Investigations on the dielectric strength of carbon dioxide and carbon dioxide mixtures for the application in gas insulated switchgear

The ongoing debate on climate change and emission restrictions for greenhouse gases also forces the search for SF₆ alternatives (sulphur hexafluoride) in the energy transmission and distribution sector. Hence several challenges for the asset manufactures result as changing the insulating medium implies a redesign of the switchgear and its components. Here one effect in gas insulated switchgear is the reduction of the dielectric strength in case of contamination of the gas compartments with metal particles. In this paper the dielectric strength of the promising SF₆ substitute CO₂ (carbon dioxide) and its mixtures with non-toxic gases under particle contamination is investigated. For this purpose an arrangement designed according to a real gas insulated switchgear is used. From the comparison of the experimental investigations results a statement on the dielectric strength of CO₂ under non-uniform field conditions and on the enhancement of this dielectric strength by the admixture of additional gaseous components. These results can serve as a means for the dielectric design of a SF₆-free gas insulated switchgear.