इंटरनेट मानक Disclosure to Promote the Right To Information Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public. “जान1 का अ+धकार, जी1 का अ+धकार” “प0रा1 को छोड न’ 5 तरफ” Mazdoor Kisan Shakti Sangathan Jawaharlal Nehru “The Right to Information, The Right to Live” “Step Out From the Old to the New” IS/IEC 62226-1 (2004): Exposure to Electric or Magnetic Fields in the low and Intermediate Frequency Range - Methods for Calculating the Current Density and internal Electric Field Induced in the Human Body, Part 1: General [LITD 9: Electromagnetic Compatibility] “!ान $ एक न’ भारत का +नम-ण” Satyanarayan Gangaram Pitroda ““IInnvveenntt aa NNeeww IInnddiiaa UUssiinngg KKnnoowwlleeddggee”” “!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता हहहहै””ै” Bhartṛhari—Nītiśatakam “Knowledge is such a treasure which cannot be stolen” IS/IEC 62226-1 : 2004 Hkkjrh; ekud fuEu o eè;orhZ vko`fr Ja[kyk esa fo|qr ;k pqEcdh; {ks=k dk vukoj.k bla kuh 'kjhj e as fo|rq èkkjk ?kuRo vkjS çfs jr — vkarfjd fo|qr {ks=k dks ifjdyu djus dh fofèk Hkkx 1 lkekU; Indian Standard EXPOSURE TO ELECTRIC OR MAGNETIC FIELDS IN THE LOW AND INTERMEDIATE FREQUENCY RANGE — METHODS FOR CALCULATING THE CURRENT DENSITY AND INTERNAL ELECTRIC FIELD INDUCED IN THE HUMAN BODY PART 1 GENERAL ICS 17.220.20 © BIS 2012 B U R E A U O F I N D I A N S T A N D A R D S MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG NEW DELHI 110002 February 2012 Price Group 5 Electromagnetic Compatibility Sectional Committee, LITD 09 NATIONAL FOREWORD This Indian Standard (Part 1) which is identical with IEC 62226-1 : 2004 ‘Exposure to electric or magnetic fields in the low and intermediate frequency range — Methods for calculating the current density and internal electric field induced in the human body — Part 1: General’ issued by the International Electrotechnical Commission (IEC) was adopted by the Bureau of Indian Standards on the recommendation of the Electromagnetic Compatibility Sectional Committee and approval of the Electronics and Information Technology Division Council. The text of IEC Standard has been approved as suitable for publication as an Indian Standard without deviations. Certain conventions are, however, not identical to those used in Indian Standards. Attention is particularly drawn to the following: a) Wherever the words ‘International Standard’ appear referring to this standard, they should be read as ‘Indian Standard’. b) Comma (,) has been used as a decimal marker while in Indian Standards, the current practice is to use a point (.) as the decimal marker. Only the English language text in the IEC Standard has been retained while adopting it in this Indian Standard, and as such the page numbers given here are not the same as in the IEC Standard. For the purpose of deciding whether a particular requirement of this standard is complied with, the final value, observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance with IS 2 : 1960 ‘Rules for rounding off numerical values (revised)’. The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard. IS/IEC 62226-1 : 2004 Indian Standard EXPOSURE TO ELECTRIC OR MAGNETIC FIELDS IN THE LOW AND INTERMEDIATE FREQUENCY RANGE — METHODS FOR CALCULATING THE CURRENT DENSITY AND INTERNAL ELECTRIC FIELD INDUCED IN THE HUMAN BODY PART 1 GENERAL 1 Scope This part of IEC 62226 provides means for demonstrating compliance with the basic restrictions on human exposure to low and intermediate frequency electric and magnetic fields specified in exposure standards or guidelines such as those produced by IEEE and ICNIRP. The object of IEC 62226 is – to propose a more realistic approach to the modelling of the human exposure to low frequency electric and magnetic fields, using a set of models of growing complexity for the field emission source, or the human body or both; – to propose standardised values for the electrical parameters of organs in human body: electrical conductivity and permittivity and their variation with the frequency. The present basic standard does not aim at replacing the definitions and procedures specified in exposure standards or guidelines, such as those produced by IEEE or ICNIRP, but aims at providing additional procedures with a view to allowing compliance assessment with these documents. The present basic standard provides means for demonstrating compliance with the basic restrictions without having to go to the sophisticated models. Nevertheless, when the exposure conditions are well characterized (such as in product standards, for example) and when results from such models are available, they can be used for demonstrating compliance with EMF standards or guidelines. NOTE 1 Examples of use of such sophisticated models can be found in the IEC Trend Technology Assessment [2]1. NOTE 2 References to the scientific literature are given in the bibliography. 2 General data on electromagnetic fields and human exposure 2.1 General The total field emitted by any electrical device when operating is composed of the electric field and the magnetic field and is called the electromagnetic field. It is characterised by its frequency f or its wavelength λ, which is the ratio of the velocity of light in vacuum (c), divided by its frequency: λ = c/f. ——————— 1 Figures in square brackets refer to the Bibliography 1 IS/IEC 62226-1 : 2004 Where the wavelength is large compared with – the distance of the individual from the equipment, and – the size of the individual, the exposure to the fields is defined as “near field exposure“. Under these conditions, electric and magnetic fields are independent and can be studied separately. In practice this is valid for the range of frequencies covered by this standard. 2.2 Electric field Electric fields cause displacement of electric charges in conductive objects (including living bodies) and, because these fields are alternating, the electric charges move to and from. The result is an “induced” alternating current, and related induced electric field, inside the conductive object. It is important to note that, for an object of uniform conductivity, to a very large degree, this current is independent of whether the object is a good or a poor conductor of electricity. By contrast, the associated induced electric field strongly depends on the electrical conductivity of the body. The current induced by an electric field depends on – the shape and size of the conducting object; – the characteristics (magnitude, polarisation, degree of non uniformity, etc.) of the unperturbed field (see definition 3.1.19); – the frequency of the field. The induced alternating current would also depend on whether the body is in electrical contact with the ground and on the presence of other conducting bodies nearby. 2.3 Magnetic field Alternating magnetic fields create alternating electric fields and associated currents in conductive media. These currents are called eddy currents. Because living tissues are electrically conducting, induction also occurs in the human body. The current induced by a magnetic field depends on – the shape, size and conductivity of the conducting object; – the characteristics (magnitude, polarisation, degree of non uniformity, etc.) of the field. In contrast to electric field, magnetic field is not normally perturbed by nearby objects; – the frequency of the field. The magnetic field level decreases with distance from its source. The variation of field with distance is described for three different types of source. – A single conductor (e.g. railway overhead power supply): the magnetic field decreases as 1/d, where d is the distance from the energised conductor (Ampere’s law). – A system of parallel conductors, energised by a system of balanced currents (e.g. electrical networks): the magnetic fields decrease as 1/d², where d is the mean distance from the energised conductors. This empirical law is valid only when d is large compared with the distance between the different conductors. 2 IS/IEC 62226-1 : 2004 – Localised sources (e.g. electrical domestic appliances) can be considered as magnetic dipoles: the magnetic fields decrease as 1/d3, where d is the distance from the source. In the same way as previously, this approximate law only applies when d is large compared with the size of the source itself. 3 Terms and definitions, symbols and abbreviations 3.1 Terms and definitions For the purposes of this document, the terms and definitions given below apply. 3.1.1 basic restrictions according to the terminology in use in health recommendations relating to the exposure to electromagnetic fields, the exposure limits based on biological effects established by biological and medical experimentation about these fundamental induction phenomena Basic restrictions usually include safety factors to allow for uncertainty in the scientific information defining the threshold for the effect. NOTE 1 The precise definition of this term may vary from one EMF health guideline to another. NOTE 2 For the frequency range covered by this standard the basic restrictions to make reference to are generally expressed in terms of induced current density or internal electric field. Because the basic restriction is a quantity inside the body that cannot be measured, a corresponding reference level is generally derived and used in EMF health guidelines. 3.1.2 coupling factor K factor used to enable exposure assessment for complex exposure situations, such as non- uniform magnetic field or perturbed electric field NOTE 1 The coupling factor K has different physical interpretations depending on whether it relates to electric or magnetic field exposure. NOTE 2 The value of the coupling factor K depends on the model used for the field source and the model used for the human body. When exposure conditions are defined, such as in a product standard, precise values of the coupling factors can be specified directly and can be used such as defined in product standards. 3.1.3 current density vector quantity whose magnitude is equal to the charge that crosses per unit time a unit surface area perpendicular to the flow of charge NOTE Current density is expressed in amperes per square metre (A/m2). 3.1.4 environmental field electric or magnetic field external to the body, and measured in the absence of the body 3.1.5 electric field strength E r r magnitude of the vector field E which determines the force F on a static electrical charge q: r r F = qE NOTE The electric field strength is expressed in units of volts per metre (V/m). 3 IS/IEC 62226-1 : 2004 3.1.6 electric displacement D r r magnitude of a field vector D that is related to the electric field E by the formula: r r D =εεE r 0 where εis the relative permittivity of the medium and ε is the permittivity of vacuum r 0 NOTE The electric displacement is expressed in units of coulombs per square metre (C/m2). 3.1.7 exposure situation that occurs wherever a person is subjected to electric, magnetic or electromagnetic fields NOTE The word “exposure” is also commonly used to mean “exposure level” (see 3.1.8). 3.1.8 exposure level value of the considered quantity when a person is exposed to electric, magnetic or electromagnetic fields 3.1.9 exposure, partial-body exposure that results from localized absorption of the energy 3.1.10 exposure, non-uniform exposure levels that result when fields are non-uniform over volumes comparable to the whole human body NOTE See also definitions 3.1.8 and 3.1.9. 3.1.11 hot spot localised area of higher field 3.1.12 induction electric or magnetic field in a conducting medium caused by the action of a time-varying external (environmental) electric or magnetic field 3.1.13 magnetic flux density B r r magnitude of a field vector B at a point in the space that determines the force F on an r electrical charge q moving with velocity v: Fr =qvr×Br NOTE Magnetic flux density is expressed in units of teslas (T). One tesla is equal to 104 gauss (G). 4 IS/IEC 62226-1 : 2004 3.1.14 magnetic field strength H r r magnitude of a field vector H that is related to the magnetic flux density B by the formula: r r B = µµH r 0 where µ is the relative permeability of the medium and µ is the permeability of the free r 0 space. NOTE The magnetic field strength is expressed in units of amperes per metre (A/m). 3.1.15 non-uniform field field that is not constant in amplitude, direction, and phase over the dimensions of the body or part of the body under consideration 3.1.16 permeability (absolute) µ scalar or tensor quantity the product of which by the magnetic field strength H in a medium is equal to the magnetic flux density B: B = µH NOTE For an isotropic medium the absolute permeability is a scalar; for an anisotropic medium it is a tensor. 3.1.16.1 relative permeability µ r the magnetic flux density B divided by the magnetic field H multiplied by µ 0 r r B = µH with µ = µ µ 0 r where µ is the absolute permeability of the medium expressed in henrys per metre (H/m) 3.1.16.2 permeability of vacuum µ 0 scalar quantity the product of which by the magnetic field strength H in vacuum is equal to the magnetic flux density B: B = µ0 H 3.1.17 perturbed field field that is changed in magnitude or direction, or both, by the introduction of an object NOTE The electric field at the surface of the object is, in general, strongly perturbed by the presence of the object. At power frequencies, the magnetic flux density is not, in general, greatly perturbed by the presence of objects that are free of magnetic materials. Exceptions to this include regions near the surface of thick electrical conductors and regions far from thick conductors, if the conductor is close to the magnetic field source. The perturbation in these instances is due to opposing magnetic fields produced by eddy currents in the conductors. 3.1.18 reference level according to the terminology in use in health recommendations relating to the exposure to electromagnetic fields, the value of the uniform electric or magnetic field, which produces the basic restriction (see 3.1.1) in a body which is exposed to that field Reference level is given for the condition of maximum coupling of the field to the exposed individual, thereby providing maximum protection. 5