Evaluation of gassing materials in switching devices using monochromatic high speed imaging technique

The purpose of this paper is to investigate quantitative information on perspective gassing materials to be used in switching devices. Previous work indicates that gassing materials have a strong effect on current interruption and current limiting in these devices. However, few papers have been published to cover quantitative information on the amount of certain gassing species released, such as hydrogen, when the gassing material is exposed to a running arc. Monochromatic high speed imaging technique was employed in this investigation to characterize hydrogen gassing properties of different materials based on hydrogen arc images and nitrogen arc images, respectively. Hydrogen plasma has a very high thermal conductivity that results in high arc voltages during interruption, which is critical to current limiting. Comparison among perspective gassing materials was made. The mass loss results derived from plasma emission intensities showed good agreement with direct mass loss measurements of gassing materials.