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.Management Sciences
Category: Polyphase Induction Motors
The stating torque of the slip ring induction motor can be increased by adding__________?
A. external inductance to the rotor
B. external resistance to the rotor
C. external capacitance to the rotor
D. both resistance and inductance to rotor
When /?2 is the rotor resistance, .X2 the rotor reactance at supply frequency and s the slip, then the condition for maximum torque under running conditions will be_____________?
A. sR2X2 = 1
B. sR2 = X2
C. R2 = sX2
D. R2 = s2X2
Insertion of resistance in the rotor of an induction motor to develop a given torque?
A. decreases the rotor current
B. increases the rotor current
C. rotor current becomes zero
D. rotor current rernains same
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
Size of a high speed motor as compared to low speed motor for the same H.P. will be__________?
A. bigger
B. smaller
C. same
D. any of the above
Rotor rheostat control method of speed control is used for____________?
A. squirrel-cage induction motors only
B. slip ring induction motors only
C. both A. and (b)
D. none of the above
The shape of the torque/slip curve of induction motor is__________?
A. parabola
B. hyperbola
C. rectangular parabola
D. straigth line
The maximum torque in an induction motor depends on___________?
A. frequency
B. rotor inductive reactance
C. square of supply voltage
D. all of the above
For driving high inertia loads best type of induction motor suggested is_____________?
A. slip ring type
B. squirrel cage type
C. any of the above
D. none of the above
In the circle diagram for induction motor, the diameter of the circle represents____________?
A. slip
B. rotor current
C. running torque
D. line voltage
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