Global electricity demand is forecast to rise sharply in the coming decade. At the same time, the race to decarbonise energy systems is placing unprecedented demands on power grids. Here, Heini Kloster, product manager at Exel Composites, explores how polymeric matrix composite (PMC) multi-wire conductor cores can support these goals and what a new technical study reveals about their resilience.
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In the quest for a more sustainable and efficient power grid, technologies are being developed to support the on-going energy transition and grid modernisation, such as the use of PMC cores in overhead line (OHL) conductors. These cores offer a higher strength-to-weight ratio than traditional steel-cores used in aluminium conductor steel reinforced (ACSR) conductors. They also expand less when heated, increase transmission capacity and reduce energy losses, helping grids operate more efficiently without costly upgrades.
PMC conductor cores come in two main types: single-wire and multi-wire. The first generation single-wire core, often comes with a hybrid structure, a carbon fibre core coated with glass fibre. While these have been on the market for some time, they are relatively inflexible and more prone to damage if mishandled. That’s why the second-generation multi-wire cores have several small rods stranded together. This design provides greater flexibility and safety, as no single wire carries the entire load of the line. Its flexibility closely matches that of traditional ACSR conductors, making damage during installation or handling highly unlikely.
Testing real-world resilience
The multi-wire structure of the conductor core ensures that, even if there is an individual damaged strand inside the core, the conductor and the electrical line still stay intact. This event was the object of a recently published study carried out in collaboration with Exel Composites and De Angeli Prodotti titled, “Influence of Broken Wire on Multistrand Core”. The research, commissioned by Belgium’s transmission system operator ELIA, examined how individual wire damage affects overall conductor performance.
To simulate real-world defects, a single wire was intentionally damaged using transverse compression, reducing its tensile strength by around 30 per cent. 6+1 wires were then stranded to form a multi-wire core, which was put through tensile testing to break the pre-damaged wire and see how it affects the rest of the core. The results clearly demonstrate that, even with a broken wire, the core maintained strength above the specified minimum, and no damage occurred to the surrounding wires. This demonstrates the high residual strength and reliability of multi-wire PMC cores in practical use.
Implications for the power grid
The study demonstrates that PMC multi-wire cores maintain their structural integrity even when individual strands are damaged. This reliability ensures safe, consistent performance when deployed in overhead lines, giving transmission system operators (TSO) confidence in using these next-generation conductors.
The research also provides valuable insights into the mechanical behaviour of multi-wire PMC cores, reinforcing their robustness and suitability for modern grids. Teams at Exel Composites and De Angeli Prodotti are eager to share these findings with the industry and continue supporting TSOs in strengthening transmission networks while meeting growing demand efficiently.