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.Management Sciences
Category: Single Phase Induction Motors
For which of the applications a reluctance motor is preferred ?
A. Electric shavers
B. Refrigerators
C. Signalling and timing devices
D. Lifts and hoists
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
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
The capacitors used in single-phase capacitor motors have no__________?
A. voltage rating
B. dielectric medium
C. polarity marking
D. definite value
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
Speed control of a universal motor is achieved by__________?
A. varying field flux with tapped field windings
B. connecting rheostat in series
C. applying variable voltage by means of silicon controlled rectifier
D. applying variable voltage by means of variable auto-transformer
E. all of the above methods
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
Which of the following motors has highest starting torque ?
A. Repulsion motor
B. Shaped pole motor
C. Capacitor-start motor
D. Split-phase motor
When a D.C. series motor is connected to A.C. supply, the power factor will be low because of____________?
A. high inductance of field and armature circuits
B. induced current in rotor due to variations of flux
C. fine copper wire winding
D. none of the above
Which of the following motors is inherently self starting ?
A. Split motor
B. Shaded-pole motor
C. Reluctance motor
D. None of these
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