McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Electrical Engineering .
| 1. |
In a split phase motor, the running winding should have |
| A. | high resistance and low inductance |
| B. | low resistance and high inductance |
| C. | high resistance as well as high inductance |
| D. | low resistance as well as low inductiance |
| Answer» B. low resistance and high inductance | |
| 2. |
If the capacitor of a single-phase motor is short-circuited |
| A. | the motor will not start |
| B. | the motor will run |
| C. | the motor will run in reverse direction |
| D. | the motor will run in the same direction at reduced r.p.m. |
| Answer» A. the motor will not start | |
| 3. |
In capacitor start single-phase motors |
| A. | current in the starting winding leads the voltage |
| B. | current in the starting winding lags the voltage |
| C. | current in the starting winding is in phase with voltage in running winding |
| D. | none of the above |
| Answer» A. current in the starting winding leads the voltage | |
| 4. |
In a capacitor start and run motors the function of the running capacitor in series with the auxiliary winding is to |
| A. | improve power factor |
| B. | increase overload capacity |
| C. | reduce fluctuations in torque |
| D. | to improve torque |
| Answer» A. improve power factor | |
| 5. |
In a capacitor start motor, the phase displacement between starting and running winding can be nearly |
| A. | 10° |
| B. | 30° |
| C. | 60° |
| D. | 90° |
| Answer» D. 90° | |
| 6. |
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» A. the starting winding is connected through a centrifugal switch | |
| 7. |
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» D. zero | |
| 8. |
Which of the following motor will give relatively high starting torque ? |
| A. | Capacitor start motor |
| B. | Capacitor run motor |
| C. | Split phase motor |
| D. | Shaded pole motor |
| Answer» A. Capacitor start motor | |
| 9. |
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» A. Capacitor run motor | |
| 10. |
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» B. a single turn of heavy copper wire which is short-circuited and carries only induced current | |
| 11. |
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» D. shading coils | |
| 12. |
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» C. picked up about 50 to 70 per cent of rated speed | |
| 13. |
If a particular application needs high speed and high starting torque, then which of the following motor will be preferred ? |
| A. | Universal motor |
| B. | Shaded pole type motor |
| C. | Capacitor start motor |
| D. | Capacitor start and run motor |
| Answer» A. Universal motor | |
| 14. |
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» C. 300 uF | |
| 15. |
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 |
| D. | none |
| Answer» B. is the same as that of brush shift | |
| 16. |
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 auxiliary winding of the motor |
| Answer» A. disconnects auxiliary winding of the motor | |
| 17. |
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» D. at the slot edge where coil enters or comes out of the slot | |
| 18. |
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» D. not start at all | |
| 19. |
Which of the following motors is used in mixies ? |
| A. | Repulsion motor |
| B. | Reluctance motor |
| C. | Hysteresis motor |
| D. | Universal motor |
| Answer» D. Universal motor | |
| 20. |
Which of the following motors is inherently self starting ? |
| A. | Split motor |
| B. | Shaded-pole motor |
| C. | Reluctance motor |
| D. | None of these |
| Answer» B. Shaded-pole motor | |
| 21. |
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» B. position of shaded pole with respect to main pole | |
| 22. |
Burning out of windings is due to |
| A. | short circuited capacitor |
| B. | capacitor value hiving changed |
| C. | open circuiting of capacitor |
| D. | none of the above |
| Answer» A. short circuited capacitor | |
| 23. |
Direction of rotation of a split phase motor can be reversed by reversing the connection of |
| A. | running winding only |
| B. | starting winding only |
| C. | either (a) or (b) |
| D. | both (a) and (b) |
| Answer» C. either (a) or (b) | |
| 24. |
Short-circuiter is used in |
| A. | repulsion induction motor |
| B. | repulsion motor |
| C. | repulsion start induction run motor |
| D. | none of the above |
| Answer» C. repulsion start induction run motor | |
| 25. |
The range of efficiency for shaded pole motors is |
| A. | 95% to 99% |
| B. | 80% to 90% |
| C. | 50% to 75% |
| D. | 5% to 35% |
| Answer» D. 5% to 35% | |
| 26. |
In a capacitor start single-phase motor, when capacitor is replaced by a resistance |
| A. | torque will increase |
| B. | the motor will consume less power |
| C. | motor will run in reverse direction |
| D. | motor will continue to run in same direction |
| Answer» D. motor will continue to run in same direction | |
| 27. |
The power factor of a single-phase induction motor is usually |
| A. | lagging |
| B. | always leading |
| C. | unity |
| D. | unity to 0.8 leading |
| Answer» A. lagging | |
| 28. |
A shaded pole motor can be used for |
| A. | toys |
| B. | hair dryers |
| C. | circulators |
| D. | any of the above |
| Answer» D. any of the above | |
| 29. |
A hysteresis motor works on the principle of |
| A. | hysteresis loss |
| B. | magnetisation of rotor |
| C. | eddy current loss |
| D. | electromagnetic induction |
| Answer» A. hysteresis loss | |
| 30. |
Which of the following motor will give the highest starting torque ? |
| A. | D.C. shunt motor |
| B. | Schrage motor |
| C. | Repulsion start and induction run motor |
| D. | Universal motor |
| Answer» B. Schrage motor | |
| 31. |
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» C. Signalling and timing devices | |
| 32. |
The motor used on small lathes is usually |
| A. | universal motor |
| B. | D.C. shunt motor |
| C. | single-phase capacitor run motor |
| D. | 3-phase synchronous motor |
| Answer» C. single-phase capacitor run motor | |
| 33. |
Which of the following motors is preferred for tape-recorders ? |
| A. | Shaded pole motor |
| B. | Hysteresis motor |
| C. | Two value capacitor motor |
| D. | Universal motor |
| Answer» B. Hysteresis motor | |
| 34. |
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» C. inherently non-self-starting with low torque | |
| 35. |
A schrage motor can run on |
| A. | zero slip |
| B. | negative slip |
| C. | positive slip |
| D. | all of the above |
| Answer» D. all of the above | |
| 36. |
A universal motor can run on |
| A. | A.C. only |
| B. | D.C. only |
| C. | either A.C. or D.C. |
| D. | none of the above |
| Answer» C. either A.C. or D.C. | |
| 37. |
Which of the following single-phase motors is suitable for timing and control purposes ? |
| A. | Reluctance motor |
| B. | Series motor |
| C. | Repulsion motor |
| D. | Universal motor |
| Answer» A. Reluctance motor | |
| 38. |
Single phase induction motor usually operates on |
| A. | 0.6 power factor lagging |
| B. | 0.8 power factor lagging |
| C. | 0.8 power factor leading |
| D. | unity power factor |
| Answer» A. 0.6 power factor lagging | |
| 39. |
In split-phase motor iauxiliary winding is of |
| A. | thick wire placed at the bottom of the slots |
| B. | thick wire placed at the top of the slots |
| C. | thin wire placed at the top of the slots |
| D. | thin wire placed at the bottom of the slots |
| Answer» C. thin wire placed at the top of the slots | |
| 40. |
Which of the following motors will operate at high power factor ? |
| A. | Shaped pole motor |
| B. | Split phase motor |
| C. | Capacitor start motor |
| D. | Capacitor run motor |
| Answer» D. Capacitor run motor | |
| 41. |
In a two value capacitor motor, the capacitor used for running purposes is |
| A. | air capacitor |
| B. | paper spaced oilfilled type |
| C. | ceramic type |
| D. | a.c. electrolytic type |
| Answer» B. paper spaced oilfilled type | |
| 42. |
Which of the following motors can be run on AC. as well as D.C. supply ? |
| A. | Universal motor |
| B. | Repulsion motor |
| C. | Synchronous motor |
| D. | Reluctance motor |
| Answer» A. Universal motor | |
| 43. |
In A.C. series motor compensating winding is employed to |
| A. | reduce the effects of armature reaction |
| B. | increase the torque |
| C. | reduce sparking at the brushes |
| D. | none of the above |
| Answer» C. reduce sparking at the brushes | |
| 44. |
Which of the following single-phase induction motors is generally used in time phonographs ? |
| A. | Resistance start |
| B. | Capacitor start capacitor run |
| C. | Shaded pole |
| D. | Universal |
| Answer» C. Shaded pole | |
| 45. |
Which of the following motors has highest starting torque ? |
| A. | Repulsion motor |
| B. | Shaped pole motor |
| C. | Capacitor-start motor |
| D. | Split-phase motor |
| Answer» C. Capacitor-start motor | |
| 46. |
The repulsion-start induction-run motor is used because of |
| A. | good power factor |
| B. | high efficiency |
| C. | minimum cost |
| D. | high starting torque |
| Answer» D. high starting torque | |
| 47. |
In case of a shaded pole motor the direction of rotation of the motor is |
| A. | from main pole to shaded pole |
| B. | from shaded pole to main pole |
| C. | either of the above depending on voltage |
| D. | either of the above depending on power factor |
| Answer» A. from main pole to shaded pole | |
| 48. |
In case of high speed universal motor which of the following needs more attention ? |
| A. | End play |
| B. | Air gap |
| C. | Insulation in rotor |
| D. | Balancing of rotor |
| Answer» D. Balancing of rotor | |
| 49. |
The wattage rating for a ceiling fan motor will be in the range |
| A. | 200 to 250 W |
| B. | 250 to 500 W |
| C. | 50 to 150 W |
| D. | 10 to 20 W |
| Answer» C. 50 to 150 W | |
| 50. |
The wattage of motor for driving domestic sewing machine will be around |
| A. | 100 to 150 W |
| B. | 40 to 75 W |
| C. | 10 to 30 W |
| D. | 5 to 10 W |
| Answer» A. 100 to 150 W | |
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