Numerical Analysis of Terminal of Armor Rods for Ground Wire Based on Electromagnetic-Thermal-Structural Coupling under the Short-Circuit Current

The terminal of armor rods (TAR) of overhead ground wire (OGW) generates high temperature under the action of short-circuit current, which affects the mechanical properties of OGW and even causes OGW fracture failure in serious cases. Therefore, it is necessary to analyze the thermal and mechanical behaviors of TAR. In this paper, we propose an elliptical contact bridge model considering the coupling relationship between electromagnetic force and contact state, and obtain the electromagnetic force and contact area under the action of short-circuit current with different amplitude of frequency by iterative calculation method. Then, TAR electromagnetic-thermal-force coupling model with contact points is constructed based on the contact bridge model, and the current density distribution and transient temperature distribution at the port are simulated and analyzed under the frequency short-circuit current. Finally, the residual tensile strength and internal stress distribution of OGW at the port are analyzed by combining the simulation results. The results show that the short-circuit current is mainly concentrated in the contact point at the port, resulting in high temperature and a sharp decrease in tensile strength of OGW near the contact point, and the maximum decrease can reach 22.3%. Therefore, OGW at this location becomes the weak point of mechanical capacity under short-circuit current. The work in this paper can be extended to be applied in the related fields of Optical Fiber Composite Overhead Ground Wire (OPGW).