Research and Manufacture of Environmental-Friendly Load Break Switch Unit Base on Shunt Vacuum Interruption

In order to solve the problem of inconsistent operation between dry air insulation load break switch and SF6 load break switch, a new design scheme for dry air insulation load break switch is proposed in this paper. It arranges vacuum interrupter in parallel with the disconnect switch, and achieves vacuum disconnection and air isolation when the disconnect switch is opened. By analyzing the breaking principle and process of parallel vacuum interrupter, key factors and solutions affecting the breaking of parallel vacuum interrupter are proposed. On this basis, a new type of dry air insulated load break switch unit was developed, and insulation analysis was conducted on key parts. A method was proposed to reduce the air gap electric field strength by using cylindrical busbars and epoxy resin coating on the outer surface of the busbar; Proposed electric field simulation criteria and application examples for fracture insulation; A branch busbar and incoming and outgoing conduit connection structure suitable for miniaturization schemes was proposed. The prototype test results show that the new switchgear has excellent insulation and breaking performance, and has passed insulation and E3 level electrical life tests under a gauge pressure of 0.05MPa. This indicates that the proposed design scheme effectively solves the problem of inconsistent operation, and the performance of the new load break switch unit is reliable, providing a feasible solution for the technical upgrade of related equipment.