INFLUENCE OF DIMENSIONS AND DENSITY OF WATER TREES ON RESIDUAL ELECTRIC FIELD IN POLYMERIC POWER CABLES INSULATIONS

摘要

In this paper, the residual electric field computation in a cable insulation in the presence of water trees and space charge is presented. Considering that, in treed areas, the variations of the permittivity and the space charge density are known, the thermal step current I_c(t) is computed and the curves I_m (t) and I_c(t) are compared. The results show an important increase of residual electric field for some dimensions and concentrations of the water trees (up to 10 MV/m). Finally, the influence of the residual electric field on electrically aged cable insulations is analyzed.