High current vacuum arc phenomena of nanocrystalline CuCr25 contact material

Research on the vacuum arc phenomena of the nanocrystalline CuCr25 contact material is interested for its potential application on high current interruption. In order to investigate the vacuum arc phenomena of the nanocrystalline CuCr25 contact material, a traditional CuCr25 material was also prepared for comparison. 12mm and 25mm diameter contacts were assembled in vacuum interrupters, which have a glass envelope and no shield. A high-speed CCD camera was used to observe the anode phenomena and the cathode phenomena through the glass envelope. The test vacuum interrupters were operated by a permanent magnet mechanism. The average opening velocity can be adjusted to two velocities: 1.3m/s to 1.8 m/s. The arc current frequency was 50Hz and arc duration was 9ms~10ms. The experimental results showed that at same current and average opening velocity, the arc energy and the mean value of arc voltage of nanocrystalline CuCr25 was lower than the traditional CuCr25 contact material. The distribution of cathode spots on the nanocrystalline CuCr25 contact was more uniformly than of the traditional CuCr25 contact. And the carrying current per cathode spot of the nanocrystalline contact material was about 1/3 of that of the traditional contact material. However, the anode phenomena of the nanocrystalline CuCr25 contact were more active than the traditional CuCr25 contact material when passing the same high currents. At a threshold current at the first high-current anode mode appeared, it was found that the threshold current of nanocrystalline CuCr25 contact material was lower than that of traditional CuCr25 contact material, which means the nanocrystalline CuCr25 contact material was more prone to appear the high-current anode mode than the traditional CuCr25 contact material.