Improvement of surface flashover characteristics about 45° insulator configuration in vacuum by a new organic insulation structure

In the present paper, a new three-layered 45° insulation structure is proposed and investigated to further improve the surface flashover performance of the 45° vacuum- insulator configuration. This structure was prepared by inserting organic composite between the electrode and insulator. With a numerical simulation method, the electric field distributions in this structure were analyzed. The result shows that by adjusting the permittivity of the inserted layer between the electrode and insulator, the electric field at the cathode and anode triple junction can be suppressed significantly in order to prevent the appearance of the surface flashover in vacuum. On the basis of these theoretical analyses, we conducted a series of vacuum flashover experiments about the new three-layered insulation structure of polyethylene composite-polyethylene-polyethylene composite. In our experimental result, it is indicated that when the permittivity of the inserted layer change in certain range, the surface flashover performance in vacuum of the 45° vacuum-insulator configuration can be improved, e.g. the highest first impulse flashover voltage reaches to 81 kV and increases by 32% compared with the polyethylene standard samples.