A New Method for Measuring Performance of Insulator Surface Based on Extended Fourier Transform of Leakage Current

Abstract

Abstract. This paper reports the investigation of measuring performance of insulator surface based on leakage current (LC) signal analysis. The LC waveforms were measured under various artificial environmental conditions such as humidity, pollution, temperatur and electric stress. The LC waveform components such as magnitude and harmonic components were observed. The harmonic components of LC are extracted with eXtended Fourier Transform (XFT). In this paper harmonic components were divided by two classifications, low frequency harmonic components, i.e. harmonic frequency less than 21st harmonic and high frequency harmonic components, i.e. harmonic frequency greater than 21st harmonic. The clean insulator observation shows that LC waveform has small magnitude and low frequency harmonic components. The polluted insulator under various environmental conditions has big manitude of LC and high frequency harmonic component. In this paper, it is defined an index of performance using SNR (Signal to Noise Rasio) as logarithmic ratio of low frequency harmonic components to high frequency harmonic components. The experiment results show that the index has a consistence measure for insulator surface performance