Two adjustable-speed dc shunt motors have maximum speeds of 1800r/min and minimum speeds of 500r/min. Speed adjustment is obtained by field-rheostat control. Motor A drives a load requiring constant power over the speed range; motor B drives one requiring constant torque. All losses and armature reaction may be neglected. a. If the power outputs of the two motors are equal

Two adjustable-speed dc shunt motors have maximum speeds of 1800r/min and minimum speeds of 500r/min. Speed adjustment is obtained by field-rheostat control. Motor A drives a load requiring constant power over the speed range; motor B drives one requiring constant torque. All losses and armature reaction may be neglected.

a. If the power outputs of the two motors are equal at 1800 r/min and the armature currents are each 125 A, what will the armature currents be at 500r/min?

b. If the power outputs of the two motors are equal at 500 r/min and the armature currents are each 125 A, what will the armature current be at 1800 r/min?

c. Answer parts (a) and (b) with speed adjustment by armature-voltage control with conditions otherwise the same.

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Related Book For answer-question

Electric Machinery

6th Edition

Authors: Charles Kingsley, Jr, Stephen D. Umans

ISBN: 978-0071230100