Study on Oxygen/Nitrogen Gas Mixtures for the Surface Insulation Performance in Gas Insulated Switchgear

Abstract

This paper presents a comparative study on SF6 alternative candidate gases for the surface insulation performance of eco-friendly Gas Insulated Switchers (GIS) and Solid Insulated Switchers (SIS). The candidate gases including N-2/O-2 mixture gas, dry air, and compressed air were proposed based on AC surface flashover experiment. These gases were compared and examined based on their surface insulation performance, pressure and gap dependence, surface insulation reliability in different temperatures, economic feasibility and easiness of manufacture. The comparison results verified that dry air had excellent properties on the comparison criteria and was the most suitable eco gas among the candidate gases for eco-friendly GIS and SIS. In addition to the comparative study on the candidate gases, their surface flashover characteristics were described in detail based on the effect of moisture contained in the candidate gases on flashover voltage and the correlation among electric field intensity, collision-ionization coefficient, electron attachment coefficient, and gap length.