Situation and analysis of sulfur hexafluoride (SF6) byproducts of gas insulated switchgear (220kV and above) in Guangdong Province and latent fault judgment of the electric equipment

In the occurrence of arcs discharges, spark discharges and corona discharges, sulfur hexafluoride (SF₆) would be decomposed to complicated byproducts such as sulfur dioxide (SO₂), carbon tetrafluoride (CF₄), etc. Analyzing the concentrations of these byproducts, which can be determined when the electric equipment is electriferous, is an effective method to judge the internal condition of GIS. The fault of GIS and the position of the fault can be known by SF₆ byproducts analysis. There are many cases about how to judge the electric equipment faults by analyzing SF6 byproducts, but with little experience about how to judge the latent faults. The article concluded the concentrations of SF₆ byproducts in 74 220 kV and 500 kV GIS transformer substation (3770 gas chambers in total) in Guangdong province. The concentrations of carbon dioxide (CO₂), CF_4, thionyl sulfide (SOF₂), sulfuryl fluoride (SO₂F₂), disulfuryl decafluoride (S₂OF₁₀), SO₂ and sulfureted hydrogen (H₂S) were in partial normal distribution. The concentrations of CO₂, CF₄, SOF₂, SO₂F₂, S₂OF₁₀ were all below 0.1% (v/v); the concentrations of SO₂ were below 3muL/L; the concentrations of H₂S were below 1muL/L. The SF₆ byproducts concentrations in 500 kV GIS were lower than those in 220 kV GIS. The SF6 byproducts concentrations were higher in GIS that have been operating longer.