A Study of Relationship between Space Charge formation and Breakdown in Low density Polyethylene under Ultra-high Electric Field

点击翻译按钮获取中文摘要

An electric power transmission cable using a crosslinked polyethylene(XLPE) as an insulating layer is widely used for AC power transmission system. However, it is not used for DC long distance cable because an unexpected breakdown sometimes occurs in the insulating layer under high DC stress. The reason for the unexpected breakdown is said that, so called, a space charge is accumulated in the bulk of insulating layer under high electric DC stress and it distorts the electric field distribution. While many researchers had attempted to find out the evidence of the above mechanism, any clear experimental result to show the mechanism directly had not been obtained. However, the authors have succeeded in observing a clear result that a huge packet-like space charge generates under ultra-high applied electric field and it distorts the electric field in the bulk of insulating layer. In this investigation, the authors to try the mechanism of the generation of the packet-like charge using a numerical analysis. Furthermore, the authors have tried to suppress to generate the packet-like charge by adding a nano-size filler in the insulating material. Finally, the authors find out that the deference of the permittivities between the filler and the base polymer material may be the reason for the suppression of packet-like charge generation.