Surface flashover characteristics of TiO2/epoxy nanocomposites in SF6

Surface flashover is one of the main factors leading to insulation failure. For example, epoxy insulator in Gas Insulated Switchgear (GIS) is the most vulnerable insulation components; the failure endangers the reliability of GIS and even leads to accidents and economic losses. Thus, developing advanced materials to be much more safely used in GIS is significant. Here we report the study on surface flashover characteristics of a nanocomposite, nano-TiO
₂
/epoxy. The samples were prepared using molded method after uniformly dispersing nano-scale TiO
₂
particles in epoxy resin with different loadings (0.1%, 0.5%, 1%, 3%, and 5%). The flashover characteristic was studied under 1.2μs/50μs standard lightning impulse voltage and DC voltage. The flashover voltage of TiO
₂
/epoxy nanocomposites was increased compared with neat epoxy resin. However, the flashover voltage decreased slightly when the filler loading exceeded 1%. At the same time, surface charge accumulation and decay behaviors and volume resistivity were also investigated. Experimental results show the trap density and trap energy in samples related with the flashover characteristics in SF
₆
. It seems that surface flashover voltage is mainly affected by deep trap density of the samples. Low trap density may lead to better flashover performance. The volume resistivity results showed that the resistivity of Nano-TiO
₂
/epoxy decreased at lower filler content which was contributed to the increase of the flashover characteristics in SF
₆
.