MCQOPTIONS
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MCQOPTIONS
This section includes 20 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. |
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 | |
| 5. |
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 | |
| 6. |
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 | |
| 7. |
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 | |
| 8. |
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 | |
| 9. |
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 | |
| 10. |
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 | |
| 11. |
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 | |
| 12. |
Why does DC motor sometimes run too fast when under-loaded? |
| A. | Due to weak field. |
| B. | Due to high line voltage |
| C. | Due to brush-shifted to neutral |
| D. | All of the above |
| Answer» B. Due to high line voltage | |
| 13. |
Run-away for large DC machine is avoided by using |
| A. | a turn or two of cumulative compounding |
| B. | compensating winding |
| C. | stablizer winding |
| Answer» C. stablizer winding | |
| 14. |
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 | |
| 15. |
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 | |
| 16. |
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 | |
| 17. |
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 | |
| 18. |
Mark the wrong option. Which of the following cause and effect behaviour in speed control is correct when field resistance is increased. |
| A. | Decrease in flux |
| B. | Increase in armature current |
| C. | Increase in EMF |
| D. | Decrease in speed |
| Answer» D. Decrease in speed | |
| 19. |
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 | |
| 20. |
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 | |