A 120 V shunt motor has armature and field resistances of 0.2 2 and 100 2, respectively. When no mechanical load is coupled to the motor shaft, it runs at 1800 RPM and draws 5 A from the supply....

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Extracted text: A 120 V shunt motor has armature and field resistances of 0.2 2 and 100 2, respectively. When no mechanical load is coupled to the motor shaft, it runs at 1800 RPM and draws 5 A from the supply. Neglect the effects of armature reaction and saturation. a. When a mechanical load is added, the motor draws 25 A. Calculate the speed of the motor at this condition, assuming the field flux remains the same. b. Calculate the resistance required in series with the armature resistance to reduce the speed to 800 rpm, while having the same torque as previous part (a). c. From the condition of part (b), find the speed of the motor if the load torque is suddenly halved, given that t o n².