Multiscale nonlinear dynamic characteristics of leakage current for monitoring polymer insulators in salt-fog conditions

Based on the present investigation of leakage current for evaluating and monitoring outdoor insulators, the multiscale nonlinear technique is proposed to analyze the dynamic characteristics of leakage current through the artificial contamination experiments. Contamination tests were conducted in a laboratory by employing heavy salt fog without the deposition of non-soluble contamination. Based on the corresponding relationship between the leakage current and the behavior in heavy-fog conditions, the temporal series of leakage current are extended to two phase space by using a phase-space reconstructed method. In accordance with the dynamic behaviors on the insulator surface, the multiscale entropy of leakage current is obtained to investigate the underlying nonlinear characteristics in relation with the variation of contamination degree, ambient temperature and relative humidity. Associated with the quantitative analysis of mutiscale technique, the results can be helpful to improve the accuracy of insulator monitoring for reducing the accidents.