Surface discharge characteristics of GIS under different gas pressures

Since the Chinese government's announcement of the "dual carbon" targets in 2020, the development of environmentally friendly power equipment in the energy sector has become an inevitable trend. Although SF₆ gas is widely used in switch gear, its high cost, potential for liquefaction, and significant greenhouse effect present serious challenges. Consequently, the search for alternative gases to SF₆ has become a research hotspot. The SF₆/N₂ gas mixture shows promising application prospects due to the advantages of N₂, including non-toxicity, non-pollution, and low cost. This study systematically investigates the surface discharge characteristics of a 30% SF₆/N₂ mixed gas within a pressure range of 0.1–0.4 MPa. By establishing a defect-simulation experimental platform, we simultaneously collected pulsed current, ultra-high frequency (UHF), and optical signals to analyze the influence of gas pressure on the discharge inception voltage (PDIV), breakdown voltage (BDV), discharge amplitude, and repetition rate. This research provides a theoretical foundation and data support for the design of pressure safety windows in environmentally friendly GIS(gas-insulated switchgear), optimization of insulator structures, and operational pressure monitoring strategies, thereby contributing to the enhancement of insulation reliability in the green transition of power systems.