Vacuum Arc Characteristics of a Novel Contact Consists of Arcing Contact and Main Contact

The objective of this paper is to propose a novel contact structure for 126 kV vacuum interrupters, and determine its arc characteristics. The contact consists of an inner arcing contact and an outer main contact. A 3/4 coil-type contact with contact diameter of 100 mm was used as the arcing contact. A butt type contact with diameter of 140 mm was used as the main contact. For this contact, nominal rated current flows through both the main contact and arcing contact. When breaking the fault current, the main contact first opens and current transfers to arcing contact. Then the arcing contact opens and vacuum arc burns and distinguishes between the arcing contact. Drawn arc experiments of the novel contact were carried out in an L-C discharging circuit. Experiment current was up to 30 kA rms. From the experimental results, the proposed contact can control vacuum arc effectively, and the erosion on outer main contact was slight. With the increasing of vertical distance between inner arcing contact and outer main contact, the arc expanded to outer main contact later. And in partial erosion case, the erosion on outer main contact was more severe than in normal case.