Abstract:

An optimization design is carried out to address the insulation problem of SF₆ interrupter for a 40.5 kV gas-insulated ring main unit. The finite element software is used to simulate the electric field of the moving and static contact structure in the 40.5 kV SF₆ arc-extinguishing chamber. The simulation results show that the electric field intensity is concentrated at the arc of the end of the moving contact and the arc of the outer end of the static arc contact, and the electric field distribution between the moving and static contacts is extremely unbalanced.Electric field simulations of the arc-extinguishing chamber are conducted with and without a voltage-equalizing structure at different opening distances, and with the voltage-equalizing structure at different positions. The influence of these conditions on the electric field distribution of the arc-extinguishing chamber is analyzed, and the structural optimization of the arc-extinguishing chamber is completed. After optimization,the maximum electric field intensity at the sampling boundary of the moving contact end decreases by up to 30.45%. The rationality of the structural optimization is verified through insulation tests.The test results show that adding a voltage-equalizing structure and arranging it at an appropriate position can meet the interrupter insulation requirements of the 40.5 kV voltage level without increasing the opening distance.

Key words: SF₆ interrupter, electric field distribution, optimization, voltage-equalizing structure