Some 2D–3D aspects of shielding of longitudinal sources of extremely low frequency magnetic fields Ener Salinas Æ Marina Rezinkina Æ Juan Atalaya Published online: 16 January 2009 Ó Springer Science+Business Media, LLC 2009 Abstract Typical sources of extremely low frequency magnetic fields include components of the power network and, as an extension, AC railway powering. The majority of these sources have longitudinal shapes. There is some- times the need to reduce these fields in specific areas of interest. In this article, practical aspects are studied of shielding design when this type of source is involved. The focus is on design features not often treated in the shielding literature. One aspect relates to the differences between 2D and 3D simulations and experimental validation for a rel- atively long system of conductor and shield; as an example, the screening of the magnetic field of a railway system is presented. Another aspect relates to issues that arise when edge effects become relevant for actual systems. It is established that shielding factors are considerably improved when shielding of the edges is properly taken into account. The presence of gaps or loose contacts that are often responsible for low shielding efficiency is also studied. Experimental tests show that overlapping shields or the use of conductive patches significantly improves shielding efficiency. A last aspect is related to cost- effectiveness of shielding designs; in this case, numerical computations are used for benchmarking shielding prop- erties for long busbars in secondary substations. Keywords Shielding Á Extremely low magnetic fields Á Finite element method Á AC powered trains Á Busbars 1 Introduction Electrical power installations, i.e. power lines, underground cables, substations and even AC railways, are sources of extremely low frequency (ELF) magnetic fields, which in some cases and in specific areas of interest are necessary to reduce. The main reason for this operation is suspected harmful effects of long-term exposure on human health; another reason is the interference on equipment sensitive to these fields. In absence of a biological mechanism that could explain such effects, the first reason has become a debated issue. Different countries have different responses to this matter. Some countries maintain the ICNIRP (International Commission on Non-Ionizing Radiation Protection 2003) value which is based on measurable effects of induced currents in the human body and its value is 100 lT for power frequencies. Yet, several organizations (especially in Europe) have adopted the precautionary principle, i.e. to reduce magnetic fields in areas of long-term public exposure when it does not represent an economical burden. Following these lines, the aim, when designing techniques for ELF mitigation, is to produce cost-effective solutions. A common type of ELF has longitudinal shape. Recent studies on AC railway powering (Buccella et al. 2004; Salinas et al. 2007) are also related to this type of source. In this article, numerical and experimental methods are E. Salinas (&) Faculty of Engineering, Science and The Built Environment, London South Bank University, 103 Borough Road, London SE1 0AA, UK e-mail: salinae@lsbu.ac.uk M. Rezinkina Science and Technology Center of Magnetism of Technical Objects, The Ukrainian National Academy of Sciences, Industrialnaja St. 19, 61106 Kharkov, Ukraine e-mail: marinar2@mail.ru J. Atalaya Chalmers University of Technology, 412 96 Gothenburg, Sweden e-mail: juan.atalaya@chalmers.se 123 Environmentalist (2009) 29:141–146 DOI 10.1007/s10669-008-9206-0