Torsional Vibrations in Large Turbine Generator Sets

The long turbogenerator shaft trains in modern power plants are loaded by considerable torsional moments, which have to be transmitted between the turbine and the generator. While the torsional moments under stationary full load conditions are well within tolerable limits from a material strength point of view, the oscillating torsional moments. imposed on the shaft under transient conditions are large enough to eventually cause a material fatigue failure in the shaft. Thus it is necessary to both control excessive torsional vibration and to check the number and magnitude of excessive torsional vibration incidents, in order to perform life time calculations.