Dielectric testing of HV vacuum interrupters during capacitive current switching

Vacuum circuit breakers are well established in the distribution voltage level due to their various advantages, e.g. frequent switching operations, low life-cycle-costs, excellent thermal arc quenching capabilities, and nearly maintenance free operation. In order to establish this technology at higher voltages, the dielectric withstand capability must be increased. E.g. non-sustained disruptive discharges, while interrupting capacitive currents, have to be identified and reduced. In this work, a special test setup to investigate this aspect on commercially available high-voltage vacuum interrupters for test voltages up to 200 kV is presented and its features are discussed. In particular, requirements in terms of measuring and analysis of low frequent pre-breakdown currents immediately…