Power Electronics problems
- 1. In the basic series inverter circuit, the source supplies load
Options- A. only in positive half cycle
- B. both in positive and negative half cycles
- C. only in part of positive half cycle
- D. in positive half cycle and part of negative half cycle Discuss
Correct Answer: only in positive half cycle
- 2. A 3 phase fully controlled bridge converter is fed by a 3 phase system having phase voltage v = Vm sin ?t. The firing angle is a. The dc output voltage is
Options- A.
- B.
- C.
- D.
Discuss
Correct Answer:
- 3. In an ordinary thyristor
Options- A. turn on and turn off times are equal
- B. turn on time is more than turn off time
- C. turn off time is more than turn on time
- D. turn on time may be equal, less than or more than turn off time Discuss
Correct Answer: turn off time is more than turn on time
- 4. A voltage VBB is applied across the terminals of a UJT. The emitter voltage at peak point is
Options- A. hVBB
- B. (h + 1) VBB
- C. hVBB + VD
- D. VD Discuss
Correct Answer: hVBB + VD
- 5. A single phase half wave rectifier circuit has a free wheeling diode. The free wheeling diode will conduct only if
Options- A. load is purely resistive
- B. load is purely inductive
- C. load is combination of R and L
- D. load is purely inductive or combination of R and L Discuss
Correct Answer: load is purely inductive or combination of R and L
- 6. In a 3 phase bridge inverter with 180° mode of operation the numbers of thyristors conducting at one time are
Options- A. 1
- B. 2
- C. 3
- D. 4 Discuss
Correct Answer: 3
- 7. In a thyristors are i = kva. The value of a is
Options- A. about 0.5
- B. about 2
- C. about 5
- D. about 20 Discuss
Correct Answer: about 5
- 8. A single phase cycloconverter feeds a resistance heating load. The heating power is provided by
Options- A. only the fundamental component of output wave
- B. only higher harmonics in the output wave
- C. both fundamental and higher harmonics in the output wave
- D. either (a) or (b) Discuss
Correct Answer: both fundamental and higher harmonics in the output wave
- 9. A full bridge inverter is fed by a battery of 30 V. The rms value of output voltage is
Options- A. 15 V
- B. 152 V
- C. 30 V
- D. 302 V Discuss
Correct Answer: 30 V
- 10. Which of the following devices exhibit negative resistance characteristics?
Options- A. UJT
- B. PUT
- C. Both UJT and PUT
- D. UJT, PUT and SBS Discuss
Correct Answer: Both UJT and PUT
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