The Formation Mechanism and Reaction Pathways of SOF2, SO2F2, SO2 and HF under Local Overheating Fault in SF6 Insulated Power Equipment

SOF
₂
, SO
₂
F
₂
, SO
₂
and HF are common decomposition products of local overheating fault in SF
₆
insulated power equipment, but the formation mechanism and reaction pathways of these are still not clear. It has brought great difficulties to detect local overheating fault based on decomposed components analysis (DCA) method. In this paper, the formation mechanism and reaction pathways of SOF
₂
, SO
₂
F
₂
, SO
₂
and HF under local overheating fault are studied by quantum chemistry theory. The quantum chemistry calculations were carried out by Gaussian software. The structural optimizations, vibrational frequency calculations and zero-point energy calculations of the reactants, products, intermediates and transition states were carried out by DFT-B3LYP/6-311++G(d,p). The single point energies are obtained by CCSD(T)/aug-cc-PVTZ. Based on the above information, the formation mechanism and reaction pathways of SOF
₂
, SO
₂
F
₂
, SO
₂
and HF under local overheating fault are accurately analyzed, and the influence of trace H
₂
O and O
₂
on SOF
₂
, SO
₂
F
₂
, SO
₂
and HF are reasonably explained. The research results can provide theoretical guidance for the condition monitoring and fault diagnosis of SF
₆
insulated power equipment.