Fracture Mechanisms and Mechanical Performance of Aluminum Conductor Alloy Reinforced Wires in High-Voltage Transmission Lines

This study investigates the failure analysis of high-voltage transmission lines, focusing on the fracture of aluminum conductor alloy reinforced (ACAR) wires produced through a cold drawing process. It includes macroscopic inspections of ACAR fractures, microscopic morphology observations, energy dispersive spectroscopy (EDS) analysis for micro-area elemental composition, hardness assessments, x-ray diffraction (XRD) analysis, and torsional fracture tests to determine the causes of the ACAR fractures. The findings reveal that some wire breaks exhibited indentations and significant plastic deformation. Notably, the hardness value of the fourth layer of aluminum wires was lower than that of the middle three layers of aluminum alloy wires, suggesting that it may have been the first to fracture. The fracture analysis results indicated that the primary cause of ACAR fractures was related to the aluminum alloy and aluminum strands undergoing severe plastic deformation due to torsion and extrusion during pre-twisting repairs. This deformation created indentations that concentrated stress, undermining the strands' homogeneous load-bearing capacity and ultimately leading to the failure of the entire wire bundle. These findings emphasize the importance of proper manufacturing processes and regular maintenance to ensure the reliability and performance of transmission lines in power equipment.