Power cable cores are the central current‑carrying components of power cables and play a decisive role in electrical performance, safety, and service life. A core typically consists of a conductor, insulation layer, and sometimes additional semi‑conductive and shielding layers, all designed to ensure efficient and reliable transmission of electrical energy in low, medium, and high‑voltage systems.The conductor is usually made from copper or aluminum due to their high electrical conductivity and favorable mechanical properties. Stranded conductors are common, as they provide improved flexibility compared with solid conductors, making installation, bending, and routing easier, especially in complex cable runs. The cross‑sectional area of the core is selected based on the required current‑carrying capacity, allowable voltage drop, short‑circuit withstand capability, and thermal limits.Surrounding the conductor, the insulation layer provides electrical separation between the core and other conductive parts, as well as between adjacent cores in multi‑core cables. Common insulation materials include cross‑linked polyethylene (XLPE), polyvinyl chloride (PVC), ethylene propylene rubber (EPR), and other specialized polymers. XLPE is widely used in modern power cable cores because of its excellent dielectric strength, thermal resistance, and low dielectric losses, which enable higher operating temperatures and improved efficiency.In medium and high‑voltage cable cores, semi‑conductive screens are usually applied both over the conductor and over the insulation. These layers smooth the electric field distribution, minimizing local stress concentrations that could lead to partial discharges and premature insulation failure. Additionally, metallic screens or tapes, often made of copper or aluminum, may be applied as a shield to control electromagnetic fields, provide a path for fault currents, and ensure proper grounding and protection coordination in power systems.Power cable cores can be designed as single‑core or multi‑core constructions. Single‑core cables are frequently used in higher voltage or higher current applications, where thermal management and magnetic effects are more critical. Multi‑core cables, which incorporate several insulated conductors within a common sheath, are particularly suitable for low‑voltage distribution, control, and auxiliary systems, offering compactness and simplified installation.Thermal performance is a key design aspect of cable cores. The maximum conductor temperature under normal and short‑circuit conditions determines the permissible current rating. Factors such as conductor material, insulation type, ambient temperature, installation method, and soil thermal resistivity must be considered. Proper core design ensures that temperature rises remain within specified limits, thus maintaining insulation integrity and extending service life.Mechanical strength and flexibility are also essential. Core construction must withstand pulling forces during installation, as well as thermal expansion and contraction during operation. Stranding, sector‑shaped cores, and compacted conductors are used to optimize space, reduce overall cable diameter, and improve mechanical behavior.In summary, power cable cores integrate conductive, insulating, and shielding functions into a single engineered element. Their design directly influences electrical performance, operational reliability, installation efficiency, and long‑term durability across utility, industrial, and infrastructure applications.