Gas-solid interface is the weak link of GIS equipment insulation. Generally

the study of the flashover voltage of an insulator is carried out under a constant temperature field.However

in the actual working condition

there is a temperature gradient field on the surface of the insulator. In order to grasp the influence of temperature on the surface flashover voltage of an epoxy column under the power frequency

a set of 126 kV gas insulation system was built in the laboratory. An effective temperature gradient field could be formed by temperature control of the single-sided electrode plates. The flashover voltage changes of the epoxy column in the presence or absence of temperature gradient were investigated. The experimental results show that the average flashover voltage of the 80 ℃～20 ℃ temperature gradient is 11.74% lower than that of 20 ℃～20 ℃. The reasons of the drop in the flashover voltage of the insulating column caused by the temperature gradient are analyzed. It is proposed that the decrease of the local gas density is the main reason for the decrease of the flashover voltage. Thereby

the local temperature and gas density of the cavity are simulated based on computational fluid dynamics. Combined with the theoretical formula of SF6 flashover voltage

the flashover voltage values at different temperatures are calculated. The theoretical calculation results are consistent with the experimental results

which prove the accuracy of the theoretical analysis.