COMPOUND POLIMERIC PENTRU CONTROLUL CAMPULUI ELECTRIC AL ACCESORIILOR CABLURILOR DE ENERGIE

摘要

In joints and terminations for medium and high voltage power cables, high potential gradients may occur in areas where the radial field has discontinuities due to the change in the field borders. These areas are situated at the end of the semi-conducting screen, near and over the joints and generally in locations under voltage and separated by a dielectric. Was researched and experimented a polymeric compound having non-linear resistance thus providing an improved electric field stress-control in the vulnerable areas of power cable accessories. The compound can be applied on the inner surface of heat-shrinkable tubes used in accessories for power cables with polymeric insulation (PVC, PE or XLPE). In dry form, the material is thermoplastic, with stable hardness, 90℃ maximum continuous operating temperature and a melt temperature value allowing perfect contact with the surfaces on which it's applied, covering even irregular shapes and eliminating the air bubbles. The compound has a volume resistivity of 10~(11) - 10~9 Ω·m in the electric field range intensity (50)/(500) V/mm (service electric stress domain) and assures a partial discharge level < 10pC. Due to the high non-linear characteristic of resistivity the stress-control system made with this material is one-component type, which has the advantage of easy installation and efficiency of cascade systems type.