Aluminum Conductors Steel Reinforced (ACSR) are the most widely used conductors in transmission, sub-transmission, and distribution lines. These conductors are manufactured by stranding aluminum wires around a steel core. Aluminum is utilized for its high electrical conductivity (and low density), while steel wires serve as the core due to their high tensile strength. The aluminum wires used are of the 1350 alloy with H19 temper, and the steel strands are high-strength, high-carbon steel.
The primary advantages of these conductors include good electrical conductivity, cost-effectiveness, and high tensile strength, which allows for increased span lengths in line design. Furthermore, due to their high tensile strength and lower coefficient of thermal expansion compared to all-aluminum conductors, they exhibit less sag during operation.
ACSR conductors come in a wide variety of configurations based on the number and diameter of the aluminum and steel strands used, resulting in a broad range of electrical and mechanical properties that must be considered when selecting the appropriate type.
These conductors are primarily categorized based on the coating of the steel core strands, with two defined types: ACSR/GA and ACSR/AW. In the first type, the steel strands are galvanized, whereas in the second type, they are aluminum-clad. The latter type is preferred for areas with significant corrosive conditions due to the use of AW strands, which offer superior corrosion resistance.