Flashover Improvement and Field Control of Insulator with Surface σ-FGM for DC GIL

Flashover failure of the epoxy insulator in DC gaseous insulated pipeline (GIL) is a major problem limiting the development of the power transmission system. The electric field distortion is the main reason for flashover faults. Effective electric field regulation and flashover enhancement methods are in urgent need. In this paper, the surface conductivity graded material ($\sigma$ -SFGM) was applied in cone-type insulator by surface fluorination technology, which was conducted in a sealed reactor connected with the gas pipelines and the temperature test probe. A fluorinated layer with a different thickness was formed at different portions of the insulator surface. The flashover tests were conducted under DC condition. The SFGM presents an ability of electric field regulation. Besides, the flashover voltage of the insulator with SFGM is higher than that of the original one by over 33 % whether there is a preload or not, indicating highly increased property by the design of SFGM. Compared with the traditional field control methods, the insulator proposed in this paper possesses a wide application prospect and provide a reference for the DC GIL.