MCQOPTIONS
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MCQOPTIONS
This section includes 10 Mcqs, each offering curated multiple-choice questions to sharpen your Power Electronics knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
The major function of the pulse transformer is to |
| A. | increase the voltage amplitude |
| B. | reduce harmonics |
| C. | isolate low & high power circuit |
| D. | create periodic pulses |
| Answer» D. create periodic pulses | |
| 2. |
The duty cycle can be written as |
| A. | f x T |
| B. | f/T |
| C. | T/f |
| D. | f |
| Answer» B. f/T | |
| 3. |
Find the triggering frequency when the average gate power dissipation = 0.3 W and the peak gate drive power is 5 Watts. The gate source has a pulse width of 20 μsec duration. |
| A. | 3 kHz |
| B. | 0.3 kHz |
| C. | 30 kHz |
| D. | 0.03 mHz |
| Answer» B. 0.3 kHz | |
| 4. |
The gate-cathode curve for an SCR is given by the relation Vg = (1+10)Ig. The gate voltage source is a rectangular pulse of peak value 15 V and current = 0.659 A. Find the source resistance. |
| A. | 90.2 Ω |
| B. | 11.24 Ω |
| C. | 46.2 Ω |
| D. | 39 Ω |
| Answer» C. 46.2 Ω | |
| 5. |
Find the amplitude of the gate current pulse, when the gate-cathode curve is given by the relation Vg = [(1+10) x Ig]The peak gate drive power is 5 Watts. |
| A. | 359mA |
| B. | 659mA |
| C. | 1.359 A |
| D. | 1.659 A |
| Answer» C. 1.359 A | |
| 6. |
The magnitude of gate voltage and gate current for triggering an SCR is |
| A. | inversely proportional to the temperature |
| B. | directly proportional to the temperature |
| C. | inversely proportional to the anode current requirement |
| D. | directly proportional to the anode current requirement |
| Answer» B. directly proportional to the temperature | |
| 7. |
Find the average gate power dissipation (Pgav) when the maximum allowable gate power dissipation (Pgm) = 10 kW, with a duty cycle = 50 %. |
| A. | 10 KW |
| B. | 5 KW |
| C. | 2.5 KW |
| D. | 7 KW |
| Answer» C. 2.5 KW | |
| 8. |
In the complete firing circuit, the driver circuit consists of |
| A. | pulse generator & power supply |
| B. | gate leads & power supply |
| C. | pulse amplifier & pulse transformer |
| D. | pulse detector & pulse amplifier |
| Answer» D. pulse detector & pulse amplifier | |
| 9. |
In a 3-phase full converter using six SCRs, gating circuit must provide |
| A. | one firing pulse every 30° |
| B. | one firing pulse every 90° |
| C. | one firing pulse every 60° |
| D. | three firing pulses per cycle |
| Answer» D. three firing pulses per cycle | |
| 10. |
In a single pulse semi-converter using two SCRs, the triggering circuit must produce |
| A. | two firing pulses in each half cycle |
| B. | one firing pulse in each half cycle |
| C. | three firing pulses in each cycle |
| D. | one firing pulse in each cycle |
| Answer» C. three firing pulses in each cycle | |