Aluminum and aluminum alloy busbars for electrical use
Aluminum and aluminum alloy busbars for electrical applications are rectangular or trough-shaped aluminum-based conductive materials used to transmit high currents in power systems. They are widely used in substations, distribution rooms, high- and low-voltage switchgear, generator terminals, and other locations as key components for collecting and distributing electrical energy. They are typically made from aluminum and aluminum alloys such as 1060, 2A12, and 6063. 1060 pure aluminum busbars prioritize high conductivity and are suitable for medium and low-voltage systems. Aluminum alloy busbars such as 2A12 and 6063 offer both high strength and good conductivity, making them suitable for high-voltage or long-span installations. Busbars come in a variety of specifications, with widths ranging from 20 mm to 300 mm and thicknesses from 3 mm to 20 mm, allowing for flexible selection based on current load and installation space.
In terms of production technology, the manufacture of aluminum and aluminum alloy busbars for electrical applications requires a series of processes, including smelting and casting, hot-rolling, cold-rolling, straightening, and surface treatment. First, the aluminum ingot and the required alloying elements are heated to 720-760°C in a smelting furnace to melt. Hydrogen and impurities are removed from the melt through inert gas degassing and flux refining to ensure a hydrogen content of ≤0.15ml/100gAl. The molten aluminum is then cast into rectangular ingots, which can be 6-12 meters long, to improve subsequent rolling efficiency. Hot-rolling involves heating the ingot to 400-500°C and then rolling it through multiple hot-rolling passes into slabs with a thickness of 10-30 mm. The hot-rolling process requires controlled rolling speed and reduction, with each pass reducing by no more than 40% to prevent cracking. Grain structure is also refined by controlling the final rolling temperature. Cold rolling is a key step in ensuring the dimensional accuracy of busbars. Hot-rolled flat slabs are rolled using a four-roll cold rolling mill, typically with a cold rolling deformation of 30%-50%, reducing the thickness to the target size. Vertical rollers control the width, ensuring a width tolerance of ≤±0.5 mm, a thickness tolerance of ≤±0.1 mm, and a flatness error of ≤1 mm/m. Long busbars require straightening, using a multi-roll straightening machine to eliminate the bends introduced during rolling and ensure straightness. Finally, surface treatment is typically performed, either by anodizing or applying anti-rust paint. Anodizing forms a 5-10μm oxide film for improved corrosion resistance, while anti-rust paint is suitable for indoor, dry environments to increase surface insulation.
The performance characteristics of aluminum and aluminum alloy busbars for electrical use give them unique advantages in power systems. First, the advantage of lightweight is significant. The density of aluminum is about 2.7g/cm³, which is only about 30% of copper. When transmitting the same current, the weight of the aluminum busbar is only half of that of the copper busbar, which greatly reduces the load on the supporting structure. It is especially suitable for large-span installations and distribution rooms in high-rise buildings, reducing civil engineering costs. Second, it has good electrical conductivity. The conductivity of 1060 pure aluminum busbar can reach more than 61% IACS, and the conductivity of 2A12 aluminum alloy busbar is about 50% IACS. By increasing the cross-section (usually 1.6 times that of copper busbar), the same current carrying capacity can be achieved, meeting the needs of most power systems. Third, it has excellent processing performance. Aluminum and aluminum alloys have good plasticity and can be made into various connection shapes such as right-angle bends, T-shaped bends, etc. through cutting, drilling, bending, etc. Type joints, etc., are convenient for on-site installation; fourthly, the cost advantage is obvious. The raw material price of aluminum is only 1/3-1/4 of that of copper. The use of aluminum busbars can significantly reduce the initial investment in power equipment, especially in large-capacity substations and distribution systems, the cost saving effect is more prominent; fifthly, it has good heat dissipation performance. The thermal conductivity of aluminum is higher than that of most metals other than copper. It can effectively dissipate the heat generated during current transmission, reduce temperature rise, and ensure safe operation of the system.
In application scenarios, electrical aluminum and aluminum alloy busbars are used in all aspects of power transmission and distribution. In substations, busbar bridges for voltage levels of 110kV and below are mostly made of aluminum and aluminum alloy busbars, supported by support insulators to enable power transmission between the transformer and switchgear. For example, the low-voltage side busbars of 220kV substations often use 6063 aluminum alloy busbars with a width of 120-200 mm and a thickness of 8-12 mm. In high- and low-voltage switchgear, aluminum busbars are widely used for the main and branch busbars inside the switchgear. Power distribution is achieved through bolted or plug-in connections. The main busbars of low-voltage switchgear often use 1060 pure aluminum busbars with a width of 60-100 mm and a thickness of 5-8 mm. At the generator output end, the busbar connected to the generator must withstand large short-circuit currents, and high-strength aluminum alloy busbars such as 2A12 are often used to ensure that they do not deform under short-circuit shocks. In the power distribution systems of industrial enterprises, the connecting busbars between workshop distribution cabinets are mostly made of aluminum to meet the enterprises’ needs for cost control. With the construction of smart grids, the application of aluminum and aluminum alloy busbars in prefabricated substations and box-type substations is also increasing, meeting modular design requirements with their compactness and economy.
Industry trends indicate that aluminum and aluminum alloy busbars for electrical applications are trending toward high conductivity, high strength, and large sizes. Through material innovation, high-conductivity aluminum alloy busbars are being developed. For example, aluminum-zirconium alloys with microalloying elements such as zirconium and niobium achieve electrical conductivity exceeding 63% IACS while maintaining high strength and reducing cross-sectional dimensions. Large-sized busbars are being developed, with widths exceeding 300 mm and thicknesses exceeding 20 mm, meeting the demands of high-capacity power systems such as UHV converter stations. Continuous rolling and straightening integrated production lines are being adopted to improve production efficiency and product dimensional accuracy, achieving flatness tolerances within 0.5 mm/m. Furthermore, continuous advancements in connection technology are being made, with the development of new aluminum busbar joints, such as ultrasonic and friction welds, to reduce contact resistance and enhance connection reliability. Environmentally friendly surface treatment processes, such as chromium-free passivation, are being employed to minimize environmental impact. In the future, with the rapid development of new energy power generation, ultra-high voltage transmission and other fields, the demand for aluminum and aluminum alloy busbars will continue to grow, driving the industry to make greater progress in material research and development, process optimization and application expansion, and providing strong support for the safe and economical operation of the power system.
