The role of contact-bridge parallelism deviation on current switching behavior and arc erosion of HVDC contactors

High-voltage DC (HVDC) contactors are indispensable to ensuring safe power connection and fault isolation in electric vehicles and more-electric aircraft. However, the impact of contact-bridge parallelism deviations on arcing and erosion remains to be clarified. In this work, a model-switch with in-situ optical observation and measurement test platform is developed to simultaneously capture electrical switching characteristics and three-dimensional erosion morphology. For the first time, side-resolved arc voltage, arc duration, and arc energy of both contact pairs are experimentally obtained, revealing an asynchronous breaking-arc mode in which the two arcs exhibit identical durations but markedly different energies. It is demonstrated that increasing parallelism deviation redistributes arc power toward the wider-gap side, leading to strongly asymmetric erosion and invalidating the conventional proportional relationship between cumulative arc energy and material loss. A monotonic correlation between the parallelism deviation and the total arc-power coefficient is further established, enabling non-invasive estimation of internal bridge alignment using external electrical signals. The results provide new physical insight into arc-energy asymmetry and offer a practical diagnostic basis for condition monitoring of sealed HVDC contactors.