Insulation Degradation Products Analysis of PTFE Insulators in Gas Spark Gap Switch Caused by High Current and High Energy Arc Influences

Electrode erosion phenomenon caused by high current and high energy arc in gas spark gap switch was unavoidable. After a series of complicated chemical reactions, erosion products were formed and attached to the surfaces of insulators, resulting in reduced insulation performance and even switch failure. The purpose of this paper was to analyze solid erosion products and gas erosion products on the surface of polytetrafluoroethylene insulator in a high energy switch after 20000 discharges by X-ray photoelectron spectroscopy and gas chromatography. The results suggested the main chemical substances of anode and cathode insulators were similar, while the composition ratios of outside and inside insulators were different. Moreover, the contents of element fluorine in both anode and cathode insulators were heavily lost, especially on the outside surfaces. Perfluorocarbons gas (CF₄) can be detected in gas erosion product, although the content is low, yet due to its high electronegativity, the electric insulating property and working performance would be affected significantly.