The effect of contact material on temperature and melting of anode surface in the vacuum interrupter

We have investigated the relationship between the contact material and the anode surface condition subjected high current arc in a vacuum by measuring and calculating the temperature of the anode surface. We tested CuCr contacts with Cr contents varying from 12.5 to 75 wt% under an axial magnetic field. The two-color pyrometer was used to measure the anode surface temperature around the contact center region. The high sensitivity CCD camera with the bandpass filter was used to measure the relative temperature distribution immediately after current interruption. We calculated the temperature of the anode surface considering melting and evaporation. It is shown that the Cr contents of the CuCr contact influence the temperature, the anode surface melting and the interruption ability. With increase in Cr content of the CuCr contact, the temperature of the anode surface and the melting duration after the current interruption increased. The maximum melting depth of the anode surface decreased with increase in Cr content. The measurement results also showed that the interruption ability improved with decrease in Cr content, and the anode surface temperature of the CuCr contact was 2000-2050 K at the interruption limit.