Modelling the Influence of Insulator Inclination on Natural Self-Cleaning Performances

Outdoor composite insulators inclined at different angles, not limited to vertical or horizontal orientations, are significantly expanded and installed on overhead line towers. However, the evidence about how this affects their long-term performance is lacking and becomes a research gap. This paper describes work carried out in an attempt to demonstrate the effects of employing unconventional angles for insulators on their inherent self-cleaning capabilities when operated at varying inclinations. Insulators will suffer from pollution and contamination accreting on their surfaces, which can lead to temporary increases in conductivity when exposed to rainfall, potentially triggering electrical discharges. However, the rainfall generally also acts to clean the insulator surfaces. When wind and rain are combined creating a complex impact, some parts of an insulator are likely to get cleaner over time while other parts may continue to be polluted. To investigate those effects on the performances, the modelling was developed in MATLAB. The locations where moisture is expected to sit on the insulator surface were examined for a range of rain droplets, wind speeds and wind velocities (with real weather data being used). This makes it possible to create a colour map showing the areas of an insulator most often exposed to rainfall and therefore most likely to remain clean. In general, the results illustrate that the vertical insulator is less likely to be cleaned by rainfall, compared to other arrangement. For the inclination, there is more opportunity of these being cleaned than the vertical insulator. However, the insulator direction in combination with the prevailing wind direction is a key important factor in determining the levels of cleaning. An insulator that is angled into the prevailing wind will be cleaner when compared to insulators inclined in other directions.