The phase transition & breakdown characteristics of SF6 in temperature decline

In this paper we use SF₆ gas(GSF₆) according to a surrounding temperature and are research to clarify the reason of GIS (Gas Insulated Switchgear) of the malfunction. The experiments of breakdown characteristics by temperature & pressure change of GSF₆, and SF₆ liquid (LSF₆) in model GIS are described. From the experimentpsilas results, the breakdown characteristics 3-Pattern are classified the vapor stage of SF₆ according to Paschenpsilas law, in which the gas & liquid coexisted stage of breakdown voltage (V_B) increases, resulting in much deviation and the V_B low stage as the interior of the chamber gets filled with a mixture of SF₆ that is not liquefacted and remaining air that can not be ventilated. The ability of LSF₆ insulation is higher than the high-pressurized SF₆ gas. Authors interpreted the 3-Patterns to the experimental and we clarify the reason of the GIS of the malfunction.