Power Electronics problems
- 1. A load commutated chopper circuit has
Options- A. one thyristor
- B. two thyristors
- C. four thyristors
- D. six thyristors Discuss
Correct Answer: four thyristors
- 2. In a single phase full wave controlled rectifier using centre tap transformer, the voltage across each half of secondary is Vm sin ?t. The peak inverse voltage is
Options- A. 2 Vm
- B. Vm
- C. 0.5 Vm
- D. 0.25 Vm Discuss
Correct Answer: 2 Vm
- 3. If peak value of input voltage is Vm and firing angle is a, the average output voltage for single phase half wave and single phase full wave regulators are
Options- A.
- B.
- C.
- D.
Discuss
Correct Answer:
- 4. Lead mounting for SCR is used for
Options- A. rating less than mA
- B. rating about 1 A or less
- C. rating of 20 A or less than 20 A
- D. rating 100 A or less Discuss
Correct Answer: rating about 1 A or less
- 5. A TRIAC can be turned on :
Options- A. by applying a positive signal to gate
- B. by applying a negative signal to gate
- C. by applying either positive or negative signal to gate
- D. none of the above Discuss
Correct Answer: by applying either positive or negative signal to gate
- 6. In a three phase series inverter, the firing frequency is
Options- A. three times output frequency
- B. six times output frequency
- C. twice the output frequency
- D. equal to output frequency Discuss
Correct Answer: six times output frequency
- 7. A 3 phase fully controlled converter is a
Options- A. 3 pulse converter
- B. 6 pulse converter
- C. 2 pulse converter
- D. 12 pulse converter Discuss
Correct Answer: 6 pulse converter
- 8. When a thyristor is conducting, the voltage drop across it is about
Options- A. 1 V
- B. 10 V
- C. 100 V
- D. 0.1 V Discuss
Correct Answer: 1 V
- 9. The use of free wheeling diode in controlled rectifier improves the waveshape of load current.
Options- A. True
- B. False Discuss
Correct Answer: True
- 10. In a half bridge inverter, the freewheeling diodes are needed
Options- A. even when load is resistive
- B. only when load is inductive
- C. only when load is inductive or capacitive
- D. for all types of loads Discuss
Correct Answer: only when load is inductive or capacitive
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