Electrothermal damage numerical analysis for overhead ground wire at terminal of armor rods under short-circuit current

Overhead ground wires (OGW) are installed to protect conductors from lightning strikes. However, the elevated temperature at the terminal of armor rods (TAR) under the influence of short-circuit currents can cause accidents resulting in breakage of OGW. To simulate the electrothermal damage process of TAR, an improved conductive bridge model considering the coupled relationship between electromagnetic force (F_E) and the contact area is established. Then, a finite element model is built based on the improved model to assess TAR damage severity by analyzing the equivalent plastic strain considering thermal behavior. In addition, the calculation results of different conductive bridge models are compared. The findings indicate that the maximum temperature at the TAR contact surface can exceed the steel melting point, leading to significant thermal stress and elevated equivalent plastic strain. The improved model considering the coupling between F_E and contact area shows better accuracy in predicting the electrothermal damage, validated by temperature rise experiments. The proposed modeling method has potential applications in related research areas.