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. |
WHICH_OF_THE_FOLLOWING_EQUATION_REPRESENTS_THE_RELUCTANCE_TORQUE_OF_A_SALIENT_POLE_SYNCHRONOUS_MACHINE??$ |
| A. | T<sub>e(av)</sub>= 1/4 I<sub>m</sub><sup>2</sup>(L<sub>d</sub>-L<sub>q</sub>)sin2δ |
| B. | T<sub>e(av)</sub>= 2 I<sub>m</sub><sup>2</sup>(L<sub>d</sub>-L<sub>q</sub>)sinδcosδ |
| C. | T<sub>e(av)</sub>= 1/8 I<sub>m</sub><sup>2</sup>(L<sub>d</sub>-L<sub>q</sub>) |
| D. | T<sub>e(av)</sub>= 1/8 I<sub>m</sub><sup>2</sup>(L<sub>d</sub>-L<sub>q</sub>)sin2δ |
| Answer» E. | |
| 2. |
An electromechanical energy conversion device has cylindrical stator but salient pole rotor. If δ is the angle between stator field and rotor field, the average torque developed is proportional to (A and B are constants) __________$# |
| A. | Asinδ |
| B. | Asin2δ |
| C. | Asinδ+Bsin2δ |
| D. | δ |
| Answer» D. ‚âà√≠¬¨‚Ä¢ | |
| 3. |
Which_component_of_torque_equation,_Te(av)=_1/8_Im2(Ld-Lq)sin2δ+1/2_IfImMmaxsinδ_represents_the_electromagnetic/interaction_torque_in_single_phase_salient_pole_synchronous_machine?$# |
| A. | 1/2 I<sub>f</sub>I<sub>m</sub>M<sub>max</sub>sinδ |
| B. | 1/8 I<sub>m</sub><sup>2</sup>(L<sub>d</sub>-L<sub>q</sub>)sin2δ |
| C. | 1/8 I<sub>m</sub><sup>2</sup>(L<sub>d</sub>-L<sub>q</sub>)sin2δ+ 1/2 I<sub>f</sub>I<sub>m</sub>M<sub>max</sub>sinδ |
| D. | none of the mentioned |
| Answer» B. 1/8 I<sub>m</sub><sup>2</sup>(L<sub>d</sub>-L<sub>q</sub>)sin2‚âà√≠¬¨‚Ä¢ | |
| 4. |
The self and mutual inductances of a doubly excited magnetic system are Ls=0.6+0.20cos2θr H and Lr=0.75+0.30cos2θr H and Msr=0.8cosθr H. For a stationary rotor at an angular position of θr=60°,what is the magnitude of torque when the currents is=20A DC and ir=10A DC?$ |
| A. | -233.88N-m |
| B. | +233.88N-m |
| C. | -467.76N-m |
| D. | +467.76N-m |
| Answer» B. +233.88N-m | |
| 5. |
An_electromechanical_energy_conversion_device_has_cylindrical_stator_but_salient_pole_rotor._Rotor_is_not_excited._If_δ_is_the_angle_between_stator_field_and_rotor_long_axis,_then_average_torque_developed_is_proportional_to_(A_and_B_are_constants)$ |
| A. | Asinδ |
| B. | Asin2δ |
| C. | Asinδ + Bsin2δ |
| D. | zero |
| Answer» C. Asin‚âà√≠¬¨‚Ä¢ + Bsin2‚âà√≠¬¨‚Ä¢ | |
| 6. |
In a two phase cylindrical rotor synchronous machine, torque Te is ____________? |
| A. | constant at some instant of time |
| B. | changing at every instant of time |
| C. | constant at every instant of time |
| D. | changing at some instant of time |
| Answer» D. changing at some instant of time | |
| 7. |
In a two phase cylindrical rotor synchronous machine, the mutual inductance Mαβ between α phase and β phase winding is __________$ |
| A. | M<sub>max</sub> |
| B. | 0 |
| C. | M<sub>min</sub> |
| D. | any of the mentioned |
| Answer» C. M<sub>min</sub> | |
| 8. |
In a two phase cylindrical rotor synchronous machine, the self inductances Lα, Lβ for phases α,β respectively are __________$ |
| A. | constant and equal |
| B. | constant and unequal |
| C. | varying and equal |
| D. | varying and unequal |
| Answer» B. constant and unequal | |
| 9. |
The following torque expression: Te=-isirMmaxsinθr is applicable in a single phase cylindrical rotor synchronous machine when the rotor is __________$ |
| A. | revolving |
| B. | stationary |
| C. | any of the mentioned |
| D. | none of the mentioned |
| Answer» D. none of the mentioned | |
| 10. |
In a single phase cylindrical rotor synchronous machine, the torque Te tends to ____________ the space angle θr.$ |
| A. | reduce |
| B. | increase |
| C. | maintain constant |
| D. | all of the mentioned |
| Answer» B. increase | |
| 11. |
Which of the following equation best represents the mutual inductance between stator and rotor in a single phase cylindrical rotor synchronous machine? |
| A. | M<sub>sr</sub>=0 |
| B. | M<sub>sr</sub>=M<sub>max</sub> |
| C. | M<sub>sr</sub>=M<sub>max</sub>cosθ<sub>r</sub> |
| D. | M<sub>sr</sub>=M<sub>max</sub>sinθ<sub>r</sub> |
| Answer» D. M<sub>sr</sub>=M<sub>max</sub>sin‚âà√≠‚Äö√†√®<sub>r</sub> | |
| 12. |
Consider a single phase synchronous machine of cylindrical rotor type. A single phase supply is given to the stator winding, and a voltmeter is connected across rotor winding. For what value of θr the voltmeter reads a zero?$ |
| A. | 0° |
| B. | 30° |
| C. | 45° |
| D. | 90° |
| Answer» E. | |
| 13. |
Consider a single phase synchronous machine of cylindrical rotor type. A single phase supply is given to the stator winding and a voltmeter is connected across rotor winding. For what value of θr, the voltmeter reads maximum? |
| A. | 90° |
| B. | 0° |
| C. | 45° |
| D. | 30° |
| Answer» C. 45¬¨¬®‚Äö√†√ª | |