Iron Losses

Iron losses occur in alternating magnetic fields (remagnetization in the iron) during the operation of electrical machines, equipment or components, due to heat losses in the iron. The remagnetization can be caused either by alternating currents and by the movement of the magnetic field or the iron. The iron losses break down into hysteresis losses and eddy current losses.
Hysteresis losses occur when materials are remagnetized. During remagnetization, energy must be expended to change the orientation of the internal elemental structure. This process causes heat in the iron. Heat losses per volume occur with each remagnetization. In the technical world, these are called hysteresis losses or remagnetization losses.
Eddy current losses occur when the magnetic flux changes. When the magnetic flux changes, the electrical conductors enclosed in the flux induce an electrical voltage. Due to the electrical conductivity of the iron, the voltage in the iron, leads to eddy currents. These currents cause the iron to heat up. Eddy current losses can be reduced if the iron is divided into stacked and insulated sheets (lamination).