Study on the Various Pollution Performance of DC post Insulators under High Altitude Area

摘要

In the design of the insulation level of the DC transmission lines, the fact we should consider at first is capability for the pollution flashover endurance. In China, altitudes of two thirds regions are above 1000m. Lots of researches of the pollution flashover in high altitude show that, with the increase of the altitude, the pollution flashover voltage will regularly decrease, and its extent is large. In the paper, for three various types of the big-tons post insulators with large diameters, the artificial contamination tests are carried out in five pressure cases corresponding to the altitude from 0m to 4000m and in two typical kinds of ESDD. The results show the difference of the sheds leads to the difference of the insulators at different altitudes. And the performance of the contaminated equal-shed insulator with deep ribs is the best. The characteristic of the pollution flashover of big-small-small type insulator is better. The value exceed 3.54 of the ratio of the creepage distance to axial length is unacceptable in the DC post insulator design. Keeping a large shed spacing while increasing distance is important, and it is ridiculous to bring forward the bigger value in the DC post insulator design.