Flashover process and leakage current characteristics of insulator model under desert pollution

Abstract

The present work aims to investigate the effect of the desert pollution on an insulating plan model behavior. We focused on the effect of the sand quantity in term of non-soluble deposit density (NSDD) and the width of polluted layer on the flashover process. For this purpose, we use the magnitude and frequency analysis of the leakage current (LC) as indicator of the insulator behavior with regard to both of the pollution level and the electrical discharges activity on the insulator surface, particularly for this kind of Algerian desert pollution, not studied so far. Indeed, most of the research works in this domain were rather interested in marine and industrial types of pollution. Careful analysis of recorded videos, filmed by digital camera, allows us to examine visually the development and the evolution of arcs, until total flashover, according to the applied voltage. The odd harmonics and the fundamental component have been investigated to characterize the insulator surface state. Furthermore, a wavelet transform technique has been adopted to study the frequency-time characteristics and to calculate the standard deviation (STD) of different harmonic components of LC. In the uniform case, the STD of low frequency details, D9, D10 and D11, respectively the ninth, the tenth and the eleventh details extracted from LC, represent a good indicator of the pollution level. In the non-uniform case of pollution, the STD of detail D11, and the STD of high_frequency details show a good correlation with polluted layer width and the activity of the electric discharges.