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. |
A three-phase half-wave controlled converter is fed from a 3-phase, 400 V source and is connected to a load which takes a constant current of 36 A. Find,the value of average output voltage and average current rating of SCR for a firing angle of 30°. |
| A. | 234 V, 36 A |
| B. | 234 V, 12 A |
| C. | 135 V, 36 A |
| D. | 135 V, 12 A |
| Answer» C. 135 V, 36 A | |
| 2. |
A three-phase M-3 converter is operated from a 3-phase, 230 V, 50 Hz supply with load resistance R = 10 Ω. Find the value of firing angle if an average output voltage of 50% of the maximum possible output voltage is required.Hint: α > 30°. |
| A. | 92.7° |
| B. | 67.7° |
| C. | 45° |
| D. | 75.7° |
| Answer» C. 45° | |
| 3. |
A three-phase three-pulse converter would operate as a line commutated inverter when |
| A. | 30° < α < 60° |
| B. | 90° < α <180° |
| C. | 90° > α |
| D. | it can never operate as a line commutated inverter |
| Answer» C. 90° > α | |
| 4. |
Find the expression for average output voltage for the given circuit if firing angle is greater than 30°. Take Vmp = secondary side maximum value of phase voltage. |
| A. | (3√3Vmp/2π) x cosα |
| B. | (3√3Vmp/2π) x (1+cosα) |
| C. | (3√3Vmp/2π) x [1+cos(30+α)]. |
| D. | (3√3Vmp/2π) x [3+cos(30+α)]. |
| Answer» D. (3√3Vmp/2π) x [3+cos(30+α)]. | |
| 5. |
In the circuit shown below, SCR T1 conducts first. If T1 is fired at an angle of α > 30°, then T1 would conduct from |
| A. | α to 180° |
| B. | 30 + α to 180° |
| C. | 30 + α to 150° |
| D. | 30 + α to 120° |
| Answer» C. 30 + α to 150° | |
| 6. |
Find the expression for average output voltage at R for the below given configuration. Take firing angle as α = 15°, transformer ratio as 1:1:1 and Vmp as the maximum value of phase voltage at the supply. |
| A. | (3Vmp/2π) x cosα |
| B. | (3√3Vmp/2π) x cosα |
| C. | (3√3Vmp/2π) x sinα |
| D. | (3Vmp/2π) x sinα |
| Answer» C. (3√3Vmp/2π) x sinα | |
| 7. |
A three-phase three pulse type controlled converter is constructed using 3 SCR devices. The circuit is supplying an R load with α < 30°. As such, each SCR device would conduct for |
| A. | 60° each cycle |
| B. | 120° each cycle |
| C. | 180° each cycle |
| D. | 360° each cycle |
| Answer» C. 180° each cycle | |
| 8. |
In a three-phase, three-pulse, M-3 type controlled converter T1 starts to conduct at 30 + n°. At what angles do T2 and T3 start to conduct? Assume that the conduction sequence is T1-T2-T3. |
| A. | 2n° and 3n° |
| B. | 150 + n° and 270 + n° |
| C. | n° each |
| D. | 30 + n° and 60 + n° |
| Answer» C. n° each | |
| 9. |
A three-phase, three-pulse, M-3 type controlled converter has firing angle for one of the SCRs set as 15°. This SCR would start conducting at |
| A. | 0° |
| B. | 15° |
| C. | 30° |
| D. | 45° |
| Answer» E. | |
| 10. |
A three-phase, three-pulse, M-3 type controlled converter uses ____________ number of SCRs. |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» D. 4 | |