抄録
This report deals with the space charge behavior in polyethylene under high DC fields. Direct observation of time-dependent space charge profiles in 3mm thick XLPE (cross-linked polyethylene) cable insulation under high electric fields was done using the pulse-electroacoustic method. An intermittent generation of packet shaped space charges and their propagation through the insulation were observed when the average DC field was as high as 1MV/cm. This phenomenon was reproduced in sheet specimens with XLPE and with LDPE (low-density polyethylene). It was indicated that the packet charge is easy to appear when the acetophenone was diffused into the LDPE specimen, however, too uniform distribution of acetophenone prevents the packet charge generation. It was suggested from several expremental results that the local ionization in the insulation brings the packet charge generation. A numerical simulation was carried out based on the above conception to reproduce the phenomenon.
