Correlation analysis between SF6 decomposed components and charge magnitude of partial discharges initiated by free metal particles

To obtain the inner correlation feature between SF₆ decomposition characteristics caused by the partial discharge (PD) of the free metal particle insulation fault and charge magnitude, a series of experiments are conducted on the designed experimental system. Three methods, namely, gas chromatograph, chromatography-mass spectrometry and Fourier infrared spectroscopy, are used to quantitatively measure the decomposed components. Their content relation under different PD magnitudes is obtained and determined as SOF₂ > SiF₄ > SOF₄ > SO₂F₂ > SO₂ > S₂F₁₀ > CO₂ > CF₄, where the content of highly toxic S₂F₁₀ greatly exceeds its safe threshold. The study also discusses the correlation feature between each component of the free metal particle insulation fault and charge magnitude, which is found only when the charge magnitude reaches the point where it promotes the obvious formation of the components. Each component formation is found positively related to PD quantity. Based on a stability analysis of the produced components, five components are proposed to represent PD strength and the diagnosis table to recognise the severity of the metal particle insulation fault. This study attempts to lay a solid foundation for the conditional assessment of SF₆ insulated equipment.