Q3. a. A D.C. series motor draws 45A from a D.C. supply when developing the rated torque at 1500 rpm. If the motor develops 1/4 rated torque, neglecting saturation and losses, evaluate: i. the current drawn by the motor; and ii. the motor speed. [3] [3] b. AD.C. shunt motor is connected to a 240 V D.C. supply, and draws the input current of 20 A at 750 rpm. The motor has an armature resistance of 0.5 2 and the field Assignment 1 Page 1 EEE4117 Electrical Machines and Drives resistance of 120 2. i. Draw the equivalent circuit of the motor; [2] ii. Evaluate the back emf of the motor; [3] 111. Evaluate the motor torque; [2] iv. Evaluate the motor efficiency. [2] iii. Evaluate the resistance connected in series with the armature if the motor speed is reduced to 600 rpm and the torque is kept unchanged. [4]