Power loss

The power loss of a transformer is made up of iron losses (caused by induction and mains frequency) and copper losses (caused by the current through the winding and its temperature). Iron losses are idle losses and are therefore always present. They can be optimized by the structure and type of core plates. Copper losses are load-dependent, they are always specified at nominal load or nominal current and can be influenced by the quality of the winding and the cross-section of the copper conductor used (ohmic resistance). A reduction in copper losses is always associated with a reduction in the resistance of the winding material used.

The iron losses consist on the one hand of hysteresis losses caused by remagnetization and on the other hand of eddy current losses in the induced alternating magnetic field.

In a real transformer, an efficiency factor is determined that calculates the ratio of the electrical power on the secondary side (output) to the power on the primary side. The difference between the two sides are the losses, which must then be differentiated under no-load losses or losses under load.