Understanding Types and Specifications of ACSR Conductors
May 15,2023
Copper wire and aluminum wire are commonly used metals in power systems, each with their own characteristics, advantages, disadvantages, and different application areas. Only by understanding the properties of these two metals can materials be effectively utilized, otherwise it may lead to improper use, increased circuit damage, or even fire hazards. This article will analyze the advantages and disadvantages of plain copper wire and bare aluminum wire from six aspects.
Copper wire has low resistance, with a resistivity about 1.68 times that of bare aluminum wire. Therefore, copper cables exhibit lower voltage loss, higher carrying capacity, and less heat generation.
For the same transmission distance, plain copper wire can maintain higher voltage quality, reduce voltage loss, and achieve longer transmission distances, which is very beneficial for power network planning and reducing the number of power supply points, effectively improving energy utilization.
With the same cross-section, the load capacity of plain copper wire is about 30% to 50% higher than that of aluminum wire. Especially with the increasing number of household appliances, copper wire is widely used in home decoration.
Under the same current, the heat generated by copper wire cables with the same cross-section is lower, much lower than that of bare aluminum wire cables, making it safer.
Mechanical performance refers to the mechanical characteristics of a material when subjected to various external loads in different environments. Copper wire and aluminum wire differ in terms of ductility, strength, and fatigue resistance.
Copper alloy has excellent ductility, with a ductility of 20% to 40%, and even more than 30% for copper used in electrical applications, while aluminum alloy has a ductility of only 18%.
Copper wire has higher strength, with an allowable stress at room temperature 7% to 28% higher than that of aluminum. The difference between the two is even greater at high temperatures.
Copper wire has excellent fatigue resistance, while aluminum material is more prone to fracture after repeated bending. In terms of elasticity, copper's performance is also 1.7 to 1.8 times higher than that of aluminum.
In practical applications, the corrosion resistance and oxidation resistance of metals are important considerations. Copper wire has good corrosion resistance, strong oxidation resistance, and stability, while bare aluminum wire is prone to oxidation and corrosion.
Aluminum wire quickly reacts with the oxygen in the air to form a dense oxide film, which can prevent further oxidation, resist corrosion and oxidation from air and rainwater, making it very suitable for high voltage, large cross-section, and long-span overhead transmission lines.
However, plain copper wire cannot form a dense oxide film after being exposed to the outdoors. With the prolongation of service life, a copper rust layer that affects current transmission may appear, making it unsuitable for outdoor overhead power lines.
Density: The solid density of copper is 8.96g/cm³, while that of aluminum is only 2.7g/cm³. Therefore, aluminum wire cables are lighter in weight for the same volume, resulting in lower construction and transportation costs. This makes aluminum wire more suitable for overhead lines.
Thermal expansion: The wire undergoes changes due to its own gravity and environmental factors. For example, aluminum wire performs better in terms of thermal expansion and contraction, making it more suitable for outdoor line laying and better able to cope with external temperature changes.
Copper wire has good flexibility, allowing for smaller bending radii, making it easy to bend and pass through pipes. Copper wire has fatigue resistance and is not easily broken after repeated bending, making it very convenient for wiring. In addition, copper wire has higher mechanical strength, can withstand large mechanical tensile forces, bringing great convenience for construction and laying, and providing conditions for mechanized construction.
Although there are differences in mechanical performance between aluminum wire such as thhn aluminum wire and copper wire, aluminum wire has the advantages of malleability, castability, and weldability, as well as being lightweight and good at resisting thermal expansion, making it perform well in outdoor overhead lines and temporary power supply.
According to market conditions, plain copper wire is more expensive, with the price of copper bars about 3.5 times that of aluminum bars, and the specific gravity of copper is approximately 3.3 times that of aluminum. Therefore, aluminum wire cables are much cheaper than copper wire cables, making them more suitable for low-cost projects or temporary power supply.
Each metal material has its unique characteristics, and copper wire and aluminum wire have their own strengths and weaknesses, suitable for different fields. Aluminum wire is particularly suitable for high-voltage lines, while copper wire has obvious advantages in using wires for household life. Therefore, understanding the characteristics of metal wires and selecting suitable materials based on actual needs is a wise choice.