What happens when voltage change in a pole piece doesn't produce a proportional change of magnetic flux?

When there is a change in voltage across a pole piece and it does not result in a proportional change in magnetic flux, this phenomenon is identified as hysteresis loss. Hysteresis loss occurs in magnetic materials when the magnetization of the material lags behind the applied magnetic field due to the material's magnetic properties. This lag creates energy losses as the magnetic domains within the material do not realign perfectly with the alternating magnetic field, leading to frictional losses as the domains are forced into alignment and then return to their original state.

In practical applications, hysteresis loss is a critical aspect to consider in electric machines and transformers, as it affects their efficiency and heat generation. This concept is tied closely to the material properties of the core in use, particularly the type of magnetic materials employed and their historical magnetization characteristics.

Understanding hysteresis loss is crucial for evaluating the performance of electric equipment and can inform decisions related to material selection and design improvements aimed at minimizing energy losses in electrical systems.