Short-circuit losses

Short-circuit losses (also known as copper losses or load losses) are the losses of a transformer that occur in the windings due to their electrical resistance. They occur when current flows through the windings and are released in the form of heat.

The short-circuit losses are determined under defined conditions: at nominal frequency and reference temperature, while the nominal current flows through the windings when the secondary side is short-circuited.

Their level depends on the load on the transformer and increases with increasing current. The short-circuit losses are proportional to the square of the current.

They are an important parameter for the efficiency and thermal design of transformers.