Abstract: In vacuum circuit breakers, the arc morphology is a major factor influencing electrode surface erosion. Concentrated arcs impart energy more intensely on the electrode surface, whereas diffuse arcs distribute energy more broadly. Different arc morphologies result in varying degrees of electrode surface erosion, a critical indicator of switchgear lifespan. This study, conducted on a detachable vacuum arc extinguishing experimental platform, involves direct pull interruption and rotational interruption experiments on oxygen-free copper flat contacts under 200 A AC. Additionally, cathode erosion simulations were performed on the moving contact. Experimental and simulation results demonstrate that, under low AC currents, rotational interruption facilitates an earlier transition of the arc to a diffuse form, thereby reducing the duration of its impact on the center of the electrode surface. Consequently, this minimizes electrode mass loss due to erosion, with the erosion mass loss decreasing as the electrode rotation angle increases.