Influence of DC Component of Short-Circuit Current on Arc Characteristics During the Arcing Period

The arcing processes of the short-circuit current with a significant dc component have been simulated under the long and short arcing time conditions, respectively, for an SF₆ auto-expansion circuit breaker based on an MHD arc model. The influences of the dc component are investigated compared with cases where the dc component is negligible. The results show that the arc temperature, pressure, and radius as well as the pressurization in the expansion volume are increased significantly under the second current peak gone up by the dc component and long arcing time condition. However, the arc temperature at the final current zero becomes high in the current peak and is reduced by the dc component and short arcing time cases. Thus, the dc component would not be ignored in the interrupting investigation and in the design of the interrupter.