Transformers Alumnium
In North America, aluminum is the predominant choice of winding material for low-voltage, dry-type transformers larger than 15 kilovolt-amperes(kVA). In most other areas of the world, copper is the predominant winding material.
Aluminium is used for transformer windings and for other wiring use. As you note, Aluminium has higher resistivity to Copper so needs a larger wire size than Copper to achieve the same number of turns OR in a given winding space Aluminium windings will have a larger resistance than if Copper is used.
