An experimental investigation of the flashover behavior of outdoor cable terminations under lightning impulse application

Designing cable terminations, today has two constraints: to be more compact requiring less space on the installation site and to reduce the amount of insulating fluids to limit the environmental impact. The trend towards higher operating voltage ranges of cable systems and the demand for maximum reliability over long service life lead to additional challenges regarding the design of new cable terminations. For the development of such new types of cable terminations, e.g. dry terminations, reliable design criteria are mandatory. This contribution shows the 50% flashover voltages of non-wetted standard oil-filled cable terminations stressed with standard lightning impulses (1.2/50 μs) for both polarities. All relevant parameters affecting the electric field distribution, such as the geometry of the insulator itself, the internal setup, and the insulation fluids, were systematically varied. The contribution compares the results of the experiments and discusses the influence of the relevant parameters. Besides the obvious dependence of the flashover voltages on the length of the hollow core insulator, the experiments reveal the distinct influences of the internal field grading parts and the insulation fluids on the positive and negative lightning flashover behavior, respectively, where there are differences for both cases. This knowledge is necessary for the design of new, ecofriendly, and reliable cable terminations.