Q4 () A 3-phase induction motor having a synchronous speed of 1200rpm draws 80kW from a 3-phase feeder. The copper losses and core losses in the stator amount to 5kW. If the motor runs at 1152rpm, calculate: the rotor input power; (i) (ii) (iii) the gross mechanical power output; (2 marks) (2 marks) the rotor copper losses; (2 marks) (vi) the net mechanical power with knowing that the windage and (2 marks) friction losses are 2kW; (v) the efficiency of the motor. (2 marks) (b) Compare the brushed motor (DC motor) and a brushless motor (10 marks) (induction motor) in FIVE aspects.