Experimental study on the cooling performances of gas mixtures with fluorocarbon used in gas insulated transmission line

SF₆ gas has been widely used currently in electric power systems, such as GIS, GIL and GIT. However, because of the high global warming potential (GWP), SF₆ was listed as one of the six restricted gases in "Kyoto Protocol" in 1997. Some fluorocarbon gases with low environmental effect and high dielectric performance are studied as the substitution candidates for SF₆. This paper presents the cooling performances of some gas mixtures with fluorocarbon at different pressures. Heat transfer coefficients of gas mixtures are calculated through measuring the surface temperature of metal pipe and the temperature of conductor under a certain current. Meanwhile, the heat transfer coefficients of gas mixtures with fluorocarbon are used to calculate the temperature of GIL in an actual case and compare the calculating result with the measurement.