4
- D. 2 or 3 Discuss
Correct Answer: 3
- 8. A thyristor circuit is feeding an R-L load. The turn on time can be reduced by
Options- A. decreasing R
- B. decreasing L
- C. increasing L
- D. decreasing R and L together Discuss
Correct Answer: decreasing L
- 9. The stud in a stud mounted SCR acts as
Options- A. anode
- B. cathode
- C. gate
- D. anode or cathode Discuss
Correct Answer: anode
- 10. Assertion (A): An ac regulator uses natural commutation
Reason (R): An ac regulator can be used for static on load tap changing of transformer.
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
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