Research on Current Sensing Coating for Power Equipment Based on Electrochromism

Current detection technologies of operation current in power systems primarily rely on electromagnetic induction principles and infrared thermal imaging. These methods suffer from inherent limitations such as dependence on external power supplies, susceptibility to interference in complex electromagnetic environments, and high equipment costs. Electrochromic materials, which can directly convert electrical signals into optical signals and enable self-sensing without external power, offer a novel technological pathway for condition monitoring of electrical equipment. However, existing electrochromic materials still face technical challenges in power equipment operating environments, including high response thresholds, poor environmental stability, and short cycle life. Based on the synergistic electrochromic effect of poly(3-hexylthiophene) (P3HT) and fluoran, this study develops a color-changing coating suitable for operating current sensing. Core–shell structured microcapsules with urea-formaldehyde resin as the wall material were prepared via in situ polymerization to effectively encapsulate the P3HT–fluoran composite core material. These microcapsules were uniformly dispersed in an epoxy acrylate/TMPTA ultraviolet-curable resin system to form a current-sensing coating with excellent adhesion and insulation properties. Test results show that the coating, applied on a busbar, undergoes a noticeable color change from red to white within 30 s when a current of 100 A passes through the busbar, with a color difference (ΔE) of 25.3. The coating exhibits adhesion strength exceeding 11.7 MPa, volume resistivity on the order of 1013 Ω·m, and a breakdown field strength higher than 85 kV/mm. After 100 cycles, ΔE remains stable, demonstrating good cyclic durability. This research provides a new visual sensing solution for high-current monitoring and shows broad application prospects in the field of power equipment operation status monitoring.