Dielectric behavior of GIS switching disconnectors comparison of possible phase opposition tests

The dielectric behavior of a GIS (gas-insulated switchgear) switching disconnector is investigated by means of full-phase opposition tests to obtain data on the discharge-to-ground phenomenon. This phenomenon, which is a function of the voltage across the disconnector switch contacts before restrike and of the amplitude of the overvoltage after restrike, displays a very large scatter. In addition, the time-to-crest of the overvoltage has a great influence on the discharge to ground. A discharge-to-ground mechanism to explain all of these features is proposed. The guarantees of same disconnector switching given by two possible phase opposition tests having different overvoltage shapes and amplitude are compared