Improved Methods for Diagnosing an Autotransformer with a Defect in a High-Voltage Bushing

The article is devoted to the improvement of methods for diagnosing an oil-filled power autotransformer of the ATDCTN-200000/330/110/10 type with an internal defect in an oil-filled high-voltage bushing of the GMTPA-45-330/1000U1 type. Purpose: improving the reliability of the results of diagnosing an oil-filled power autotransformer with an internal defect in its oil-filled high-voltage bushing by improving the methods of diagnosing, taking into account the results of electrical tests of this equipment and analyzing samples of mineral oil from them. Studies of the electrical characteristics of an oil-filled power autotransformer and an oil-filled high-voltage bushing and mineral oils’ physicochemical, thermophysical, and electrical properties have been conducted. Numerical values of indicators of electrical characteristics for an oil-filled power autotransformer and its high-voltage input are determined, and for mineral transformer oils, numerical values of indicators are determined - breakdown voltage; flash point of oil vapor in an open crucible; acid number; water-soluble acids; dielectric loss tangent; density; moisture contents; the content of dissolved diagnostic gases, additives “Ionol”, furan compounds. The analysis of the studies makes it possible to increase the reliability of the results of technical diagnostics of a power electric oil autotransformer with an internal defect in a high-voltage oil-filled bushing.