Power Electronics problems
- 1. 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
Correct Answer: 2
- 2. 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
Correct Answer: a resistor and capacitor in series connected across thyristor
- 3. 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
Correct Answer: even when load current is zero
- 4. 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
Correct Answer: Both A and R are correct and R is correct explanation of A
- 5. In Jone chopper, the commutating element
Options- A. is a capacitor
- B. is a capacitor and an inductor
- C. is a capacitor and an auto transformer
- D. none of the above Discuss
Correct Answer: is a capacitor and an auto transformer
- 6. The total number of leads in SCR, DIAC and TRIAC respectively are
Options- A. 3, 2, 3
- B. 2, 3, 3
- C. 3, 3, 2
- D. 3, 2, 4 Discuss
Correct Answer: 3, 2, 3
- 7. Forward
rating of an SCR is
Options- A. the maximum rate of rise of anode voltage which will trigger the SCR
- B. the maximum rate of rise of anode voltage which will not trigger the SCR if gate signal is applied
- C. the maximum rate of rise of anode voltage which will not trigger the SCR if gate signal is not applied
- D. either (b) or (c) Discuss
Correct Answer: the maximum rate of rise of anode voltage which will not trigger the SCR if gate signal is not applied
- 8. The load circuit of a single phase full bridge inverter
Options- A. must be underdamped
- B. must be overdamped
- C. may be underdamped or overdamped
- D. may be any type of load Discuss
Correct Answer: may be any type of load
- 9. When a single phase dual converter is operating in circulating current mode
Options- A. both converters are working as rectifiers simultaneously
- B. one converter is always working as rectifier and the other as inverter
- C. only one converter is working at one time
- D. both converters are either working as rectifiers or as inverters simultaneously Discuss
Correct Answer: one converter is always working as rectifier and the other as inverter
- 10. In disc mounting of SCR
Options- A. SCR is clamped on one side of disc shaped heat sink
- B. SCR is clamped between two disc shaped heat sinks
- C. The SCR has low current rating
- D. None of the above Discuss
Correct Answer: SCR is clamped between two disc shaped heat sinks
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