CONFIDENTIAL EE/DEC 2016/EPO640/644 QUESTION 1 a) With the aid of a suitable diagram with labels, describe the four quad
Posted: Sun May 15, 2022 4:01 pm
CONFIDENTIAL EE/DEC 2016/EPO640/644 QUESTION 1 a) With the aid of a suitable diagram with labels, describe the four quadrants of operation of a motor drive? How does this apply to motion control system? (10 marks) b) Compare the merits and demerits of DC drives and AC drives (5 marks) c) A 24hp DC Shunt motor is running full-load at 900 rpm at armature voltage 600V. The armature and field resistances of the motor are 10 and 800 Q respectively. The efficiency of the motor at full load is 90%. 1) If the motor is braked by dynamic braking, calculate the value of the braking resistor that will limit the initial braking current to 150% of the rated value. it) If the motor operates in regenerative braking mode at speed of 1000 rpm calculate the line current and braking torque. Sketch the circuit for counter-current braking (by reversing the supply voltage). Determine the braking resistor that will limit the initial braking current to 140% of the rated current. (10 marks) 1)