MCQOPTIONS
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MCQOPTIONS
This section includes 13 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. |
Synchronous compensators are __________ |
| A. | overexcited synchronous motor with no mechanical load |
| B. | overexcited synchronous motor with mechanical load |
| C. | underexcited synchronous motor with no mechanical load |
| D. | normal excited synchronous motor with no mechanical load |
| Answer» B. overexcited synchronous motor with mechanical load | |
| 3. |
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 | |
| 4. |
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 | |
| 5. |
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 | |
| 6. |
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 | |
| 7. |
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 | |
| 8. |
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 | |
| 9. |
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 | |
| 10. |
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 | |
| 11. |
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 | |
| 12. |
Synchronous_compensators_are |
| A. | overexcited synchronous motor with no mechanical load |
| B. | overexcited synchronous motor with mechanical load |
| C. | underexcited synchronous motor with no mechanical load |
| D. | normal excited synchronous motor with no mechanical load |
| Answer» B. overexcited synchronous motor with mechanical load | |
| 13. |
The armature current is ________ at UPF when compared to leading power factor for a motor. |
| A. | minimum |
| B. | maximum |
| C. | equal |
| D. | none of the mentioned |
| Answer» B. maximum | |