Surface Flashover of GIS Insulator Attached with Metal Particles Under Lightning Impulse

Insulator surface flashover is one of the main causations for the gas insulated metal enclosed switchgear (GIS) devices failure. According to the previous studies, the metal particles plays an important role in the flashover of insulators, and the flashover voltage decreases more under impulse voltage than AC/DC voltage. As a result, the lightning impulse voltage is regarded as an effective way to detect of the metal particle. In this paper, epoxy resin post insulators with concave, convex and wave shape were manufactured, and a Marx generator was used to supply the standard lightning impulse (1.2/50µs). The flashover voltage of the samples with aluminum particle attached in different surface position were studied. The surface electric field strength of samples were calculated by the finite element method. The results show that there is an obvious flashover voltage reduction (up to 41.8%) when the particle attached to the high electric field region. Otherwise, there is little influence on the surface flashover voltage (down to 0%). The wave insulator of which the surface electric field varies the most is the least sensitivity to the metal particle. As a result, to improve the metal particle tolerance, insulator with a varied surface electric field along the surface should be designed.