A. reduce windage losses
B. reduce eddy currents
C. reduce accumulation of dirt and dust
D. reduce magnetic hum
Related Mcqs:
- In the squirrel-cage induction motor the rotor slots are usually given slight skew__________?
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 - 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 - 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 - 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 - In three-phase squirrel-cage induction motors____________?
A. rotor conductor ends are short-circuited through slip rings
B. rotor conductors are short-circuited through end rings
C. rotor conductors are kept open
D. rotor conductors are connected to insulation - 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 - 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
