Discussion
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- Question
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.
- Correct Answer
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- 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
- 2. In a full bridge inverter, the waveshape of load current depends on
Options- A. relative values of load parameters R, L and C
- B. relative values of load parameters R and L
- C. relative values of load parameters L and C
- D. gating frequency Discuss
- 3. A current source inverter has simple commutation circuit.
Options- A. True
- B. False Discuss
- 4. In a 3 phase semiconverter, the freewheeling diode comes into operation only if firing angle
Options- A. is zero
- B. is 60°
- C. is more than 60°
- D. is more than 90° Discuss
- 5. A relaxation oscillator uses
Options- A. tunnel diode
- B. UJT
- C. both tunnel diode and UJT
- D. PIN diode Discuss
- 6. 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
- 7. 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
- 8. 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
- 9. 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
- 10. 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
Power Electronics problems
Search Results
Correct Answer: only in positive half cycle
Correct Answer: relative values of load parameters R, L and C
Correct Answer: True
Correct Answer: is more than 60°
Correct Answer: UJT
Correct Answer: turn off time is more than turn on time
Correct Answer: hVBB + VD
Correct Answer: load is purely inductive or combination of R and L
Correct Answer: 3
Correct Answer: about 5
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