ACSR (Aluminium Conductor Steel Reinforced):
Owing to the low tensile strength of aluminium, aluminium conductors produce greater sag which prohibits their use for longer spans and make them unsuitable for long distance transmission. The tensile strength of aluminium conductor is increased with a core of galvanized steel wires. The composite conductor thus obtained is called as ACSR. The steel conductors used are galvanized in order to prevent rusting and electrolytic corrosion. The cross sections of two metals are in the ratio 1: 6, but in the case of high strength conductors their ratio may be 1: 4.
1. The steel core takes a greater percentage of mechanical stresses while the aluminium carriers bulk of current.
2. ACSR, conductor has a larger diameter than any other type of conductor of same resistance, so corona losses are reduced but stronger supports are required for a given span.
3. ACSR, conductors get deteriorated in service due to atmospheric corrosion (as a result of bimetallic action of zinc and aluminium, electro-chemical in nature).
4. Since the skin effect is very predominant in ASCR conductor, therefore, its resistance (composite conductor) is taken equal to that of the aluminium covering alone. The resistance of ASCR conductor is taken to be equal to that of a non-magnetic conductors having diameter equal to that outside of the ACSR conductor.
Uses: ACSR conductor being of high tensile and lighter in weight produces small sag and therefore longer spans can be used.