Discussion
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- Question
As compared to BJT, MOSFET has
Options- A. lower switching losses and higher conduction losses
- B. higher switching losses and higher conduction losses
- C. higher switching losses and lower conduction losses
- D. lower switching losses and lower conduction losses
- Correct Answer
- lower switching losses and higher conduction losses
- 1. In a 3 phase full converter, the firing angle is less than 60°. The instantaneous output voltage
Options- A. will have positive part only
- B. will have both positive and negative parts
- C. may have both positive and negative parts
- D. will have negative part if load is inductive Discuss
- 2. A separately excited dc motor is run from a dc source through a chopper. At 600 rpm and rated torque, the duty cycle of chopper is 0.8. At 600 rpm and half the rated torque, the duty cycle is likely to be
Options- A. 0.9
- B. 0.8
- C. 0.75
- D. 0.6 Discuss
- 3. If 4 quadrant operation is required we need
Options- A. dual converter
- B. full converter
- C. semi converter
- D. none of the above Discuss
- 4. In a step down chopper using time ratio control, the input voltage is V and duty cycle is a. The load is purely resistive having resistance R. The average and rms load currents are
Options- A.
- B.
- C.
- D.
Discuss
- 5. In brushless excitation system of modern alternators, the main exciter is
Options- A. dc generator
- B. ac generator
- C. either dc or ac generator
- D. induction generator Discuss
- 6. In pulse width modulation of chopper
Options- A. T is kept constant and Ton is varied
- B. Ton is kept constant T is varied
- C. both T and Ton are varied
- D. either T or Ton is varied Discuss
- 7. All other parameters remaining the same, a 3 phase bridge inverter with 180° mode of operation
Options- A. has the same peak thyristor current as in 120° mode of operation
- B. has higher peak thyristor current than in 120° mode of operation
- C. has lower peak thyristor current than in 120° mode of operation
- D. any of the above Discuss
- 8. A class D chopper
Options- A. can operate in first quadrant only
- B. can operate in second quadrant only
- C. can operate in either first or fourth quadrant
- D. can operate in all the quadrants Discuss
- 9. In sinusoidal PWM for inverters the width of different pulses are not the same.
Options- A. True
- B. False Discuss
- 10. When an SCR is in forward blocking mode, the applied voltage
Options- A. appears across only one junction
- B. is equally shared by two junctions
- C. is equally shared by three junctions
- D. may appear across one or more junctions Discuss
Power Electronics problems
Search Results
Correct Answer: will have positive part only
Correct Answer: 0.75
Correct Answer: dual converter
Correct Answer:
Correct Answer: ac generator
Correct Answer: T is kept constant and Ton is varied
Correct Answer: has higher peak thyristor current than in 120° mode of operation
Correct Answer: can operate in either first or fourth quadrant
Correct Answer: True
Correct Answer: appears across only one junction
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