The Influence of Cable Conductor Shape on Cable Performance

Common cable conductor shapes include solid circular, stranded circular, sector-shaped, and segmental (arc-shaped) profiles. The cross-sectional shape of a conductor directly affects key performance characteristics such as electrical resistance, heat dissipation, flexibility, electric field distribution, overall outer diameter, manufacturing costs, and bending performance.

Structural Characteristics

Consist of a single round copper or aluminum rod (solid) or multiple fine round wires stranded together, resulting in a circular cross-section.

Performance Impact

• Optimal Electric Field Distribution The uniform curvature of the circular surface ensures the most even distribution of the electric field, minimizing localized electric field concentration. Circular conductors are preferred for high-voltage and medium-to-high-voltage power cables, as they reduce the risk of partial discharge and extend the service life of the insulation.
• Resistance and Skin Effect Solid circular conductors: Exhibit a pronounced skin effect, leading to increased effective resistance at high frequencies. Stranded circular conductors: Composed of multiple fine wires, which mitigate skin and proximity effects; suitable for large-cross-section AC cables.
• Flexibility Solid circular conductors: High rigidity and resistance to bending; typically used for fixed installations involving small-cross-section cables. Stranded circular conductors: High flexibility; suitable for applications involving movement or frequent bending (e.g., flexible cables, control cables).
• Disadvantages In multi-core cables, the gaps between the cores are relatively large, resulting in a larger overall outer diameter, higher material consumption, and increased costs.

Structural Characteristics

Conductors are compressed into a sector shape; primarily used in low-voltage multi-core power cables (3-core, 4-core, and 5-core).

Performance Impact

• Reduced Outer Diameter When multiple sector-shaped cores are assembled, they form a shape approximating a circle with minimal inter-core gaps. Compared to stranded circular conductors, this results in a smaller overall cable diameter, saving on insulation and sheathing materials and lowering costs.
• Less Favorable Electric Field Distribution The presence of edges and corners leads to electric field concentration, resulting in higher localized electric field intensity at these points. ❌ Not suitable for medium- or high-voltage cables; intended only for low-voltage (1 kV and below) cables.
• Reduced flexibility Compacted sector-shaped conductors are quite rigid; their bending performance is inferior to that of circular stranded conductors, requiring a larger bending radius.
• High process requirements If the compaction process is not well-controlled, burrs can easily form, potentially piercing the insulation and creating a risk of electrical breakdown.

Structural characteristics

Intermediate between circular and sector-shaped, these conductors feature a tile-like profile. They are commonly used in 2-core or 3-core low-voltage cables with large cross-sectional areas.

Impact on performance

• Balancing outer diameter and electric field Compared to sector-shaped conductors, they have fewer sharp edges, resulting in less intense electric field concentration. Compared to circular conductors, they leave fewer internal voids, allowing for a smaller overall outer diameter.

Application limitations

Due to the complex manufacturing process, they are generally used only for large-cross-section low-voltage cables and are rarely employed for small- or medium-cross-section cables.