Analysis of gas content in oil-filled equipment with low energy density discharges

Abstract

In the ageing conditions of the high-voltage oil-filled equipment stock, increasing the diagnostics reliability of its condition is an urgent and practically significant task. One possible way to solve this problem is to modify diagnostic criteria used to recognize the type of equipment defects, especially for those cases when the use of known methods does not allow establishing the correct diagnosis. In the article, the gas percentage and values of gas ratios for 184 units of equipment with electrical discharges of low energy density are analysed. It is shown that for 144 units out of 184, the values of these criteria differ significantly from the values regulated in the current standards for recognition of low energy density discharges. Nomograms (graphic areas) for 8 types of defects that are not regulated in any of the current standards are given. The comparative analysis of recognition reliability of the analysed defects with the use of known standards and methods is carried out. The given in work values of percentage and relations of gases, and also graphic areas (nomograms) of defects are the advanced diagnostic scheme which use allows to increase accuracy of defect type recognition by results of the dissolved gases analysis. This, in turn, significantly increases the operational reliability of oil-filled equipment.