Vibrations in engineering and technology

Valeriy Granyak - Candidate of Technical Sciences, Associate Professor of the Department of Power Engineering, Electrical Engineering and Electromechanics, Vinnytsia National Agrarian University (3 Sonyachna Street, Vinnytsia, Ukraine e-mail: titanxp2000@ukr.net

To date, even in the developed countries of Europe, more than 50% of the power generating equipment of hydropower plants have worked their design life. In the CIS countries, the percentage of such equipment is even higher. The complete replacement of such equipment requires a large amount of investment, while a significant part of the latter has a satisfactory technical condition for the further extension of the service life. However, with an increase in the operating time of every electrical equipments, the probability of its failure inevitably increases, which can lead to significant material losses and to a significant danger to the life and health of the power plant personnel. Therefore, in view of the foregoing, monitoring and early diagnosis systems, which are entrusted with the protection function of both hydraulic turbines and auxiliary power equipment, are becoming increasingly relevant. One of the most promising methods of technical control and diagnostics of hydraulic units is the analysis of their vibro-acoustic characteristics. Including the axial component. However, a significant technical problem that arises in the construction of such systems is the limited use of known absolute vibration displacement sensors due to the lack of their high-precision mathematical models.

In the article a mathematical model of an overhead parametric eddy current primary measuring transducer of absolute displacement has been developed. It is shown that both the effective value of the output current and the shift of its initial phase are found to be functionally dependent on the distance between the sensor and the conductive medium with a stable supply voltage. It has been established that, while ensuring acceptable overall dimensions, this sensor has sufficient sensitivity to convert the displacement to the effective (amplitude) value of the output current, which is constant in the range of movement from 0 to 5 mm, to ensure the required measurement accuracy.

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