Related Questions

In three-phase induction motors sometimes copper bars are placed deep in the rotor to
A Improve starting torque
B Reduce copper losses
C Improve efficiency
D Improve power factor
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
Which type of bearing is provided in small induction motors to support the rotor shaft?
A Ball bearings
B Cast iron bearings
C Bush bearings
D None of the above
A wound rotor induction motor is preferred, as compared to squirrel cage induction motor, when major consideration is
A Slop speed operation
B High starting torque
C Low windage losses
D All of the above
Which one of the following is not necessarily the advantage of D.C. motors over A.C. motors?
A Low cost
B Wide speed range
C Stability
D High starting torque
In which of the following motors the stator and rotor magnetic field rotate at the same speed ?
A Universal motor
B Synchronous motor
C Induction motor
D Reluctance motor
The mechanical displacement of the rotor with respect to the stator, in polyphase multipolar synchronous motors running at full load, is of the order of
A zero degree
B two degrees
C five degrees
D ten degrees
In which of the following motors the stator and rotor fields rotate simultaneously ?
A D.C. motor
B Reluctance motor
C Universal motor
D Synchronous motor
Which of the following single-phase induction motors is generally used in time phonographs?
A Resistance start
B Capacitor start capacitor run
C Shaded pole
D Universal
In squirrel cage induction motors which of the following methods of starting cannot be used?
A Resistance in rotor circuit
B Resistance in stator circuit
C Autotransformer starting
D Star-delta starting

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