Why use aluminum cable instead of copper in overhead lines?
Weight of Aluminum cable vs copper cable
- Overhead lines are supported by poles or towers to hang the cables in the air. Since overhead line cables are suspended in the air, the weight of the cables must be taken into account. In fact, the conductivity of aluminum is second only to copper. The conductivity of aluminum is about 2/3 of copper, but the density of aluminum is only 1/3 of copper. Therefore, in the aerial, aluminum wire is more appropriate.
- Outdoor cables are also affected by their own gravity and environmental changes. For example, it will be affected by changes in air temperature, also known as thermal expansion and contraction. The aluminum conductor is better than the copper conductor in terms of thermal expansion and contraction, so it is more appropriate to use the aluminum cable for overhead lines.
Dense oxide of aluminum cable
- Aluminum conductor is suitable as bare overhead wire because it will form a dense oxide film in outdoor conditions. This prevents it from corroding and rusting from air and rain. In addition, the oxide film has a certain degree of insulation. Therefore, aluminum wire is more widely used in outdoor circuit systems.
- Copper wire laid in the open air cannot form a dense oxide film. And over the years, a layer of copper patina may appear that will affect the transmission of current. Therefore, the copper conductor is not suitable for bare overhead wires in the open air.
Aluminum cable price
- The price of aluminum wire is much cheaper than that of copper wire. Now, the price of each ton of copper can be almost close to $10,000, while the price of aluminum is half or less. Therefore, considering the price, the copper conductor is also not used for the outdoor cables due to the huge quantity.
- The demand for the number of overhead line very high. From the point of view of investment, a more suitable and economical material should be chosen. Therefore, aluminum cables are the preferred option. This is the same for all countries in the world.