Some Considerations About Environmental Elf Magnetic Field Reduction

The paper presents some aspects connected with the reduction of ELF magnetic fields in civil and industrial environments. After an introduction to the problems arising from the exposure of human beings to low frequency magnetic fields and from the disturbances caused to electronic appliances and Video Display Units (VDU), a brief description of the numerical models for the magnetic field evaluation is presented, discussing their merits and drawbacks. The attention is then devoted to the analysis of possible solutions for magnetic field reduction, as the conductor arrangement and the passive and active shielding techniques. The efficiency of ferromagnetic, conductive or combined shields having different shape and position is investigated, describing the results of a research activity developed both by experiments and simulation. In particular, the shielding efficiency of different types of soft ferromagnetic materials (low-carbon steel, non-oriented Fe-Si, grain-oriented Fe-Si) is evaluated. Finally, some results of the studies aiming at reducing the magnetic fields from overhead power lines or industrial sources are presented.