MCQOPTIONS
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MCQOPTIONS
This section includes 18 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Machines knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
A 3-phase, 50 Hz, 6-pole induction motor has a shaft output of 10kW at 930 rpm. Friction and windage losses is 1% of the output. Total stator losses is 600W. What is the stator input? |
| A. | 10860 W |
| B. | 10100 W |
| C. | 11460 W |
| D. | 11000 W |
| Answer» D. 11000 W | |
| 2. |
A 3-phase, 50 Hz, 6-pole induction motor has a shaft output of 10kW at 930 rpm. Friction and windage losses is 1% of the output. Total stator losses is 600W. What is the rotor input? |
| A. | 10860 W |
| B. | 10100 W |
| C. | 11460 W |
| D. | 11000 W |
| Answer» B. 10100 W | |
| 3. |
Mark the stable operating point when the load torque shifts from Tl1 to Tl2. |
| A. | A |
| B. | A,B |
| C. | B,C |
| D. | A,C |
| Answer» B. A,B | |
| 4. |
The stable point to use the induction motor possesing the below characteristic. |
| A. | C |
| B. | D |
| C. | C and D |
| D. | Machine will not start |
| Answer» B. D | |
| 5. |
At which point shall the induction machine be operated to attain a stable operation? |
| A. | The machine will not start |
| B. | A |
| C. | B |
| D. | Both A as well as B |
| Answer» B. A | |
| 6. |
The stable point in the operation of the induction motor is? |
| A. | C |
| B. | D |
| C. | B |
| D. | A |
| Answer» B. D | |
| 7. |
For a three phase induction motor, maximum torque is double the full load torque and starting torque is 1.6 times the full load torque. To get a full load slip of 5%, percentage reduction in the rotor resistance should be? |
| A. | 62.7% |
| B. | 75% |
| C. | 60% |
| D. | 35% |
| Answer» B. 75% | |
| 8. |
Introducing the external resistance decreases _________ |
| A. | (iii) |
| B. | (ii), (iii) |
| C. | (i), (ii) |
| D. | (i), (ii), (iii)View Answer |
| Answer» D. (i), (ii), (iii)View Answer | |
| 9. |
Introducing the external resistance increases _________ |
| A. | (iii) |
| B. | (ii), (iii) |
| C. | (ii) |
| D. | (i), (ii), (iii)View Answer |
| Answer» B. (ii), (iii) | |
| 10. |
A 10 kW, 400 V, 3-phase, 4-pole, 50 Hz induction motor develops the rated output at rated voltage with its slip rings shorted. The maximum torque is twice the full load torque occurs at the slip of 10% with zero external resistance in the rotor circuit. An external resistance is now tripled in the rotor circuit. Then the stator current will _________ |
| A. | remain constant |
| B. | increase |
| C. | decrease |
| D. | any of the mentioned |
| Answer» B. increase | |
| 11. |
A 10 kW, 400 V, 3-phase, 4-pole, 50 Hz induction motor develops the rated output at rated voltage with its slip rings shorted. The maximum torque is twice the full load torque occurs at the slip of 10% with zero external resistance in the rotor circuit. An external resistance is now tripled in the rotor circuit. Then the slip at which maximum torque occur for the same load torque is? |
| A. | 0.3 |
| B. | 0.268 |
| C. | 0.03 |
| D. | 3 |
| Answer» B. 0.268 | |
| 12. |
A 10 kW, 400 V, 3-phase, 4-pole, 50 Hz induction motor develops the rated output at rated voltage with its slip rings shorted. The maximum torque is twice the full load torque occurs at the slip of 10% with zero external resistance in the rotor circuit. The speed at the full load torque will be? |
| A. | 1460 rpm |
| B. | 1400 rpm |
| C. | 1360 rpm |
| D. | 1470 rpm |
| Answer» B. 1400 rpm | |
| 13. |
A 10 kW, 400 V, 3-phase, 4-pole, 50 Hz induction motor develops the rated output at rated voltage with its slip rings shorted. The maximum torque equal to twice the full load torque occurs at the slip of 10% with zero external resistance in the rotor circuit. The slip at the full load torque will be? |
| A. | 2.7% |
| B. | 5% |
| C. | 3.7% |
| D. | 10% |
| Answer» B. 5% | |
| 14. |
A 3-phase, 50 Hz, 6-pole induction motor has a shaft output of 10kW at 930 rpm. Friction and windage losses is 1% of the output.Total stator losses is 600W. |
| A. | |
| B. | 10860 W |
| C. | 10100 W |
| Answer» B. 10860 W | |
| 15. |
For a three phase induction motor, maximum torque is double the full load torque and starting torque is 1.6 times the full load torque. |
| A. | |
| B. | 62.7% |
| C. | 75% |
| Answer» B. 62.7% | |
| 16. |
Introducing the external resistance increases |
| A. | speed |
| B. | output power |
| C. | starting torque |
| D. | (iii) |
| Answer» B. output power | |
| 17. |
A 10 kW, 400 V, 3-phase, 4-pole, 50 Hz induction motor develops the rated output at rated voltage with its slip rings shorted. The maximum torque is twice the full load torque occurs at the slip of 10% with zero external resistance in the rotor circuit. An external resistance is now tripled in the rotor circuit. Then the stator current will |
| A. | remain constant |
| B. | increase |
| C. | decrease |
| D. | any of the mentioned |
| Answer» B. increase | |
| 18. |
A 10 kW, 400 V, 3-phase, 4-pole, 50 Hz induction motor develops the rated output at rated voltage with its slip rings shorted. |
| A. | |
| B. | |
| Answer» B. | |