Contact ablation of intermediate-frequency vacuum circuit breakers considering arc dynamic characteristics and polarity reversal mechanisms

A simulation method for contact ablation in intermediate-frequency vacuum circuit breakers used in aviation power systems (360 – 800 Hz) is proposed. In contrast to existing studies which are primarily focused on power-frequency conditions, both arc dynamic characteristics and polarity reversal mechanisms are incorporated in this model. Source terms such as surface resistance Joule heating and recoil pressure are introduced to characterize contact surface heating and molten pool stress effects. The evolution of the contact surface is tracked using the level-set method. Results indicate that at 360 Hz, arc energy decays rapidly, causing uneven melting traces on the anode without extensive ablation. For Cu and CuCr50 contacts, the maximum radial ablation widths are measured as 9.21 mm and 6.11 mm, molten pool depths as 0.23 mm and 0.17 mm, and material loss depths as 0.028 mm and 0.021 mm, respectively. Contact melting weakens with increasing Cr content. The maximum anode surface temperatures are recorded as 1529.90 K for Cu and 2029.70 K for CuCr50, indicating that the peak temperature rises as Cr content increases. Ablation primarily occurs near the contact edges, within radial positions of 17.90－27.11 mm for Cu and 22.89－29.00 mm for CuCr50. Moreover, arc reignition in the second half-wave is the primary cause of contact ablation. Numerical and experimental results show close agreement.