Thermal interruption performance of SF₆ replacement gases and its dependence on material properties

The importance of correctly understanding and assessing the interruption capability of gases that have the potential to replace SF₆ for switching purposes is discussed. Issues relating to the assessment of the interruption capability are addressed. A brief summary is also given to recent industrial tests in the search of SF₆ replacement gases. The dominant energy exchange mechanisms responsible for the differing interruption capabilities of N₂, CO₂ and SF₆ are analysed using a calibrated arc model. Correlation between the interruption capability and material properties of a number of gases has been established, thus providing theoretic evidence on the selection criteria for SF₆ replacement gases in future.