It’s a bimetallic conductors. The inner layers are composed by steel wires and the external layers are composed by hard-drawn aluminium AA1350-H19. The steel wires guarantee high mechanical performances.
This kind of conductor is used for medium and long spans thanks to the high value of specific mechanical resistance and good transport capacity.
The steel section will change to obtain the RTS requested. The modulus of elasticity of single steel wire is three time greater than an aluminium single wire. The final modulus of elasticity is defined by the composition of ACSR conductor (number of steel wires, number of aluminium wires).
The same behaviour will be found for the coefficient of linear expansion. The final value is determined by the single value of the material used and the modulus of elasticity and the section of the two components.
To guarantee the protection of steel, a thin zinc coating on the wire is carried out. The zinc coating is important to prevent the galvanic corrosion.
ACSR conductors has always been given high reliability thanks for the presence of steel that ensures the conductor large safety margins.