Questions
42
As hysteresis motors are free from mechanical and magnetic vibrations therefore these are considered as suitable for
Answer: sound equipment
43
Which motor is normally free from mechanical and magnetic vibrations ?
Answer: Hysteresis motor
44
In which single-phase motor, the rotor has no teeth or winding ?
Answer: Hysteresis motor
45
The direction of rotation of universal motor can be reversed the by reversing the flow of current through
Answer: either armature winding or field winding
46
When a D.C. series motor is connected to A.C. supply, the power factor will be low because of
Answer: high inductance of field and armature circuits
47
Which of the following motors can be used for unity power factor ?
Answer: Schrage motor
48
The speed of a universal motor is generally reduced by using
Answer: gear trains
49
Which type of load is offered by cranes and hoists ?
Answer: Reversing, heavy start
50
Which of the following single-phase motors has relatively poor starting torque ?
Answer: Capacitor motor
51
The wattage of motor for driving domestic sewing machine will be around
Answer: 100 to 150 W
52
The wattage rating for a ceiling fan motor will be in the range
Answer: 50 to 150 W
53
In case of high speed universal motor which of the following needs more attention ?
Answer: Balancing of rotor
54
In case of a shaded pole motor the direction of rotation of the motor is
Answer: from main pole to shaded pole
55
The repulsion-start induction-run motor is used because of
Answer: high starting torque
56
Which of the following motors has highest starting torque ?
Answer: Capacitor-start motor
57
Which of the following single-phase induction motors is generally used in time phonographs ?
Answer: Shaded pole
58
In A.C. series motor compensating winding is employed to
Answer: reduce sparking at the brushes
59
Which of the following motors can be run on AC. as well as D.C. supply ?
Answer: Universal motor
