Why is Copper or Aluminum Used for Low Voltage Transformers?

Why Is Copper Or Aluminum Used For Low Voltage Transformers? April 10, 2022

There lies a constant drift between copper and aluminum as winding materials for low voltage transformers. Both the materials have successfully proven their efficient applications in the transformers. However, the low voltage transformer manufacturers have a steep inclination for copper for multiple reasons - galvanic reaction, creep level, thermal conductivity, electrical conductivity, etc. Nonetheless, aluminum nowhere falls behind in producing similar levels of efficiency levels, losses, and performance.


With this blog, let’s study why and how are these materials used in a low voltage transformer. They share multiple similarities concerning oxidization and performance losses depending on the method of coiling or winding. However, a few dissimilarities leading to  a never-ending debate and leaving the manufacturers out in the middle are -



Difference between the use of Aluminum/Copper






It is a cheaper winding option, welcoming commercial benefits.

Copper is relatively more expensive than aluminum.



Being a soft metal, aluminum extends the better scope for being wounded in the manufacturing process.

Creating a winding out of copper is tougher, considering its level of hardness.

Current capacity

Aluminum comparatively offers a low current carrying capacity, thus demanding the use of 1.8 times more material to align with that of copper. 

The current carrying capacity of copper is much higher than that of aluminum.

Transformer Size

The aluminum wound transformers are built in huge sizes due to larger coil sizes and windings.

Copper wounded transformers are smaller in the size.


These metals continue to offer certain benefits over its counterpart, making them worthy of debate. For instance, the thin layer of oxides on the surface of aluminum aids in effective corrosion resistance. Consequently, generating lower eddy losses and abating the risks for hot spots. The smaller sizes of copper transformers curtail the cost of magnetic steel, tank, and oil used in its design. Contrastingly, the aluminum wound coils are larger implying increased costs of related transformer components. Additionally, the transformer manufacturers use pound-for-pound aluminum for doubling the conductivity of aluminum over copper.


The next arising question turns out to be how these metals are used to construct a low voltage transformer. The basic application involves the construction of transformer windings. Furthermore, the decision of which material, why, and the means of its deployment becomes discretionary. The decision relies on multiple factors - the preferred size of that transformer, connectivity, conductivity, current carrying capacity, amount of energy loss generation, material cost, related components, etc.


Determining the right material for a transformer is not defined by the industry preference for one metal over another. But on the specific reasons laid for those preferences. Because of the growing success of aluminum due to cost benefits, amazing performance of attentively designed aluminum joints over copper joints. Whereas, in contrast, copper successfully allows for saving space, low levels of creep, improved performance, etc.


The preferences within the industry are shifting. And for always, it will give the credence to the practices of building electrical connections that are helpful for the entire industry.

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