Analysis of the Condition Transformer after a Fault using the SFRA and FDS method

The paper deals with the analysis of the condition of the power oil transformer after a fault when connected to the network using the methods Sweep Frequency Response Analysis (SFRA) and Frequency Dielectric Spectroscopy (FDS). With the SFRA method, it is possible to find out whether it is a fault on the transformer winding, and then with the FDS method, it is possible to find out the cause of the winding fault due to longer-term increased humidity of the transformer paper (above 3 %). After the mentioned measurements, the effect of increased humidity in the paper insulation on the failure of the primary and secondary windings after switching on the transformer was determined, which proved the correctness of the methodical experimental diagnostic procedure.