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.