Question 2 A 460 V 25 Hp, 60 Hz, 4-pole, Y-connected induction motor has the following parameters in ohms per phase referred to the stator circuit. R1= 0.641 Ω R2= 0.332 Ω Χι= 1.106 Ω Χ2=0.464 Ω X-26.3 Ω The rotational losses are 1100 W and are assumed to be constant. The core loss is included in this figure. The motor is supplied at rated voltage and rated frequency. Calculate; i. ii. iii. iv. Synchronous speed Slip at which maximum torque occurs Maximum torque of the motor Assuming that the torque curve is linear between Tmax and synchronous speed, what is the motor mechanical torque at STmax/2? The supply frequency is reduced to 30 Hz. i) What should be the supply voltage to keep the pole flux constant at 60 Hz value? ii) Repeat the solution for 30 Hz iii) Compare results of 30 Hz and 60 Hz operation.