Identification of a Turn-to-Turn Short Circuit in a Transformer Winding

Power transformers with a high voltage of 10 kV and low voltage of 0.4 kV are the most widely used in the electric power industry. According to the annual statistics on power transformer failures, the largest number of power transformer accidents occurs due to a turn-to-turn short circuit, the consequences of which can either render the transformer inoperative and require major repairs, or require its complete replacement, which makes the task of monitoring and forecasting the condition and ability to operate transformer windings one of the most pressing. The “direct current decay test” is adopted as a tool, since it has a number of advantages compared to other tools and methods that require the availability of appropriate and complex-to-use equipment, as well as sufficiently qualified personnel to use such methods and tools. Based on the theory of conducting a direct current decay test, a hardware and software complex was assembled and test modes were determined. The parameters of the transformer equivalent circuit were obtained and identified. High accuracy of the selected method in determining the development of a turn-to-turn short circuit in the transformer windings was shown.