Electromagnetics in induction heating

The longstanding IEEE definition of induction heating- "the heating of a nominally conducting material in a varying electromagnetic field due to its internal losses" is interpreted here as including processes in which these losses are associated with conducted, as well as induced, currents. During the past three decades, induction heating, utilizing induced currents, has grown into a multimillion dollar industry - heating for melting, forging, hardening, brazing, welding, and many more applications. Equipment ratings are from a few hundred watts to over 60000 KW, at frequencies ranging from 50 Hz to several MHz. More recently, a number of processes known generally as High Frequency Resistance Heating have received worldwide acceptance, especially in the tube and pipe welding fields. They employ the same electromagnetic phenomena to cause internal losses in nominally conducting material, but these losses are associated with current which is introduced through contacts. This paper describes these electromagnetic phenomena, and emphasizes the similarity of these commonly-called different processes.