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Free download in PDF Single Phase Induction Motor Multiple Choice Questions with Answers for competitive exams. These short objective type questions with answers are very important for Board exams as well as competitive exams. These short solved questions or quizzes are provided by Gkseries.
61
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
62
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
63
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)
64
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: Three-phase series motor
65
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: capacitor-start capacitor-run motor
66
Which of the following motors is used for unity power factor ?
[A]
Hysteresis motor
[B]
Schrage motor
[C]
Universal motor
[D]
Reluctance motor
67
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: provide mechanical balance
68
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.C. series motor
69
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: helps in reducing the tendency of the rotor teeth to remain under the stator teeth
70
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: low starting torque
71
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: secondary winding surrounds the primary winding
72
Speed torque characteristic of a repulsion induction motor is similar to that of a D.C.
[A]
shunt motor
[B]
series motor
[C]
compound motor
[D]
separately excited motor
73
If the centrifugal switch does not open at 70 to 80 percent of synchronous speed of motor, it would result in
[A]
damage to the starting winding
[B]
damage to the centrifugal switch
[C]
overloading of running winding
[D]
none of the above
Answer: damage to the starting winding
74
In repulsion motor, maximum torque is developed when
[A]
brush axis is at 45° electrical to the field axis
[B]
brush axis coincides with the field axis
[C]
brush axis is at 90° electrical to the field axis
[D]
none of the above
Answer: brush axis is at 45° electrical to the field axis
75
In split phase motor main winding is of
[A]
thin wire placed at the top of the slots
[B]
thin wire placed at the bottom of the slots
[C]
thick wire placed at the bottom of the slots
[D]
thick wire placed at the top of the” slots
Answer: thick wire placed at the bottom of the slots
76
Torque developed by a single phase induction motor at starting is
[A]
pulsating
[B]
uniform
[C]
none of the above
[D]
nil
77
The speed control of universal motor used for sewing machines is by
[A]
friction
[B]
varying the resistance
[C]
tapping the field
[D]
centrifugal mechanism
Answer: varying the resistance
78
Which of the following applications always have some load whenever switched on ?
[A]
Vacuum cleaners
[B]
Fan motors
[C]
Pistol drills
[D]
All of the above
79
The electric motor used in portable drills is
[A]
capacitor run motor
[B]
hysteresis motor
[C]
universal motor
[D]
repulsion motor
80
The rotor of a hysteresis motor is made of
[A]
aluminium
[B]
cast iron
[C]
chrome steel
[D]
copper
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