Abstract
The article presents results of a comprehensive analysis of the gas content in oil of 252 pieces of high-voltage equipment with defects, for which ethane is the key gas. There are 14 types of defects with maximum ethane content, which correspond both to overheating with temperature 150-300°C and low temperature overheating accompanied by discharges with different energy density (partial discharges, spark discharges, discharges with low and high energy density, arc discharges). The most typical defects are analysed and examples of their recognition by different researchers are given. For each type of defect, ranges of gas percentage values and gas ratio values are obtained. This is particularly important for the recognition of combined defects (overheating that is accompanied by discharges), because for such defects the values of these criteria are not regulated in any known standard for the interpretation of the results of the analysis of gases dissolved in oil. For the first time, 14 nomograms and graphic areas of defects for which ethane is the key gas have been obtained, which makes it possible to significantly expand the range of reference nomograms, as the regulatory document in force in Ukraine does not contain reference nomograms for defects with the maximum content of ethane. For all 252 pieces of equipment, a comparative analysis of known diagnoses with diagnoses made using the Duval triangle was made. It has been determined that diagnoses made using different methods may differ significantly from each other as well as from real diagnoses. The ranges of gas percentage and gas ratio values obtained in the work, together with the defect nomograms, make it possible to use three of these criteria simultaneously to recognise the type of defect with a maximum ethane content, which in turn will improve the reliability of defect type recognition based on the analysis of gases dissolved in oil.
Highlights
Faults detection and recognition in high-voltage oil-filled equipment, especially the one that is in operation for a long time, allows both to provide a predetermined level of operational reliability of the equipment and to extend its residual life
Keywords – analysis of gases dissolved in oil, high-voltage equipment, defect recognition, ethane content, gas ratios, percentage of gases, Duval triangle, defect nomograms, graphic areas
In the nomograms method [10], the fault type is determined by the graphical image, which is based on the ratio of five gases (H2, CH4, C2H6, C2H4 and C2H2) to the gas with the maximum content
Summary
Faults detection and recognition in high-voltage oil-filled equipment, especially the one that is in operation for a long time, allows both to provide a predetermined level of operational reliability of the equipment and to extend its residual life. Dissolved gases analysis in oil (DGA) is the one of the most widely used diagnosis methods of oil-filled equipment Using this method to detect the fault, concentrations values and rises speed of such gases as hydrogen (H2), methane (CH4), ethane (C2H6), ethylene (C2H4), acetylene (C2H2), carbon monoxide (CO), carbon dioxide (CO2), oxygen (O2) and nitrogen (N2) are analysed. Both analytical and graphical methods are used to recognize the fault type. In the nomograms method [10], the fault type is determined by the graphical image, which is based on the ratio of five gases (H2, CH4, C2H6, C2H4 and C2H2) to the gas with the maximum content. The task of improving the existing methods of recognition is relevant and provides practical interest
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