Status of Evaluating the Fatigue of Large Steam Turbine-Generators Caused by Electrical Disturbances

The torsional fatigue impact of different and successive electrical transients on the shafts of nearby turbine-generators is explained and quantitatively compared for various fault conditions and system switching operations. The basis for evaluating fatigue is explained and the many contributory factors are discussed. Results of measurements of the damping of shaft torsional oscillations are presented. The operating principle of the newly developed Torsional Stress Analyzer is described. The necessity for close cooperation between operating utilities and turbine-generator manufacturers in obtaining more data on the behavior of large machine shafts in response to electrical disturbances is emphasized.