High temperature PD characteristics of polyimide and liquid crystal polymer

Partial discharge (PD) characteristics and PD degradation mechanisms of high voltage equipment have been studied by many researchers from the point of view of insulation diagnosis and insulation breakdown prediction. Since PD pulse occurrence in insulation systems is affected by many factors such as void gas, electrode materials, electrode configuration, void shape, applied electric field strength and remaining charge effect of previous PD, the relationship between PD characteristics and PD mechanism still remains ambiguous. Life time estimation of insulating material at high temperature becomes very important due to severe design condition and environmental conditions in power apparatus and electronic insulation. Unfortunately there have been few research works on PD endurance characteristics of insulating materials. The gas temperature is also a very important factor affecting PD characteristics. This paper describes some aspects of PD characteristics and PD endurance life at elevated temperature with several insulating materials such as liquid crystal polymer (Xydar), epoxy resins, polyimide and polyethylenetelephthalate (PET).