Application of new test procedure for verification of water drop corona on innovative insulation cross-arms

The use of composite insulators has grown rapidly over the last couple of years. They are especially popular solution for refurbishment and upgrading of high voltage overhead lines. In these cases the insulator set-up can be a rather complex insulated cross-arm combining composite insulators in different operating positions. This will in turn lead to an increased electric field around the insulator end fittings and hardware including arcing horns and grading rings if they are not dimensioned properly. It is agreed internationally that to be able to dimension a composite insulator from corona point of view two main criteria for E-field parameters should be taken into consideration. The first one is the limitation of E-field on the metallic hardware at 1,8 kV/mm and the second is the…