Copper losses

Copper losses are electrical losses that occur in the current-carrying conductors of electrical equipment, particularly in the windings of transformers and electrical machines. They are caused by the electrical resistance of the conductors and occur in the form of heat.

In transformers, copper losses occur in both the primary and secondary windings. They are dependent on the current and increase quadratically with increasing current. The relationship can be described by P = I² – R, where I is the current and R is the electrical resistance.

As the resistance is temperature-dependent, the copper losses also increase as the operating temperature rises. They belong to the so-called load losses, as they depend directly on the load on the transformer.

A reduction in copper losses can be achieved through larger conductor cross-sections, high-quality materials or optimized windings. They are a key factor for the efficiency and thermal design of transformers.