Selection of copper against aluminium windings for distribution transformers

Copper and aluminium are the two conductors most commonly used in transformer windings. This study presents a comprehensive comparison of distribution transformers built either with copper or with aluminium windings. The comparison is based on winding material conductivity, density, cost, connectivity, oxidation, machinability and behaviour under short-circuit. Additionally, a parametric analysis of transformer designs as a function of the cost of copper against aluminium is presented. The study establishes the winding material cost range that indicates when it is more economical to build the transformer windings with copper or with aluminium. All comparisons are carried out with cost of optimised transformer designs that fulfil all specifications together with manufacturing and operating constraints.