Investigation on Dynamic Modeling of Hinge Wear in Motor-Direct-Drive High-Voltage Circuit Breakers

The reliable operation of high-voltage circuit breakers is critical to the safety and stability of modern power systems, where the actuating mechanism serves as the core component enabling rapid switching and intelligent control. Electrically driven actuating mechanisms not only enhance the breaker's dynamic responsiveness but also offer potential for fault diagnosis through real-time monitoring of electrical signals. Common operational anomalies-such as delayed response, incomplete contact closure, and vibration rebound-are primarily attributed to motion clearance enlargement caused by hinge wear. However, current research predominantly relies on simulating these symptoms to obtain fault data, with limited diagnostic focus on actual clearance-induced wear phenomena. The absence of a dedicated fault model further complicates systematic analysis. This paper investigates the dynamic characteristics of motordriven high-voltage circuit breakers and the mechanism of hinge wear faults. A permanent magnet servo motor model, a hinge clearance model, and an electromechanical coupling dynamic model are established. The normal contact force of the hinge clearance is described by using the L-N nonlinear spring-damper model, while the tangential friction is characterized by a velocitydependent modified Coulomb model. A multi-body dynamic equation for the circuit breaker is developed, considering material properties, geometric features, and dynamic loads. A non-uniform hinge wear model is established by analyzing the collision process during opening/closing operations. Simulation results reveal that hinge wear at the crank arm exhibits significant aggregation in the contact angle range of $[-1.6,-0.8]$ rad. After wear, the oscillation amplitude of the moving contact displacement increases by 12.7 %, the opening speed decreases by 18.4 %, the peak motor torque rises by 23.5 %, and the effective phase current increases by 15.2 %. These results validate the effectiveness and engineering applicability of the proposed model, providing a theoretical tool and data foundation for reliability assessment and fault prediction in motor-driven circuit breakers.