The power transformer circuit is useful in studying the behavior of this equipment, connected to a load or to a system. For the determination of a correct equivalent circuit, it is necessary to electrically model the phenomena and the electrical losses resulting from its operation.
When a variant time magnetic flux is superimposed on a conductor, eddy currents are distorted inside this conductor. These parasitic currents cause extra Joule losses, even if there is no main electric current flowing in the conductor.
Large amounts of magnetic dispersion flux are caused when the transformer is fully charged. The dispersion flow lines do not enter the winding conductors, but will cross other metal parts, inducing parasitic currents in them. In this way, we can conclude that the losses due to eddy currents are proportional to the square of the loading current.
Likewise, the circuit should have all copper losses, eddy currents, losses by hysteresis and dispersion flow, and also predict the excitation current. The losses in copper have been clarified and we conclude that these losses are directly proportional to the square of the current passing through the conductor.