This paper explores the decomposition characteristics of a new type of environmentally friendly insulating gas C₆F₁₂O and N₂ mixed gas under AC voltage. The breakdown behavior of 3% C₆F₁₂O and N₂ mixed gas in quasi-uniform field was investigated through a breakdown experiment. The self-recovery of the mixed gas was analyzed by 100 breakdown experiments. The decomposition products of C₆F₁₂O and N₂ under breakdown voltage were determined by gas chromatography–mass spectrometer (GC-MS). Finally, the decomposition process of the products was calculated by density functional theory, and the ionization energy, affinity, and molecular orbital gap of the decomposition products were also calculated. The properties of the decomposition products were analyzed from the aspects of insulation and environmental protection. The experimental results show that the 3% C₆F₁₂O and N₂ mixed gas did not show a downward trend over 100 breakdown tests under a 0.10 MPa breakdown voltage. The decomposition products after breakdown were CF₄, C₂F₆, C₃F₆, C₃F₈, C₄F₁₀, and C₅F₁₂. The ionization energies of several decomposition products are more than 10 eV. The Global Warming Potential (GWP) values of the main products are lower than SF₆. C₂F₆, C₃F₈, and C₄F₁₀ have better insulation properties.

TM–N₄ embedded b-PC can be a promising bifunctional catalyst for the ORR/OER.

Pompon-like WS ₂ nanostructure-based gas sensor was fabricated, and the sensing performance with micro mechanism to SF ₆ decompositions were discussed. At optimal working temperature, the sensor experiences resistance increasing for all four SF ₆ decompositions (SO ₂ , SOF ₂ , SO ₂ F ₂ , and H ₂ S). At low concentration (0~50 ppm), the sensor shows high linearity (R ² >0.99), and the rank of the sensitivity is: H ₂ S>SO ₂ >SO ₂ F ₂ >SOF ₂ . Furthermore, the first-principles results indicate that the different sensitivity is derived from the chemical interactions and electron transfer between the adsorbed molecule and the edge structures of WS ₂ . This work gives experimental and theoretical support of TMDCs based gas sensor to detect SF ₆ decompositions, and provides insights to design high-performance TMDCs based gas sensor from theoretical aspect.

In this paper we investigated SF ₆ decomposition behaviour of typical insulation defects in gas‐solid insulated converter transformer valve‐side bushing under partial discharge (PD). Additionally, we compared the results with that of gas insulated switchgear (GIS). The results indicated that SF ₆ decomposition behaviour varies with the insulation defects type. For metal protrusion defects, the proportion ranking of CO ₂ and SO ₂ can be related to whether the needle tip is wrapped with epoxy resin‐impregnated paper (ERIP). The proportion of carbon‐containing products is much higher under contamination defect than under other defects. Moreover, the proportion of carbon‐containing components is higher under flashover condition than under PD condition and is accompanied by the appearance of H ₂ S and CS ₂ . However, the yield of SO ₂ F ₂ is always low. Compared to negative DC voltages, positive DC voltages have a higher proportion of carbon‐containing components, mainly in the form of more CO ₂ and less SOF ₂ . Compared to the PD decomposition behaviour of typical insulation defects in GIS, when PD involves ERIP, the proportion of carbon‐containing products, especially CO ₂ , is significant higher, while the proportion of sulphur containing products, especially SO ₂ F ₂ , is lower.

C ₆ F ₁₂ O has been introduced as a potential substitute to the most greenhouse gas SF ₆ used in the medium-voltage (MV) electrical equipment due to its great insulation and environmental performance. While there are few studies on the compatibility between C ₆ F ₁₂ O and metal materials used in the equipment which needs to be investigated and understood to avoid the negative impact on the material or gas. In this paper, we carried out experimental and theoretical studies on the interaction between C ₆ F ₁₂ O and copper, silver, aluminum. We found that the interaction between C ₆ F ₁₂ O and copper, aluminum introduces fluorine to the metal surface and generates some metal oxide. There was no significant change in the element composition and surface chemical states of silver after interacting with C ₆ F ₁₂ O. The interaction mechanism between C ₆ F ₁₂ O and copper, aluminum is attributed to the chemical adsorption and the interaction between C ₆ F ₁₂ O and silver belongs to the physical adsorption. The compatibility between C ₆ F ₁₂ O and silver is greater than that of copper, aluminum. Relevant results provide a reference for the design and manufacture of equipment using C ₆ F ₁₂ O gas mixture as the insulating medium.

The flow of contaminated transformer oil has a significant influence on the formation of bridges composed of impurity particles and in turn affects its breakdown progress, but the relevant phenomenon may be not well interpreted by the classical suspended solid particle mechanism. In this paper, an oil circulation device was built, and the development of cellulosic bridges in slightly non-uniform electric field at different flow velocities was recorded by a high-speed camera. The results show that, when DC voltage was applied, the time required to form cellulosic bridges across the oil gap (named complete bridge) firstly decreased and then increased with the rise of flow velocity. It indicates that the low-speed oil flow could accelerate the formation of complete bridge in the DC field while the high-speed oil flow delays or prevents it. When AC voltage was applied, the length of the longest partial bridge (it did not bridge two electrodes) and the number of cellulose particles accumulated in the gap both increased first and then decreased with the rise of flow velocity. Finally, the results were analyzed according to the force conditions of particles. This paper contributes to understanding the effect of oil flow on bridging characteristics of cellulose particles and lays the foundation for the subsequent studies of breakdown mechanism about flowing contaminated liquid dielectrics.