Identification of winding faults in power transformers by low voltage impulse test and neutral current method using wavelet transform approach

This paper presents the application of wavelets for the detection of minor faults in the HV winding of a power transformer by analyzing the impulse voltage and neutral current during the low voltage impulse test conducted on a HV winding of the power transformer. Effectiveness and efficiency of wavelet transforms in signal processing and differentiating incipient faults from electrical transients over other frequency response analysis (FRA) methods like transfer function (TF) method and Fourier transforms (FT) approach are discussed. The experimental results on the HV winding of a 61 MVA, 11 kV/230 kV power transformer are also presented.