Question

The external rotor resistance of a 3-\(\phi\) induction motor is increased more than the resistance required to get maximum starting torque. Then maximum torque occurs in \underline{\hspace{2cm} of Torque (y-axis) – Speed (x-axis) characteristic plot.

• A. Second Quadrant
• B. Third Quadrant
• C. Fourth Quadrant
• D. First Quadrant

Hint:

Torque-speed curves shift left with increased rotor resistance, especially during braking (2nd quadrant).

Answer 1

The Correct Option is A

If the rotor resistance is increased beyond the optimum value, the point of maximum torque shifts to a higher slip (lower speed). For a braking or plugging condition, torque vs speed enters the negative direction — represented in the second quadrant.