PD Inception and Breakdown Voltage Characteristics in PFC and SF₆ gas mixtures

Abstract

Since SF₆ gas has excellent properties like a high dielectric strength, and is chemically inert, nontoxic, and so on, it has been widely used as an insulation material for gas insulated switchgears (GIS) and insulated transmission lines (GIL)^(1,2). However, SF₆ gas is a potent green house gas and its global warming potential (GWP) is estimated as a very large at 23,900. Accordingly, SF₆ gas was designated as one of the emission gases to regulate at COP3. It is necessary to decrease the use of SF₆ gas, design techniques to retrieve SF₆ gas and reduce its emission into the atmosphere and develop alternative gases having much lower GWP values. SF₆/N₂ gas mixtures have been proposed as a promising alternative to SF₆. To date, the authors have shown that adding a small amount of CO₂ to an SF₆/N₂ gas mixture results in a prominent increase in the insulation performance under both uniform and nonuniform electric fields^(2,3).