Gas-Blasting Effects on Contact Erosion in Self-Blast-Type High-Voltage Circuit Breakers: Experimental Study and Mechanistic Insights

During the current interruption process in high-voltage circuit breakers, gas-blasting effects interact with arc-electrode phenomena and these affect each other. This paper presents an experimental study on Cu-W arcing contacts in a self-blast-type gas circuit breaker, at current peak values of 5 kA, 20 kA and 35 kA representing low, medium, and high current conditions. Mass loss measurements are complemented by surface morphology analysis to elucidate erosion mechanisms. The results show that erosion behavior is governed by the combined influence of electrode surface temperature and gas flow. When the contact temperature remains below the tungsten melting point, the tungsten skeleton offers strong resistance to erosion. Once a molten pool forms, however, gas-blasting significantly accelerates material removal, leading to increased mass loss. These findings provide mechanistic insight into erosion processes under gas-blasting conditions and establish a baseline reference in SF6for future comparative studies in alternative gases such as CO2-based mixtures.