Study on the influence mechanism of trace H2O on SF6 thermal decomposition characteristic components

To explore the influence mechanism of trace H
₂
O on SF6 decomposition characteristics under partial thermal fault and establish the foundation of using SF6 thermal decomposition principle to diagnose the thermal fault of SF
₆
electrical equipment, a series of artificial thermal fault decomposition experiments with different H
₂
O concentrations were conducted on the designed SF6 thermal decomposition experimental system. A trace water injector was used to control the content of trace H2O accurately and gas chromatograph, chromatography-mass spectrometry as well as Fourier transform infrared spectroscopy were used to measure decomposed components. Finally, the thermal decomposition characteristic under 340 ° was achieved. The analysis results indicate no matter how much H
₂
O content is, SF
₆
can decomposes into many kinds of decomposition characteristics, such as CO
₂
, SOF
₂
, SO
₂
, SOF
₄
, SO
₂
F
₂
, H
₂
S, HF. The concentrations of all these decomposition characteristics increase with the time extended, but change differently with the increase of H
₂
O content, because H
₂
O plays different role in the formation process of each decomposition characteristic components. The variation of H
₂
O content not only affects the production of the decomposition characteristic components, but also makes SO
₂
and HF gradually evolved into the main characteristic components of SF
₆
thermal decomposition. In addition, the higher the H
₂
O content is, the stronger the promoting effect on SO
₂
and HF is.