Prebreakdown phenomena in CO2/SF6 under very fast transients in non-uniform field

The Gas Insulated Line (GIL) is a reliable system for electrical energy transport. One of the important parts of the GIL is the insulating gas that can be stressed not only with lightning impulses, but also with very fast transients (VFT) if a busduct connector is being closed or opened. An alternative gaseous medium is needed in order to substitute completely or at least partially the expensive gas SF₆. This aspect is also important with respect to environmental considerations (greenhouse effect). As an alternative, CO₂/SF₆ mixtures are chosen. Prebreakdown phenomena were investigated for 1,33 MHz of VFT, positive polarity, non-uniform field distribution with admixtures of SF₆ to CO₂ of 10 %, 20 %, 30 %, 40 % and a pressure range from 0,1 to 0,8 MPa.