MCQOPTIONS
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MCQOPTIONS
This section includes 12 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. |
Run-away for large DC machine is avoided by using _________ |
| A. | a turn or two of cumulative compounding |
| B. | compensating winding |
| C. | stablizer winding |
| D. | all of the mentioned |
| Answer» C. stablizer winding | |
| 2. |
A laboratory group was working with a set of 3-hp shunt DC motor. But there was a mistake that it was fused with a 0.3A fuse instead 3A fuse. Then it was started _________ |
| A. | a flash occurred instantly |
| B. | it ran for 3s and fuse was blown |
| C. | it ran normal |
| D. | none of the mentioned |
| Answer» C. it ran normal | |
| 3. |
The torque limit of speed for a shunt motor _________ |
| A. | remains constant till base speed |
| B. | remains constant after base speed |
| C. | varies linearly after base speed |
| D. | varies inversely till base speed |
| Answer» B. remains constant after base speed | |
| 4. |
How does the power varies with the variations in the speed, for a dc shunt motor? |
| A. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q10a.png"><img alt="The power varies with the variations in the speed for a dc shunt motor - option a" class="alignnone size-full wp-image-160870" height="213" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q10a.png" width="300"/></a> |
| B. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q10b.png"><img alt="The power varies with the variations in the speed for a dc shunt motor - option b" class="alignnone size-full wp-image-160871" height="232" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q10b.png" width="300"/></a> |
| C. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q10c.png"><img alt="The power varies with the variations in the speed for a dc shunt motor - option c" class="alignnone size-full wp-image-160872" height="220" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q10c.png" width="300"/></a> |
| D. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q10d.png"><img alt="The power varies with the variations in the speed for a dc shunt motor - option d" class="alignnone size-full wp-image-160873" height="202" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q10d.png" width="300"/></a> |
| Answer» B. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q10b.png"><img alt="The power varies with the variations in the speed for a dc shunt motor - option b" class="alignnone size-full wp-image-160871" height="232" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q10b.png" width="300"/></a> | |
| 5. |
Armature voltage control works for speeds _____ base speed and field resistance control works well for speed _____ base speed. |
| A. | below, above |
| B. | above, below |
| C. | above, above |
| D. | below, below |
| Answer» B. above, below | |
| 6. |
The armature resistance speed control is best illustrated by which of the following? |
| A. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q8a.png"><img alt="The armature resistance speed control - option a" class="alignnone size-full wp-image-160866" height="203" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q8a.png" width="300"/></a> |
| B. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q8b.png"><img alt="The armature resistance speed control - option b" class="alignnone size-full wp-image-160867" height="227" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q8b.png" width="300"/></a> |
| C. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q8c.png"><img alt="The armature resistance speed control - option c" class="alignnone size-full wp-image-160868" height="204" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q8c.png" width="300"/></a> |
| D. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q8d.png"><img alt="The armature resistance speed control - option d" class="alignnone size-full wp-image-160869" height="221" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q8d.png" width="300"/></a> |
| Answer» B. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q8b.png"><img alt="The armature resistance speed control - option b" class="alignnone size-full wp-image-160867" height="227" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q8b.png" width="300"/></a> | |
| 7. |
To implement armature voltage control, it must be ensured that _________ |
| A. | it is used on separately excited machine |
| B. | it is used on shunt machine |
| C. | it is used on series machine |
| D. | any of the mentioned machine |
| Answer» B. it is used on shunt machine | |
| 8. |
Small DC motors have best speed control by _________ |
| A. | armature voltage control |
| B. | field resistance control |
| C. | any of the methods |
| D. | none of the mentioned |
| Answer» B. field resistance control | |
| 9. |
At a very low speed, increase in field resistance will _________ |
| A. | decrease the speed of motor |
| B. | increase the speed of motor |
| C. | not have signicant effect on speed |
| D. | no effect |
| Answer» B. increase the speed of motor | |
| 10. |
The effect of field resistance speed control on a shunt motor speed torque characteristic is? |
| A. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q4a.png"><img alt="Effect of field resistance speed control on shunt motor speed torque - option a" class="alignnone size-full wp-image-160863" height="205" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q4a.png" width="300"/></a> |
| B. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q4b.png"><img alt="Effect of field resistance speed control on shunt motor speed torque - option b" class="alignnone size-full wp-image-160864" height="198" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q4b.png" width="266"/></a> |
| C. | <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q4c.png"><img alt="Effect of field resistance speed control on shunt motor speed torque - option c" class="alignnone size-full wp-image-160865" height="209" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q4c.png" width="276"/></a> |
| D. | none of the mentioned |
| Answer» B. <a href="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q4b.png"><img alt="Effect of field resistance speed control on shunt motor speed torque - option b" class="alignnone size-full wp-image-160864" height="198" src="https://www.sanfoundry.com/wp-content/uploads/2017/05/electrical-machines-questions-answers-speed-control-dc-motors-q4b.png" width="266"/></a> | |
| 11. |
Ward-Leonard system of system of speed control is not recommended for _________ |
| A. | constant speed operation |
| B. | Wide speed |
| C. | frequent-motor reversed |
| D. | very slow speed |
| Answer» B. Wide speed | |
| 12. |
The PWM control of DC motor varies _________ |
| A. | linearly with speed |
| B. | inversely with speed |
| C. | parabolically with speed |
| D. | exponentially with speed |
| Answer» B. inversely with speed | |