Instability of DC arc in SF/sub 6/ circuit breaker

Instability of the arc in an HVDC circuit breaker was investigated both analytically and experimentally. The analytical work showed that the amplification coefficient and the frequency of the oscillation that leads to the current zero can be given as functions of parallel impedance and arc characteristics. The process to estimate the arc characteristics from the amplification coefficient and the frequency experimentally observed was proposed and the result was compared with the estimation of the same characteristics by the analysis of the current zero behavior. It was shown that a description of the DC arc by a simple Mayr type model could reproduce the initiation and the growth of the oscillation and the interruption of the current.