The Influence of O2 on Decomposition Characteristics of c-C4F8/N2 Environmental Friendly Insulating Gas

Abstract

The c-C 4 F 8 gas is considered to have great potential as a gaseous medium for gas-insulated equipment, due to its good insulation properties and its relatively low greenhouse gas potential (GWP) relative to SF 6 . However, the decomposition is an important indicator of its use in equipment. In this paper, the decomposition characteristics of c-C 4 F 8 and the influence by oxygen have been explored through experiments and theoretical calculations. Firstly, the breakdown test of mixed gas was carried out and the precipitated elements of the electrodes and breakdown products of gas mixture were analyzed by X-ray photoelectron spectroscopy (XPS) and gas chromatography mass spectrometry (GC-MS). At the same time, the differences in decomposition products have also been studied when a small amount of O 2 was present. The path and mechanism of c-C 4 F 8 decomposition is then discussed, based on density functional theory (DFT). The results show that the black powdery substance descends on the electrode surface after the breakdown of the mixture of c-C 4

Alternative Environmentally Friendly Insulating Gases for SF6

“…O 2 promotes the decomposition of c-C 4 F 8 and generates the very toxic and corrosive COF 2 . Thus c-C 4 F 8 should be used without O 2 [20].…”

Application of C 6 F 12 O/CO 2 mixture in 10 kV medium‐voltage switchgear

“…The most of by-products are insulated gas and they are studied as SF 6 alternative gases [8,[27][28][29][30][31], so they can be considered safe. In addition, these gases have lower GWP values than SF 6 [32].…”

SF6 Alternatifi Yalıtkan Gazların Çevresel ve Fizyokimyasal Özellikleri

“…LC 50 , a unit of toxicity, indicates that half of all living things exposed to a gas over a certain concentration and time interval are killed. When FCs are examined for toxicity, C 3 F 6 , C 3 F 8 , C 4 F 6 and C 4 F 8 are toxic and their use in high amounts in industrial applications should be avoided [19,20]. FCs are used in GIS and switching equipment in double or triple gas mixtures [42].…”

“…One of the characteristic features of fluorocarbons is that they are among the gases proposed to be restricted by the Kyoto Protocol and Doha Amendment [17,18]. [19,20]. FCs are used in GIS and switching equipment in double or triple gas mixtures [42].…”

“…The use of SF 6 , which has one of the highest GWP among the synthetic gases used for industrial purposes, is recommended to be limited to the countries that are parties to the United Nations Framework Convention on Climate Change (UNFCCC) with the 1997 Kyoto Protocol and the 2012 Doha Amendment to the Kyoto Protocol agreements [17,18]. The atmospheric lifetime of SF 6 is about 3200 years, making these environmental effects more important [19,20]. Despite these agreements that recommend restricting the use of SF 6 , its proportion in the atmosphere continues to increase.…”