Experimental Research on Flashover Characteristics of Insulator with N2

Low-pressure N2 has been considered as a potential alternative to SF 6 in area of gas insulation for its abundant resources, low price, environmental friendliness and good insulation performance. In this paper, flashover characteristics of insulator with N2 was tested. 50% flashover voltage under lightning impulse was measured. It is found that, with the increase of the gas pressure, flashover voltage increases approximately linearly. And polarity effect become stronger with the pressure rises. The flashover voltage first decreases and then rises with the increase of the surface roughness of the insulator. The experimental result indicated that adsorption and blocking actions of rough surface are the main factors for this phenomenon. And the effect of roughness on the flashover voltage under the positive lightning impulse is greater than it under the negative lightning impulse.