Influence of breaking current and arc energy on SF₆ decomposition products under arcing conditions in high voltage switchgear

SF₆ is widely used in high voltage switchgear due to its excellent insulation and arc extinguishing performance. It is an important method for fault diagnosis and electrical life assessment of SF₆ switchgear to detect and analyze gas decomposition products. Breaking current and arc energy have a significant effect on the species and concentrations of SF₆ decomposition products so relevant studies were carried out. A test platform for SF₆ decomposition products of switchgear under arc discharge was built and a series of SF₆ decomposition tests with breaking current of 0.8kA, 5kA, and 31.5kA were carried out on a 40.5kV SF₆ circuit breaker. The decomposition components were detected by a gas chromatography. It has been found that the larger breaking current is, the more species of SF₆ decomposition products are. When breaking current remains constant, the higher accumulated arc energy is, the higher concentrations of SF₆ decomposition products are. After 31.5kA breaking test, the order of the generation amount of SF₆ decomposition products is SOF₂>CF₄>>SO₂>CO₂>>C₂F₆>SO₂F₂. The influence of breaking current and arc energy on SF₆ decomposition products is clarified, which is important for the fault diagnosis and electrical life assessment of high-voltage SF₆ switchgear based on decomposition products analysis.