MCQOPTIONS
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MCQOPTIONS
This section includes 8 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_COMPONENT_OF_TORQUE_IN_THE_FOLLOWING_EQUATION_IS_CALLED_THE_ELECTROMAGNETIC_TORQUE_OF_ELECTROMAGNETIC_ENERGY_CONVERSION_DEVICE??$ |
| A. | |
| B. | 1/2i<sub>s</sub><sup>2</sup>dL<sub>s</sub>/dθ<sub>r</sub> |
| C. | 1/2i<sub>r</sub><sup>2</sup>dL<sub>r</sub>/dθ<sub>r</sub> |
| Answer» D. | |
| 2. |
Which of the following statements are true about electromagnetic torques and reluctance torques:$ |
| A. | electromagnetic torque can exist only if both windings carry current |
| B. | reluctance torque depend on the direction of current in stator or rotor windings |
| C. | reluctance torque doesn’t depend on the direction of current in stator or rotor windings |
| D. | electromagnetic torque depend on the direction of currents i<sub>s</sub> and i<sub>r</sub> |
| Answer» E. | |
| 3. |
In a doubly excited magnetic system of salient pole type stator and rotor, the reluctance torque is present only when ____________? |
| A. | both stator and rotor currents are acting |
| B. | stator current is acting alone |
| C. | rotor current is acting alone |
| D. | any of the stator or rotor currents acting alone |
| Answer» C. rotor current is acting alone | |
| 4. |
In a doubly excited magnetic systems, the magnetic torques and forces act in such a direction as to tend to |
| A. | decrease the field energy at constant currents |
| B. | decrease the field co-energy at constant currents |
| C. | increase the field energy at constant currents |
| D. | none of the mentioned |
| Answer» E. | |
| 5. |
In a doubly excited magnetic system of salient pole stator and rotor, the magnetic torque (Te) depends on |
| A. | the instantaneous values of currents i<sub>s</sub> and i<sub>r</sub> |
| B. | the angular rate of change of inductances |
| C. | the differential changes of current di<sub>s</sub> and di<sub>r</sub> |
| D. | only the instantaneous values of self inductance |
| Answer» C. the differential changes of current di<sub>s</sub> and di<sub>r</sub> | |
| 6. |
In a doubly excited magnetic system with salient pole type stator and rotor, if the rotor is not allowed to move, then the equation for magnetic field stored energy in establishing the currents from zero to is and ir is __________ |
| A. | W<sub>fld</sub>=1/2 i<sub>s</sub><sup>2</sup>L<sub>s</sub>+1/2 i<sub>r</sub><sup>2</sup>L<sub>r</sub> |
| B. | W<sub>fld</sub>=1/2 i<sub>s</sub><sup>2</sup>L<sub>s</sub>+M<sub>rs</sub> i<sub>s</sub> i<sub>r</sub> |
| C. | W<sub>fld</sub>=1/2 i<sub>s</sub><sup>2</sup>L<sub>s</sub>+1/2 i<sub>r</sub><sup>2</sup>L<sub>r</sub>+M<sub>rs</sub> i<sub>s</sub> i<sub>r</sub> |
| D. | W<sub>fld</sub>=1/2 i<sub>r</sub><sup>2</sup>L<sub>r</sub>+M<sub>rs</sub> i<sub>s</sub> i<sub>r</sub> |
| Answer» D. W<sub>fld</sub>=1/2 i<sub>r</sub><sup>2</sup>L<sub>r</sub>+M<sub>rs</sub> i<sub>s</sub> i<sub>r</sub> | |
| 7. |
Most of the electromagnetic energy conversion devices belong to __________ |
| A. | singly excited magnetic systems |
| B. | doubly excited magnetic systems |
| C. | multiply excited magnetic systems |
| D. | both doubly excited magnetic systems and multiply excited magnetic systems |
| Answer» E. | |
| 8. |
Which of the following are examples of doubly-excited magnetic systems? |
| A. | Synchronous Machines |
| B. | Loudspeakers and Tachometers |
| C. | D.C Shunt Machines |
| D. | Any of the mentioned |
| Answer» E. | |