1.Why Use Aluminum to Replace Copper?

In power and electrical engineering, replacing copper conductors with aluminum conductors offers significant advantages in long-distance power transmission, large cross-section conductors, lightweight design, and cost-sensitive projects. Although copper has much higher electrical conductivity than aluminum, there are compelling reasons to use aluminum conductors:

(1) Lower Cost
Based on current domestic metal market spot prices, copper is priced at approximately 97,000–98,000 yuan per ton (98 yuan per kilogram), while aluminum is priced at about 20,000 yuan per ton (20 yuan per kilogram).

This means the material cost of aluminum conductors is roughly one-fifth that of copper, providing a clear cost advantage for aluminum in large-scale power transmission and project applications (though actual costs may be slightly higher due to aluminum’s lower conductivity, which is only 61% that of copper).

(2) Lightweight
Aluminum has a density about half that of copper, meaning aluminum conductors are lighter for the same length and cross-sectional area. This results in:

• Lower transportation costs
• Easier installation
• Reduced requirements for supporting structures and load design

This makes aluminum particularly suitable for applications with high lightweight demands, such as overhead power lines, vehicles, and ships.

(3) Better Corrosion Resistance
Aluminum naturally forms a dense oxide layer on its surface, providing better corrosion resistance than bare copper in many environments. In humid, salty, or similar conditions, aluminum conductors exhibit greater durability.

(4) Suitability for High-Temperature Environments
Aluminum conductors experience a relatively gradual increase in resistance as temperature rises, maintaining stable conductive performance within certain temperature ranges. This enhances reliability in high-temperature operating conditions.

2. Basic Characteristics of Aluminum Conductors

Compared to copper conductors, the most significant difference in aluminum conductors lies in their electrical conductivity.

Aluminum has approximately 61% of the electrical conductivity of copper, meaning aluminum conductors have a lower current-carrying capacity for the same cross-sectional area. Therefore, in applications requiring higher current, aluminum conductors must increase their cross-sectional area to compensate.

Aluminum’s density is only about half that of copper, giving aluminum conductors a significant weight advantage, particularly in applications where lightweight design is critical.

Additionally, aluminum exhibits better corrosion resistance than copper, especially in humid or harsh environments, where aluminum conductors can offer greater durability.

Electrical Conductivity and Thermal Conductivity

In material selection, electrical conductivity and thermal conductivity are two key performance indicators. As illustrated in the figure below, aluminum alloys exhibit relatively high electrical and thermal conductivity. Although not as high as copper, their performance is sufficient compared to other commonly used metals.

Copper alloys (top right of the chart) offer the best combination of electrical and thermal conductivity.

Aluminum alloys follow closely, with moderate electrical conductivity and high thermal conductivity, making them particularly suitable for applications requiring heat dissipation.

In fields such as large cross-section power transmission and lightweight design, aluminum continues to demonstrate significant practical value.

3. Applications of Aluminum Conductors

Aluminum conductors have been widely adopted, particularly in applications requiring large cross-sections and long-distance transmission, such as high-voltage power transmission, distribution systems, electric vehicle battery busbars, transformers, and various types of cables.

(a) High-Voltage Power Transmission
Aluminum conductors are used in high-voltage transmission lines to support large-scale power delivery, leveraging their lightweight nature and cost-effectiveness for spanning long distances.

(b) High-Voltage Busbars
Aluminum conductors are employed in high-voltage busbars, offering advantages in weight reduction, thermal performance, and overall system efficiency in substations and power distribution setups.

(c) Electric Vehicle Battery Busbars
In electric vehicles, especially within battery systems, aluminum conductors provide a balanced combination of good electrical conductivity and corrosion resistance, contributing to lighter and more efficient energy distribution.

(d) Transformers
Transformers with aluminum windings help reduce the overall weight and cost of the equipment while maintaining reliable performance in power conversion and distribution applications.

(e) Cable Design
Aluminum conductors are used in high-voltage cables and special-purpose cables, where they demonstrate excellent electrical conductivity and heat dissipation properties, making them suitable for demanding electrical infrastructure.

4. Factors Influencing Aluminum Conductor Performance

The main factors affecting the performance of aluminum conductors include:

(1) Material Alloying
By adding elements such as magnesium and silicon, the mechanical strength and conductivity of aluminum alloys can be enhanced. However, this may slightly reduce electrical conductivity.

(2) Temperature Rise and Heat Dissipation Management
Aluminum conductors have higher resistance than copper, leading to a greater temperature rise under the same current conditions. To prevent aging and failure due to excessive heat, thermal management and heat dissipation design require special attention.

(3) Environmental Impact
Humidity and corrosive environments can accelerate galvanic corrosion in aluminum conductors, especially when aluminum comes into contact with other metals like copper. To improve durability in harsh conditions, corrosion-resistant aluminum alloys or appropriate surface coatings can be used.

(4) Mechanical Stress and Fatigue
Aluminum has relatively low mechanical strength and is susceptible to fatigue fracture or plastic deformation (e.g., sagging or elongation of wires) under high-frequency vibrations or overload conditions. These factors must be carefully considered during design.

5. Failure Modes of Aluminum Conductors

(1) Galvanic Corrosion
In humid or corrosive environments, when aluminum comes into contact with other metals (such as copper), galvanic corrosion is prone to occur, leading to accelerated corrosion of the conductor.

(2) Thermal Fatigue
Due to the relatively high temperature rise in aluminum conductors, prolonged thermal cycling can lead to fatigue failure. Particularly under conditions of thermal expansion mismatch, cracks or delamination may occur at interfaces.

(3) Mechanical Fatigue and Poor Contact
During long-term use, aluminum conductors may develop fatigue cracks, especially at joints or soldering points. These cracks can result in poor electrical contact and increased resistance, eventually affecting performance and safety.

Conclusion
Lightweight, low cost, and strong corrosion resistance are the key advantages of aluminum conductors. Through techniques such as alloying and microstructure optimization, the electrical and mechanical performance of aluminum conductors can be effectively enhanced. However, design considerations must still address challenges such as temperature rise, mechanical properties, and failure modes to ensure long-term reliability and performance in practical applications.