MCQOPTIONS
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MCQOPTIONS
This section includes 20 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. |
No load test has been conducted on an induction motor for different supply voltages and input power vs voltage plot has been drawn. The curve is extrapolated to intersect the y-axis. This point is? |
| A. | friction and windage losses |
| B. | core losses |
| C. | stray losses |
| D. | all of the mentioned |
| Answer» B. core losses | |
| 2. |
A 3-phase induction motor is running for a constant load torque at rated voltage and frequency. If both the frequency and voltage are halved following will be the related statements ignoring the stator losses. |
| A. | A, C, D |
| B. | A, B, C, D |
| C. | B, C, D |
| D. | C, DView Answer |
| Answer» B. A, B, C, D | |
| 3. |
A 3-phase induction motor taking a line current of 200 A, is started by direct switching. If an auto transformer of with 50% tapping is made to be used, the motor line current and supply line current will be respectively? |
| A. | 100, 50 |
| B. | 50, 100 |
| C. | 50, 200 |
| D. | 50*1.73, 200 |
| Answer» B. 50, 100 | |
| 4. |
When the poles of a 3-phase wound rotor induction motor increased, it _________ |
| A. | will decrease maximum power factor |
| B. | will increase maximum power factor |
| C. | will make no change in power factor |
| D. | can not be depicted |
| Answer» C. will make no change in power factor | |
| 5. |
Reducing the poles of a 3-phase induction motor, it _________ |
| A. | will decrease maximum power factor |
| B. | will increase maximum power factor |
| C. | will make no change in power factor |
| D. | can not be depicted |
| Answer» B. will increase maximum power factor | |
| 6. |
When a 3-phase 350V, 50Hz squirrel-cage induction motor is run at 35 Hz supply, then? |
| A. | A, C |
| B. | A, B, E |
| C. | A, B |
| D. | C, D, EView Answer |
| Answer» B. A, B, E | |
| 7. |
If a 3-phase 350V, 50Hz squirrel-cage induction motor is run at 55 Hz supply, then? |
| A. | C, D, E |
| B. | A, C, E |
| C. | A, B |
| D. | EView Answer |
| Answer» B. A, C, E | |
| 8. |
We can not operate a cage induction motor on a variable frequency load due to ___________ |
| A. | no availability of varying the speed |
| B. | availability of variable speed |
| C. | low starting torque |
| D. | fixed slip |
| Answer» B. availability of variable speed | |
| 9. |
Relatively a squirrel-cage induction motor is advantageous over wound rotor type induction motor of identical rating due to ___________ |
| A. | less conductor material used. |
| B. | lower leakage flux |
| C. | ruggedness |
| D. | all of the mentioned |
| Answer» E. | |
| 10. |
Wound rotor induction motor is most appropriate for the applications requiring ______________ |
| A. | high starting torque |
| B. | variable starting torque |
| C. | fixed starting torque |
| D. | all of the mentioned |
| Answer» C. fixed starting torque | |
| 11. |
REDUCING_THE_POLES_OF_A_3-PHASE_INDUCTION_MOTOR,_IT?$ |
| A. | will decrease maximum power factor |
| B. | will increase maximum power factor |
| C. | will make no change in power factor |
| D. | can not be depicted |
| Answer» B. will increase maximum power factor | |
| 12. |
A 3-phase induction motor taking a line current of 200 A, is started by direct switching. If an auto transformer of with 50% tapping is$ |
| A. | |
| B. | 100, 50 |
| C. | 50, 100 |
| Answer» B. 100, 50 | |
| 13. |
When the poles of a 3-phase wound rotor induction motor increased, it$ |
| A. | will decrease maximum power factor |
| B. | will increase maximum power factor |
| C. | will make no change in power factor |
| D. | can not be depicted |
| Answer» C. will make no change in power factor | |
| 14. |
No load test has been conducted on an induction motor for different supply voltages and input power vs voltage plot has been drawn. |
| A. | |
| B. | friction and windage losses |
| C. | core losses |
| Answer» B. friction and windage losses | |
| 15. |
The torque in an induction motor varies as ______ and in synchronous motor as _________ |
| A. | square of voltage, proportion to voltage |
| B. | proportion to voltage, proportion to voltage |
| C. | proportion to voltage, square of voltage |
| D. | square of voltage, square of voltage |
| Answer» B. proportion to voltage, proportion to voltage | |
| 16. |
Which of the following can be done using a synchronous motor but not by induction motor? |
| A. | Power factor improvement |
| B. | Supplying mechanical load |
| C. | Power factor improvement and supply mechanical load |
| D. | None of the mentioned |
| Answer» B. Supplying mechanical load | |
| 17. |
Speed control is possible for _______ and not possible for __________ |
| A. | induction motor, synchronous motor |
| B. | induction motor, differential motor |
| C. | synchronous motor, synchronous-induction motor |
| D. | dc motor, induction motor |
| Answer» B. induction motor, differential motor | |
| 18. |
We can not operate a cage induction motor on a variable frequency load due to |
| A. | no availability of varying the speed |
| B. | availability of variable speed |
| C. | low starting torque |
| D. | fixed slip |
| Answer» B. availability of variable speed | |
| 19. |
Relatively a squirrel-cage induction motor is advantageous over wound rotor type induction motor of identical rating due to |
| A. | less conductor material used. |
| B. | lower leakage flux |
| C. | ruggedness |
| D. | all of the mentioned |
| Answer» E. | |
| 20. |
Wound rotor induction motor is most appropriate for the applications requiring |
| A. | high starting torque |
| B. | variable starting torque |
| C. | fixed starting torque |
| D. | all of the mentioned |
| Answer» C. fixed starting torque | |