The fast detection of classical contaminants and their distribution on high-voltage transmission line insulators is essential for ensuring the safe operation of the power grid. The analysis of existing insulator contamination has traditionally relied on taking samples during a power cut, taking the samples back to the lab and then testing them with elemental analysis equipment, especially for sugars, bird droppings, and heavy metal particulates, which cannot be analysed by the equivalent salt deposit density (ESDD) or non-soluble deposit density (NSDD) methods. In this study, a novel method called laser-induced breakdown spectroscopy (LIBS) offering the advantages of no sample preparation, being nearly nondestructive and having a fast speed was applied for the analysis of metal contamination. Several LIBS parameters (laser energy and delay time) were optimized to obtain better resolution of the spectral data. The limit of detection (LOD) of the observed elements was obtained using a calibration curve. Compared to calibration curves, multivariate analysis methods including principal component analysis (PCA), k-means and partial least squares regression (PLSR) showed their superiority in analyzing metal contamination in insulators. Then, the elemental distribution of natural pollution was predicted using LIBS to fully capture information about the bulk elements (Na, Ni, Cu, Mn, Ca, etc.) of entire areas with PLSR. The results showed that LIBS could be a promising method for accurate direct online quantification of metal contamination in insulators.

The C 5 F 10 O gas mixture has great application prospects as a potential SF 6 substitute gas. It is necessary to study the compatibility of the C 5 F 10 O gas mixture with copper and aluminum used in the electrical insulation equipment before the engineering application. In this paper, we studied the interaction of C 5 F 10 O/CO 2 with copper and aluminum at various temperatures experimentally. The results show that the compatibility of copper with the C 5 F 10 O/CO 2 gas mixture is obviously inferior to that of aluminum. Considering the temperature rise effect during normal operation of the equipment, it is found that the interaction between C 5 F 10 O/CO 2 gas mixture and copper at 80 • C will lead to slight corrosion on the copper surface. The corrosion degree increased at the higher temperature. SEM shows that massive cubic grains will be formed on the copper surface at 150 • C-250 • C. No corrosion was observed on the aluminum surface at 150 • C∼250 • C, which is related to the protective effect of the oxide layer Al 2 O 3 on the aluminum. The relevant results reveal the compatibility of the C 5 F 10 O/CO 2 gas mixture with metal materials and provide an important reference for the engineering application of the C 5 F 10 O gas mixture. INDEX TERMS C 5 F 10 O/CO 2 , copper, aluminum, compatibility, SF 6 substitute gas.

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C₅F₁₀O-CO₂ mixtures are possible alternatives to SF₆ - which has a high global warming potential - as the interruption medium in gas circuit breakers. This paper experimentally studies the arcing characteristics of C₅F₁₀O-CO₂ mixture, with an experimental model with viewing windows, and measures the arc voltage, current and emission spectrum. The arc evolution process is captured with a high speed camera through an inspection window. The two-dimensional distribution of arc is obtained and analyzed by the inverse transformation of Abel. The results show that, the C₅F₁₀O-CO₂ mixture arc is more volatile than SF₆ gas, and adding C₅F₁₀O into CO₂ improves the stability of the arc, and significantly reduces the arc temperature.