Comparison of the breakdown strength of N2, CO2 and SF6 using the extended up-and-down method

Conference paper (2006)

Authors

A Girodet External organisation
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Published Date

2006

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Undefined/Unknown

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Abstract

Nowadays in Gas Insulated Systems (GIS), SF6 is often used as insulating medium. Due to the fact that SF6 is a greenhouse gas with a very high global warming potential (GWP), alternatives have been searched for over the last years. In particular, SF6/N2 gas mixtures have been extensively investigated for the use in Gas Insulated Lines (GIL) and is being used in several applications. However, in these cases SF6 is still part of the insulating gas and the search for alternatives continues. In this respect, nitrogen (N2) and carbon dioxide (CO2) are interesting alternatives. In this paper, investigations into the breakdown strength of these gases will be described. Both gases were investigated in a plane-plane configuration, with a distance of 10 mm between the planes. The gas pressure was varied in steps of 2 bar, from 7 to 11 bar. To get to the 5% breakdown value under positive and negative lightning as well as switching impulses, the extended up-and-down method was applied and will be discussed in the paper. The results are compared to 3 and 4 bar SF6 to get the required data that can be used for design purposes.