A new concept in construction of cable terminations for medium voltages

This paper describes a new concept in construction of cable terminations for medium voltages. Layers with a high permittivity and embedded electrodes (EEs) were used. Three groups of configurations were examined. In the first group, the layer of high permittivity was placed partly over the cable insulation and partly over the cable screen. In the second group, the high permittivity layer (HPL) was placed partly over the cable insulation and partly under the semiconducting material, connecting with the cable insulation screen. In the third group the cable screen was partly inserted into the HPL whose other part was placed over the cable insulation. The EEs were made in a shape of rings around the HPL. The rings were made either of copper tape or copper wire. Different positions of the EEs were examined. Numerical models of the cable terminations were used to monitor how the electric field changes as a function of the EE distance from the cable screen end. Finally, the new terminations were tested in a high voltage laboratory, according to the standards VDE 0278 and IEEE-404.