The A-C resistance of solid magnetic wires

With the development of new types of ferromagnetic materials, magnetic conductors are increasingly used in connection with automatic control and electric power, and for industrial and scientific purposes. Here, the a-c resistance varies not only with the frequency but also with the current, as the permeability is not constant over the cross section of the wire. Previous authors1??3 have given experimental results, and have used qualitative solutions. To make the solution possible, the theoretical analysis has been mainly based on assuming average constant permeability over the cross section of the conductor; this, however, is not actually the case, as the permeability varies from the axis to the circumference; see Figs. 1 through 3. As a consequence, previous authors have not found it possible to obtain numerical correlation between the magnetic properties of such wire deduced from its impedance measurement and those measured by direct magnetic methods. There is still less possibility of predicting the a-c resistance or inductance of these wires from their measured magnetic properties.