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Reasons for aluminium conductors

Short answer

Aluminium is widely used because it is cheaper and lighter than copper, has a larger diameter that reduces corona loss, and offers good conductivity. ACSR adds a steel core for high tensile strength, enabling long spans with low sag, and its oxide layer resists corrosion.

Give reasons for extensive use of aluminium conductors in overhead transmission lines.

Aluminium, mostly as ACSR, has replaced copper on overhead lines for the following reasons.

  • Lower cost: Aluminium is much cheaper than copper and more readily available.
  • Light weight: Its density (2.7 g/cm³) is about 30 % of copper's (8.9 g/cm³). For the same resistance, an aluminium conductor weighs about half as much, so towers and insulators can be lighter.
  • Larger diameter: For the same resistance its diameter is about 1.26 times that of copper. This lowers the surface electric stress, so corona loss is reduced, which matters at high voltage.
  • Good conductivity: It has about 60 % of copper's conductivity, which is acceptable when the cross-section is increased.
  • Steel reinforcement: Aluminium alone has low tensile strength. ACSR adds a galvanised steel core, which allows long spans with less sag.
  • Corrosion resistance: A thin oxide layer protects the surface.

Its drawbacks are a larger area exposed to wind and ice, a higher coefficient of expansion, and difficult jointing. These are acceptable given its advantages.

✓ Answer checked by Claude Opus 5.5 (high effort)

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