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.Management Sciences
Category: Polyphase Induction Motors
Less maintenance troubles are experienced in case of___________?
A. slip ring induction motor
B. squirrel cage induction motor
C. both A. and (b)
D. none of the above
The efficiency of an induction motor can be expected to be nearly____________?
A. 60 to 90%
B. 80 to 90%
C. 95 to 98%
D. 99%
Which of the following component is usually fabricated out of silicon steel ?
A. Bearings
B. Shaft
C. Statorcore
D. None of the above
A squirrel cage induction motor is not selected when___________?
A. initial cost is the main consideration
B. maintenance cost is to be kept low
C. higher starting torque is the main consideration
D. all above considerations are involved
Stepless speed control of induction motor is possible by which of the following methods ?
A. e.m.f. injection in rotor eueuit
B. Changing the number of poles
C. Cascade operation
D. None of the above
Which motor is preferred for use in mines where explosive gases exist ?
A. Air motor
B. Induction motor
C. D.C. shunt motor
D. Synchronous motor
Slip of an induction motor is negative when_____________?
A. magnetic field and rotor rotate in opposite direction
B. rotor speed is less than the synchronous speed of the field and are in the same direction
C. rotor speed is more than the synchronous speed of the field and are in the same direction
D. none of the above
The frame of an induction motor is usually made of____________?
A. silicon steel
B. cast iron
C. aluminium
D. bronze
Reduced voltage starter can be used with_____________?
A. slip ring motor only but not with squirrel cage induction motor
B. squirrel cage induction motor only but not with slip ring motor
C. squirrel cage as well as slip ring induction motor
D. none of the above
Slip ring motor is recommended where____________?
A. speed control is required
B. frequent starting, stopping and reversing is required
C. high starting torque is needed
D. all above features are required
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