MCQOPTIONS
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MCQOPTIONS
This section includes 27 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. |
(I)For constant power of an isolated alternator, V-curves can be obtained. (II)For constant power of an alternator connected to IBB, V-curves can be obtained. |
| A. | I is true, II is false |
| B. | Both the statements are true |
| C. | I is false while II is true |
| D. | Both are false |
| Answer» D. Both are false | |
| 2. |
(I) Speed of an isolated alternator can be altered. (II) Speed of an alternator connected to IBB can be also altered. |
| A. | I is true, II is false |
| B. | Both the statements are true |
| C. | I is false while II is true |
| D. | Both are false |
| Answer» B. Both the statements are true | |
| 3. |
For a synchronous motor, mark the appropriate. |
| A. | A-Inductor, B-Capacitor |
| B. | A-Capacitor, B-Resistor |
| C. | A-Inductor, B-Inductor |
| D. | A-Capacitor, b-Inductor |
| Answer» B. A-Capacitor, B-Resistor | |
| 4. |
Synchronous compensators are ________ |
| A. | over excited synchronous motor with no mechanical load |
| B. | over excited synchronous motor with mechanical load |
| C. | under excited synchronous motor with no mechanical load |
| D. | normally excited synchronous motor with no mechanical load |
| Answer» B. over excited synchronous motor with mechanical load | |
| 5. |
For a power system having induction motor loads, an overexcited synchronous motor is also attached. The induction motor will now operate at ________ |
| A. | lagging |
| B. | leading |
| C. | reduced power factor |
| D. | increased power factor |
| Answer» B. leading | |
| 6. |
For a power system having induction motor loads, an overexcited synchronous motor is also attached. Then the over all power factor? |
| A. | improves |
| B. | degrades |
| C. | becomes upf |
| D. | remains same |
| Answer» B. degrades | |
| 7. |
The inverted V plots is plotted between ________ |
| A. | power factor vs field current for constant shaft load |
| B. | field current vs power factor for variable shaft load |
| C. | armature current vs field current |
| D. | terminal voltage vs power factor |
| Answer» B. field current vs power factor for variable shaft load | |
| 8. |
The armature current is _______ at UPF than motor at lagging power factor. |
| A. | minimum |
| B. | maximum |
| C. | zero |
| D. | none of the mentioned |
| Answer» B. maximum | |
| 9. |
When the excitation voltage is increased from 1 to 1.3 pu of a 3-phase synchronous motor. Then load angle for the constant power operation ________ |
| A. | must be decreased |
| B. | can also be increased |
| C. | increased |
| D. | decreased |
| Answer» B. can also be increased | |
| 10. |
When a constant power output is desired to maintain ________ |
| A. | Ef*sinδ and Ia*cosθ are to be maintained constant |
| B. | Ef*sinδ is be maintained constant |
| C. | Ia*cosθ is to be maintained constant |
| D. | Ef*sinδ and Ia*sinθ are to be maintained constant |
| Answer» B. Ef*sinδ is be maintained constant | |
| 11. |
The excess flux in synchronous motor is neutralized by ________ |
| A. | armature winding by drawing demagnetizing component of the current from ac supply |
| B. | armature winding by drawing magnetizing component of the current from ac supply |
| C. | field winding by drawing demagnetizing component of the current from dc supply |
| D. | field winding by drawing magnetizing component of the current from dc supply |
| Answer» B. armature winding by drawing magnetizing component of the current from ac supply | |
| 12. |
FOR_A_POWER_SYSTEM_HAVING_INDUCTION_MOTOR_LOADS,_AN_OVEREXCITED_SYNCHRONOUS_MOTOR_IS_ALSO_ATTACHED._THEN_THE_OVER_ALL_POWER_FACTOR?$ |
| A. | improves |
| B. | degrades |
| C. | becomes upf |
| D. | remains same |
| Answer» B. degrades | |
| 13. |
Synchronous compensators are$ |
| A. | over excited synchronous motor with no mechanical load |
| B. | over excited synchronous motor with mechanical load |
| C. | under excited synchronous motor with no mechanical load |
| D. | normally excited synchronous motor with no mechanical load |
| Answer» B. over excited synchronous motor with mechanical load | |
| 14. |
For a power system having induction motor loads, an overexcited synchronous motor is also attached. The induction motor will now operate at$ |
| A. | lagging |
| B. | leading |
| C. | reduced power factor |
| D. | increased power factor |
| Answer» B. leading | |
| 15. |
The active power delivered by an alternator will _______ when the prime mover input is increased for the alternator connected to infinite bus bar. |
| A. | increases |
| B. | decreases |
| C. | remains constant |
| D. | no relation exists between the power and prime mover droop characteristic |
| Answer» B. decreases | |
| 16. |
The operating frequency and voltage of an isolated alternator ________ if the prime mover input to motor is increased. |
| A. | increases |
| B. | decreases |
| C. | remains constant |
| D. | no relation exists between the power and frequency |
| Answer» B. decreases | |
| 17. |
(I)For constant power of an isolated alternator, V-curves can be obtained. |
| A. | For constant power of an alternator connected to IBB, V-curves can be obtained |
| B. | I is true, II is false |
| C. | Both the statements are true |
| D. | I is false while II is true |
| Answer» D. I is false while II is true | |
| 18. |
(I) Speed of an isolated alternator can be altered. |
| A. | Speed of an alternator connected to IBB can be also altered. |
| B. | I is true, II is false |
| C. | Both the statements are true |
| D. | I is false while II is true |
| Answer» B. I is true, II is false | |
| 19. |
The inverted V plots is plotted betwee? |
| A. | power factor vs field current for constant shaft load |
| B. | field current vs power factor for variable shaft load |
| C. | armature current vs field current |
| D. | terminal voltage vs power factor |
| Answer» B. field current vs power factor for variable shaft load | |
| 20. |
The armature current is _______ at UPF than motor at lagging power factor? |
| A. | minimum |
| B. | maximum |
| C. | zero |
| D. | none of the mentioned |
| Answer» B. maximum | |
| 21. |
The armature current is ________ at UPF when compared to leading power factor. |
| A. | minimum |
| B. | maximum |
| C. | equal |
| D. | none of the mentioned |
| Answer» B. maximum | |
| 22. |
When the excitation voltage is increased from 1 to 1.3 pu of a 3-phase synchronous motor. Then load angle for the constant power operation |
| A. | must be decreased |
| B. | can also be increased |
| C. | increased |
| D. | decreased |
| Answer» B. can also be increased | |
| 23. |
When a constant power output is desired to maintain |
| A. | Ef*sinδ and Ia*cosθ are to be maintained constant |
| B. | Ef*sinδ is be maintained constant |
| C. | Ia*cosθ is to be maintained constant |
| D. | Ef*sinδ and Ia*sinθ are to be maintained constant |
| Answer» B. Ef*sin‚âà√≠¬¨‚Ä¢ is be maintained constant | |
| 24. |
The V-curves of synchronous motor is plotted between ________ |
| A. | Ia Vs If with constant shaft load |
| B. | If Vs Ia with constant shaft load |
| C. | power factor vs If |
| D. | power factor vs Ia |
| Answer» B. If Vs Ia with constant shaft load | |
| 25. |
The excess flux in synchronous motor is neutralized by |
| A. | armature winding by drawing demagnetizing component of the current from ac supply |
| B. | armature winding by drawing magnetizing component of the current from ac supply |
| C. | field winding by drawing demagnetizing component of the current from dc supply |
| D. | field winding by drawing magnetizing component of the current from dc supply |
| Answer» B. armature winding by drawing magnetizing component of the current from ac supply | |
| 26. |
A 3 phase synchronous motor is working at normal excitation, then the flux deficient in circuit is ________ |
| A. | given by armature winding mmf |
| B. | given by field winding mmf |
| C. | supplied to armature winding mmf |
| D. | supplied to field winding mmf |
| Answer» B. given by field winding mmf | |
| 27. |
The magnetization current drawn from an AC supply a synchronous motor is used to _________ |
| A. | set up flux in magnetic circuit of device |
| B. | compensate core losses |
| C. | set up magnetizing armature reaction |
| D. | all of the mentioned |
| Answer» B. compensate core losses | |