Development of New Polymer Insulating Materials for HV DC Cable (Part 2)

Abstract

In a previous report, we described the process for the selection of modified HDPE, as a new insulating material for HV DC cable. The effect of insulation thickness and the long-term V-t characteristics for DC breakdown of the modified HDPE cable were continuosly investigated and promising results for an application to HV DC cable were obtained.
In order to clarify the mechanism of the excellent DC characterittics of modified HDPE cable, we examined the quantitative space charge characteristics of modified HDPE compared with XLPE, by using a pulsed electro-acoustic method. XLPE gives hetero space charge distribution, although modified HDPE gives homo space charge distribution. In addition, in modified HDPE, the small dependence of space charge amount on DC applied time and DC applied stress are thought to be the reason for such excellent DC characteristics. The advantageous space charge distribution in modified HDPE is found to be the complex effect of a modified group and additives which are included in modified HDPE.