Approximate Calculation of Equivalent Excitation Length in Induction Heating with Flux Conductor Containing Ferromagnetic Plate

In the first part of the article the electromagnetic field is determined between the ferromagnetic plate and the flux conductor - inductor system with approximating analytical calculation. Then the power is calculated, penetrated into the ferromagnetic plate and from this the equivalent excitation length can be obtained with the condition that a uniform excitation of equivalent length gives the same power. The ferromagnetic skin effect is handled by the MacLean´s model, which considers the magnetisation curve as rectangular lines.