The operation of large turbo-alternators to reduce rotor winding deformation

The failure of turbo-alternator rotors as a result of copper distortion now constitutes a major cause of outage of electrical generating plant and calls for a closer investigation of the causes of such distortion. The authors expand existing theories based on the work-hardening of copper by temperature cycles and give data of the plastic deformation of copper at working temperatures. The results are given of measurements of both temperatures and the stresses in the windings on alternator rotors in service. An analysis of the phenomena causing the stressed condition indicates means for controlling the stresses. The authors describe the modified operating conditions which have been adopted and some of the difficulties arising therefrom, as well as the equipment installed to measure and control the temperature of alternator-rotor windings. A brief reference is made to the economics of the problem.