MCQOPTIONS
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MCQOPTIONS
This section includes 15 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. |
If it is desired to approximate the efficiency of an induction motor operating at slip s , then its efficiency is given by? |
| A. | 1-s/1+s |
| B. | 1/1+s |
| C. | s/s+1 |
| D. | s/1-s |
| Answer» B. 1/1+s | |
| 2. |
A delta connected capacitance bank is preferred over a star connected bank. This is done to ensure _________ |
| A. | lesser capacitance |
| B. | easy calculation |
| C. | easier connection |
| D. | all of the mentioned |
| Answer» B. easy calculation | |
| 3. |
A star connected capacitor bank is connected to the induction motor having capacitance C and VA rating as VAs. If the capacitor bank is replaced by a delta bank then? |
| A. | C = C/3, VA = VAs |
| B. | C = 3C, VA = VAs |
| C. | C = C, VA = VAs/3 |
| D. | C = C/3, VA = VAs/3 |
| Answer» B. C = 3C, VA = VAs | |
| 4. |
Induction generators will deliver power at _________ |
| A. | leading p.f. |
| B. | lagging p.f. |
| C. | unity p.f. |
| D. | zero p.f. |
| Answer» B. lagging p.f. | |
| 5. |
A 3-phase induction machine is running at super synchronous speed. For the machine to be self excited it _________ |
| A. | draws reactive power from mains |
| B. | draws real power from mains |
| C. | feeds reactive power to mains |
| D. | generates emf by gradual voltage build up |
| Answer» B. draws real power from mains | |
| 6. |
In a 3-phase induction generator which is self excited, load has been increased. To keep the frequency of the generated voltage constant, speed of the induction machine should be _________ |
| A. | increased |
| B. | decreased |
| C. | maintained less than rated synchronous speed |
| D. | maintained more than rated synchronous speed |
| Answer» B. decreased | |
| 7. |
The characteristics required of the three phase induction motor to match that of the load with the criteria of load torque inversely proportional to the shaft speed is? |
| A. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9a.png"><img alt="Graph for induction motor operating with load torque proportional to square - option a" class="alignnone size-full wp-image-161028" height="220" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9a.png" width="300"/></a> |
| B. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9b.png"><img alt="Graph for induction motor operating with load torque proportional to square - option b" class="alignnone size-full wp-image-161029" height="218" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9b.png" width="300"/></a> |
| C. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png"><img alt="Graph for induction motor operating with load torque proportional to square - option c" class="alignnone size-full wp-image-161031" height="235" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png" width="300"/></a> |
| D. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9d.png"><img alt="Graph for induction motor operating with load torque proportional to square - option d" class="alignnone size-full wp-image-161032" height="224" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9d.png" width="300"/></a> |
| Answer» E. | |
| 8. |
The characteristics required of the induction motor to match that of the load for load torque independent of the shaft speed is? |
| A. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9a.png"><img alt="Graph for induction motor operating with load torque proportional to square - option a" class="alignnone size-full wp-image-161028" height="220" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9a.png" width="300"/></a> |
| B. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9b.png"><img alt="Graph for induction motor operating with load torque proportional to square - option b" class="alignnone size-full wp-image-161029" height="218" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9b.png" width="300"/></a> |
| C. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png"><img alt="Graph for induction motor operating with load torque proportional to square - option c" class="alignnone size-full wp-image-161031" height="235" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png" width="300"/></a> |
| D. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9d.png"><img alt="Graph for induction motor operating with load torque proportional to square - option d" class="alignnone size-full wp-image-161032" height="224" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9d.png" width="300"/></a> |
| Answer» C. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png"><img alt="Graph for induction motor operating with load torque proportional to square - option c" class="alignnone size-full wp-image-161031" height="235" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png" width="300"/></a> | |
| 9. |
An induction motor is operating for the load with torque developed proportional to the shaft speed. The characteristics below is? |
| A. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9a.png"><img alt="Graph for induction motor operating with load torque proportional to square - option a" class="alignnone size-full wp-image-161028" height="220" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9a.png" width="300"/></a> |
| B. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9b.png"><img alt="Graph for induction motor operating with load torque proportional to square - option b" class="alignnone size-full wp-image-161029" height="218" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9b.png" width="300"/></a> |
| C. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png"><img alt="Graph for induction motor operating with load torque proportional to square - option c" class="alignnone size-full wp-image-161031" height="235" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png" width="300"/></a> |
| D. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9d.png"><img alt="Graph for induction motor operating with load torque proportional to square - option d" class="alignnone size-full wp-image-161032" height="224" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9d.png" width="300"/></a> |
| Answer» C. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png"><img alt="Graph for induction motor operating with load torque proportional to square - option c" class="alignnone size-full wp-image-161031" height="235" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png" width="300"/></a> | |
| 10. |
The graph for the induction motor operating with load torque proportional to square of the shaft speed. |
| A. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9a.png"><img alt="Graph for induction motor operating with load torque proportional to square - option a" class="alignnone size-full wp-image-161028" height="220" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9a.png" width="300"/></a> |
| B. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9b.png"><img alt="Graph for induction motor operating with load torque proportional to square - option b" class="alignnone size-full wp-image-161029" height="218" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9b.png" width="300"/></a> |
| C. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png"><img alt="Graph for induction motor operating with load torque proportional to square - option c" class="alignnone size-full wp-image-161031" height="235" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9c.png" width="300"/></a> |
| D. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9d.png"><img alt="Graph for induction motor operating with load torque proportional to square - option d" class="alignnone size-full wp-image-161032" height="224" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9d.png" width="300"/></a> |
| Answer» B. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9b.png"><img alt="Graph for induction motor operating with load torque proportional to square - option b" class="alignnone size-full wp-image-161029" height="218" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q9b.png" width="300"/></a> | |
| 11. |
At standstill the equivalent of the 3-phase induction motor is similar to _________ |
| A. | short-circuited two winding transformer |
| B. | open circuit two winding transformer |
| C. | stand still synchronous motor |
| D. | none of the mentioned |
| Answer» B. open circuit two winding transformer | |
| 12. |
The actual rotor resistance referred to the stator if the induction motor is? |
| A. | r2 |
| B. | (r2)/s |
| C. | (r2)/(1-s) |
| D. | (r2)*(1-s)/s |
| Answer» B. (r2)/s | |
| 13. |
The electrical anlogous of the mechanical load in the induction machine is given by? |
| A. | (r2)*(1-s)/s |
| B. | (r2) |
| C. | (r2)/s |
| D. | (r2)/(1-s) |
| Answer» B. (r2) | |
| 14. |
The actual rotor equivalent of an induction motor is best depicted by? |
| A. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1a.png"><img alt="The equivalent circuit for polyphase induction motor - option a" class="alignnone size-full wp-image-161021" height="159" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1a.png" width="300"/></a> |
| B. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1b.png"><img alt="The equivalent circuit for polyphase induction motor - option b" class="alignnone size-full wp-image-161022" height="198" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1b.png" width="294"/></a> |
| C. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1c.png"><img alt="The equivalent circuit for polyphase induction motor - option c" class="alignnone size-full wp-image-161023" height="106" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1c.png" width="300"/></a> |
| D. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1d.png"><img alt="The equivalent circuit for polyphase induction motor - option d" class="alignnone size-full wp-image-161024" height="119" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1d.png" width="300"/></a> |
| Answer» C. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1c.png"><img alt="The equivalent circuit for polyphase induction motor - option c" class="alignnone size-full wp-image-161023" height="106" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1c.png" width="300"/></a> | |
| 15. |
Stator equivalent circuit for polyphase induction motor is? |
| A. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1a.png"><img alt="The equivalent circuit for polyphase induction motor - option a" class="alignnone size-full wp-image-161021" height="159" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1a.png" width="300"/></a> |
| B. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1b.png"><img alt="The equivalent circuit for polyphase induction motor - option b" class="alignnone size-full wp-image-161022" height="198" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1b.png" width="294"/></a> |
| C. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1c.png"><img alt="The equivalent circuit for polyphase induction motor - option c" class="alignnone size-full wp-image-161023" height="106" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1c.png" width="300"/></a> |
| D. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1d.png"><img alt="The equivalent circuit for polyphase induction motor - option d" class="alignnone size-full wp-image-161024" height="119" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1d.png" width="300"/></a> |
| Answer» B. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1b.png"><img alt="The equivalent circuit for polyphase induction motor - option b" class="alignnone size-full wp-image-161022" height="198" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-equivalent-circuit-q1b.png" width="294"/></a> | |