Evaluation methods of frequency response analysis

Reliable work of transformers in the power system affects the efficiency of power supplies to consumers. Each transformer should be subjected to periodic diagnostic tests in order to detect damage or prevent the development of defects, which may lead to excluding unit from operation. One of the diagnostic methods of a transformer's active part is Frequency Response Analysis (FRA). Tests carried out using frequency response analysis give a wide range of information about the transformer's technical condition, but the interpretation of the results is very difficult and requires a lot of experience. To facilitate and automate the analysis of measurement results, various types of algorithms for assessment of the transformer's technical condition are developed. The paper presents a comparison of the most frequently used formulas in FRA method, based on data recorded on a test transformer in laboratory conditions using two measuring setups.