End-Winding Vibrations in Large Synchronous Generators

A variety of generator problems are associated with end-winding vibrations. Understanding these vibrations can, therefore, contribute signficantly towards improving the generator´s overall availability rate. The vibration measurements taken ona large 2-pole steam turbine generator operating in the field have been reported in this paper. Tests showed significant increase in vibrations at leading power factors, which is explained by considering the effect of core vibrations on the end-windings. An approximate formula has been developed to predict the rated load vibrations from the open-circuit and short-circuit vibrations which can be measured in the factory.