Anyone in the cable industry knows that copper-core cables dominate the market. While the advantages of copper-core cables are self-evident, the price of copper is also significant, leading to increased production costs and inconvenient installation. Consequently, aluminum alloy cables have surged in popularity in recent years, raising questions for users of traditional copper-core cables. Can aluminum alloy cables replace copper-core cables? What are the advantages of aluminum alloy cables compared to conventional copper-core cables?
What are the differences between aluminum and copper cables?
1. Tensile Strength and Elongation
Compared to pure aluminum conductors, aluminum alloy conductors have significantly improved tensile strength and elongation by up to 30% due to the addition of special ingredients and specialized processing techniques, making them safer and more reliable.
2. Creep Resistance
The alloy material and annealing process of aluminum alloy conductors reduce the conductor's tendency to "creep" under heat and pressure. Compared to pure aluminum, their creep resistance is 300% higher, eliminating the problem of relaxation caused by cold flow or creep.
3. Coefficient of Thermal Expansion
The coefficient of thermal expansion is used to calculate the dimensional change of a material with changes in temperature. Aluminum alloys have a coefficient of thermal expansion comparable to that of copper. Aluminum connectors have been reliably used with copper and aluminum conductors for many years, and the majority of electrical connectors in use today are made of aluminum, making them particularly well-suited to aluminum alloys. Therefore, the expansion and contraction of aluminum alloy conductors and connectors are perfectly aligned.
4. Corrosion Resistance
Aluminum's inherent corrosion resistance stems from the thin, durable oxide layer that forms on its surface when exposed to air. This oxide layer is highly resistant to various forms of corrosion. The addition of rare earth elements to the alloy further improves its corrosion resistance, particularly galvanic corrosion. Aluminum's ability to withstand harsh environments has led to its widespread use as conductors in cable trays, as well as in many industrial components and containers. Corrosion often occurs when dissimilar metals are joined in humid environments. Appropriate protective measures, such as lubricants, antioxidants, and protective coatings, can be used to prevent this. Alkaline soils and certain types of acidic soils are particularly corrosive to aluminum, so aluminum conductors installed directly in the ground should be insulated or protected with a molded jacket. In sulfur-containing environments, such as railway tunnels and other similar locations, aluminum alloys offer significantly better corrosion resistance than copper.
5. Connection Performance
Electrical connections made with aluminum alloys are just as safe and stable as those made with copper conductors. The composition of aluminum alloys significantly improves their connection performance. When the conductor is annealed, the added iron imparts high creep resistance, ensuring a stable connection even under prolonged overload and overheating.
6. Strong Weight-Bearing Capacity
Aluminum alloys improve the tensile strength of pure aluminum. Aluminum alloy cables can support a length of 4,000 meters, while copper cables can only support 2,750 meters. This advantage is particularly evident when wiring long-span buildings, such as stadiums.
7. Flexibility
Aluminum alloys offer excellent bending properties. Their unique alloy formulation and processing significantly enhance their flexibility. Aluminum alloys are 30% more flexible than copper and have 40% less springback. While the bending radius of typical copper cables is 10 to 20 times the outer diameter, aluminum alloy cables have a bending radius of only 7 times the outer diameter, making terminal connections easier.
8. Compression Properties
Based solely on volume conductivity, aluminum alloy is inferior to copper. However, the conductors we develop not only offer improvements in material properties but also significant breakthroughs in processing. We utilize exceptional compression technology to achieve a compression coefficient of 0.93, while the compression coefficient for special-shaped wires reaches 0.95, a domestic first. This extreme compression compensates for the aluminum alloy's insufficient volume conductivity, making the stranded conductor core behave like a solid conductor. This significantly reduces the outer diameter of the core and improves conductivity. At the same current carrying capacity, the conductor's outer diameter is only 10% larger than that of copper cable.
9. Armor Properties
Commonly used armored cables in China mostly use steel tape armor, which has a low safety rating and poor resistance to external forces, making it prone to breakdown. They are also heavy, resulting in high installation costs, and suffer from poor corrosion resistance, resulting in a short service life. The cable utilizes aluminum alloy interlocking armor. The interlocking structure between the layers ensures that the cable can withstand strong external forces. Even when subjected to high pressure and impact, it is less susceptible to penetration, thus enhancing safety. The armor structure also isolates the cable from the outside world. Even in the event of a fire, the armor layer enhances the cable's flame retardancy and fire resistance, reducing the risk of fire.
Can aluminum alloy cables replace copper-core cables?
Aluminum alloy improves the cable's flexibility and oxidation resistance, making it a viable alternative to copper cables in many situations, significantly saving users money. However, national mandatory standards, such as MT818, the mining cable industry standard (which is more authoritative than the national standard), explicitly prohibit the use of aluminum and aluminum alloy cables underground. Furthermore, since control cables generally have a smaller cross-section, the use of aluminum alloy requires a larger cross-section to meet the current carrying capacity. Compared to copper-core control cables, the price advantage is not significant, so relevant companies do not recommend it. Similarly, aluminum alloy cables are not recommended for marine and locomotive applications. However, for most applications involving power cables, aluminum alloy cables are adequate.
The above is a brief introduction to copper and aluminum cables. Comparing their merits depends primarily on the intended use, taking into account environmental factors, social factors (such as theft), design requirements (currents too high for existing aluminum wires, often used for low-voltage, high-power loads), and financial budget. It's generally accepted that any cable is good for the right application; there's no straightforward way to judge which is better.
