Evaluation of Surface Discharge of Polluted Insulator Based on Optical Emission Spectroscopy Measurements

The detection of polluted insulator discharge in humid environments is crucial for power system examination. In this article, we propose novel classification and evaluation methods by using the spectral and thermal properties of different discharge states from pollution insulators under stable alternating current voltage. The discharge temperature of polluted insulators was measured using spectral analysis techniques. Faults were classified into four states based on leakage current and temperature thresholds, which were also related to the spectral properties of polluted substances. The results show that the salt density component Na of polluted insulators was easily excited, resulting in a visible light spectrum, while the component of nonsoluble deposit density (NSDD) Fe was also easily excited followed by Ca, leading to an ultraviolet spectrum. Under the first two fault states of polluted insulators, the leakage currents were both less than 10 mA, and the arc temperatures were below 1400 K. The arc temperatures in the last two fault states increased significantly. The characteristic light intensity weights of different fault states were calculated using a triangle calculation method. The proportion of ultraviolet light intensity in the last two fault states decreased significantly, while the proportion of visible light intensity increased. The numerical relationships between the excitation strength of different pollution substances with temperature and leakage current analyzed in this study will help in comprehensively understanding the complex physical and chemical processes of pollution discharge.