Conductors are reinforced with a steel core to increase their mechanical strength, which is crucial for supporting long-distance spans where the conductor's own weight and external forces like wind and ice can cause significant sag. The steel core in an ACSR conductor bears the mechanical tension, while the aluminum strands handle the electrical current.

In contrast, an AAAC conductor is made entirely from a specialized aluminum alloy that provides both conductivity and sufficient mechanical strength, eliminating the need for a separate steel core. This makes AAAC lighter and more corrosion-resistant, as it avoids the galvanic corrosion that can occur between aluminum and steel in an ACSR conductor. The choice between ACSR and AAAC depends on the specific project requirements, including span length, environmental conditions, and desired sag characteristics.