Impact testing of hydro generators end-winding in different temperature state

Abstract

The fault detection of rotating electrical machines has become very attractive field of research from vibrational aspect, because these machines are susceptible to failure due to thermal, electrical, mechanical or environmental stresses. Therefore, the vibrational analysis of generators as rotating machines will be beneficial for the generator design in the initial stage and also for online monitoring and faults diagnostics during generator operation. This paper presents a novel methodology for hammer impact testing ("bump-test") of stators end-winding vibrations with an accent on the influence of the physical parameters such as temperature. Introductory, a brief survey of recent research in the area is presented. Furthermore, a detailed description of the used instrumentation and conducted testing methodology according to established standards is systematically exposed. The measurement methodology is implemented on two generators, a cold one in its' repairing phase and second identical, generator in a warm condition in order to detect the damaged elements and to investigate the influence of the temperature on the dynamic characteristics (natural frequencies and rigidity) of the structures. A year later, series of same measurements on one of the generators during a process of its' cooling were conducted. This work provides graphical, as well as numerical results for the dynamical behaviour of the structures under different thermal conditions. Ultimately, a conclusion for the dependence between the temperature and the dynamics parameters of the generator is drawn.

Dynamic Characterization of Ball Bearing in Turbine Propeller Using Bump Test Method

“…Therefore, the generators' vibrational analysis as rotating machines will be beneficial for the generator design in the initial stage and online monitoring and faults diagnostics during generator operation. The bump test (hammer impact testing) of stators endwinding vibrations with an accent on the physical parameters' influence temperature [3]. The bump test on the turbine side and the exciter side of the endwinding generator identify natural frequency (resonance) around 95 Hz to 115 Hz.…”