Influence of moisture on the insulation characteristics of nitrogen

AbstractUsing N2 or dry air to replace SF6 as high-voltage switchgear insulation media is a hot topic in the development of environmental friendly switching equipment. In order to make switchgear equipment with N2 has a much compact structure in space, engineers should fully understand the insulation characteristics of N2. In this paper, the breakdown characteristics of N2 at power frequency and with lightning pulse in the sphere-plate electrodes has been investigated and the effect of humidity on breakdown voltage analyzed. From the test results, it was revealed that the AC and impulse breakdown voltages of N2 were not seriously affected by different moisture content ranging from 0 to 1000 μL/L in N2. And the breakdown voltage was decreased 8~15% with increasing moisture contents from 1500 to 2000 μL/L.