A 3-phase, 440-V,4-pole, 60Hz induction motor has maximum power Pmech=220hp and a maximum torque Tmech= 1140 N-m. Use simplified circuit and ignore stator impedance.
(a) Find the slip at the maximum developed torque.
(b) If we would like to get the maximum torque at starting (s=1), a method is to add more resistance to the rotor, R2,new=R2,old + Rextra, while the rotor reactance X2 stays the same.