Experimental Study and Modeling of the Effect of ESDD/NSDD on AC Flashover of SiR Outdoor Insulators

Abstract

Pollution flashover occurs when soluble and nonsoluble materials cover the surface of an insulator, and this may ultimately cause a reduction in its performance. In this paper, the common type of sodium chloride (NaCl) was used as a soluble pollutant (ESDD) and kaolin as a nonsoluble pollutant (NSDD). Samples of silicone rubber (SiR) insulators were selected for this study and fabricated at the Advanced High Voltage Engineering Research Centre (AHIVEC) at Cardiff University. The samples were preconditioned and polluted according to standard specifications. Additionally, the AC voltage ramp technique was used to achieve flashover (FOV) voltage with different pollution levels. The aim of this work was to investigate the effect of nonsoluble materials on flashover characteristics to understand their interaction with dry-band arcs by using FOV electrical equations and experimental data. The test results show that the FOV voltage of the silicone rubber insulator substantially decreased with the increase in both ESDD and NSDD values. It was also identified from these results that the dry-band arcs were considerably influenced by both ESDD and NSDD levels. This impact can be quantified by determining the variation of discharge parameters (N, n). Based on the FOV equations and experimental data, a mathematical model was suggested, taking into account the effect of both ESDD and NSDD.

Experimental Investigation of Parameters Influencing the Formation of Dry Bands and Related Electric Field

“…Dry band formation is a major parameter influencing the development of flashover phenomena on high-voltage polluted surfaces [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16], as well as the distribution of the potential and electric field along these surfaces [17][18][19][20][21][22][23][24][25][26]. Flashover of polluted insulators is a complex phenomenon induced by partial arcs initially established along dry bands and propagating along the insulator surface, owing to local heating of the pollution layer induced by a local increase in leakage current density [1][2][3].…”

“…Experimental investigations have identified several parameters significantly influencing polluted insulator flashover, including the pollution level, characterized by the equivalent salt deposit density (ESDD) and the non-soluble deposit density (NSDD) [7,10,13,15,21,22]; ambient temperature and humidity [6,11]; and the position, number, and width of the dry bands [5,9,11]. In general, the flashover voltage of a polluted insulator increases with increasing ESDD/NSDD, ambient temperature, and humidity.…”

“…Another aspect of dry band formation at the surface of a polluted insulator is the influence on the potential and E-field distribution along the polluted surface. Many studies have examined this topic, but most have used numerical approaches on real insulators or rectangular plates [17][18][19][20][21][22][23][24][25][26]. The results have generally suggested that the presence of dry bands leads to redistribution of the potential along the polluted surface, where voltage drops can be observed along the different dry bands.…”

“…The results have generally suggested that the presence of dry bands leads to redistribution of the potential along the polluted surface, where voltage drops can be observed along the different dry bands. These voltage drops are responsible for the rapid increase in the E-field value along different dry bands [17][18][19][20][21][22][23][24][25][26].…”

Hydrophobicity grade discrimination of high voltage composite insulators based on water trace image processing

“…Grade discrimination of pollution flashes and HC has appeared in the application of composite insulators. With the development of science and technology, research on composite insulators has gradually changed from qualitative to quantitative to prevent the occurrence of pollution flash accidents [9][10][11]. Through long-term observations, it was found that the distribution of water beads and water tracks on the insulator surface has different characteristics under different hydrophobic grades of insulators.…”