Detection of Transformer Faults Using Frequency-Response Traces in the Low-Frequency Bandwidth

This paper describes a new procedure which facilitates the frequency-response curve interpretation in the low-frequency bandwidth. The procedure is able to estimate the magnetization inductance and winding capacitance, for each transformer phase by only using data from its frequency response. The described calculation procedure uses an R-L-C electrical equivalent circuit developed to simulate the impedance measured in the frequency-response test. The procedure takes into account the magnetic coupling among different phases and allows their analysis separately, enabling the identification of a possible failure. This paper describes the procedure to obtain the parameters and its application for interpreting the low-frequency results of frequency-response analysis measurement cases.