Internal Defect Monitoring System Design for Aluminum Conductor Composite Cores Using a Magnetic-Coating Interlayer in Power Transmission Lines

As power grids demand higher capacity and efficiency, aluminum conductor composite core (ACCC) cables have become increasingly important. However, the reliability of these conductors depends on the structural integrity of their internal composite cores, where hidden defects are difficult to detect due to electromagnetic shielding by surrounding aluminum conductors. This paper proposes a magnetic coating interlayer integrated into the composite core to enable electromagnetic detection of internal defects. The coating enhances the magnetic permeability of the core, improving sensitivity to defect-induced field variations measured by an external sensor. The sensor configuration was optimized through electromagnetic analysis to maximize detection capability. The magnetic coating, composed of epoxy resin and magnetic particles, was further optimized by evaluating signal-to-noise ratio (SNR) and adhesion strength. Numerical simulations, cross-cut adhesion tests, and Pareto analysis were conducted to identify the optimal balance between sensitivity and durability. Experimental validation using a coated composite core embedded in an aluminum pipe confirmed the effectiveness of the proposed method. This technique provides a practical solution for both pre-installation and in-service defect monitoring of ACCC composite cores.