Abstract
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.
Highlights
SF6 gas has an excellent insulation and interruption performance, so that it has been extensively used as an insulating medium in high-voltage electric devices [1].in 1997, by Kyoto Protocol, SF6 gas was classified as a greenhouse gas because it has 23,900 times higherGWP than that of CO2 [2,3]
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
It was generally accepted that the control of moisture content in N2 is the critical factor to determine the performance of N2 but, there are only a few fundamental research works regarding the insulation characteristics affected by the ratio of moisture content in N2 [11,12,13,14]
Summary
SF6 gas has an excellent insulation and interruption performance, so that it has been extensively used as an insulating medium in high-voltage electric devices [1]. In order to decrease and substitute SF6 gas, many research works have been done, and one of the candidates which could replace SF6 gas in the medium voltage-level is the application of N2 as an insulating medium. In order to expand the usage of N2 for extra high voltage level, detailed knowledge and experimental works on the breakdown characteristics of N2 should be proceeded. It was generally accepted that the control of moisture content in N2 is the critical factor to determine the performance of N2 but, there are only a few fundamental research works regarding the insulation characteristics affected by the ratio of moisture content in N2 [11,12,13,14]. The author study the relation between moisture content in N2 and breakdown characteristics of N2. AC withstand tests and lightning impulse breakdown tests were performed using sphere to plane electrode N2 gap configurations
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