EBM 510: Electric Motor Drive Systems Continuous Assessment Test

Forty-minute continuous assessment paper on electric motor drive systems in which any three of six questions are answered. A three-phase fifty-hertz induction motor with equal stator and rotor resistances of five hundredths of an ohm and reactances of three tenths of an ohm, run at half its rated voltage and half its rated frequency: the maximum torque at the reduced supply as a fraction of its normal value. The wound-rotor induction motor rated twenty-five kilowatts at nine hundred revolutions per minute on four hundred and fifteen volts, fed through a three-phase rectifier and a chopper at two hundred and fifty hertz with an open-circuit line voltage of three hundred and fifty volts and a one-ohm load resistance: the chopper on-time that develops a gross torque of one hundred and eighty newton metres at eight hundred revolutions per minute against a synchronous speed of one thousand. For a synchronous motor, three torques associated with it and two methods of starting it. The derivation of the expression relating torque and speed of a cylindrical rotor synchronous motor. A four-pole induction motor on a fifty-hertz supply: synchronous speed, rotor speed at five per cent slip, and rotor frequency when the rotor runs at one hundred revolutions per minute. And the labelled torque-speed characteristic of an induction motor showing the plugging, motoring and generating regions, with regenerative braking explained.