Wavelet transform of the leakage current to monitoring the insulator surface under non-uniform desert pollution

This work is devoted to study the insulator behavior under non-uniform desert pollution. Our investigation is focused on monitoring of both position and width of polluted layer, and the electric discharge activity on the insulator surface, by the analysis of the leakage current waveform. The wavelet transform technique is used to decompose the leakage current signal at several frequency bands (details). The standard deviation (STD) is calculated for each detail. It is employed to find the details the most significant to get information on the surface state of the insulator. The STD of the high frequency details shows a good correlation with the electric discharges activity.