Study on the decomposition by-products of SF6 under the overheat faults

Overheat fault is the main type of the insulating faults in gas-insulated apparatus, which can produce various decomposition by-products. This paper presents the relationship between the decomposition by-products and the severity of overheat fault, by carrying out a series of overheat experiments. The various experimental conditions, including overheat temperatures, heating durations, overheat metal materials and SF6 gas pressures, were simulated during the overheat experiments. Then the produced decomposition gases were detected by gas chromatograph-mass spectrometry. Based on the experimental results, it is concluded that the types and concentrations of the decomposition by-products are closely related to the severity degree of the overheat fault. Moreover, some significant features and characteristics of the decomposition by-products were concluded, which can be regarded as the indexes for identifying the overheat fault.