AC breakdown characteristics of air insulated point-plane gaps with polycarbonate barriers

The breakdown voltage of a gas insulated gap under a non-uniform electric field can be increased by inserting a barrier due to extending the arc development path, which is of great potential to be applied to environmentally friendly gas insulation system. In this paper, the AC breakdown voltages of different air insulated point-plane gaps with polycarbonate barriers of different sizes were experimentally investigated. Every case was tested for 20 times. The breakdown voltages with the point radius of 1-5 mm and gap distance of 2-5 cm were obtained. In addition, the effects of barrier size under different conditions were compared. The electric field distributions in the inter-electrode gap were analyzed by a finite element method. It was found that the AC breakdown voltages of the considered hybrid gas-solid insulation system have a close relationship with the non-uniform coefficient of the electric field.