IEC 62489-2:2011

IEC 62489-2 ®
Edition 1.0 2011-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electroacoustics – Audio-frequency induction loop systems for assisted
hearing –
Part 2: Methods of calculating and measuring the low-frequency magnetic field
emissions from the loop for assessing conformity with guidelines on limits for
human exposure
Electroacoustique – Systèmes de boucles d’induction audiofréquences pour
améliorer l'audition –
Partie 2: Méthodes de calcul et de mesure des émissions de champ magnétique
basse fréquence à partir de la boucle pour l’évaluation de la conformité aux
instructions sur les limites d’exposition humaine

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IEC 62489-2 ®
Edition 1.0 2011-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electroacoustics – Audio-frequency induction loop systems for assisted
hearing –
Part 2: Methods of calculating and measuring the low-frequency magnetic field
emissions from the loop for assessing conformity with guidelines on limits for
human exposure
Electroacoustique – Systèmes de boucles d’induction audiofréquences pour
améliorer l'audition –
Partie 2: Méthodes de calcul et de mesure des émissions de champ magnétique
basse fréquence à partir de la boucle pour l’évaluation de la conformité aux
instructions sur les limites d’exposition humaine

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX Q
ICS 17.140.50 ISBN 978-2-88912-318-6
– 2 – 62489-2  IEC:2011
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Rated values . 5
4 Situation regarding current standards . 6
5 Configurations of loops . 6
5.1 Main types of configuration . 6
5.2 General considerations . 6
5.3 Large-area loops . 6
5.4 Medium-area loops . 7
5.5 Small-area loops . 7
5.6 Solenoid antennas . 7
6 Calculations . 8
6.1 General . 8
6.2 Solenoid antennas . 8
7 Measurements . 8
7.1 General . 8
7.2 Input signal . 8
7.3 Measuring instrument . 9
8 Comparison of calculated or measured results with guidelines or limits . 9
9 Meeting limits or guidelines . 10
10 Measurement uncertainty . 10
Annex A (informative) Rationale for this product-family magnetic field emission
standard for audio-frequency induction-loop systems (AFILS) in the context of human
exposure to non-ionizing radiation . 11
Annex B (informative) Example calculation using the coupling factor K . 15
Bibliography . 16

Figure 1 – An earhook induction transducer, with a BTE (Behind The Ear) hearing aid
body for scale . 7
Figure 2 – K factor as a function of least distance between wire and disc . 10
Figure A.1 – ICNIRP magnetic field reference levels . 11

Table A.1 – Extract from IEC 62311, Table A.1 – Characteristics and parameters of the
equipment to be considered, with the application to AFILS added . 13

62489-2  IEC:2011 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROACOUSTICS –
AUDIO-FREQUENCY INDUCTION LOOP SYSTEMS
FOR ASSISTED HEARING –
Part 2: Methods of calculating and measuring the low-frequency
magnetic field emissions from the loop for assessing conformity
with guidelines on limits for human exposure

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62489-2 has been prepared by IEC technical committee 29:
Electroacoustics.
The text of this standard is based on the following documents:
FDIS Report on voting
29/728/FDIS 29/736/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.

– 4 – 62489-2  IEC:2011
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 62489 series, published under the general title Electroacoustics –
Audio-frequency induction loop systems for assisted hearing, can be found on the IEC
website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
62489-2  IEC:2011 – 5 –
ELECTROACOUSTICS –
AUDIO-FREQUENCY INDUCTION LOOP SYSTEMS
FOR ASSISTED HEARING –
Part 2: Methods of calculating and measuring the low-frequency
magnetic field emissions from the loop for assessing conformity
with guidelines on limits for human exposure

1 Scope
This part of IEC 62489 applies to audio-frequency induction-loop systems for assisted
hearing. It may also be applied to such systems used for other purposes, as far as it is
applicable. The standard is intended for assessment of human exposure to low-frequency
magnetic fields produced by the system, by calculation and by in-situ testing.
This standard does not deal with other aspects of safety, for which IEC 60065 applies, or with
EMC.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60118-4, Electroacoustics – Hearing aids – Part 4: Induction loop systems for hearing aid
purposes – Magnetic field strength
IEC 60268-1, Sound system equipment – Part 1: General
IEC 60268-2, Sound system equipment – Part 2: Explanation of general terms and calculation
methods
IEC 60268-10:1991, Sound system equipment – Part 10: Peak programme level meters
IEC 61786, Measurement of low-frequency magnetic and electric fields with regard to
exposure of human beings – Special requirements for instruments and guidance for
measurements
IEC 62226-2-1:2004, 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 2-1: Exposure to magnetic fields – 2D models
IEC 62311:2007, Assessment of electronic and electrical equipment related to human
exposure restrictions for electromagnetic fields (0 Hz – 300 GHz)
3 Rated values
The term rated means 'the value stated by the manufacturer'. Rated values are of two kinds:
rated conditions, fundamental values that cannot be verified by measurement, and others that
can be so verified. For a full explanation, see IEC 60268-2.

– 6 – 62489-2  IEC:2011
4 Situation regarding current standards
Current published and draft IEC standards on EMF exposure do not give unambiguous
guidance on the approach that should be taken by product committees. The differences
between the signals that we are concerned with and those considered in depth in EMF
exposure standards are the following:
• wide relative bandwidth (ratio of highest to lowest frequency present, 100 Hz to 5 kHz);
• no predominant frequency within the band;
• rapidly-varying amplitude;
• high ratio of peak amplitude to average r.m.s. amplitude (at least 4).
5 Configurations of loops
5.1 Main types of configuration
There are four main types of configuration:
a) large area loops, with the smallest dimension larger than 1 m, usually installed at floor
level in a room;
b) medium-area loops, with dimensions of the order of 1 m, often oriented in a vertical plane,
installed at service desks and similar positions;
c) small area loops, with the largest dimension less than 1 m;
d) solenoid antennas, including the ear-hook.
NOTE Examples of small-area loops are portable systems, clipboards, neck loops, cushion loops (including those
for use in vehicles) and chair loops.
5.2 General considerations
All loops produce strong fields close to the loop conductor(s). This is shown by the
relationship between current I in a long, straight wire and the magnetic field strength H
produced at a distance R from the centre of the wire, where R is greater than the radius r of
the wire:
H = I/2πR (1)
NOTE 1 Within the wire, the field strength decreases linearly from I/2πr at the surface to zero at the centre.
NOTE 2 For n parallel conductors very close together (i.e. a multi-turn loop), the magnetic field strength is n times
that produced by a single conductor.
For calculations of field strengths in the high field strength regions, very close to the
conductor(s), the 'long, straight wire' approximation is almost always sufficiently accurate,
except for solenoids, which need a completely different treatment (see 6.2).
5.3 Large-area loops
The occupants of the room are likely to come close to the loop conductor only by stepping on
the floor at a point below which the conductor is installed. Such proximity is normally
transient. However, in places of worship, devotional postures may bring parts of the body
other than the feet into proximity. This may also apply in hospitals, treatment rooms and
gymnasia.
Maintenance staff might come into closer contact and for longer periods, but it is unlikely that
the system would then be operating.

62489-2  IEC:2011 – 7 –
5.4 Medium-area loops
For these, there are three considerations:
a) The hearing-aid user is normally at a distance from the loop comparable to its dimensions.
Thus the loop current required to produce a maximum r.m.s. field strength of 400 mA/m (in
compliance with IEC 60118-4) at the hearing-aid is much larger than the current required
to produce it at the centre of the plane of the loop.
b) Nevertheless, the separation ensures that the hearing-aid user is not exposed to the high
fields strengths near the loop conductor.
c) However, staff may come into close proximity of the loop conductor while the system is
working unless steps are taken to maintain a minimum separation.
NOTE These loops often have more than one turn, so that the loop current can be kept reasonably small.
5.5 Small-area loops
For these, again, there are three considerations:
a) The separation for portable loops is very much greater than the loop dimensions, but for
other types, the separation distance may be small or very small unless steps are taken to
maintain a minimum separation.
b) The current apparently required is quite large, because of the large separation.
c) Both users and staff may come into close proximity of the loop, even that of a portable
system.
NOTE These loops usually have many turns, so that the actual current is not so large.
5.6 Solenoid antennas
One example that is commercially available is the ear-hook. This device is typically as shown
in Figure 1. A very small solenoid is incorporated in the stem of the device.

IEC  050/11
Figure 1 – An earhook induction transducer, with a BTE (behind the ear)
hearing aid body for scale
– 8 – 62489-2  IEC:2011
6 Calculations
6.1 General
Calculation of the field strength can be reliably made using Equation (1) in almost all cases,
except where the loop is very small or is a solenoid of length which is not very small
compared with its plan dimensions, such as for the ear-hook device. It is necessary to
calculate the current required in the loop to produce a field strength of 400 mA/m at the
hearing-aid position, taking into account the orientation of the pick-up coil in the hearing-aid
relative to the plane of the loop. In general, this calculation is not easy, but simple
approximate methods give sufficiently accurate results when used with insight. Proprietary
calculation software, based on published mathematical analyses, exists. General-purpose
mathematics software can also be used.
Translating the calculated field strengths into a form comparable with exposure guidelines or
limits is again, not simple. See Clause 8.
6.2 Solenoid antennas
There is no simple expression for the field strength at a point outside a solenoid. A solenoid
may be treated as a stack of loops, or as a magnetic dipole, or the field strength can be
calculated by means of a rather complex equation (See Bibliography).
7 Measurements
7.1 General
In the audio-frequency range, exposure time is irrelevant, because the predominant
physiological effect, if it occurs, is nerve stimulation, which operates over a time-scale of a
few milliseconds. It is therefore appropriate to use a quasi-peak measurement of field
strength. Furthermore, exposure limits and guidelines are given in r.m.s. values, so the quasi-
peak meter should be scaled to read r.m.s. values with a sinusoidal signal. This type of meter,
the peak programme meter (PPM), is further described in IEC 60118-4 and IEC 60268-10
(type II).
It is also necessary to consider the type of magnetic field pick-up coil or sensor. Sensors may
be single-axis, with just one coil, or three-axis, with three orthogonal coils. For use with a
PPM, the single-axis sensor is most convenient, and if it is properly constructed, it is not
difficult to orient it for maximum reading, especially as the likely direction of the field can
usually be predicted from text-book field patterns.
The first measurement to be made shall determine that the field strength is correct at the
point or points where it is intended to be 400 mA/m (or the agreed lower value if adjusted to
reduce loudness, as specified in IEC 60118-4).
NOTE IEC 60118-4 specifies the use of either a PPM or an r.m.s. meter with a 125 ms integration time for the
measurement of magnetic field strength. However, for the purpose of this standard, the 125 ms integration time is
incompatible with the requirement to measure field strengths over times of the order of a few milliseconds.
The instrument specified for measurements on other equipment and systems, such as in IEC 62233, has an
averaging time specified only as an upper limit of 1 s, which is also too slow for the assessment of fields due to
audio-frequency signals.
7.2 Input signal
The input signal for the amplifier shall be the simulated programme signal described in
IEC 60268-1, with additional filtering, -3 dB at 100 Hz and 5 kHz relative to the 1 kHz level,
with ultimate attenuation slopes of at least 12 dB/octave.

62489-2  IEC:2011 – 9 –
7.3 Measuring instrument
It is unlikely that a suitable complete instrument is commercially available at present, since
the application is extremely specialized. However, the design of an adapter for use with
widely-available audio test equipment, or that itself provides the PPM function, is not very
difficult. The elements are the following:
• the pick-up coil, which, because the field strengths of interest are high, needs few turns
and no magnetic core material. Because the fields are highly inhomogeneous, the coil
should be of small dimensions, to minimise averaging. A coil covering four faces of a 1 cm
cube of insulating material is convenient;
• a frequency-response correction circuit, which produces a constant output from a
magnetic field that varies with frequency in the same way as the guidelines or limits, with
bandwidth control so as to discard out-of band interference signals;
• amplification of the signal such that the maximum permissible field strength produces an
output voltage of 0,775 V for connection to the audio test equipment;
• optionally, a quasi-peak detector substantially as specified in IEC 60268-10 (type II) and
means to display its output with a resolution of 1 dB.
8 Comparison of calculated or measured results with guidelines or limits
IEC 62226-2-1 uses the approach specified in IEC 62226-1, whereby a coupling factor, K, is
used to determine the allowance to be made for non-uniformity of the induced current density
in a thin disc, caused by an inhomogeneous magnetic field:
K =J /J (2)
n u
where J is the actual maximum current density and J is the maximum current density due to
n
u
a homogeneous field:
J = σπRfB (3)
u
where
σ is the conductivity of the disc;
R is the radius of the disc;
f is the frequency; and
B is the magnetic induction (flux density) at the edge of the disc nearest to the source of the
magnetic field.
For most purposes, σ may be taken as 0,2 S/m, but for particular cases, the values in Table
C.1 of IEC 62311:2007 should be used. For the majority of cases, Equation (1) applies and
thus Annex B of IEC 62226-2-1:2004 is relevant. Since the values of K are larger for the 100
mm radius disc, this radius is adopted for this standard.
Using the data from Tables B.1 and B.2 of IEC 62226-2-1:2004, a convenient presentation of
the value of K as a function of the distance between the source and the nearest point of the
disc is given in Figure A.1.
– 10 – 62489-2  IEC:2011
1,0
0,9
0,8
0,7
0,6
0,5
0,4
0,3
0,2
0,1
0 1 2 3 4
1×10 1×10 1×10 1×10 1×10
Distance  (mm)
IEC  051/11
NOTE The dotted line represents the equation K = 0,2ln(r) – 0,24, where r is the distance. An example of a
calculation using K is given in Annex B.
Figure 2 – K factor as a function of least distance between wire and disc
9 Meeting limits or guidelines
The field strength near the loop conductor is fixed by the current, which in turn is fixed by the
field strength required at the hearing-aid position. It is clearly not possible to meet exposure
requirements by reducing the current. It is also obvious that any form of shielding is unlikely
to be practicable in most cases.
However, what can be done is to insert a physical barrier between the loop conductor and the
person who might otherwise come too close to it. This barrier can be of any non-magnetic,
non-electrically conducting material.
10 Measurement uncertainty
The total measurement uncertainty includes sensor position and orientation, operating
conditions and, for in-situ measurements, magnetic background noise (although if the system
complies with IEC 60118-4, the effect of noise is negligible). Guidance on uncertainty is
provided in IEC 61786.
K factor
62489-2  IEC:2011 – 11 –
Annex A
(informative)
Rationale for this product-family magnetic field emission standard for
audio-frequency induction-loop systems (AFILS) in the context of human
exposure to non-ionizing radiation

A.1 General
Why do we need such a standard? Because the European Low Voltage Directive includes
'radiation' in its Essential Requirements, and although that was probably originally thought of
as 'ionizing radiation' from cathode-ray tubes, it is now interpreted to include non-ionizing
radiation as well. There are also exposure limits in place in the USA and probably other
countries, or there will be in the foreseeable future. Consequently, the manufacturer of any
product that emits electric or magnetic fields or electromagnetic energy shall be able to
demonstrate that its emissions are not hazardous, and in practice, if there is any doubt this is
very difficult to do, and very costly, without a standard to apply. The CE mark may not legally
be applied to the product, and it may not be marketed in the EU, unless it satisfies all the
Essential Requirements of the Low Voltage Directive.
In the case of AFILS, a person may be able to approach the loop conductor arbitrarily closely,
in fact this is inherent in the function of neck loops, looped cushions, pillow-pads and looped
chairs. But it can also occur with portable AFILS and floor-level area-coverage loops. The
magnetic field strength close to a loop conductor is always very high indeed.
For complex reasons, the European exposure limits are included in a Council
Recommendation, and will be in future Directives, rather than in harmonized standards. They
come from a published paper by the International Commission on Non-Ionizing Radiation
Protection (ICNIRP). The limits are of two kinds; reference levels and basic restrictions.
Reference levels are intended to simplify the determination of compliance, but they may be
exceeded if it can be shown that the basic restrictions are met. The numerical values are still
subject to much discussion and new research is being conducted. For low-frequency magnetic
fields, the reference levels are shown in Figure A.1 below.

1 000
1 00
0,01 0,1 1 10
Frequency  (kHz)
IEC  052/11
Figure A.1 – ICNIRP magnetic field reference levels
EXAMPLE
Since the ICNIRP reference levels are almost certainly exceeded, it is necessary to determine
conformity with the basic restrictions. In the critical high field strength regions, the influence of
the magnetic fields of other conductors than the one nearest to the measuring point is
Field strength A/m
– 12 – 62489-2  IEC:2011
normally negligible. The field distribution can thus be assumed to be that of a single
conductor, with a field strength falling in inverse proportion to the radial distance from the
centre of the conductor. This allows a vast simplification of the assessment procedure.
However, it is unclear which characteristics (r.m.s. or quasi-peak, and what averaging or
attack and release times) of the magnetic field strength are significant in the context of human
exposure. At present, it is assumed that a quasi-peak measurement, substantially in
accordance with the peak programme meter type II of IEC 60268-10 is appropriate and
convenient.
The basic restrictions in the audio frequency range are expressed in terms of current density
(ICNIRP Guidelines, Table 4), and we can use Equation 4 from the Guidelines to relate
current density to known quantities:
J =πRfσB
where J is the current density in the loop of tissue of radius R, f is the frequency, σ is the
tissue conductivity and B is the induction.
For a neck loop, we may take πR = 0,2 m, f = 5 kHz, σ = 0,34 S/m (value for muscle at 10 kHz,
from Table C.1 of IEC 62311:2007). The maximum permissible value of J is f/500 mA/m at f =
5 kHz for exposure of the general public (ICNIRP Guidelines, Table 4). Hence the maximum
permissible value of B is given by:
B=J/πRfσ
which is 29,4 µT, corresponding to a magnetic field strength of H = 23,4 A/m. For a loop
conductor current I of 0,5 A (maximum r.m.s. value, normally occurring for less than 5 s), this
value of H is exceeded within a distance:
r=I/2πH
which is 3,4 mm in this case. So compliance with the basic restriction can be achieved if the
diameter of the loop cable, over the insulation, exceeds by 6,8 mm at least the diameter of the
loop conductor bundle (normally between 10 and 20 turns). This is practicable, but it does not
reflect current practice.
The longer-term (60 s) average r.m.s. current may be as low as 100 mA, which, if it were
approved for use in the above equation, would mean that current neck-loop products meet the
guideline 'basic restriction' requirements.

62489-2  IEC:2011 – 13 –
Table A.1 – Extract from IEC 62311, Table A.1 – Characteristics and parameters of the
equipment to be considered, with the application to AFILS added
Information Further detailed description of the Information needed Applied to AFILS
needed
Frequency Frequency of emissions Nominally 100 Hz to 5 kHz
Waveform Waveform and other information such as duty factor for Speech and music. Very
establishment of peak-and/or average emission complex: needs special
attention.
Multiple frequency Does the equipment produce fields at more than one Yes Yes
sources frequency or fields with a high harmonic content? Are the
emissions simultaneous?
Emission of Voltage differences and any coupling parts e.g., metallic No
electric fields surfaces charged at a voltage potential
Emission of Current flow and any coupling parts e.g., coils, transducers Yes
magnetic fields or loops
Emission of Generation or transmission of high frequency signals and Not significant (EMC
electromagnetic any radiating parts e.g., antennas, loops, transducers and considerations ensure that).
fields external cables
Contact currents Possibility of touching conducting surfaces when either the No
surface or the person is exposed to electromagnetic fields?
Whole body Fields produced by equipment extend over region occupied In some cases
exposure by the whole body
Partial body Fields produced by equipment extend over only part of In some cases
exposure region occupied by the body, or over region occupied by
limbs
Duration/time Duty cycle of emissions, on/off time of power used or Very variable; minutes to
variation emitted by equipment. Variation of power use or emissions hours
during production process
Homogeneity Extent to which the strength of the fields varies over the Very great
body or region of the body that is exposed. Shall be
measured without the presence of a body
Far/near field Are exposures in near field? (see Annex A) Propagating Near field
near field? Far field?
Pulsed/transient Are the emissions pulse-modulated or true pulses? Are No Yes
fields there occasional or periodic transients in the field?
Is the equipment so small that any significant exposure will In some cases.
be to part of the body?
In relation to the wavelength (operating frequency) It is very small compared with
Physical size
the wavelength.
Is it so big that different parts will contribute to exposures In some cases
"independently"?
Power What is the emitted power? What is the power Very low indeed
consumption? If there is an antenna system, what is the
effective radiated power?
Distance (source What is the spatial relationship between the equipment and Very variable, close contact to
to user) the operator or user when it is used normally? The distance many metres separation
used for the assessment shall be specified by the
manufacturer and be consistent with the intended usage of
the equipment
– 14 – 62489-2  IEC:2011
Information Further detailed description of the Information needed Applied to AFILS
needed
Intended usage How is the equipment commonly used? Conditions of Very variable they may be
intended usage producing the highest emission or very close or very distant Yes,
absorption? Operating conditions? How does the intended if there are large metal objects
usage affect the spatial relationship between the equipment in the vicinity of a portable
and the user? Can the usage affect the emission system. It IS a system
characteristics of the equipment? Can the equipment be
part of a system?
Interaction Do the emitted fields change if the equipment is close to the No
sources/user body?
Does the equipment couple to the body during use? Yes

A.2 Reference documents
Guidelines for limiting exposure to time-varying electric, magnetic, and electromagnetic fields
(up to 300 GHz), International Commission on Non-Ionizing Radiation Protection (ICNIRP)
EN 50392:2004, Generic standard to demonstrate the compliance of electronic and electrical
apparatus with the basic restrictions related to human exposure to electromagnetic fields
(0 Hz – 300GHz)
CLC/TR 50442:2005, Guidelines for product committees on the preparation of standards
related to human exposure from [sic] electromagnetic fields

62489-2  IEC:2011 – 15 –
Annex B
(informative)
Example calculation using the coupling factor K

A looped clipboard requires about 30 ampere-turns to be usable, and more would be better
but then the battery life is not as good. In a typical construction, the user's hand may be 15
mm from the loop.
At 15 mm from the loop, using:
H=I/2πr
H = 318 A/m
Then:
J =σπRfB
u
J = 50 mA/m
u
Taking f = 2 kHz, because the energy spectrum of programme material falls at high
frequencies and so the calculated current does not occur at higher frequencies.
At a distance of 15 mm, K = 0,3 (from Figure 2), so J = 15 mA/m , while the ICNIRP
n
(International Commission on Non-Ionizing Radiation Protection) recommended basic
2 2
restriction value for the general public is 4 mA/m , and 20 mA/m for occupational exposure,
at 2 kHz.
The conclusion may be that it is desirable to increase the distance between the hands and the
loop by making the clipboard somewhat thicker or wider. Making the loop smaller is not an
option, because that would increase the number of ampere-turns necessary to produce the
required magnetic field strength.

– 16 – 62489-2  IEC:2011
Bibliography
IEC 62226-1, 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
IEC 62233, Measurement methods for electromagnetic fields of household appliances and
similar apparatus with regard to human exposure
F W GROVER, Inductance Calculations, New York, Dover Publications, 2009

____________
– 18 – 62489-2  CEI:2011
SOMMAIRE
AVANT-PROPOS . 19
1 Domaine d’application . 21
2 Références normatives . 21
3 Valeurs assignées . 22
4 Situation concernant les normes actuelles . 22
5 Configurations des boucles . 22
5.1 Principaux types de configuration . 22
5.2 Considérations générales . 22
5.3 Boucles de grande surface . 23
5.4 Boucles de surface moyenne . 23
5.5 Boucles de petite surface . 23
5.6 Antennes solénoïdes . 23
6 Calculs . 24
6.1 Généralités. 24
6.2 Antennes solénoïdes . 24
7 Mesures . 24
7.1 Généralités. 24
7.2 Signal d’entrée . 25
7.3 Instrument de mesure . 25
8 Comparaison des résultats calculés ou mesurés avec les indications ou les limites . 25
9 Respect des limites ou des instructions . 26
10 Incertitude de mesure . 27
Annexe A (informative) Justifications pour cette norme de famille de produits relative
aux émissions de champ magnétique, concernant les systèmes de boucle d’induction
audiofréquences (AFILS) dans un contexte d’exposition humaine au rayonnement non
ionisant . 28
Annexe B (informative) Exemple de calcul utilisant le facteur de couplage K . 33
Bibliographie . 34

Figure 1 – Un transducteur d’induction auriculaire, avec un corps de prothèse auditive
contour d’oreille pour fournir une échelle . 24
Figure 2 – Facteur K en fonction de la plus petite distance entre le câble et le disque . 26
Figure A.1 – Niveaux de référence du champ magnétique ICNIRP . 29

Tableau A.1 – Extrait de la CEI 62311, Tableau A.1 – Caractéristiques et paramètres

de l’équipement à considérer, également appliqués à l’AFILS . 31

62489-2  CEI:2011 – 19 –
COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE
____________
ÉLECTROACOUSTIQUE –
SYSTÈMES DE BOUCLES D’INDUCTION AUDIOFRÉQUENCES
POUR AMÉLIORER L'AUDITION –
Partie 2: Méthodes de calcul et de mesure des émissions de champ
magnétique basse fréquence à partir de la boucle pour l’évaluation
de la conformité aux instructions sur les limites d’exposition humaine

AVANT-PROPOS
1) La Commission Electrotechnique Internationale (CEI) est une organisation mondiale de normalisation
composée de l'ensemble des comités électrotechniques nationaux (Comités nationaux de la CEI). La CEI a
pour objet de favoriser la coopération in
...