The efficiency of a transformer is influenced by its load, and understanding this relationship is essential for optimal performance. Transformer efficiency is typically highest at or near its full-load capacity and tends to decrease at lower loads.

At full load, the transformer operates more efficiently because a significant portion of its core and copper losses are utilized to transfer power to the load. As the load decreases from full load, a higher percentage of the losses becomes a significant proportion of the total power, leading to a reduction in efficiency.

At lower loads, core losses, which include hysteresis and eddy current losses, become relatively more dominant compared to copper losses. Since copper losses depend on the square of the current, they decrease more rapidly than core losses as the load decreases. This results in a decline in overall transformer efficiency at lighter loads.

It’s important to note that transformers are designed to operate most efficiently near their rated load. Operating a transformer at significantly lower loads not only reduces efficiency but can also lead to other issues, such as increased no-load losses and decreased power factor.

In summary, the efficiency of a transformer tends to be highest at or near full load and decreases as the load decreases. Proper matching of the transformer to the intended load is crucial for achieving optimal efficiency in practical applications.