A. to reduce the magnetic hum and locking tendency of the rotor
B. to increase the tensile strength of the rotor bars
C. to ensure easy fabrication
D. none of the above
Related Mcqs:
- In squirrel cage induction motors, the rotor slots are usually given slight skew in order to__________?
A. reduce windage losses
B. reduce eddy currents
C. reduce accumulation of dirt and dust
D. reduce magnetic hum - In an induction motor the relationship between stator slots and rotor slots is that_____________?
A. stator slots are equal to rotor slots
B. stator slots are exact multiple of rotor slots
C. stator slots are not exact multiple of rotor slots
D. none of the above - Slip ring motor is preferred over squirrel cage induction motor where___________?
A. high starting torque is required
B. load torque is heavy
C. heavy pull out torque is required
D. all of the above - If an induction motor with certain ratio of rotor to stator slots, runs at 1/7 of the normal speed, the phenomenon will be termed as____________?
A. humming
B. hunting
C. crawling
D. cogging - The number of slip rings on a squirrel cage induction motor is usually____________?
A. two
B. three
C. four
D. none - The starting torque of a squirrel-cage induction motor is___________?
A. low
B. negligible
C. same as full-load torque
D. slightly more than full-load torque - A double squirrel-cage induction motor has______________?
A. two rotors moving in oppsite direction
B. two parallel windings in stator
C. two parallel windings in rotor
D. two series windings in stator - Which of the following methods is easily applicable to control the speed of the squirrel-cage induction motor _____________?
A. By changing the number of stator poles
B. Rotor rheostat control
C. By operating two motors in cascade
D. By injecting e.m.f. in the rotor circuit - The speed of a squirrel-cage induction motor can be controlled by all of the following except_____________?
A. changing supply frequency
B. changing number of poles
C. changing winding resistance
D. reducing supply voltage - 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
