Breakdown Effects of Dissolved SF₆ Gas on Uniform Field in Perfluorocarbon Liquid

Abstract

Non-flammable large-capacity and liquid-cooled transformers have been developed. The transformers are used perfluorocarbon (PFC) liquid and SF6 gas for the cooling and insulating systems.
This paper describes the uniform breakdown characteristics in PFC liquid with the solubility of SF6 under AC and lightning impulse voltages. The breakdown strengths of the PFC liquid with dissolved SF6 have been effected the PFC vapor and SF6 gas pressure above the liquid. Further, the breakdown voltage decreases extremely in existence of gas bubbles in the liquid under AC.