Ablation-Assisted Current Interruption in a Medium Voltage Load Break Switch

Near an electric arc some polymers, known as ablation materials, change the properties of the arcing medium in a beneficial manner. The interruption capability for current interruption improves by increasing the pressure and the heat dissipation from the arc. The present paper studies medium voltage (MV) current interruption by ablation. In an MV test laboratory, current interruption experiments are carried out with polypropylene (PP) ablation plates. Both the current and transient recovery voltage are varied. The results reveal that the PP ablation has the potential to interrupt the thermal phase for all tested currents, up to 800 A. The dielectric strength in the arcing zone after the thermal phase is however poor, and dielectric re-strikes easily occur, causing the interruption to fail.