9. A 3-o induction motor has a synchronous speed of 250 r.p.m. and 4 per cent slip at full-load. The rotor has a resistance of 0.02 2/phase and a standstill leakage reactance of 0.15 2/phase....

Extracted text: 9. A 3-o induction motor has a synchronous speed of 250 r.p.m. and 4 per cent slip at full-load. The rotor has a resistance of 0.02 2/phase and a standstill leakage reactance of 0.15 2/phase. Calculate (a) the ratio of maximum and full-load torque (b) the speed at which the maximum torque is devel- oped. Neglect resistance and leakage of the stator winding.