On the behaviour of insulations with interfaces voltage cable accessories-model investigations

Electrical insulation systems for medium and for high-voltage cable terminations often contain several electrically stressed macroscopic interfaces. In the case of high-voltage insulators a chemical bondage between the different insulating materials is necessary to protect the interfaces against breakdown. For medium voltage cable accessories it is possible to use interfaces without a chemical bonding between the two interface partners. In this case the required insulating ability can also be achieved by means of the interface pressure of a stretched elastic insulating material. To evaluate the reliability of such interfaces the influences of the electrode distance d, the interface pressure p and the roughness R, of a plastic interface partner as well as the effect of a lubrication agent have been investigated. Additional measurements have been done to evaluate the long term behaviour of the interfaces