An opening displacement characteristic determined by high-current anode phenomena of vacuum interrupter

A vacuum interrupter reaches its interruption limit once high-current anode phenomena occur. It is well-known that contact diameter, contact material, and magnetic field have a significant influence on high-current anode phenomena formation. However, an opening displacement characteristic of movable contact is another contribution for an anode spot formation. The objective of this paper is to propose an opening displacement characteristic for a vacuum interrupter to avoid a formation of high-current anode phenomena. The anode phenomena were observed by using high speed CCD camera. The vacuum interrupters were used in the experiments, which had a glass envelope and there was no stainless shield installed. The diameters of butt type contacts were 12 mm and 25 mm, respectively. The average opening velocities during 10ms after contacts separated were ranged from 1.1m/s to 2.0m/s. And arcing time was adjusted from 2ms to 10ms with a fixed velocity and peak arc current. The results showed that in an anode diagram for each vacuum interrupter, an arcing curve can be obtained, which avoids the regions of intense arc mode and anode spot mode. And this arcing curve corresponds to an opening displacement curve of vacuum interrupter. With the proposed opening displacement curve, high-current anode phenomena will not occur, which has a positive impact on the interrupting performance of the vacuum interrupter.