The anode surface temperature of CuCr contacts at the limit of current interruption

This paper estimates vacuum interrupter anode surface temperature at the current interruption limit by measuring the melting time of a contact material after current interruption and simulating the anode surface temperature. As a result, the minimum anode surface temperature of CuCr (50/50) contact material was about 1750 K. The authors also calculated the metal vapor density between electrodes with a simplified model. The calculation results showed that the critical vapor density was about 3/spl times/10/sup 20/ atoms/m/sup 3/. This vapor density is equivalent to an averaged pressure of 8 Pa, which is close to the value of the Pachen minimum.