A new technique to improve the dielectric strength of a multi-dielectric insulation system

In this study, an attempt is made to improve withstand-ability of the multi-dielectric medium by the effect of an additional electric field in the transverse direction to the main applied electric field. High voltage HV insulation system is chosen in this study is an air-solid insulation system. In this study, two types of gaps are used simultaneously: the first one is the main tested gap MG, and the other is the transverse gap TG. The MG consists of two parts: part one is air insulation, and part two is solid insulation. The transverse field is applied to part one, i.e., air gap of the MG. According to the results extracted from this work, the flashover voltage of the dielectric medium two increases as the transverse voltage TV within the region one increases whereas the conduction current of the MG decreases as the TV increases. Moreover, the effect of TV increases as gap pressure decreases. Actually, the effect of TV is much marked in low vacuum gaps than in atmospheric air gaps and compressed air gaps. The improvement in flashover behaviors in the presence of a transverse electric field illustrates a marked dependence on the item of pressure; the type of transverse applied electric field (AC or DC), and the transverse field plane level. However, the improvement does not depend on the specimen material. In addition, it is worth mentioning that this improvement in the flashover behaviors of solid dielectric in the region two is related fundamentally to the process of lowering electric stress in the region one of the MG.