Thermal Damage Process and Failure Mechanism of Epoxy/SF6 Composite Insulation Subjected to Arc Ablation

In this work, the effects of arc ablation on the surface of epoxy (EP) in EP/SF
₆
composite insulation are analyzed. Based on the results, the characteristics of streamers on the surface of EP is captured by a photomultiplier array and the failure mechanism of the EP is studied. The results show that the arc heat flow applied to the EP/SF
₆
interface can lead to the decomposition of EP molecular chains and degradation of the SF
₆
. The pyrolysis products re-couple to generate complex carbides and pyrolysis gases, resulting in severe irregular carbonization on the EP surface and the increase in surface conductivity. When an external electric field is applied, a large quantity of photons will accumulate in the carbonization region on the EP surface and this gives rise to the surface streamer and thereby greatly decreases the surface electrical strength of EP/SF
₆
composite insulation.