Surface Electrical Performance of Polytetrafluoroethylene and Epoxy Resin under Arc Ablation

The resistance performance under arc ablation is a critical factor to determine the surface electrical performance of the break of HVDC circuit breaker. In order to study the effects of arc energy on the surface electrical performance of polytetrafluoroethylene (PTFE) and epoxy resin (EP) insulation, an arc ablation test platform was set up to simulate the arc ablation process during the operation of HVDC circuit break. And the surface microtopography of two insulations under arc ablation was analyzed using atomic force microscope (AFM). The results show that DC flashover voltage of PTFE and EP insulation decreased by 16.0% and 64.7% respectively when the arc energy is equal to 156.5 J. The decrease in surface electrical performance is closely related to the changes of surface microtopography. Compared with PTFE, a plenty of drastic fluctuations and random defects appeared on EP surface after ablating. These defects can distort the surface electric field and thereby promote the development of flashover process, which is considered as one of the likely reasons that drastically decrease the surface electrical performance of EP insulation.