Thermal stability of SF6 associated with metallic conductors incorporated in gas insulated switchgear power substations

Dervos, CT; Vassiliou, P; Mergos, JA

dc.contributor.author	Dervos, CT	en
dc.contributor.author	Vassiliou, P	en
dc.contributor.author	Mergos, JA	en
dc.date.accessioned	2014-03-01T01:27:28Z
dc.date.available	2014-03-01T01:27:28Z
dc.date.issued	2007	en
dc.identifier.issn	0022-3727	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/18460
dc.subject	Thermal Stability	en
dc.subject	Gas Insulated Switchgear	en
dc.subject.classification	Physics, Applied	en
dc.subject.other	Electric conductors	en
dc.subject.other	Electric switchgear	en
dc.subject.other	Porosity	en
dc.subject.other	Sulfur compounds	en
dc.subject.other	Thermodynamic stability	en
dc.subject.other	Construction metals	en
dc.subject.other	Gas insulated switchgear power substations	en
dc.subject.other	Metallic conductors	en
dc.subject.other	Metallic surfaces	en
dc.subject.other	Electric substations	en
dc.title	Thermal stability of SF6 associated with metallic conductors incorporated in gas insulated switchgear power substations	en
heal.type	journalArticle	en
heal.identifier.primary	10.1088/0022-3727/40/22/015	en
heal.identifier.secondary	http://dx.doi.org/10.1088/0022-3727/40/22/015	en
heal.language	English	en
heal.publicationDate	2007	en
heal.abstract	SF6 is generally treated as thermally stable and inert for applications below 500 °C. This work investigates the thermal stability of pure SF6 gas under 1.2 atm pressure between 200 and 450 °C in the presence of construction metals (Cu, Al), without any applied electric field. The obtained experimental results indicate that SF6 may react with metallic surfaces forming solid and gaseous by-products, either in the gas matrix or diffused in the metallic surfaces. The phenomenon is enhanced in the presence of adsorbed moisture. For copper surfaces, sulfide layers are formed. By-products are not formed for pure Al surfaces. However, when Al is covered by a few micrometres thick Al2O3 film, hot SF6 molecules have a structure change effect, i.e. reduce porosity in the oxide and in the substrate, provide smooth transition layers Al/Al2O3 and increase the Al2O3 layer width. In the presence of moisture this phenomenon is significantly intensified and a diffused overlayer of AlF3 also forms. The by-products in the gas matrix are mainly sulfur oxides for hot spot temperatures below 300 °C, while at higher temperatures oxyfluorides SO2Fx and HF are mainly formed. These by-products are either toxic or corrosive. Thus, the thermal stability issue of SF6 may have to be reconsidered. © 2007 IOP Publishing Ltd.	en
heal.publisher	IOP PUBLISHING LTD	en
heal.journalName	Journal of Physics D: Applied Physics	en
dc.identifier.doi	10.1088/0022-3727/40/22/015	en
dc.identifier.isi	ISI:000250606200017	en
dc.identifier.volume	40	en
dc.identifier.issue	22	en
dc.identifier.spage	6942	en
dc.identifier.epage	6952	en