Main features of using the shock pulse method for vibration diagnostics of turbogenerator stators

The present work is devoted to the calculation and experimental study of the vibrational state of the stator end zone elements at high-power turbogenerators. Due to the design features and operating conditions under the combined effect of temperature and non-stationary electromagnetic fields, the structural elements of the stator end zones at powerful turbo generators are subject to vibration. Excessive levels of the structure vibration lead to the appearance of fatigue cracks in the vibration-loaded elements and their subsequent failure, leading to the stop of the generator and, as a consequence, the whole power unit. In this regard, the creation of a reliable electric machine is an important and urgent scientific and technical task. To solve such problems, various computational and experimental methods are being actively used at present, which are often used independently of each other. A feature of this work is the joint use of modern design and experimental methods for solving the problem of ensuring vibrational reliability of the end zone elements of stators at powerful turbo-generators. The paper considers the use of the method of shock impulses for vibration diagnostics of turbogenerator stators, in order to increase the vibrational reliability. Numerical simulation of the impulse dynamic impact on the end winding element of a powerful turbogenerator is performed. The model comprises a bus holder rigidly fixed on the base of the pressure plate, and an output end with composite insulation. The physical and mechanical properties of insulations are assumed according to results of design and experimental studies. The results of computation studies have made it possible to determine the dependencies of the recorded responses on the location and duration of the impact, and also to select the point of pulse application, depending on the shape of the oscillations. Recommendations for conducting vibration diagnostics by shock pulses have been developed on the example of output busbars of turbo generator stators, which allow to increase the level of received signals and the probability of detecting all forms of oscillations in the required frequency range.

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