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A DC shunt motor has rated rpm of 480. Certain industrial application requires this motor to run at 540 rpm for some time. Which speed control will be desirable? A) Ward Leonard control B) Armature current control C) Field resistance control D) It is not possible to run the motor at more than the rated rpm 

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A DC shunt motor has rated rpm of 480. Certain industrial application requires this motor to run at 540 rpm for some time. Which speed control will be desirable? A) Ward Leonard control B) Armature current control C) Field resistance control D) It is not possible to run the motor at more than the rated rpm 

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