A 230 V, 500 rpm, 100 A separately- excited dc motor has anarmature resistance of 0.1 ohms. The motor is driving, under ratedconditions, a load whose torque is constant and independent ofspeed. The speeds below the rated speed are obtained with armaturevoltage control (with full field) and the speeds above the ratedspeed are obtained by field control (with rated armaturevoltage).
What motor terminal voltage is needed to run it at 400 rpm?
By what amount should flux be reduced to get a motor speed of800 rpm?
Neglect the motor’s rotational losses.
3.The separately- excited motor of the previous problem is nowcoupled to an overhauling load with a torque of 800 N-m. Determinethe speed at which the motor can hold the loadby regenerativebraking. Source voltage is 230 V. Neglect the motor’s rotationallosses.
