Copper and copper alloy busbars for electrical use
Electrical copper and copper alloy busbars are key conductors for transmitting high currents in power systems. They are widely used in substations, distribution rooms, switchgear, and other locations, fulfilling the core function of collecting and distributing electrical energy. These busbars are made from high-purity copper (T1, T2) or copper alloys (such as Cu-Cr and Cu-Zn) and feature rectangular, trough, or tubular cross-sections. Specifications range from 30 to 400 mm in width and 5 to 30 mm in thickness. Pure copper busbars prioritize high conductivity and are suitable for medium and low voltage systems. Copper alloy busbars, while alloyed for enhanced strength and heat resistance, are suitable for high-voltage or long-span installations.
The production process for electrical copper and copper alloy busbars requires rigorous steps, including ingot melting, hot rolling, cold finishing, straightening, and surface protection. First, electrolytic copper with a purity of at least 99.95% or a proportionately formulated alloy is smelted in an industrial frequency induction furnace at a controlled temperature of 1150-1200°C. Degassing with inert gas and flux refining are used to reduce the oxygen content to below 0.003%, preventing the formation of pores and inclusions. A semi-continuous casting process is used to produce rectangular ingots 6-10 meters in length. The ingots are then milled to remove scale and surface defects. Hot rolling heats the ingots to 800-900°C and rolls them through multiple passes to a thickness of 15-40 mm. The reduction and cooling rate are controlled during rolling to ensure uniform grain refinement. Cold rolling finishing is performed using a four-roll reversing mill, 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 ≤±0.3 mm, a thickness tolerance of ≤±0.05 mm, and a flatness error of ≤0.5 mm/m. Long busbars are straightened using a multi-roll straightener to eliminate bends and ensure straightness. Finally, the surface is treated by anodizing or coating with an antioxidant to form a 5-10μm protective film, enhancing resistance to atmospheric corrosion.
The performance advantages of electrical copper and copper alloy busbars make them occupy a core position in the power system. First, it boasts exceptional electrical conductivity. The conductivity of T2 pure copper busbars can reach over 97% IACS, significantly higher than that of aluminum busbars. While carrying the same current, the cross-section can be reduced by over 30%, saving installation space. Second, it boasts excellent mechanical properties. The tensile strength of Cu-Cr alloy busbars can reach over 400 MPa, 1.5 times that of pure copper, making them suitable for large-span installations, with spans exceeding 6 meters without the need for intermediate supports. Third, it offers outstanding heat dissipation capabilities. Copper’s thermal conductivity is 1.6 times that of aluminum, allowing it to quickly dissipate heat generated by current. At the same current, its temperature rise is 15-20°C lower than that of aluminum busbars, improving system operational safety. Fourth, it offers high connection reliability. Copper has excellent ductility, resulting in low and stable contact resistance when bolted or welded, with the increase in contact resistance exceeding 20% after long-term operation. Fifth, it offers strong corrosion resistance. The oxide film formed on the copper surface effectively resists corrosion in dry environments, while the corrosion resistance of Cu-Zn alloy busbars in humid environments is even better than that of pure copper, resulting in a service life of over 30 years.
In various applications, electrical copper and copper alloy busbars are the “aorta” of power transmission. In ultra-high voltage substations, busbar bridges for voltage levels of 500kV and above utilize T2 copper busbars, supported by support insulators. A single busbar can carry over 5000A, meeting the demands of high-capacity power transmission. In switchgear for urban distribution networks, main busbars are typically 100-200mm wide copper busbars, distributed via plug-in connections to accommodate frequent operation. In data center computer rooms, high-density distribution systems utilize trough-type copper busbars, which combine high current carrying capacity with compactness, supporting single-cabinet power outputs exceeding 50kW. In industrial sectors such as metallurgy and chemicals, distribution systems operating in high-temperature environments utilize Cu-Cr alloy busbars, capable of long-term stable operation above 150°C. In new energy power plants, such as the combiner boxes of large-scale photovoltaic power plants, copper busbars combine the current from multiple photovoltaic panels, ensuring low-loss transmission. With the development of smart grid and UHV technology, the application of copper and copper alloy busbars in modular substations and DC transmission systems is also increasing rapidly.
Industry trends indicate that electrical copper and copper alloy busbars are moving toward high conductivity, high strength, and energy efficiency. Through material innovation, nano-reinforced copper alloy busbars, such as Cu-Al2O3 composite materials, have been developed. These materials maintain electrical conductivity exceeding 90% IACS and boast tensile strength exceeding 500 MPa, making them suitable for UHV applications. Advanced large-scale busbar manufacturing technology has enabled the production of ultra-wide busbars with a width of 400 mm and a thickness of 30 mm, capable of carrying up to 10,000 A per busbar, meeting the needs of large converter stations. Energy-saving connection technologies are being promoted, with ultrasonic welding or diffusion welding replacing traditional bolted connections, reducing contact resistance by over 50% and minimizing energy losses. Furthermore, green manufacturing concepts are driving the industry’s adoption of recycled copper raw materials. Recycled copper busbars offer performance comparable to virgin copper, while consuming 40% less energy to produce. With the rapid development of renewable energy power generation and UHV transmission, demand for high-performance copper and copper alloy busbars will continue to grow, driving the industry to achieve new breakthroughs in material research and development, process optimization, and application expansion.
