A 75 kW, 440 V, Y-connected,3-phase, 6-pole, 50 Hz wound rotor induction motor has a full load slip of 0.04 and the slip at maximum torque of 0.2 when operating at rated voltage and frequency with...

A 75 kW, 440 V, Y-connected,3-phase, 6-pole, 50 Hz wound rotor induction motor has a full load slip of 0.04 and the slip at maximum torque of 0.2 when operating at rated voltage and frequency with rotor winding short circuited at the slip rings. Take X1=X2= 0.5 n/ph ,and assume the stator resistance to be negligible. Find: maximum torque ,and starting torque? If the rotor resistance is now doubled by adding an external series resistance, determine: maximum torque ?