A dc, separately excited motor drives a conveyor belt (constant torque). The terminal voltage of the motor is 120 V. When the conveyor belt is fully loaded, the armature current of the motor is 15 A and the speed of the motor is 180 rpm. The armature resistance of the motor is 2 ?.

a. Calculate the steady-state speed of the motor if the field voltage is reversed.
b. Calculate the motor speed if after the field voltage is reversed, the field voltage
is reduced by 10%.
c. Sketch the speed-torque characteristics and show all operating points.
Hint: Assume that the field MMF is linearly proportional to the field voltage.




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