MCQOPTIONS
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MCQOPTIONS
This section includes 110 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering Questions knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Locked rotor current of a shaded pole motor is____________? |
| A. | equal to full load current |
| B. | less than full load current |
| C. | slightly more than full load current |
| D. | several times the full load current |
| Answer» D. several times the full load current | |
| 2. |
Which of the following statements regarding a reluctance motor is incorrect ? |
| A. | It cannot be reversed, ordinarily |
| B. | It requires no D.C. field excitation for its operation |
| C. | It is nothing else but a single-phase, salient pole synchronous-induction motor |
| D. | Its squirrel cage-rotor is of unsym-metrical magnetic construction in order to vary reluctance path between stator and rotor |
| Answer» B. It requires no D.C. field excitation for its operation | |
| 3. |
Centrifugal switch disconnects the auxiliary winding of the motor at about ______ percent of synchronous speed? |
| A. | 30 to 40 |
| B. | 70 to 80 |
| C. | 80 to 90 |
| D. | 100 |
| Answer» C. 80 to 90 | |
| 4. |
The rotor developed by a single-phase motor at starting is___________? |
| A. | more than i.he rated torque |
| B. | rated torque |
| C. | less than the rated torque |
| D. | zero |
| Answer» E. | |
| 5. |
As hysteresis motors are free from mechanical and magnetic vibrations therefore these are considered as suitable for__________? |
| A. | fans |
| B. | blowers |
| C. | sound equipment |
| D. | mixer grinders |
| Answer» D. mixer grinders | |
| 6. |
In a A.C. series motor armature coils are usually connected to commutator____________? |
| A. | through resistance |
| B. | through reactances |
| C. | through capacitors |
| D. | solidly |
| Answer» B. through reactances | |
| 7. |
In repulsion motor, zero torque is developed when___________? |
| A. | brush axis is 45° electrical to field axis |
| B. | brush axis coincides with the field axis |
| C. | brush axis is 90° electrical to field axis |
| D. | both B. and (c) |
| Answer» E. | |
| 8. |
A universal motor is one which______________? |
| A. | can be operated either on D.C. or A.C. supply at approximately the same speed and output |
| B. | can be marketed internationally |
| C. | runs at dangerously high speed on no-load |
| Answer» B. can be marketed internationally | |
| 9. |
A shaded pole motor does not possess___________? |
| A. | centrifugal switch |
| B. | capacitor |
| C. | commutator |
| D. | all of the above |
| Answer» E. | |
| 10. |
If a D.C. series motor is operated on A.C. supply, it will____________? |
| A. | spark excessively |
| B. | have poor efficiency |
| C. | have poor power factor |
| D. | all of the above |
| Answer» E. | |
| 11. |
The capacitors used in single-phase capacitor motors have no__________? |
| A. | voltage rating |
| B. | dielectric medium |
| C. | polarity marking |
| D. | definite value |
| Answer» D. definite value | |
| 12. |
Two-value capacitor motor finds increased application as compressor motor in small home air-conditioners because_____________? |
| A. | it is comparatively cheaper |
| B. | it has almost non-destructible capacitor |
| C. | it has low starting as well as running currents at relatively high power factor |
| D. | it is quiet in operation |
| Answer» D. it is quiet in operation | |
| 13. |
Which of the following motors is used in tape-recorders ____________? |
| A. | Hysteresis motor |
| B. | Reluctance motor |
| C. | Capacitor-run motor |
| D. | Universal motor |
| Answer» B. Reluctance motor | |
| 14. |
Which of the following motors is used for unity power factor ? |
| A. | Hysteresis motor |
| B. | Schrage motor |
| C. | Universal motor |
| D. | Reluctance motor |
| Answer» C. Universal motor | |
| 15. |
Which of the following motors is used in a situation where load increases with speed ? |
| A. | Induction motor |
| B. | Three-phase series motor |
| C. | Schrage motor |
| D. | Hysteresis motor |
| Answer» C. Schrage motor | |
| 16. |
The rotor slots, in an induction motor, are usually not quite parallel to the shaft because it_____________? |
| A. | improves the efficiency |
| B. | helps the rotor teeth to remain under the stator teeth |
| C. | helps in reducing the tendency of the rotor teeth to remain under the stator teeth |
| D. | improves the power factor |
| Answer» D. improves the power factor | |
| 17. |
The motor used for the compressors is____________? |
| A. | d.c. series motor |
| B. | shaded pole motor |
| C. | capacitor-start capacitor-run motor |
| D. | reluctance motor |
| Answer» D. reluctance motor | |
| 18. |
To reverse the direction of rotation of acapacitor start motor while it is running we should___________? |
| A. | disconnect motor from the supply till it stops then reconnect it to supply with reversed connection of main or auxiliary winding |
| B. | disconnect motor from supply and immediately reconnect it to supply with reversed connections of the main winding |
| C. | reverse the direction of connection of the auxiliary winding and after motor comes to rest then connect auxiliary winding to the supply |
| D. | reverse the direction of connections of the auxiliary winding and immediately connect it to supply |
| Answer» B. disconnect motor from supply and immediately reconnect it to supply with reversed connections of the main winding | |
| 19. |
The purpose of stator winding in the compensated repulsion motor is to_____________? |
| A. | provide mechanical balance |
| B. | improve power factor and provide better speed regulation |
| C. | prevent hunting in the motor |
| D. | eliminate armature reaction |
| Answer» C. prevent hunting in the motor | |
| 20. |
Most of the fractional horsepower motors have either___________? |
| A. | hard and annealed bearings |
| B. | ball or roller bearings |
| C. | soft and porous bearings |
| D. | plain or sleeve bearings |
| Answer» E. | |
| 21. |
In a ceilingfan employing capacitor run motor____________? |
| A. | secondary winding surrounds the primary winding |
| B. | primary winding surrounds the secondary winding |
| C. | both are usual arrangements |
| D. | none of the above |
| Answer» B. primary winding surrounds the secondary winding | |
| 22. |
If the centrifugal switch of a two-value capacitor motor using two capacitors fails to open then____________? |
| A. | motor will not come up to speed |
| B. | motor will not carry the load |
| C. | current drawn by the motor will be excessively high |
| D. | electrolytic capacitor will, in all probability, suffer break down |
| Answer» E. | |
| 23. |
If starting winding of a single-phase induction motor is left in the circuit, it will____________? |
| A. | run faster |
| B. | spark at light loads |
| C. | draw excessive current and overheat |
| D. | run slower |
| Answer» D. run slower | |
| 24. |
In a universal motor, the most common cause of brush sparking is___________? |
| A. | open armature winding |
| B. | shorted armature winding |
| C. | shorted field winding |
| D. | high commutator mica |
| E. | all of the above |
| Answer» F. | |
| 25. |
Which of the following statements regarding reluctance-start motor is incorrect ? |
| A. | It is similar to reluctance motor |
| B. | It is basically an induction motor and not a synchronous one |
| C. | So far as its basic working principle is concerned, it is similar to shaded pole motor |
| D. | the air-gap between rotor and salient poles is non- uniform |
| Answer» B. It is basically an induction motor and not a synchronous one | |
| 26. |
Which of the following statements regarding two value capacitor motor is incorrect ? |
| A. | It is a reversing motor |
| B. | It is preferred to permanent-split single-value capacitor motor where frequent reversals are required |
| C. | It has low starting as well as rushing currents |
| D. | It has high starting torque |
| Answer» C. It has low starting as well as rushing currents | |
| 27. |
If a single phase induction motor runs slower than normal, the most likely defect is_____________? |
| A. | worn bearings |
| B. | short-circuit in the winding |
| C. | open-circuit in the winding |
| D. | none of the above |
| Answer» B. short-circuit in the winding | |
| 28. |
Which of the following motor will have relatively higher power factor ? |
| A. | Capacitor run motor |
| B. | Shaded pole motor |
| C. | Capacitor start motor |
| D. | Split phase motor |
| Answer» B. Shaded pole motor | |
| 29. |
In repulsion motor direction of rotation of motor____________? |
| A. | is opposite to that of brush shift |
| B. | is the same as that of brush shift |
| C. | is independent of brush shift |
| Answer» C. is independent of brush shift | |
| 30. |
A repulsion motor is equipped with__________? |
| A. | slip rings |
| B. | commutator |
| C. | both A. and (b) |
| D. | none of the above |
| Answer» C. both A. and (b) | |
| 31. |
In case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will_____________? |
| A. | become unstable |
| B. | draw excessive armature current and may burn out |
| C. | fall out of synchronism and come to stand still |
| D. | run as induction motor |
| Answer» E. | |
| 32. |
Starting winding of a single phase motor of a refrigerator is disconnected from the circuit by means of a___________? |
| A. | magnetic relay |
| B. | thermal relay |
| C. | centrifugal switch |
| D. | none of the above |
| Answer» B. thermal relay | |
| 33. |
The speed/load characteristics of a universal motor is same as that of_____________? |
| A. | A.C. motor |
| B. | D.C. shunt motor |
| C. | D.C. series motor |
| D. | none of the above |
| Answer» D. none of the above | |
| 34. |
Which of the following motors has two separate windings on the motor ? |
| A. | Repulsion motor |
| B. | Repulsion induction motor |
| C. | Repulsion start induction run motor |
| D. | None of the above |
| Answer» C. Repulsion start induction run motor | |
| 35. |
The shaded pole motor is used for__________? |
| A. | high starting torque |
| B. | low starting torque |
| C. | medium starting torque |
| D. | very high starting torque |
| Answer» C. medium starting torque | |
| 36. |
A single-phase induction motor is__________? |
| A. | inherently self-starting with high torque |
| B. | inherently self-starting with low torque |
| C. | inherently non-self-starting with low torque |
| D. | inherently non-self-starting with high torque |
| Answer» D. inherently non-self-starting with high torque | |
| 37. |
A capacitor-start single phase induction motor is switched on to supply with its capacitor replaced by an inductor of equivalent reactance value. It will______________? |
| A. | start and then stop |
| B. | start and run slowly |
| C. | start and run at rated speed |
| D. | not start at all |
| Answer» E. | |
| 38. |
In a shaded pole single-phase motor, the revolving field is produced by the use of_________? |
| A. | inductor |
| B. | capacitor |
| C. | resistor |
| D. | shading coils |
| Answer» E. | |
| 39. |
In a shaded pole motor, the shading coil usually consist of___________? |
| A. | a single turn of heavy wire which is in parallel with running winding |
| B. | a single turn of heavy copper wire which is short-circuited and carries only induced current |
| C. | a multilayer fine gauge copper wire in parallel with running winding |
| D. | none of the above |
| Answer» C. a multilayer fine gauge copper wire in parallel with running winding | |
| 40. |
In a split phase motor____________? |
| A. | the starting winding is connected through a centrifugal switch |
| B. | the running winding is connected through a centrifugal switch |
| C. | both starting and running windings are connected through a centrifugal switch |
| D. | centrifugal switch is used to control supply voltage |
| Answer» B. the running winding is connected through a centrifugal switch | |
| 41. |
In a single phase motor the centrifugal switch____________? |
| A. | disconnects auxiliary winding of the motor |
| B. | disconnects main winding of the motor |
| C. | reconnects the main winding the motor |
| D. | reconnects the main winding the motor |
| Answer» B. disconnects main winding of the motor | |
| 42. |
The running winding of a single phase motor on testing with meggar is found to be ground. Most probable location of the ground will be___________? |
| A. | at the end connections |
| B. | at the end terminals |
| C. | anywhere on the winding inside a slot |
| D. | at the slot edge where coil enters or comes out of the slot |
| Answer» E. | |
| 43. |
The direction of rotation of an hysteresis motor is determined by____________? |
| A. | interchanging the supply leads |
| B. | position of shaded pole with respect to main pole |
| C. | retentivity of the rotor material |
| D. | none of these |
| Answer» C. retentivity of the rotor material | |
| 44. |
Which of the following motors is used in mixies ? |
| A. | Repulsion motor |
| B. | Reluctance motor |
| C. | Hysteresis motor |
| D. | Universal motor |
| Answer» E. | |
| 45. |
The value of starting capacitor of a fractional horse power motor will be__________? |
| A. | 100 uF |
| B. | 200 uF |
| C. | 300 uF |
| D. | 400 uF |
| Answer» D. 400 uF | |
| 46. |
A centrifugal switch is used to dis- connect ‘starting winding when motor has___________? |
| A. | run for about 1 minute |
| B. | run for about 5 minutes |
| C. | picked up about 50 to 70 per cent of rated speed |
| D. | picked up about 10 to 25 per cent of rated speed |
| Answer» D. picked up about 10 to 25 per cent of rated speed | |
| 47. |
Hysteresis motor is particularly useful for high-quality record players and tape-recorders because___________? |
| A. | it revolves synchronously |
| B. | it is not subject to any magnetic or mechanical vibrations |
| C. | it can be easily manufactured in extremely small sizes of up to 1 W output |
| D. | it develops hysteresis torque which is extremely steady both in amplitude and phase |
| Answer» E. | |
| 48. |
For which of the applications a reluctance motor is preferred ? |
| A. | Electric shavers |
| B. | Refrigerators |
| C. | Signalling and timing devices |
| D. | Lifts and hoists |
| Answer» D. Lifts and hoists | |
| 49. |
Which of the following statements regarding repulsion-start induction motor is incorrect ? |
| A. | It requires more maintenance of commutator and other mechanical devices |
| B. | It makes quite a bit of noise on starting |
| C. | In fractional horse power motors, it has replaced the capacitor motors |
| D. | It is not easily reversed |
| Answer» D. It is not easily reversed | |
| 50. |
After the starting winding of a single phase induction motor is disconnected from supply, it continues to run only on ______________? |
| A. | running winding |
| B. | rotor winding |
| C. | field winding |
| D. | compensating winding |
| Answer» B. rotor winding | |