Double breaks in vacuum: technical benefit and flashover mechanism

The success of MV vacuum switchgear is based on the high performance of vacuum interrupters for clearances of up to 15 mm. Due to the vacuum specific flashover process, a degressive rise of the breakdown voltage with enlarging gap space is observed. This effect prevents the economic application of vacuum technology in high-voltage applications above 52 kV. Here, the authors investigate the breakdown voltage of double break arrangements because of the high performance of small vacuum gaps. A possible high voltage interrupter could consist of a static mid-electrode and two movable contact elements. Their aim is to show whether double (or multiple) breaks are able to increase the electric strength in a vacuum.