Material-Driven Failure Mechanisms in Field-Aged Overhead Line Conductors Operating in Harsh Environments

Abstract

Overhead transmission line conductors are expected to maintain mechanical integrity and predictable thermal performance over multidecade service lives. Operation under harsh environmental conditions can accelerate material degradation and reduce the reliability of power delivery. This paper presents a laboratory investigation of material-driven failure mechanisms in field-aged overhead conductors extracted from long-serving transmission lines in Saudi Arabia. Multiple conductor designs, including AAAC, ACAR, ACSR (greased), ACSR/AW, and GAP, were evaluated after exposure to coastal, coastal-urban, desert-coastal, and urban environments. The study integrates layer-by-layer visual inspection, bending tests, galvanizing retention and cladding verification, torsion and tensile testing, and surface emissivity measurements. Results show that unprotected aluminium conductors exhibit severe outer-layer embrittlement and visible corrosion products, whereas greased and aluminium-clad designs retain ductility and protective coatings.