Analytical method of identifying the type of defect of oil-filled equipment according to the results of analysis of gases dissolved in oil

Abstract

Purpose. Development of a method for recognizing the type of defect of oil-filled equipment based on the results of the analysis of gases dissolved in oil. Methodology. Analysis of gas ratio values in oil-filled equipment with various types of defects, synthesis of a method for recognizing the type of defects.        Findings. A description of the analytical method for recognising the type of defects in oil-filled equipment based on the results of the dissolved gases analysis is given. To recognise the type of defect, the values of three ratios are used: CH4/H2, C2H4/C2H6, and C2H2/C2H4. Using these ratios, 40 different types of defects and their combinations can be recognised. These defects  correspond to 25 different ranges of gas ratios obtained as a result of gas content studies for 3715 units of oil-filled equipment The type of defect is determined by analysing the obtained gas ratio values and classifying them according to the ranges of gas ratios for each fault. In the case when the obtained ratio values correspond to several types of faults in the same range, characteristic nomograms of defects and recommendations according to the key gas method are used to clarify the type of fault. A comparative analysis of the reliability of fault type recognition using the developed method and some well-known methods for interpreting the results of dissolved in oil gases analysis was performed. Originality.  An analytical method for recognising the type of faults in oil-filled equipment of electrical networks based on the results of the dissolved gases analysis is proposed. This method differs from the existing ones in that, when using three known gas ratios, it allows recognising a larger number of defects of different types (40), including those for which the known methods do not allow establishing a diagnosis. This result is ensured by the use of 25 ranges of gas ratios obtained from the results of gas content studies for 3715 units of oil-filled equipment. Practical value. The use of the developed method for recognising the type of faults in oil-filled equipment of electrical networks allows increasing the reliability of defect recognition based on the results of dissolved gases analysis. This, in turn, makes it possible to increase the operational reliability of electric power equipment and extend the service life of this equipment.