IEC 61347-2-14:2018

SLOVENSKI SIST IEC 61786:2005
STANDARD
junij 2005
Merjenje nizkofrekvenčnih elektromagnetnih polj z vidika izpostavljenosti ljudi
– Posebne zahteve za instrumente in napotki za merjenje
Measurement of low-frequency magnetic and electric fields with regard to exposure
of human beings – Special requirements for instruments and guidance for
measurements
ICS 17.220.20 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

NORME
CEI
INTERNATIONALE
IEC
INTERNATIONAL
Première édition
STANDARD
First edition
1998-08
Mesure de champs magnétiques et électriques
à basse fréquence dans leur rapport à l’exposition
humaine – Prescriptions spéciales applicables
aux instruments et recommandations
pour les procédures de mesure
Measurement of low-frequency magnetic
and electric fields with regard to exposure
of human beings – Special requirements for
instruments and guidance for measurements
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PRICE CODE
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For price, see current catalogue

61786 © IEC:1998 – 3 –
CONTENTS
Page
FOREWORD . 5
INTRODUCTION . 7
Clause
1 Scope. 9
2 Normative references. 9
3 Definitions. 11
4 Symbols. 21
5 Measurement of alternating magnetic fields . 23
5.1 Instrumentation specifications. 23
5.2 Calibration. 31
5.3 Measurement uncertainty. 39
5.4 Recording and reporting measurement results. 41
5.5 Measurement procedure. 43
6 Measurement of alternating electric fields . 45
6.1 Instrumentation specifications. 45
6.2 Calibration. 49
6.3 Measurement uncertainty. 55
6.4 Recording and reporting measurement results. 55
6.5 Measurement procedure. 57
Annexes
A (normative) Calibration methods. 61
B (normative) Sources of measurement uncertainty . 83
C (informative) General characteristics of quasi-static magnetic
and electric fields . 105
D (informative) Magnetic flux density meters (magnetic field meters) –
Guidance for measurements . 113
E (informative) Electric field strength meters (electric field meters) –
Guidance for measurements . 143
F (informative) Static magnetic field-measuring instrumentation . 165
G (informative) Units . 167
H (informative) Bibliography . 169

61786 © IEC:1998 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MEASUREMENT OF LOW-FREQUENCY MAGNETIC AND ELECTRIC FIELDS
WITH REGARD TO EXPOSURE OF HUMAN BEINGS –
SPECIAL REQUIREMENTS FOR INSTRUMENTS AND
GUIDANCE FOR MEASUREMENTS
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, the IEC publishes International Standards. Their preparation is
entrusted to technical committees; any IEC National Committee interested in the subject dealt with may
participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. The IEC collaborates closely with the International Organization
for Standardization (ISO) in accordance with conditions determined by agreement between the two
organizations.
2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has representation
from all interested National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical reports or guides and they are accepted by the National Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61786 has been prepared by IEC technical committee 85:
Measuring equipment for electromagnetic quantities.
The text of this standard is based on the following documents:
FDIS Report on voting
85/191/FDIS 85/193/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.
Annexes A and B form an integral part of this standard.
Annexes C, D, E, F, G and H are for information only.
Words in bold in the text are defined in clause 3.

61786 © IEC:1998 – 7 –
INTRODUCTION
The increasing interest in characterizing human exposure to quasi-static magnetic and electric
fields in a number of environments has led to the development and marketing of many field
meters with a range of specifications. Sources of quasi-static fields include devices that
operate at power frequencies (50/60 Hz) and produce power frequency and power frequency
harmonic fields, as well as devices which produce fields that are independent of the power
frequency. Examples in the latter category include video display terminals (vertical scan
/
magnetic field), electric railroads (16 Hz and 25 Hz), mass transportation systems (0 Hz to
3 kHz depending on characteristics of adjustable speed drive), commercial airplanes (400 Hz),
induction heaters (50 Hz to 9 kHz), and electric automobiles. Because of differences in the
characteristics of the fields from sources in the various environments, e.g. frequency content,
temporal and spatial variations, polarization, and magnitude, the instrumentation requirements
and measurement procedures will be different in the various environments. Commercially
available instrumentation exists to measure human exposure to the field levels as well as to
other parameters that characterize the fields. The instrumentation and measurement methods,
as they may pertain to human exposure, are the focus of this document. It should be noted that
the parameters that describe quasi-static fields and the mechanisms for their interaction with
humans during magnetic and electric field exposure are still unknown.
The intended users of this International Standard include manufacturers of instrumentation and
groups or individuals interested in characterizing quasi-static magnetic and electric fields as
they relate to human exposure. It is assumed that users intending to perform measurements
have some knowledge of the instrumentation as well as field sources and their characteristics.
In the absence of such knowledge, it is strongly advised that some training be received. This
standard may serve as a textbook for the training process because of the technical information
provided in the annexes.
61786 © IEC:1998 – 9 –
MEASUREMENT OF LOW-FREQUENCY MAGNETIC AND ELECTRIC FIELDS
WITH REGARD TO EXPOSURE OF HUMAN BEINGS –
SPECIAL REQUIREMENTS FOR INSTRUMENTS AND
GUIDANCE FOR MEASUREMENTS
1 Scope
This International Standard provides guidance for measuring the steady-state root-mean-
square (r.m.s.) values of quasi-static magnetic and electric fields which have a frequency
content in the range 15 Hz to 9 kHz. Sources of quasi-static fields include devices that
operate at power frequencies and produce power frequency and power frequency harmonic
fields, as well as devices that produce fields independent of the power frequency. The
magnitude ranges covered by this standard are 100 nT to 100 mT and 1 V/m to 50 kV/m for
magnetic fields and electric fields, respectively. When measurements outside this range are
performed, most of the provisions of this standard will still apply, but certain provisions such as
specified uncertainty and calibration procedure may need modification. Specifically, this
standard
– defines terminology;
– identifies requisite field meter specifications;
– indicates methods of calibration;
– defines requirements on instrumentation uncertainty;
– describes general characteristics of fields;
– surveys operational principles of instrumentation;
– describes measurement methods that achieve defined goals pertaining to human exposure.
Sources of uncertainty during calibration and measurements are also identified and guidance is
provided on how they should be combined to determine total measurement uncertainty. In
regard to electric field measurements, this standard considers only the measurement of the
unperturbed electric field strength at a point in space (i.e. the electric field prior to the
introduction of the field meter and operator) or on conducting surfaces.
NOTE – Some separation between the normative measurement requirements in clauses 5 and 6 and the example
measurement protocols and guidance for measurements in annexes D and E is unavoidable because of format
requirements.
2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this International Standard. At the time of publication, the editions
indicated were valid. All normative documents are subject to revision, and parties to
agreements based on this International Standard are encouraged to investigate the possibility
of applying the most recent editions of the normative documents indicated below. Members of
IEC and ISO maintain registers of currently valid International Standards.
IEC 61000-3-2:1995, Electromagnetic compatibility (EMC) – Part 3: Limits – Section 2: Limits
for harmonic current emissions (equipment input current ≤16 A per phase)

61786 © IEC:1998 – 11 –
IEC 61000-4-2:1995, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 2: Electrostatic discharge immunity test – Basic EMC Publication
IEC 61000-4-3:1995, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 3: Radiated, radio-frequency, electromagnetic field immunity test
IEC 61000-4-4:1995, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 4: Electrical fast transient/burst immunity test – Basic EMC publication
IEC 61000-4-6:1996, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 6: Immunity to conducted disturbances, induced by radio-frequency fields
IEC 61000-4-8:1993, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 8: Power frequency magnetic field immunity test – Basic EMC Publication
CISPR 11:1990, Limits and methods of measurement of electromagnetic disturbance
characteristics of industrial, scientific and medical (ISM) radio-frequency equipment
ISBN 92-67-01075-1:1993, International vocabulary of basic and general terms in metrology,
International Organization for Standardization.
ISBN 92-67-10188-9:1995, ISO TAG, ISO Technical Advisory Group on Metrology, Working
Group 3, Guide to the expression of uncertainty in measurement.
IEEE Std 539:1990, IEEE Standard Definitions of Terms Relating to Corona and Field Effects of
Overhead Power Lines.
3 Definitions
For the purposes of this International Standard, the following definitions apply.
NOTE – Throughout this standard, the words "magnetic flux density" and "magnetic field" will be considered
synonymous.
3.1 Tests
3.1.1
acceptance tests
contractual test to prove to the customer that the device meets certain conditions of its
specifications
3.1.2
type test
test of one or more devices made to a certain design to show that the design meets certain
specifications
NOTE – This test is normally performed by the designer/manufacturer of the device.

61786 © IEC:1998 – 13 –
3.2 Meters
3.2.1
alternating electric field strength meter
meter designed to measure alternating electric fields. Three types of electric field strength
meters are available: free-body meter, ground reference meter, electro-optic meter.
NOTE – Electric field meters consist of two parts: the probe or field-sensing element, and the detector which
processes the signal from the probe and indicates the r.m.s. value of the electric field with an analogue or digital
display.
3.2.2
electro-optic meter
meter that measures the electric field strength by changes in the transmission of light through a
fibre or crystal which are due to the influence of the electric field
NOTE – While there are several electro-optic methods that can be used for measuring electric fields, e.g. the
Pockels effect, the Kerr effect, and interferometric techniques, this standard only considers electro-optic field
meters that utilize the Pockels effect.
3.2.3
free-body meter
meter that measures the electric field strength at a point above the ground and is supported in
space without conductive contact to earth
NOTE – are commonly constructed to measure the induced current between two isolated parts
Free-body meters
of a conductive body. Since the induced current is proportional to the time derivative of the electric field strength,
the meter's detector circuit often contains an integrating stage in order to recover the waveform of the electric field.
The integrated current waveform also coincides with that of the induced charge. The integrating stage is also
desirable, particularly for the measurement of electric fields with harmonic content, because this stage (i.e. its
integrating property) eliminates the excessive weighting of the harmonic components in the induced current signal.
3.2.4
fluxgate magnetometer
instrument designed to measure magnetic fields by making use of the non-linear magnetic
characteristics of a probe or sensing element that has a ferromagnetic core
3.2.5
ground reference meter
meter that measures the electric field at or close to the surface of the ground, frequently
implemented by measuring the induced current or charge oscillating between an isolated
electrode and ground. The isolated electrode is usually a plate located level with or slightly
above the ground surface.
NOTE – Ground reference meters measuring the induced current often contain an integrator circuit to compensate
for the derivative relationship between the induced current and the electric field.
3.2.6
magnetic flux density meter
meter designed to measure the magnetic flux density
NOTE 1 – Magnetic field meters consist of two parts: the probe or field-sensing element, and the detector which
processes the signal from the probe and indicates the r.m.s. value of the magnetic field with an analogue or digital
display.
NOTE 2 – Several types of meters are in common use, e.g. field meters with coil probes, meters with Hall-effect
probes, and meters that combine two coils with a ferromagnetic core as in a fluxgate magnetometer.
3.2.7
survey meter
lightweight battery-operated meter that gives a real time read-out and that can be held
conveniently by hand in order to conduct survey type measurements in different locations

61786 © IEC:1998 – 15 –
3.2.8
coil probe
magnetic flux density sensor comprised of a coil of wire that produces an induced voltage
proportional to the time derivative of the magnetic field
NOTE 1 – Since the induced voltage is proportional to the time derivative of the magnetic flux density, the detector
circuit of the sensor requires an integrating stage to recover the waveform of the magnetic flux density.
NOTE 2 – This probe can also be used to measure static (d.c.) magnetic flux density if the probe is rotated.
3.2.9
Hall effect probe
magnetic flux density sensor containing an element exhibiting the Hall effect to produce a
voltage proportional to the magnetic flux density
NOTE – Hall effect probes respond to static as well as time-varying magnetic flux densities. Due to limited
sensitivity and saturation problems sometimes encountered when attempting to measure small power frequency flux
densities in the presence of the substantial static geomagnetic flux of the earth, Hall-effect probes have seldom
been used to measure magnetic fields of a.c. power lines.
3.3 Meter characteristics
3.3.1
crest factor
for periodic functions, the ratio of the waveform crest (peak, maximum) value to its r.m.s. value
3.3.2
crosstalk
noise or extraneous signal caused by a.c. or pulse-type signals in adjacent circuits
3.3.3
frequency response
response (reading) of a field meter to a field of constant amplitude but different frequencies
3.3.4
pass-band
(1) (data transmission) a range of frequency spectra which can pass at low attenuation
(2) (circuits and systems) a band of frequencies that pass through a filter with little attenuation
(relative to other frequency bands such as a stop-band)
3.3.5
rectified average (calibrated in r.m.s.) detector (see 3.3.6)
detector circuit that rectifies the signal from the probe and is calibrated to give the correct
r.m.s. value of a sinusoidal field at a given frequency
NOTE – If there are harmonics in the field, a field meter with a rectified average (r.m.s.) detector will not indicate
the true r.m.s. value of the field if the signal from the probe is proportional to the time derivative of the field. If the
detector contains a stage of integration, the error is reduced. The error will also be a function of the phase relation
between the harmonic and fundamental field components [36], [61].
3.3.6
true r.m.s. detector (see rectified average (calibrated in r.m.s.) detector)
detector that contains a circuit component that performs the mathematical operation

61786 © IEC:1998 – 17 –
T
[(vt) dt (1)
]
∫
T
to a periodic signal v(t), where T is the period of the signal.
NOTE 1 – If v(t) is proportional to the time-derivative of the field, the detector circuit also requires a stage of
integration prior to the r.m.s. operation in order to recover the waveform of the magnetic flux density [25], [61]. This
type of detector gives the true r.m.s. value of a field containing harmonics provided that the frequency response of
the detector is flat over the frequency range of interest.
NOTE 2 – If significant levels of harmonics are present in v(t), particular attention should be given to the possibility
of amplifier saturation effects if the integration follows one or more stages of amplification.
3.4 Field characteristics
3.4.1
maximum r.m.s. value of electric field (maximum electric field)
measurement of elliptically polarized quasi-static electric and magnetic fields. At a given point,
the root-mean-square (r.m.s.) value of the semi-major axis of the electric field ellipse
3.4.2
maximum r.m.s. value of magnetic field (maximum magnetic field)
measurement of power frequency electric and magnetic fields. At a given point, the root-mean-
square (r.m.s.) value of the semi-major axis of the magnetic field ellipse
3.4.3
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.
3.4.4
unperturbed field
field at a point that would exist in the absence of persons or movable objects
3.4.5
quasi-static field
field that satisfies the condition f << c÷l, where f is the frequency of the field, c is the speed of
light, and l is a characteristic dimension of the measurement geometry, e.g. the distance
between the field source and the measurement point
NOTE – Power frequency magnetic and electric fields near power lines and appliances are examples of quasi-
static fields.
3.4.6
resultant electric field
electric field given by the expression
22 2
= + + (2)
EE E E
R xy z
where E , E , and E are the r.m.s. values of the three orthogonal field components
x y z
61786 © IEC:1998 – 19 –
The resultant electric field is also given by the expression
2 2
E=+ (3)
EE
max
min
R
where E and E are the r.m.s. values of the semi-major and semi-minor axes of the
max min
electric field ellipse, respectively. The resultant E is always ≥E . If the electric field is
R max
linearly polarized, E = 0 and E = E . If the electric field is circularly polarized, E = E
min R max max min
and E ≈ 1,41 E .
R max
NOTE – The definition of "effective field strength" in CENELEC prestandard ENV 50166-1 [5] is equivalent to the
resultant magnetic field or resultant electric field, as the case may be.
3.4.7
resultant magnetic field
magnetic field given by the expression
22 2
B= + + (4)
B B B
R xy z
where B , B , and B are the r.m.s. values of the three orthogonal field components
x y z
The resultant magnetic field is also given by the expression
2 2
B= + (5)
B B
R max
min
where B and B are the r.m.s. values of the semi-major and semi-minor axes of
max min
the magnetic field ellipse, respectively. The resultant B is always ≥B . If the magnetic field
R max
is linearly polarized, B = 0 and B = B . If the magnetic field is circularly polarized,
min R max
B = B and B ≈ 1,41 B .
max min R max
NOTE – The definition of "effective field strength" in CENELEC prestandard ENV 50166-1 [5] is equivalent to the
resultant magnetic field or resultant electric field, as the case may be.
3.5 Measurements
3.5.1
correction factor
numerical factor by which the uncorrected result of a measurement is multiplied to compensate
for a known error
NOTE – Since the known error cannot be determined perfectly, the compensation cannot be complete.
3.5.2
coverage factor
numerical factor used as a multiplier of the combined standard uncertainty in order to obtain
an expanded uncertainty
NOTE – For a quantity z described by a normal distribution with expectation µ and standard deviation σ, the
z
interval µ ± kσ encompasses 68,27, 95,45, and 99,73 percent of the distribution for a coverage factor k = 1, 2,
z
and 3, respectively.
3.5.3
scale factor
factor by which the instrument reading is multiplied to obtain its input quantity

61786 © IEC:1998 – 21 –
3.5.4
spot measurement (point-in-time measurement)
measurement that is performed at some instant and point in space, that does not provide
information regarding temporal or spatial variations of the field
3.5.5
standard uncertainty
uncertainty of the result of a measurement expressed as a standard deviation
3.5.6
uncertainty of measurement
parameter, associated with the result of a measurement, that characterizes the dispersion of
the values that could reasonably be attributed to the measurand
NOTE – Uncertainty of measurement generally comprises many components. Some of these components may be
estimated on the basis of the statistical distribution of the results of series of measurements, and can be
characterized by experimental standard deviations. Estimates of other components can be based on experience or
other information.
4 Symbols
a = radius of coil probe; radius of spherical electric field probe
2a, 2b = side dimensions of rectangular coil
B = magnetic flux density vector
B = magnetic flux density (fundamental frequency)
f
B = magnetic flux density at jth frequency (j = 1 for fundamental frequency)
j
B = CENELEC magnetic flux density reference level at jth frequency
RLj
B = amplitude of alternating magnetic field
B = resultant magnetic field
R
B = axial magnetic flux density
z
B = r.m.s. values of orthogonal components of magnetic flux density
x,y,z
B , B = r.m.s. values of semi-major and semi-minor axes of magnetic field ellipse
max min
C = stray capacitance of coil probe
c = electro-optic coefficient of Pockels crystal
e
d = spacing of parallel plates; distance from electromagnetic field source
D = electric displacement vector
E = electric field strength
E = electric field at ith frequency (i = 1 for fundamental frequency)
i
E = CENELEC electric field reference level at ith frequency
i
RL
E = resultant electric field
R
E = uniform electric field strength
E′ = electric field in Pockels crystal
E = r.m.s. values of orthogonal components of electric field
x,y,z
E , E = r.m.s. values of semi-major and semi-minor axes of electric field ellipse
max min
61786 © IEC:1998 – 23 –
I = current to magnetic field coils
I = incident light (electro-optic field meter)
i
I = transmitted light (electro-optic field meter)
t
l = Pockels crystal thickness
L = inductance of coil probe
n = index of refraction
N = number of turns of wire (magnetic field coil system)
Q = induced charge
r = distance between magnetic field source and measurement location; resistance
of coil probe and leads
R = approximate input impedance of detector circuit (magnetic field meter)
S = electrode surface area (electric field meter)
t= time
T = period of periodic signal
V = voltage
v(t) = periodic electrical signal
v = coil probe voltage
p
W = ratio of coil probe voltage to induced voltage
Z = impedance in current injection circuit
α = fraction of ith harmonic in magnetic field
i
∆B = largest difference in percentage between magnetic field at centre of single-axis
max1
probe and average field (across area of probe) at maximum reading in dipole
magnetic field
∆B = largest difference in percentage between average resultant magnetic field and
max3
magnetic field at centre of three-axis probe in dipole magnetic field
ε = permittivity of free space
λ = wavelength of light
µ = permeability of free space
φ = magnetic flux
ω = angular frequency of alternating field
5 Measurement of alternating magnetic fields
5.1 Instrumentation specifications
The various types of instrumentation available for characterizing quasi-static magnetic fields
are described in D.1. Sufficient information shall be provided with the instrumentation, including
instrument specifications and a clearly written instruction manual, to enable users to determine
compliance with this standard, to aid them in the proper operation of the field meter, and to
assess the usefulness of the device for the user's application. Complicated operating

61786 © IEC:1998 – 25 –
procedures should be avoided. The instrument specifications that should be provided and/or
satisfied are given below.
NOTE – Instruments not complying with the specifications below may be used if it can be demonstrated that, under
the conditions the instrument is used, the results obtained will not differ significantly from those obtained with a
meter which is in compliance with this standard. For example, a meter with a rectified average detector with or
without an integrating stage may be used if it can be shown that the harmonics in the field are negligible, and if the
instrument has been calibrated for the fundamental frequency in the field.
5.1.1 Instrumental uncertainty
The measuring system for alternating magnetic fields should indicate the r.m.s. value of
uniform magnetic fields with an uncertainty of less than ±(10 % of reading +20 nT) after
correction factors have been applied, if appropriate.
NOTE 1 – The uncertainty of the instrument is determined from several components such as the calibration
uncertainty, temperature drift of the electronics, stability and external noise sources. The above uncertainty is
associated with the design and functioning of the magnetic flux density meter in a nearly uniform field. The 10 %
element refers to the uncertainty during calibration over the frequency range (pass-band) specified for the
instrument and includes uncertainties in the value of the magnetic flux density and additional uncertainties during
the calibration process (see 5.2.2). The coverage factor is 2. The inclusion of 20 nT anticipates instrumental
uncertainties during the calibration of the most sensitive scales and when fields in the order of 0,1 µT are
measured.
NOTE 2 – Other sources of measurement uncertainty and guidelines on the treatment of uncertainties are given in
clause B.1 and 5.3, respectively.
5.1.2 Magnitude range
The magnitude range over which the instrument operates within the specified uncertainty shall
be clearly indicated.
5.1.3 Pass-band
The instrument shall be provided with calibration data or specifications that enable the user to
assess the uncertainty in determining field levels when using the instrument in fields containing
different frequencies. This information should also include the sensitivity of the instrument to
frequencies beyond the intended useful range, e.g. the –3 dB points. The frequency response
of the instrument shall be such that the requirement of the instrumental uncertainty (see 5.1.1)
is fulfilled over the frequency range for which it is intended.
NOTE – The permitted instrumental uncertainty associated with the frequency response is increased to ±20 %
(coverage factor 2) for small personal exposure meters, devices that can be worn, and which periodically record
the power frequency and power frequency harmonic resultant magnetic field (see clause D.1).
5.1.4 Operating temperature and humidity ranges
The temperature and relative humidity ranges over which the instrument operates within the
specified uncertainty should be no less than 0 °C to 45 °C and 5 % to 95 %, respectively.
Sudden temperature changes that can lead to condensation in the instrument should be
avoided (see clause B.1).
5.1.5 Power supplies
If batteries are used, provision should be made to indicate whether the battery condition is
adequate for proper operation of the field meter. Instruments used to record personal exposure
should be capable of at least 8 h operation within their rated uncertainty before replacement or
recharging of the batteries becomes necessary. If rechargeable batteries are used, it is
recommended that the instrumentation is not operated while connected to the mains voltage.

61786 © IEC:1998 – 27 –
When such connections are necessary, it should be demonstrated that stray fields from the
battery charger, conducted disturbances from the mains voltage, and electromagnetic coupling
via the connecting leads (to the battery charger) do not affect the measurement (see 5.1.8).
NOTE – If batteries with ferromagnetic jackets are used in exposure meters, care must be exercised that the
jackets do not significantly influence readings by the instrument (see clause B.1).
5.1.6 Readability of scale
The meter dial markings or digital displays of magnetic field survey meters should be large
enough to be easily read at arm's length. If more than one range of sensitivity is provided, the
full scale value of the selected range should be indicated, and the units should be readily
interpretable. For auto-ranging instrumentation, the magnitude range may be indicated
elsewhere, e.g. in the user manual. The instrumentation should provide a clear indication of the
units being displayed.
NOTE – To comply with this standard, instrumentation marketed prior to the issue of this standard, which does not
indicate the units, should be provided with an appropriate label indicating the units. This may be accomplished by
the user applying a label to the body of the field meter. Alternatively, a label provided by the manufacturer to the
user may be applied by the user.
5.1.7 Instrument dimensions
The dimensions of the enclosure containing the detector circuit and any connecting cables
should be provided. The size of the probes or sensing elements should be appropriate to the
spatial variation of the field measured (see clause B.1). The sensing elements should be of
area 0,01 m , or smaller. With three-axis instruments, the three sensing elements may be
concentric (i.e. coil probes that have a common central point) or, if the sensing elements are
no larger than 0,05 m, they should be as close together as possible (see clause B.1). The
maximum dimension of the volume containing the three coil probes combined should not
exceed 0,2 m. Coil probes should be either circular or square in cross-section; small
deviations from these shapes, for example where concentric coils cross each other, are
permitted.
The locations and orientations of probes that are contained within the housings of magnetic
field meters should be clearly indicated on the instrument or in the instruction manual.
5.1.8 Electromagnetic compatibility
5.1.8.1 Immunity
a) Power frequency electric field
Instrumentation intended for use in the vicinity of high-voltage equipment operating at
power frequencies should not be affected significantly by ambient electric fields as large as
20 kV/m, i.e. the influence of the electric field on the magnetic field reading should be less
than 20 nT. This immunity requirement may need to be increased for some extreme
environments where electric fields as large as 100 kV/m may exist, e.g. near high-voltage
transmission line conductors.
NOTE 1 – Tests for immunity to power frequency electric fields may be performed using the parallel plates
systems described in clause A.2.
NOTE 2 – The proximity effect of the instrument user (see clause B.2) can shield or enhance the electric field,
depending on the geometry of the field and the location of the magnetic field meter relative to the user.

61786 © IEC:1998 – 29 –
b) Radiated electromagnetic fields
The operation of instrumentation shall not be affected by electromagnetic radiation between
80 MHz and 1 GHz for an electric field level of 3 V/m r.m.s. Testing of instrumentation
should be in accord with the methods described in IEC 61000-4-3.
The operation of instrumentation shall not be affected by electromagnetic radiation between
150 kHz and 80 MHz. Tests should be conducted according to the methods described in
IEC 61000-4-6 at a voltage level of 3 V r.m.s. The instrumentation should continue to
operate normally during both of the above tests.
NOTE 1 – Battery-powered equipment (dimension <λ/4) which has no connection(s) to the ground nor to any
other (non-insulated) equipment, and which will not be used during battery charging, does not need to be tested
according to IEC 61000-4-6.
NOTE 2 – It is important to perform the radiated immunity tests over the entire frequency range from 26 MHz to
1 GHz. The lower frequency boundary is important because of the high probability that the instruments will
experience radiation in the 27 MHz citizen's band.
NOTE 3 – The immunity requirements may need to be increased under certain conditions, e.g. during
measurements near radio-broadcasting antennas and mobile telephones (see clause B.1, table B.2).
c) Immunity to transients
Specifications for instrumentation connected to the mains in order to carry out
measurements should also be tested at the a.c. power port (interface of field meter with
external power source or mains) for compliance with IEC 61000-4-4 (electrical fast
transient) for a peak voltage of 2 kV. A temporary degradation of performance during the
test which is self-recoverable is acceptable.
d) Electrostatic discharge (ESD)
During most measurement applications, electrostatic discharges to or from the
instrumentation are not anticipated. However, the enclosure port of the instrumentation
shall be immune to a contact or discharge voltage of at least 2 kV and tested in accordance
with the methods described in IEC 61000-4-2. No degradation of performance shall occur.
5.1.8.2 Emissions
a) Harmonic emissions
The harmonic emissions of instrumentation with a power rating of 50 W or greater shall be
restricted according to the requirements of IEC 61000-3-2.
b) Conducted disturbances – 0,15 MHz to 30 MHz (instrumentation connected to mains)
The limits for mains terminal disturbance voltages may be characterized using quasi-peak
or average detectors and are given below as a function of frequency (see CISPR 11,
class B).
Table 1 – Mains terminal disturbance voltage limits
Frequency band Quasi-peak Average
MHz
dB(µV) dB(µV)
0,15 – 0,50 66 56
Decreasing with logarithm of Decreasing with logarithm of
frequency to 56 frequency to 46
0,50 – 5 56 46
5 – 30 60 50
61786 © IEC:1998 – 31 –
Testing of instrumentation should be in accordance with the methods described in
CISPR 11.
c) Radiated disturbances – 30 MHz to 1 000 MHz
The electromagnetic emissions from instrumentation containing devices operating at
frequencies of 9 kHz or higher shall be limited to the values listed below (see CISPR 11,
class B).
30 dB (µV/m) at 10 m 30 MHz to 230 MHz
37 dB (µV/m) at 10 m 230 MHz to 1 000 MHz
Testing of instrumentation should be in accordance with the methods described in
CISPR 11.
NOTE – The above test requirements have been taken from CISPR 11 and are subject to revision. Tests should
be conducted according to the most recent edition of that standard.
5.1.9 Crest factor
The measuring system should measure correctly the true r.m.s. value of the field, even when
the crest factor of the magnetic field is 3 (see clause B.1).
NOTE – Many practical fields exhibit a large crest factor and the presence of a large crest factor may lead to
unwanted saturation in the amplifier stages of the detector.
5.1.10 Durability
The indicating meter and other system components should be rugged enough to withstand
vibration and shock resulting from transport. A carrying case is desirable.
5.1.11 Weight
The weight of the instrumentation should be provided. The weight of portable instrumentation
should be kept as low as is practical to permit hand-held operation under restrictive conditions,
e.g. in some industrial environments.
5.2 Calibration
5.2.1 General
Measurement systems are required to undergo calibration and verification of their calibration
throughout their service life. The calibration tests referred to in this standard are type tests
and acceptance tests. Type tests are normally performed by the manufacturer on one or
more devices. Acceptance tests are normally performed only once by the manufacturer on
each field meter. Acceptance tests need to be repeated if major changes or repairs of the
instrument have been made. Verification tests are performed at time intervals during use of the
instrument (see 5.2.4). All calibrations should be traceable to national and international
standards through an unbroken chain of calibrations, all having stated uncertainties.
The following three methods of calibration are covered by this standard:
a) calibration by introduction of the field meter probe into a calculated magnetic field (following
measurements of coil dimensions and current to the coil system);
b) calibration using a voltage injection technique, and
c) calibration by comparison with a reference measurement system (see clause A.1).

61786 © IEC:1998 – 33 –
5.2.2 Calibration procedure
Calibrations are required as part of type tests, acceptance tests (see 5.2.1), and periodic
verification tests (see 5.2.4). The procedures of this section should be followed, as appropriate,
in all cases. For calibration of the higher magnitude ranges (i.e. ranges not significantly
influenced by background magnetic fields), the magnetic field probe should be placed in a
nearly uniform field produced by a coil system (see clause A.1). The probe axis should coincide
with the axis of the coil system and the largest departure of the field from the central value
should be less than 1 % over the cross-sectional area of the probe.
NOTE 1 – Information on fields generated by rectangular, square, and circular loop systems (including Helmholtz
coils) is given in [17], [35], [56], [69] and A.1. For example, the magnetic flux density produced by a single square
loop (of many turns of wire) 1 m × 1 m will satisfy the uniformity requirement for a probe with a 0,10 m diameter
(see clause A.1). The loop size may be scaled upwards or downwards for larger or smaller probes, respectively, to
maintain the indicated level of uniformity across the probe. The calibration may also be performed using the voltage
injection technique or by comparison with a reference magnetic field meter (see clause A.1).
NOTE 2 – The field uniformity requirement during calibration may be relaxed for large probes that are used for
determining average values of non-uniform fields and, or for applications where spatial resolution requirements are
not considered important. In this case, the largest departure of the calibration field from the central value should be
≤1,5 % over the cross-sectional area of the probe. For example, the field produced by a square loop 1,3 m × 1,3 m
will satisfy this uniformity requirement for a probe with a 0,20 m diameter.
Calibrations of single-axis field meters and each axis of three-axis field meters should be
performed with
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