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Please answer each part of the question in a detailed manner.
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3. (a) A 6-pole, 60-Hz, three-phase induction motor delivers an output power of 8 kW at a speed of 1170 rpm. If the constant rotational losses are 300 W and the stator copper loss can be neglected, determine (i) the rotor copper loss, and (ii) the efficiency of the motor. (7 Marks) (b) A three-phase, 230-V, 60-Hz, 4-pole, wye-connected induction motor has the following per phase parameters referred to the stator: R = 0.12, R2 = 0.05 12, X m = 50 12, X, = 0.112, X2 = 0.112 Determine (i) the maximum torque developed, and (ii) the starting torque developed. (10 Marks) (C) For the motor in part (3b), external resistances are connected in series with the rotor circuit. If the starting torque developed is to be 80% of the maximum torque developed, determine (i) the value of the external resistance to be added in each phase of the rotor circuit, referred to the stator, and (ii) the resultant speed at which maximum torque is developed. (8 Marks)