1. In a split phase motor, the running winding should have
Correct : B. low resistance and high inductance
2. If the capacitor of a single-phase motor is short-circuited
Correct : A. the motor will not start
3. In capacitor start single-phase motors
Correct : 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
Correct : A. improve power factor
5. In a capacitor start motor, the phase displacement between starting and running
winding can be nearly
Correct : D. 90°
6. In a split phase motor
Correct : A. the starting winding is connected through a centrifugal switch
7. The rotor developed by a single-phase motor at starting is
Correct : D. zero
8. Which of the following motor will give relatively high starting torque ?
Correct : A. Capacitor start motor
9. Which of the following motor will have relatively higher power factor ?
Correct : A. Capacitor run motor
10. In a shaded pole motor, the shading coil usually consist of
Correct : 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
Correct : D. shading coils
12. A centrifugal switch is used to dis- connect 'starting winding when motor has
Correct : 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 ?
Correct : A. Universal motor
14. The value of starting capacitor of a fractional horse power motor will be
Correct : C. 300 uF
15. In repulsion motor direction of rotation of motor
Correct : B. is the same as that of brush shift
16. In a single phase motor the centrifugal switch
Correct : 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
Correct : 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
Correct : D. not start at all
19. Which of the following motors is used in mixies ?
Correct : D. Universal motor
20. Which of the following motors is inherently self starting ?
Correct : B. Shaded-pole motor
21. The direction of rotation of an hysteresis motor is determined by
Correct : B. position of shaded pole with respect to main pole
22. Burning out of windings is due to
Correct : A. short circuited capacitor
23. Direction of rotation of a split phase motor can be reversed by reversing the
connection of
Correct : C. either (a) or (b)
24. Short-circuiter is used in
Correct : C. repulsion start induction run motor
25. The range of efficiency for shaded pole motors is
Correct : D. 5% to 35%
26. In a capacitor start single-phase motor, when capacitor is replaced by a resistance
Correct : D. motor will continue to run in same direction
27. The power factor of a single-phase induction motor is usually
Correct : A. lagging
28. A shaded pole motor can be used for
Correct : D. any of the above
29. A hysteresis motor works on the principle of
Correct : A. hysteresis loss
30. Which of the following motor will give the highest starting torque ?
Correct : B. Schrage motor
31. For which of the applications a reluctance motor is preferred ?
Correct : C. Signalling and timing devices
32. The motor used on small lathes is usually
Correct : C. single-phase capacitor run motor
33. Which of the following motors is preferred for tape-recorders ?
Correct : B. Hysteresis motor
34. A single-phase induction motor is
Correct : C. inherently non-self-starting with low torque
35. A schrage motor can run on
Correct : D. all of the above
36. A universal motor can run on
Correct : C. either A.C. or D.C.
37. Which of the following single-phase motors is suitable for timing and control
purposes ?
Correct : A. Reluctance motor
38. Single phase induction motor usually operates on
Correct : A. 0.6 power factor lagging
39. In split-phase motor iauxiliary winding is of
Correct : C. thin wire placed at the top of the slots
40. Which of the following motors will operate at high power factor ?
Correct : D. Capacitor run motor
41. In a two value capacitor motor, the capacitor used for running purposes is
Correct : B. paper spaced oilfilled type
42. Which of the following motors can be run on AC. as well as D.C. supply ?
Correct : A. Universal motor
43. In A.C. series motor compensating winding is employed to
Correct : C. reduce sparking at the brushes
44. Which of the following single-phase induction motors is generally used in time
phonographs ?
Correct : C. Shaded pole
45. Which of the following motors has highest starting torque ?
Correct : C. Capacitor-start motor
46. The repulsion-start induction-run motor is used because of
Correct : D. high starting torque
47. In case of a shaded pole motor the direction of rotation of the motor is
Correct : A. from main pole to shaded pole
48. In case of high speed universal motor which of the following needs more attention ?
Correct : D. Balancing of rotor
49. The wattage rating for a ceiling fan motor will be in the range
Correct : C. 50 to 150 W
50. The wattage of motor for driving domestic sewing machine will be around
Correct : A. 100 to 150 W
51. Which of the following single-phase motors has relatively poor starting torque ?
Correct : C. Capacitor motor
52. Which type of load is offered by cranes and hoists ?
Correct : D. Reversing, heavy start
53. The speed of a universal motor is generally reduced by using
Correct : A. gear trains
54. Which of the following motors can be used for unity power factor ?
Correct : D. Schrage motor
55. When a D.C. series motor is connected to A.C. supply, the power factor will be low
because of
Correct : A. high inductance of field and armature circuits
56. The direction of rotation of universal motor can be reversed the by reversing the flow
of current through
Correct : C. either armature winding or field winding
57. In which single-phase motor, the rotor has no teeth or winding ?
Correct : C. Hysteresis motor
58. Which motor is normally free from mechanical and magnetic vibrations ?
Correct : C. Hysteresis motor
59. As hysteresis motors are free from mechanical and magnetic vibrations therefore
these are considered as suitable for
Correct : C. sound equipment
60. A reluctance motor
Correct : D. all of the above
61. In a hysteresis motor, the rotor must have
Correct : A. retentivity
62. The rotor of a hysteresis motor is made of
Correct : C. chrome steel
63. The electric motor used in portable drills is
Correct : C. universal motor
64. Which of the following applications always have some load whenever switched on ?
Correct : C. Pistol drills
65. The speed control of universal motor used for sewing machines is by
Correct : B. varying the resistance
66. Torque developed by a single phase induction motor at starting is
Correct : D. nil
67. In split phase motor main winding is of
Correct : C. thick wire placed at the bottom of the slots
68. In repulsion motor, maximum torque is developed when
Correct : A. brush axis is at 45° electrical to the field axis
69. If the centrifugal switch does not open at 70 to 80 percent of synchronous speed of
motor, it would result in
Correct : A. damage to the starting winding
70. Speed torque characteristic of a repulsion induction motor is similar to that of a D.C.
Correct : C. compound motor
71. In a ceilingfan employing capacitor run motor
Correct : A. secondary winding surrounds the primary winding
72. The shaded pole motor is used for
Correct : B. low starting torque
73. The rotor slots, in an induction motor, are usually not quite parallel to the shaft
because it
Correct : C. helps in reducing the tendency of the rotor teeth to remain under the stator teeth
74. The speed/load characteristics of a universal motor is same as that of
Correct : C. D.C. series motor
75. The purpose of stator winding in the compensated repulsion motor is to
Correct : B. improve power factor and provide better speed regulation
76. Which of the following motors is used for unity power factor ?
Correct : B. Schrage motor
77. The motor used for the compressors is
Correct : C. capacitor-start capacitor-run motor
78. Which of the following motors is used in a situation where load increases with speed ?
Correct : B. Three-phase series motor
79. In repulsion motor, zero torque is developed when
Correct : D. both (b) and (c)
80. Centrifugal switch disconnects the auxiliary winding of the motor at about ____
percent of synchronous speed
Correct : B. 70 to 80
81. Starting winding of a single phase motor of a refrigerator is disconnected from the
circuit by means of a
Correct : A. magnetic relay
82. If a single phase induction motor runs slower than normal, the most likely defect is
Correct : A. worn bearings
83. Which of the following motors is used in tape-recorders ?
Correct : A. Hysteresis motor
84. Which of the following statements regarding two value capacitor motor is incorrect ?
Correct : B. It is preferred to permanent-split single-value capacitor motor where frequent reversals are required
85. Two-value capacitor motor finds increased application as compressor motor in small
home air-conditioners because
Correct : C. it has low starting as well as running currents at relatively high power factor
86. If the centrifugal switch of a two-value capacitor motor using two capacitors fails to
open then
Correct : D. electrolytic capacitor will, in all probability, suffer break down
87. In a universal motor, the most common cause of brush sparking is
Correct : D. all of the above
88. If starting winding of a single-phase induction motor is left in the circuit, it will
Correct : C. draw excessive current and overheat
89. Most of the fractional horsepower motors have either
Correct : D. plain or sleeve bearings
90. Which of the following statements regarding reluctance-start motor is incorrect ?
Correct : A. It is similar to reluctance motor
91. To reverse the direction of rotation of acapacitor start motor while it is running we
should
Correct : A. disconnect motor from the supply till it stops then reconnect it to supply with reversed connection of main or auxiliary winding
92. In case of a reluctance motor, when the load is increased so that it cannot maintain
synchronous speed the motor will
Correct : D. run as induction motor
93. Which of the following motors has two separate windings on the motor ?
Correct : B. Repulsion induction motor
94. A shaded pole motor does not possess
Correct : D. all of the above
95. In a A.C. series motor armature coils are usually connected to commutator
Correct : A. through resistance
96. Which of the following statements regarding a reluctance motor is incorrect ?
Correct : A. It cannot be reversed, ordinarily
97. A universal motor is one which
Correct : A. can be operated either on D.C. or A.C. supply at approximately the same speed and output
98. A repulsion motor is equipped with
Correct : B. commutator
99. The capacitors used in single-phase capacitor motors have no
Correct : C. polarity marking
100. If a D.C. series motor is operated on A.C. supply, it will