Breaking Operations of a Double Break Vacuum Interrupter Test Setup Using a Belt Drive

For switching operations in higher voltage levels sulfur hexafluoride (SF6) is a common insulating and switching medium. In medium to high voltage levels vacuum has advantages compared to SF6. In order to expand the operation voltage levels of vacuum circuit breakers (VCB) two approaches are possible. The enlargement of the single gap and the series arrangement. In both cases the Time-Distance-Curve of the contact travel is one factor that influences the switching performance of VCBs. The usage of a single gap for higher voltage levels requires an increased contact stroke. In dependence of different switching operations a controlled Time-Distance-Curve is useful. Due to the non-linear dielectric strength of vacuum in dependence of the contact gap, the enlargement of the single gap is limited for operating voltage levels above several 100 kV. The usage of two VCBs in series arrangements enables higher operating voltage levels. In this case the time of the electrical contact separation, which is influenced by the used drive(s) train and the symmetric voltage distribution over the switching distance, mainly influenced by external electromagnetic fields, are the main challenges. For practical investigation a vacuum single- and double break test setup using a brushless servo drive with a frequency converter is built up. The electrical control of the drive enables parameter variations of the Time-Distance-Curve. The velocity, acceleration, deceleration and final contact gap can be adjusted. In case of a double breaking VCB, two transmission belts and one drive are used to ensure synchronous opening curves of both VCB chambers in series. For fine tuning a mechanical simulation considering the regulation loop between frequency converter and drive as well as the mechanical components is employed. Finally, actual tests of the setup are presented.