Types of Cable Conductors: A Comprehensive Guide

I. Classification by Conductor Structure

According to international standard IEC 60228 and national standard GB/T 3956, cable conductors are primarily divided into four categories:

1. Class 1 Conductors (Solid Conductors)

Solid conductors consist of a single wire with a circular or sector-shaped cross-section. These conductors feature simple structure and high stability, making them suitable for fixed installation cables. For specialized applications, large cross-section solid copper conductors can be manufactured using segmentation techniques (such as four-segment or five-segment designs) to reduce skin effect.

2. Class 2 Conductors (Stranded Conductors)

Stranded conductors are formed by twisting multiple thin wires together, with cross-sections that can be circular, sector-shaped, or segment-shaped. These conductors utilize compression technology (with compression coefficients ≥0.9) to reduce gaps, thereby decreasing cable diameter and cost while enhancing longitudinal water resistance. They are widely used in low-voltage power cables.

3. Class 5 Conductors (Standard Flexible Conductors)

Comprised of bundles of finer copper wires twisted together, these conductors offer moderate flexibility and are suitable for general movable cables, such as household appliance power cords.

4. Class 6 Conductors (Extra Flexible Conductors)

With even thinner individual wire diameters, these conductors provide excellent flexibility and are commonly used in scenarios requiring frequent bending, such as welding machine cables.

II. Classification by Conductor Material

The material composition of conductors determines their electrical conductivity, mechanical strength, and cost. Common types include:

1. Copper Conductors

• Advantages: Superior conductivity (resistivity approximately 0.01724×10⁻⁶Ω·m), excellent corrosion resistance, and good ductility, making them ideal for high-reliability applications such as power systems and precision instruments.

• Coating Variations:

  • Tin-Plated Copper: Enhanced oxidation resistance, suitable for humid environments

  • Silver-Plated Copper: Excellent high-frequency performance, used in medical or aviation equipment

  • Nickel-Plated Copper: High temperature resistance (up to 250°C), but slightly lower conductivity

2. Aluminum Conductors

Lightweight (30% the density of copper) and cost-effective, but with inferior conductivity (resistivity 1.64 times that of copper) and lower mechanical strength. Primarily used in overhead lines or non-critical applications.

3. Composite Conductors

• Copper-Clad Aluminum: Combines copper's high conductivity with aluminum's light weight, with copper layer comprising 10%-20% of the cross-section. Suitable for large cross-section cables or busbars.

• Aluminum Alloys: Enhanced with elements like silicon and magnesium to improve mechanical properties, though with slightly lower conductivity than pure aluminum. Corrosion resistance must be considered.

III. Special Structure Conductors

1. Compressed Conductors

These conductors undergo mechanical compression to reduce stranding gaps, improving structural stability and reducing insulation material requirements. Commonly found in low-voltage cables with circular or shaped cross-sections (such as sector-shaped or segment-shaped).

2. Shaped Conductors

• Sector-Shaped Conductors: Feature smaller cabling diameters and reduced material usage, widely applied in low-voltage multi-core cables (such as three-core cables)

• Segment-Shaped Conductors: Used in five-core cables with "3+2" or "4+1" structures to optimize space utilization

IV. Environmentally Friendly Conductors and New Trends

1. Environmental Cable Requirements

Modern cables must comply with EU RoHS directives, avoiding heavy metals like lead and cadmium as well as halogen flame retardants. When burned, they should produce low smoke and no toxic emissions. Low-smoke, halogen-free materials are currently the mainstream choice.

2. Future Development Directions

• High-conductivity alloy materials (such as high-purity copper-aluminum alloys)

• Superconducting cable technology (requires low-temperature environments, still in experimental stages)

V. Conductor Selection Recommendations

• Fixed Installations: Prioritize Class 1 or Class 2 copper conductors

• Mobile Applications: Choose Class 5 or Class 6 flexible conductors

• Cost-Sensitive Scenarios: Aluminum or copper-clad aluminum conductors

• High-Frequency/High-Temperature Environments: Silver-plated or nickel-plated copper conductors

By understanding conductor structures, materials, and characteristics, users can select the most appropriate cable types based on their specific requirements for conductivity, flexibility, and cost. For more technical details, refer to relevant standards (such as GB/T 3956) or contact us.