Hydrophobicity evaluation of polymer insulator based on surface discharge characteristics

The hydrophobicity evaluation for polymer insulators continues to be a prominent characteristic. For the purpose of evaluating the hydrophobicity of polymer insulator, a VHF antenna was utilized to receive high frequency electromagnetic signals, which were induced during the surface discharge on the sample surface. The wavelet theory was applied to analyze the electromagnetic signals that were processed by signal-processing system. The obtained 3-D images of surface discharge, which contains the frequency, the time and the amplitude, can figure out the hydrophobicity of polymer insulator with different ageing time efficiently. Based on 3-D images, 2-D contour line spectra were set up for investigating the complexity of discharge. The fractal dimensions of 2-D spectra and lacunarity were computed to assess the severity of surface discharge quantificationally. It is found that the series of methods using PD-induced electromagnetic wave can efficiently recognize the characteristics the discharge on the surface of insulators, which can be utilized to evaluate the hydrophobicity of polymer insulators.