A study on the selection of outdoor insulators used in high altitude areas

In recent years, large-scale development of China´s western region has been vigorously promoted. As part of the development, several very high voltage transmission lines have been or are planning to be built in China´s western region with a high altitude. The contamination flashover of insulators depends not only on the severity and type of contamination, but also on the altitude at which these insulators are situated. Reduced pressure or air density combined with light contamination at high altitudes decrease the flashover voltage. This paper analyzes the affects of low air pressure on the insulation characters of the transmission lines theoretically and experimentally, and a suggestion is given for the selection of outdoor insulator that will be used in the 110 kV AC power transmission line along Qinghai-Tibet railway.