With the adjustment of national policies on the power grid industry and the increased construction of ultra-high voltage transmission lines, many major cable manufacturers have begun to adjust their development priorities and innovate their business transformation strategies. Based on their existing production scale, they are further investing in enhancing their production capacity of aluminum alloy products, carbon fiber, and large-section special conductors. For example, Far East Cable has made significant progress in the carbon fiber field in recent years, while Hengtong Cable, another major cable manufacturer in Jiangsu, has increased its efforts in aluminum alloy cables. These innovative models undoubtedly greatly help reduce enterprise costs and increase profits, and also bring the Chinese cable industry closer to the world.
The advantages of aluminum alloy conductors have become increasingly apparent with the advancement of power transmission and transformation technology and the development of transmission lines. Judging from the widespread application of aluminum alloy conductors, it seems they could completely replace copper and steel core conductors. In fact, many countries around the world currently use aluminum alloy conductors in their power lines, primarily high-strength, medium-strength, and heat-resistant series. High-strength aluminum alloy conductors are mainly used in medium to heavy icing areas and for crossing power lines, to increase the span between towers, reduce the number of towers and their footprint, and ultimately improve conductor conductivity. Heat-resistant aluminum alloy conductors are mainly used in areas with medium to heavy capacity expansion needs, limited power line corridors, economically developed cities, large peak-to-valley electricity consumption differences, and short construction periods.
Aluminum alloy cables also underwent a long development period in the United States. Initially, they were ordinary grade aluminum core building wires made of pure aluminum, with the grade AA-1350. Many buildings in North America installed this type of aluminum core wire. Later, frequent splicing faults occurred in aluminum core electrical circuits, leading to numerous complaints from power companies and residents. To solve these problems, wire and cable companies, along with companies in other industries such as electrical product laboratories and connector companies, developed a plan to re-evaluate aluminum conductors.
The electrical laboratory re-evaluated the aluminum core building wires, and the connector company remanufactured new connectors for them. After rigorous screening of the aluminum core building wires, the wire and cable company ultimately selected the 8000 series aluminum alloy and began using it in the manufacture of building wires. Among these, AA-8030 aluminum alloy is the most widely used. Compared to AA-1350 pure aluminum, AA-8030 aluminum alloy has higher tensile and yield strength, better elongation, and greater flexibility. US national standards mandate the use of the new AA-8000 series electrical grade aluminum alloy. Comparing the AA-8000 series aluminum alloy with previous alloys, its superior performance makes it an ideal material for manufacturing various specifications of aluminum core building wires. Currently, AA-8000 series aluminum alloy wires with specifications of AWG8 and above can be manufactured. In addition to continuing research on conductor splicing, new aluminum alloy conductor materials with better flexibility, lower resilience, and easier field installation are also being developed.
Aluminum alloy conductors are widely used in Europe and America, but the application patterns of aluminum alloy cables in Europe and America cannot be directly copied to China. The main reason is the difference in living environments. North American residences are mostly townhouses and detached houses, with power supply trunk lines laid outside the buildings. Some industrial facilities and public places use aluminum conductor cables locally because electrical construction and maintenance standards are higher abroad, and the protection conditions are more adequate. According to feedback from the National Fire Protection Association (NFPA), engineers, for safety reasons, tend to use copper cables for the vertical power supply trunk lines in densely populated high-rise buildings.
The application of aluminum alloy cables is limited; for example, cables with very small cross-sections are not suitable. Technical personnel from the Architectural Electrical Branch of the Architectural Society of China and the international organization IEEE held a forum in Shanghai to discuss the application of aluminum conductor cables. The conclusion reached at the forum was that for cables smaller than 16mm², copper conductors should be used due to mechanical strength issues. Because aluminum conductors are lighter than copper conductors, they have a clear advantage for larger cross-sections.
In general applications, such as factories, residences, commercial buildings, schools, and municipal engineering projects, aluminum conductor cables can completely replace copper cables. However, in some critical or special locations, such as urban power supply trunk lines, large power plants, heavily polluted environments, or environments difficult to maintain, aluminum conductor cables are not the best choice. These locations prioritize the safety and reliability of the power supply, requiring extremely high power stability. In such cases, the risks associated with aluminum conductor cables, which are not present in ordinary locations, become apparent. Therefore, copper cables, offering higher safety, are recommended as the first choice.
Because of aluminum's low melting point, aluminum conductors are unsuitable for use as conductors in fire-resistant cables. GB/T 19216.11-2003 stipulates that under flame conditions, the test apparatus and the flame temperature should be a single-source fire with a temperature not lower than 750℃. Aluminum's melting point is 660℃, and the melting point of aluminum alloys is lower than that of pure aluminum, while copper's melting point can reach 1080℃. In actual fires, the highest temperature at the scene is around 1000℃. Therefore, aluminum conductors are not suitable for use as conductors in fire-resistant cables.
Aluminum alloy conductors are now widely used in many power lines in Europe and America. Data shows that they account for over 50% of all power lines in these countries. Internationally, aluminum alloy conductors have been used since the 1950s, and are now widely adopted in Western Europe, Northern Europe, the United States, Canada, Japan, and other countries. In France, nearly 90% of transmission lines use aluminum alloy conductors, and in Japan, this figure exceeds 50%. Usage in Southeast Asian countries is also increasing rapidly year by year. However, the application of aluminum alloy conductors in China is not widespread. In China, the application rate is less than 2%, a pitiful figure. Currently, my country has sufficient technological development and production capacity for high-strength and heat-resistant aluminum alloy conductors, but these products are not widely used domestically, mainly for export, resulting in a low domestic market share. This is primarily due to economic considerations.
In recent years, some Chinese cable companies have made significant progress in aluminum alloy conductors. For example, some Chinese cable companies now offer several major categories of conductor products, including "aluminum alloy conductors and related products," "capacity-enhancing and energy-saving conductors," "large-section special conductors," "aluminum profile conductors," and "expanded diameter conductors." These products mainly cover hundreds of high-performance conductors, such as high-strength aluminum alloy conductors, medium-strength aluminum alloy conductors, heat-resistant aluminum alloy conductors, carbon fiber conductors, large-section (1250, 1520) profile conductors, and expanded diameter conductors. Many of these products are internationally leading. However, Chinese cable companies still need to learn more from global experience in the application of aluminum alloy conductors to lay a solid foundation for improving cable quality and efficiency.
