MCQOPTIONS
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MCQOPTIONS
This section includes 9 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. |
Switched reluctance motors are basically __________ |
| A. | salient pole synchronous motor but without excitation winding |
| B. | stepper motor with salient poles |
| C. | synchronous motor with salient poles on stator and rotor |
| D. | stepper motor with closed loop control and with rotor position sensor |
| Answer» E. | |
| 2. |
We can increase the torque of a reluctance synchronous motor if we __________ |
| A. | Increase reluctance of the magnetic circuit along the direct axis |
| B. | Decrease the reluctance of the magnetic circuit along the quadrature axis |
| C. | Increase the ratio of the quadrature axis reluctance to direct axis reluctance |
| D. | Decrease the ratio of quadrature axis reluctance to direct axis reluctance |
| Answer» D. Decrease the ratio of quadrature axis reluctance to direct axis reluctance | |
| 3. |
For the below graph depicting the performance of a synchronous motor, coordinates x and y are respectively?
|
| A. | n<a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q13.png"><img alt="V curve is between the armature current & the field current in given diagram" class="alignnone size-full wp-image-160927" height="188" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q13.png" width="300"/></a> |
| B. | Armature current and field current |
| C. | Power factor and field current |
| D. | Armature current and torque |
| E. | Torque and field current |
| Answer» B. Armature current and field current | |
| 4. |
Identify the over excited synchronous motor operating at zpf. |
| A. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q11d.png"><img alt="The over excited alternator operating at zpf - option d" class="alignnone size-full wp-image-160925" height="248" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q11d.png" width="194"/></a> |
| B. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q12b.png"><img alt="The over excited synchronous motor operating at zpf - option b" class="alignnone size-full wp-image-160926" height="240" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q12b.png" width="174"/></a> |
| C. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q11b.png"><img alt="The over excited alternator operating at zpf - option b" class="alignnone size-full wp-image-160923" height="256" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q11b.png" width="243"/></a> |
| D. | None of the mentioned |
| Answer» B. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q12b.png"><img alt="The over excited synchronous motor operating at zpf - option b" class="alignnone size-full wp-image-160926" height="240" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q12b.png" width="174"/></a> | |
| 5. |
Identify the over excited alternator operating at zpf. |
| A. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q11a.png"><img alt="The over excited alternator operating at zpf - option a" class="alignnone size-full wp-image-160922" height="284" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q11a.png" width="178"/></a> |
| B. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q11b.png"><img alt="The over excited alternator operating at zpf - option b" class="alignnone size-full wp-image-160923" height="256" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q11b.png" width="243"/></a> |
| C. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q11c.png"><img alt="The over excited alternator operating at zpf - option c" class="alignnone size-full wp-image-160924" height="276" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q11c.png" width="231"/></a> |
| D. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q11d.png"><img alt="The over excited alternator operating at zpf - option d" class="alignnone size-full wp-image-160925" height="248" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q11d.png" width="194"/></a> |
| Answer» B. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q11b.png"><img alt="The over excited alternator operating at zpf - option b" class="alignnone size-full wp-image-160923" height="256" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q11b.png" width="243"/></a> | |
| 6. |
The operating point for an over excited alternator working near zpf lagging power factor gives A as the operating point. Then if the same machine is working as an over excited synchronous motor will give same operating point at __________ |
| A. | zpf leading |
| B. | zpf lagging |
| C. | upf |
| D. | there will never be the same operating point for the machine as motor as well as generator |
| Answer» B. zpf lagging | |
| 7. |
The synchronous motor is operating at upf load. The most suitable phasor will be? |
| A. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q6a.png"><img alt="The synchronous motor is operating at upf load - option a" class="alignnone size-full wp-image-160920" height="240" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q6a.png" width="171"/></a> |
| B. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q5b.png"><img alt="The synchronous motor is operating at upf load - option b" class="alignnone size-full wp-image-160919" height="183" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q5b.png" width="250"/></a> |
| C. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q2b.png"><img alt="The synchronous motor is operating at upf load - option c" class="alignnone size-full wp-image-160916" height="248" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q2b.png" width="225"/></a> |
| D. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q2c.png"><img alt="The synchronous motor is operating at upf load - option d" class="alignnone size-full wp-image-160917" height="201" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q2c.png" width="185"/></a> |
| Answer» B. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q5b.png"><img alt="The synchronous motor is operating at upf load - option b" class="alignnone size-full wp-image-160919" height="183" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-synchronous-motor-phasor-diagram-q5b.png" width="250"/></a> | |
| 8. |
Synchronous motor delivers lagging power at __________ |
| A. | leading pf |
| B. | lagging pf |
| C. | zero pf |
| D. | unity pf |
| Answer» B. lagging pf | |
| 9. |
The voltage equation of synchronous motor is? |
| A. | Ef = Vt + Ia*(ra+jXa) |
| B. | Ef = Vt Ia*(ra+jXa) |
| C. | Ef = Vt + Ia*(ra-jXa) |
| D. | Ef = Vt Ia*(ra-jXa) |
| Answer» B. Ef = Vt Ia*(ra+jXa) | |