Electromagnetic inductor with ferrite core for heating electrically conducting material

A heating system for heating a moving surface of electrically conductive material to temperatures up to 300.degree. C., said system comprising a plurality of induction heating devices for heating said moving surface which is made of ferromagnetic material, said heating devices being disposed across the direction of movement of said electrically conduction material from opposed edges thereof, each said device comprising an open induction heating device for heating electroconductive and mainly ferromagnetic material surfaces to temperatures up to 300.degree. C., said device comprising an open core of ferrite material, a coil of Litz wire wound around said core, a power source connected across said coil to produce an excitation current in said coil within a frequency range of 12 to 25 kHz to generate a magnetic field when energized, magnetic flux concentrator tubes of electrically highly conductive material are disposed between magnetic poles of said core in order to repel and concentrate the magnetic flux lines outside said poles by means of induced eddy currents in said concentrator tubes, said concentrator tubes being placed adjacent to said coil, said concentrator tubes and coil being set into a thermo-conductive, electrically-insulating material and having a cooling fluid circulating through said concentrator tubes for cooling said core and said coil, said magnetic flux lines being able to generate powerful superficial eddy currents and heat in electrically conducting surfaces placed in front of said poles.