Influence of External Parameters on Transformer FRA Signature and Statistical Indices

Frequency Response Analysis (FRA) is the common tool for transformer condition diagnosis. FRA allows to detect alterations in the transformer structure due to coverage of wide frequency range. Nevertheless, the frequency response is sensitive to external parameters. In this work, different connection schemes for external parameters are implemented and investigated. The theoretical justification is provided for each scenario. The measurement trend is visualized. The interpretation of frequency response signature requires expert knowledge. Statistical indices can be used for unbiased interpretation. Therefore, four statistical indices are employed to analyze the effect of external resistance, capacitance and inductance on the test objects