PD characteristics of a void between semiconducting layer and insulating layer

PD measurement is important in the after laying test for an ultra-high voltage power cable line because PD is sensitive to defects in a cable system. However, the PD characteristics for defects in the cable system strongly depend upon the type or the size of defects. PD characteristics of a void, for example, and their change with time are not well understood yet. In this paper, the PD characteristics of a void between semiconducting layer and insulating layer have been investigated. Especially, the changes in PD pattern with time and applied voltages were discussed. These results give us important information to improve the insulation diagnosis of cable line.