FprEN IEC 62271-208:2025

High-voltage switchgear and controlgear - Part 208: Methods to quantify the steady state, power-frequency electromagnetic fields generated by HV switchgear assemblies and HV/LV prefabricated substations, both for rated voltages above 1 kV and up to and including 52 kV

IEC 62271-208:2025 gives practical guidance for the evaluation and documentation of the external steady state power-frequency electromagnetic fields which are generated by HV switchgear and controlgear assemblies and prefabricated substations. Basic requirements to measure or calculate the electric and magnetic fields are summarised for assemblies covered by IEC 62271-200 and IEC 62271-201, and for prefabricated substations covered by IEC 62271-202. NOTE 1 The methods described in this document refer to three-phase equipment. However, the methodology can be used correspondingly for any single- or multi-phase equipment covered by this document. This document applies to equipment rated for voltages above 1 kV up to and including 52 kV and power-frequencies from 15 Hz to 60 Hz. The electromagnetic fields which are generated by harmonics or transients are not considered in this document. However, the methods described are equally applicable to the harmonic fields of the power-frequency. Detailed generic information on requirements and measurements of low-frequency electromagnetic fields is given in IEC 61786-1 and IEC 61786-2. This document covers evaluation under factory or laboratory conditions before installation. The electric and the magnetic fields can be evaluated either by measurements or by calculations. NOTE 2 Where practicable, the methods described in this document can also be used for installations on site. It is not within the scope of this document to specify limit values of electromagnetic fields or methods for the assessment of human exposure.

Hochspannungs-Schaltgeräte und -Schaltanlagen - Teil 208: Methoden zur Bestimmung der stationären, betriebsfrequenten elektromagnetischen Felder von HS-Schaltanlagen und fabrikfertigen HS-/ NS-Stationen, beides für Bemessungsspannungen über 1 kV und bis einschließlich 52 kV

Appareillage à haute tension - Partie 208: Méthodes de quantification des champs électromagnétiques à fréquence industrielle en régime établi générés par les ensembles d'appareillages HT et les postes préfabriqués HT/BT, à la fois pour les tensions assignées supérieures à 1 kV et inférieures ou égales à 52 kV

IEC 62271-208:2025 La présente partie de l'IEC 62271 fournit des recommandations pratiques pour l'évaluation et la documentation des champs électromagnétiques à fréquence industrielle en régime établi externes qui sont générés par les ensembles d'appareillages et les postes préfabriqués HT. Les exigences élémentaires pour le mesurage ou le calcul des champs électriques et magnétiques sont récapitulées pour les ensembles couverts par l'IEC 62271-200 et l'IEC 62271-201 et pour les postes préfabriqués couverts par l'IEC 62271-202. NOTE 1 Les méthodes décrites dans le présent document s'appliquent aux équipements triphasés. Toutefois, la méthodologie peut être utilisée respectivement pour tout équipement monophasé ou multiphasé couvert par le présent document. Le présent document s'applique aux équipements assignés pour des tensions supérieures à 1 kV et inférieures ou égales à 52 kV et des fréquences industrielles comprises entre 15 Hz et 60 Hz. Les champs électromagnétiques qui sont générés par des harmoniques ou des transitoires ne sont pas pris en compte dans le présent document. Toutefois, les méthodes décrites s'appliquent également aux champs harmoniques de la fréquence industrielle. L'IEC 61786-1 et l'IEC 61786-2 fournissent des informations génériques détaillées concernant les exigences et les mesurages des champs électromagnétiques à basse fréquence. Le présent document traite de l'évaluation dans les conditions d'usine ou de laboratoire avant l'installation. Les champs électriques et magnétiques peuvent être évalués par des mesurages ou par des calculs. NOTE 2 Lorsque cela est possible, les méthodes décrites dans le présent document peuvent également être utilisées pour les installations sur site. La spécification de valeurs limites pour les champs électromagnétiques ou de méthodes d'évaluation de l'exposition humaine ne relève pas du domaine d'application du présent document.

Visokonapetostne stikalne in krmilne naprave - 208. del: Metode za kvantifikacijo elektromagnetnih polj v ustaljenem stanju z močjo in frekvenco, ki jih generirajo visokonapetostne VN omrežne stikalne naprave in VN/NN montažne postaje, tako za nazivno napetost nad 1 kV kot do vključno 52 kV

General Information

• Status: Not Published
• Publication Date: 05-Oct-2025
• ICS: 29.130.10 - High voltage switchgear and controlgear
• Technical Committee: CLC/TC 17AC - High-voltage switchgear and controlgear
• Drafting Committee: IEC/SC 17C - IEC_SC_17C
• Current Stage: 5060 - Voting results sent to TC, SR - Formal Approval
• Start Date: 04-Jul-2025
• Completion Date: 04-Jul-2025
• Ref Project: kSIST FprEN IEC 62271-208:2025 - High-voltage switchgear and controlgear - Part 208: Methods to quantify the steady state, power-frequency electromagnetic fields generated by HV switchgear assemblies and HV/LV prefabricated substations, both for rated voltages above 1 kV and up to and including 52 kV

Relations

• Revises: CLC/TR 62271-208:2010 - High-voltage switchgear and controlgear - Part 208: Methods to quantify the steady state, power-frequency electromagnetic fields generated by HV switchgear assemblies and HV/LV prefabricated substations
• Effective Date: 23-Jan-2023

Overview

FprEN IEC 62271-208:2025 establishes standardized methods to quantify steady‑state, power‑frequency electromagnetic fields (EMF) produced by high‑voltage (HV) switchgear assemblies and HV/LV prefabricated substations with rated voltages above 1 kV and up to and including 52 kV. Prepared by IEC SC 17C, this part of the IEC 62271 series guides manufacturers, test laboratories and regulators on consistent evaluation, measurement, calculation and documentation of both electric (E‑field) and magnetic (B‑field) emissions.

The document complements other switchgear standards and includes procedures for evaluation, measurement set‑ups, calculation methods, validation and presentation of results. The draft indicates a proposed stability date of 2033 and contains informative annexes with sample measurement presentations and analytical benchmark calculations.

Key Topics

• Evaluation requirements for reporting and assessing EMF from HV assemblies and HV/LV prefabricated substations.
• Two measurement procedures: Hot spot and Isoline methods, with guidance on when each is appropriate.
• Measurement setup guidance including test circuits, external connections and measurement volumes.
• Requirements for measuring instruments, measurement procedures and quality assurance.
• Calculation procedures, software considerations and validation of numerical results.
• Documentation and presentation formats for both measurement and calculation outcomes.

The standard emphasizes clear presentation of E and B field data, listing hot spot coordinates, field variation with distance, isoline mapping and background field reporting. Annexes provide examples and analytical benchmarks to aid interpretation.

Applications

This standard is practical for:

• Manufacturers preparing EMF data for product information and compliance.
• Independent test labs conducting EMF characterisation of switchgear assemblies and prefabricated substations.
• System designers and asset owners evaluating site EMF levels near substations.
• Regulators and authorities requiring consistent documentation of power‑frequency EMF.

Benefits include:

• Consistent, repeatable measurement and reporting across vendors and test bodies.
• Clear methods to compare measured and calculated fields for design validation.
• Improved transparency for end users and stakeholders about steady‑state EMF characteristics.

Related Standards

• Other parts of the IEC 62271 series covering HV switchgear design, testing and safety.
• EMC, environment, quality assurance and safety guidance referenced by SC 17C.

For implementation, users should consult the normative references listed in the standard, apply recommended measurement instrumentation and follow the documentation templates provided for presenting hot spot and isoline results. The annexes offer worked examples and analytical solutions useful for benchmarking measurement and calculation methods.

Standards Content (Sample)

SLOVENSKI STANDARD
oSIST prEN IEC 62271-208:2024
01-julij-2024
Visokonapetostne stikalne in krmilne naprave - 208. del: Metode za kvantifikacijo
elektromagnetnih polj v ustaljenem stanju z močjo in frekvenco, ki jih generirajo
visokonapetostne VN omrežne stikalne naprave in VN/NN montažne postaje, tako
za nazivno napetost nad 1 kV kot do vključno 52 kV
High-voltage switchgear and controlgear - Part 208: Methods to quantify the steady
state, power-frequency electromagnetic fields generated by HV switchgear assemblies
and HV/LV prefabricated substations, both for rated voltages above 1 kV and up to and
including 52 kV
Appareillage à haute tension - Partie 208: Méthodes de quantification des champs
électromagnétiques à fréquence industrielle en régime établi générés par les ensembles
d'appareillages ht et les postes préfabriqués ht/BT, à la fois pour les tensions assignées
supérieures à 1 kv et inférieures ou égales à 52 kv
Ta slovenski standard je istoveten z: prEN IEC 62271-208:2024
ICS:
29.130.10 Visokonapetostne stikalne in High voltage switchgear and
krmilne naprave controlgear
oSIST prEN IEC 62271-208:2024 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN IEC 62271-208:2024
oSIST prEN IEC 62271-208:2024
17C/932/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 62271-208 ED1
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2024-05-03 2024-07-26
SUPERSEDES DOCUMENTS:
17C/893/CD, 17C/915A/CC
IEC SC 17C : ASSEMBLIES
SECRETARIAT: SECRETARY:
Germany Mr Mark Kuschel
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:

TC 17,SC 17A
Other TC/SCs are requested to indicate their interest, if
any, in this CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft
for Vote (CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of
which they are aware and to provide supporting documentation.
Recipients of this document are invited to submit, with their comments, notification of any relevant “In Some
Countries” clauses to be included should this proposal proceed. Recipients are reminded that the CDV stage is the
final stage for submitting ISC clauses. (SEE AC/22/2007 OR NEW GUIDANCE DOC).

TITLE:
High-voltage switchgear and controlgear - Part 208: Methods to quantify the steady
state, power-frequency electromagnetic fields generated by HV switchgear assemblies
and HV/LV prefabricated substations, both for rated voltages above 1 kV and up to and
including 52 kV
PROPOSED STABILITY DATE: 2033
NOTE FROM TC/SC OFFICERS:
download this electronic file, to make a copy and to print out the content for the sole purpose of preparing National
Committee positions. You may not copy or "mirror" the file or printed version of the document, or any part of it, for
any other purpose without permission in writing from IEC.

oSIST prEN IEC 62271-208:2024
IEC CDV 62271-208 © IEC 2024 2 17C/932/CDV

1 CONTENTS
3 FOREWORD. 4
4 INTRODUCTION . 6
5 1 Scope . 7
6 2 Normative references . 7
7 3 Terms and definitions . 8
8 4 Evaluation requirements . 9
9 4.1 General . 9
10 4.2 Methods of evaluation . 9
11 4.3 Evaluation of electric fields . 10
12 4.3.1 HV assemblies . 10
13 4.3.2 HV/LV prefabricated substations . 10
14 4.4 Evaluation of magnetic fields . 10
15 4.4.1 HV assemblies . 10
16 4.4.2 HV/LV prefabricated substations . 11
17 5 Measurements . 11
18 5.1 General . 11
19 5.2 Measuring instruments . 12
20 5.3 Measurement procedures . 12
21 5.3.1 General . 12
22 5.3.2 Hot spot measurement procedure . 13
23 5.3.3 Isoline measurement procedure . 17
24 5.4 Measurement set-up . 18
25 5.4.1 General . 18
26 5.4.2 Hot spot measurement set-up . 18
27 5.4.3 Isoline measurement set-up . 20
28 5.4.4 External connections . 21
29 5.4.5 Additional provisions for HV/LV prefabricated substations . 22
30 6 Calculations . 22
31 6.1 General . 22
32 6.2 Software . 22
33 6.3 Calculation procedures . 23
34 6.4 Results . 23
35 6.5 Validation . 23
36 7 Documentation . 24
37 7.1 Characteristics of the HV assembly or prefabricated substation . 24
38 7.2 Evaluation method . 24
39 7.3 Presentation of the measurement results. 24
40 7.4 Presentation of the calculation results . 24
41 Annex A (informative) Presentation of E or B field measurement data – Examples for
42 a typical HV/LV prefabricated substation . 26
43 A.1 Presentation of Hot spot B-field measurement results . 26
44 A.1.1 Hot spot locations . 27
45 A.1.2 Hot spot locations with its E or B field values . 27
46 A.1.3 Variation of the E or B field as a function of the distance . 28
47 A.1.4 Field variation around substation at hot spot locations . 29
48 A.1.5 Background fields . 29
49 A.2 Presentation of Isoline E or B field measurement results . 30

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50 A.2.1 Location of measurement points on Isoline . 30
51 A.2.2 Background fields . 31
52 A.2.3 Example of an Isoline measurement on a 1600 kVA power
53 transformer substation . 31
54 Annex B (informative) Examples of analytical solutions to benchmark EMF
55 calculations . 32
56 B.1 Magnetic field . 32
57 B.2 Electric field . 40
59 Figure 1 – Example of test circuits configuration to obtain the maximum external
60 magnetic field of a switchgear assembly and/or a prefabricated substation. . 11
61 Figure 2 – Reference surface (RS) for equipment of irregular shape. . 13
62 Figure 3 – Scanning areas to find the hot spots. . 14
63 Figure 4 – Determination of the field variation as a function of the distance from the
64 hot spot locations (perpendicular to the reference surface). . 15
65 Figure 5 - Height of measurement plane. . 17
66 Figure 6 – Test circuit for electric and magnetic field measurement. . 19
67 Figure 7 – Test set-up of main components, external cables, hot spot locations and
68 measurement volume. . 20
69 Figure 8 – Test set-up of main components, external cables and measurement
70 volume. . 21
72 Figure A. 1 – Hot spot locations representing the field maxima. . 27
73 Figure A. 2 – Graphical presentation of the field variation. . 28
74 Figure A. 3 – Example diagram for the field variation at hot spots. . 29
75 Figure A. 4 – Graphical presentation of measurement points on Isoline. . 30
76 Figure A. 5 – Isoline of 10 µT for a 1600 kVA substation. . 31
78 Figure B. 1 – Schematic for 3-phase magnetic field calculation. . 32
79 Figure B. 2 – Variation of resultant magnetic field around 3-phase cable. . 35
80 Figure B. 3 – Maximum resultant magnetic field around 3-phase cable. . 36
81 Figure B. 4 – Schematic for 3-phase electric field calculation. . 40
82 Figure B. 5 – Variation of resultant electric field around 3-phase cable. . 43
83 Figure B. 6 – Maximum resultant electric field around 3-phase cable. . 45
85 Table A. 1 – Listing of the hot spot coordinates. . 27
86 Table A. 2 – Variation of field values for one hot spot. . 28
87 Table A. 3 – Background fields. . 29
88 Table A. 4 – Listing of the location (coordinates) of the measurement points . 30
89 Table A. 5 – Background fields ……………………………………………………………………….31
91 Table B. 1 – Values of H [A/m] for spatial angles θ and time angles ωt. . 35
res
92 Table B. 2 – Values of maximum H [A/m] for spatial angles θ. . 37
res
93 Table B. 3 – Values of E [V/m] for spatial angles θ and time angles ωt. . 43
res
94 Table B. 4 – Values of maximum E for spatial angles θ. . 45
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96 INTERNATIONAL ELECTROTECHNICAL COMMISSION
97 ____________
99 HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
101 Part 208: Methods to quantify the steady state,
102 power-frequency electromagnetic fields
103 generated by HV switchgear assemblies
104 and HV/LV prefabricated substations,
105 both for rated voltages above 1 kV
106 and up to and including 52 kV
109 FOREWORD
110 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
111 all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
112 international co-operation on all questions concerning standardization in the electrical and electronic fields. To
113 this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
114 Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
115 Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
116 in the subject dealt with may participate in this preparatory work. International, governmental and non -
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118 with the International Organization for Standardization (ISO) in accordance with conditions determined by
119 agreement between the two organizations.
120 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
121 consensus of opinion on the relevant subjects since each technical committee has representation from all
122 interested IEC National Committees.
123 3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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127 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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130 the latter.
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133 services carried out by independent certification bodies.
134 6) All users should ensure that they have the latest edition of this publication.
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138 expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
139 Publications.
140 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
141 indispensable for the correct application of this publication.
142 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
143 patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
144 The main task of IEC technical committees is to prepare International Standards. However, a
145 technical committee may propose the publication of a technical report when it has collected
146 data of a different kind from that which is normally published as an International Standard, for
147 example "state of the art".
148 IEC 62271-208 document has been prepared by subcommittee 17C: High-voltage switchgear
149 and controlgear assemblies, of IEC technical committee 17: Switchgear and controlgear.
oSIST prEN IEC 62271-208:2024
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151 The text of this document is based on the following documents:
Enquiry draft Report on voting
17C/450/DTR 17C/462/RVC
152 With respect to previous TR, in the current version of this document the Isoline measurement
153 procedure is introduced and compared to the Hot spot one when it is required a measurement
154 for the characterization of a generated electromagnetic field.
155 Full information on the voting for the approval of this document can be found in the report on
156 voting indicated in the above table.
157 This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
158 A list of all the parts in the IEC 62271 series, under the general title High-voltage switchgear
159 and controlgear, can be found on the IEC website.
160 The committee has decided that the contents of this publication will remain unchanged until
161 the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
162 the data related to the specific publication. At this date, the publication will be
163 • reconfirmed,
164 • withdrawn,
165 • replaced by a revised edition, or
166 • amended.
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168 INTRODUCTION
169 Manufacturers of electricity supply equipment may be asked to provide information about the
170 electromagnetic field characteristics to enable the user to
171 • assess the electromagnetic field conditions to assist with planning, installation, operating
172 instructions and service,
173 • take measures to meet requirements or regulations on electromagnetic fields,
174 • compare different products as far as their level of electromagnetic fields is concerned.
175 The purpose of this document is to describe a methodology for the evaluation (measurement
176 or calculation) of generated electromagnetic fields. In particular, if a measurement is required,
177 Hot spot and Isolines procedures are introduced and described.
178 The electromagnetic field characteristic of the equipment comprises the values of the electric
179 and the magnetic fields around its accessible surfaces.
180 The electromagnetic field characteristic defined in this document refers to a single product as
181 defined in the scope. In real installations, several field sources can superimpose, so the
182 resulting electromagnetic fields on site may differ significantly from the single product
183 characteristics.
184 This document does not define a mandatory test for the products mentioned in the scope.
185 Neither the establishment of limits for the electromagnetic fields generated by equipment, nor
186 the establishment of assessment methods for the human exposure to electromagnetic fields is
187 within the content or intent of this document.
oSIST prEN IEC 62271-208:2024
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189 HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
191 Part 208: Methods to quantify the steady state,
192 power-frequency electromagnetic fields
193 generated by HV switchgear assemblies
194 and HV/LV prefabricated substations,
195 both for rated voltages above 1 kV
196 and up to and including 52 kV
201 1 Scope
202 This part of IEC 62271 gives practical guidance for the evaluation and documentation of the
203 external steady state power-frequency electromagnetic fields which are generated by HV
204 switchgear and controlgear assemblies and prefabricated substations. Basic requirements to
205 measure or calculate the electric and magnetic fields are summarised for assemblies covered
206 by IEC 62271-200 and IEC 62271-201, and for prefabricated substations covered by
207 IEC 62271-202.
208 NOTE 1 The methods described in this document refer to three-phase equipment. However, the methodology can
209 be used correspondingly for any single- or multi-phase equipment covered by this document.
210 This document applies to equipment rated for voltages up to and including 52 kV and power-
211 frequencies from 15 Hz to 60 Hz. The electromagnetic fields which are generated by
212 harmonics or transients are not considered in this document. However, the methods described
213 are equally applicable to the harmonic fields of the power-frequency.
214 Detailed generic information on requirements and measurements of low-frequency
215 electromagnetic fields is given in IEC 61786.
216 This document covers evaluation under factory or laboratory conditions before installation.
217 The electric and the magnetic fields can be evaluated either by measurements or by
218 calculations.
219 NOTE 2 Where practicable, the methods described in this document can also be used for installations on site.
220 It is not within the scope of this document to specify limit values of electromagnetic fields or
221 methods for the assessment of human exposure.
222 2 Normative references
223 The following referenced documents are indispensable for the application of this document.
224 For dated references, only the edition cited applies. For undated references, the latest edition
225 of the referenced document (including any amendments) applies.
226 IEC 61000-6-2, Electromagnetic compatibility (EMC) – Part 6-2: Generic documents -
227 Immunity for industrial environments
228 IEC 61786, Measurement of low-frequency magnetic and electric fields with regard to
229 exposure of human beings – Special requirements for instruments and guidance for
230 measurements
231 IEC 62110, Electric and magnetic field levels generated by AC power systems – Measurement
232 procedures with regard to public exposure

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233 IEC 62271-200, High-voltage switchgear and controlgear – Part 200: AC metal-enclosed
234 switchgear and controlgear for rated voltages above 1 kV and up to and including 52 kV
235 IEC 62271-201, High-voltage switchgear and controlgear – Part 201: AC solid-insulation-
236 enclosed switchgear and controlgear for rated voltages above 1 kV and up to and including 52
237 kV
238 IEC 62271-202, High-voltage switchgear and controlgear – Part 202: AC prefabricated
239 substations for rated voltages above 1 kV and up to and including 52 kV
240 3 Terms and definitions
241 For the purposes of this document, the following terms and definitions apply.
242 3.1
243 EMF
244 abbreviation for the term “electromagnetic field(s)”
245 3.2
246 electric field characteristic
247 values (RMS) and spatial distribution of the electric field strength (E) expressed in kV/m at
248 rated voltage and frequency around all accessible surfaces of the equipment
249 Note 1 to entry: The electric field characteristic is the resultant of the RMS values of the three orthogonal vector
250 components.
251 3.3
252 magnetic field characteristic
253 values (RMS) and spatial distribution of the magnetic field strength (H) expressed in A/m or
254 the magnetic flux density (B) expressed in µT, at rated continuous current and frequency
255 around all accessible surfaces of the equipment
256 Note 1 to entry: The magnetic field characteristic is the resultant of the RMS values of the three orthogonal vector
257 components.
258 Note 2 to entry: The terms “resultant electric field” and “resultant magnetic field” are defined in IEC 61786.
259 3.4
260 accessible surfaces
261 those parts of the walls and roof of prefabricated substations or HV switchgear and
262 controlgear assemblies that can be touched with all covers and doors in closed position in
263 normal service conditions
264 3.5
265 reference surface
266 RS
267 virtual envelope containing the equipment for evaluation purposes
268 3.6
269 measurement surface
270 MS
271 virtual envelope defined outside the reference surface at 20 cm distance for measuring hot
272 spots
273 3.7
274 hot spot
275 centre of an area of a local maximum of the electric or the magnetic field at the measurement
276 surface
277 3.8
278 EMF characteristic
279 spatial distribution of the Electric Field characteristic and of the Magnetic Field strength

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281 Note 1 to entry: The spatial distribution is derived from a measurement or calculation grid.
282 3.9
283 measurement volume
284 MV
285 virtual space in which the electromagnetic background field does not exceed an appropriate
286 level to permit the uninfluenced measurement of the electric and magnetic fields generated by
287 the high-voltage switchgear and controlgear assembly or the prefabricated substations
288 3.10 measurement plane
289 horizontal virtual plane on a specific height above floor level on which the measurement
290 points are taken
291 3.11
292 isoline
293 line of constant electric or magnetic field characteristic on a measurement plane
294 4 Evaluation requirements
295 4.1 General
296 The EMF characteristic of HV switchgear and controlgear assemblies or HV/LV prefabricated
297 substations is the measured or calculated electric field strength and magnetic flux density
298 around all accessible surfaces under the conditions for evaluation described below. These
299 conditions represent the service, where the loading of the switchgear and controlgear
300 assemblies and, in a substation, of the power transformer is at defined values.
301 As the electric and magnetic fields are dependent on the physical arrangement of incoming
302 and outgoing cables and their loadings, these parameters have to be recorded. The presence
303 of other field sources and shielding or other metallic structures shall be recorded.
304 The recordings shall be carried out in such a way that the loadings, material characteristics,
305 and geometrical configuration (including metric distances) are clearly indicated.
306 The EMF characteristic shall be evaluated for the conditions that would result in the highest
307 levels of electric and magnetic fields in normal, undisturbed service. These conditions include
308 the highest currents and largest loops realistically possible through the assembly working at
309 maximum capacity. EMF caused by switching operations, including interruption of fault
310 currents, or other transient phenomena is deemed to be incidental and shall not be
311 considered.
312 Electric field strength and magnetic flux density shall be recorded as the resultant of the RMS
313 values of the three orthogonal vector components.
314 The evaluation shall be carried out at the rated frequency of the equipment.
315 However, in the frequency range from 15 Hz up to and including 60 Hz the actual value of
316 frequency does not significantly affect the levels of generated E fields for any given values of
317 voltage. Therefore, evaluation at any frequency up to and including 60 Hz is considered valid.
318 Similarly, the difference in attenuation of B fields by metallic enclosures at 50 Hz and 60 Hz
319 can be ignored for the purpose of this document. Therefore, evaluation at 50 Hz is considered
320 applicable also for 60 Hz and vice versa.
321 In the power-frequency range covered by this document the electric and magnetic fields may
322 be treated separately. When selecting the conditions to obtain the highest level of electric and
323 magnetic fields as realistically as possible in undisturbed service, the following subclauses
324 should be considered.
325 4.2 Methods of evaluation
326 The EMF characteristic may be evaluated by measurement or by calculation.

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327 4.3 Evaluation of electric fields
328 4.3.1 HV assemblies
329 The equipment shall be evaluated at the rated voltage of the HV switchgear and controlgear
330 assemblies.
331 Only if the evaluation cannot be carried out at rated voltage, the results shall be extrapolated
332 to the rated value. Since the electric field strength is a linear function of the voltage, the field
333 strengths for different high voltages may be extrapolated linearly.
334 4.3.2 HV/LV prefabricated substations
335 The equipment shall be evaluated at the rated high voltage of the HV/LV power
336 transformer(s).
337 Only if the evaluation cannot be carried out at rated voltage, the results shall be extrapolated
338 to the rated value. Since the electric field strength is a linear function of the voltage, the field
339 strengths for different high voltages may be extrapolated linearly.
340 4.4 Evaluation of magnetic fields
341 4.4.1 HV assemblies
342 To evaluate the HV assembly magnetic field, use the rated continuous current given on the
343 switchgear nameplate. The HV circuit shall be selected to form the widest possible current
344 loop between the incoming and outgoing functional units (panels) of the switchgear and
345 controlgear assemblies to obtain the maximum magnetic field by using the smallest number of
346 circuits, taking into account their rated continuous current. An example is shown in Figure 1.
347 If the evaluation cannot be carried out at the rated continuous current the results shall be
348 extrapolated to the rated value. Any saturation effect will be less pronounced at lower
349 currents, therefore extrapolation from lower to higher values of current is allowed since it can
350 only result in an overestimate of the B field.
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HV/LV prefabricated substation
LV switchgear assembly
HV switchgear assembly
I
Transformer/s
I I I
1 2 4
IEC  2039/09
353 Key
354 I = HV assembly highest loop current
355 I = HV/LV loop (HV side) current
356 I = HV/LV loop (LV side) highest current
357 I = HV/LV (LV outgoing) highest current
358 Figure 1 – Example of test circuits configuration to obtain the maximum external
359 magnetic field of a HV assembly and/or a prefabricated substation
361 4.4.2 HV/LV prefabricated substations
362 For the HV assembly, 4.4.1 applies.
363 The LV switchgear and controlgear assembly and the power transformer shall be loaded with
364 the highest continuous current derived from the rated power of the prefabricated substation
365 and the highest LV rated current of the corresponding power transformer for a given LV level.
366 The circuit shall be configured to form the highest concentration of currents to obtain the
367 maximum magnetic field. This can be achieved by using the smallest number of circuits,
368 choosing those located closest to the enclosure of the prefabricated substation and taking into
369 account their rated continuous currents. An example is shown in Figure 1.
370 NOTE: See 5.5 of IEC 62271-202:2022 for further information about the different rated currents
371 If the evaluation cannot be carried out at the rated power for a given LV level, the results shall
372 be extrapolated to the rated value. Any saturation effect will be less pronounced at lower
373 currents, therefore extrapolation from lower to higher values of current is allowed since it can
374 only result in an overestimate of the B field.
375 The extrapolation of magnetic field values is not permitted if the currents on the HV and LV
376 sides of the prefabricated substation vary independently.
377 5 Measurements
378 5.1 General
379 At power-frequency the electric and magnetic field are independent from each other. Hence,
380 magnetic flux density and electric field strength characteristic need not be recorded
381 simultaneously.
382 The electric field characteristic of the equipment is independent of the load current.

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383 The magnetic field characteristic of the equipment is independent of the voltage.
384 NOTE General guidance on measurement procedures for electric and magnetic fields can also be found in
385 IEC 62110 and IEC 61786.
386 5.2 Measuring instruments
387 Instruments for measuring electric and magnetic fields shall meet the requirements of
388 specification and calibration given by IEC 61786. The calibration report shall be traceable to
389 national or International Standards. These instruments should be used in appropriate
390 conditions, in particular with regard to
391 • electromagnetic immunity according to IEC 61000-6-2,
392 • immunity of power-frequency electric field on magnetic field measurement,
393 • temperature and humidity ranges as recommended by the instrument manufacturer.
394 A three-axis instrument measures RMS values of resultant field F . A single-axis instrument
r
395 may be used to obtain F by measuring F , F , and F , using Equation (1), where F , F and F
r x y z x y z
396 are RMS values of the orthogonal three-axis components of electric or magnetic field.
2 2 2
397 F = F + F + F (1)
r x y z
398 The use of a three-axis instrument with three concentric sensors is preferred. However, if a
399 single-axis instrument is used, special attention should be paid to the orientation of the sensor
400 along three orthogonal directions. The orientation of the sensor shall be changed without
401 moving the position of its centre.
402 In the case of non-concentric sensors, the locations and orientations of the sensors that are
403 contained within the housings of field meters shall be clearly indicated on the instr ument or in
404 the instruction manual.
405 During the evaluation of the magnetic field generated by HV assemblies and HV/LV
406 prefabricated substations, the distance between the field source and the measuring
407 instrument is relatively short (in comparison to other AC power equipment like overhead
408 lines). In general, the measurements will be carried out in non-uniform fields. In case of the
409 magnetic field measurement, it is necessary to consider the ratio of distance (d ) from the
sc
410 field source and sensor radius (a). For measurements with a three-axis instrument, a
411 minimum ratio of 4 is considered suitable.
412 For example, when using a probe with radius 5 cm the minimum distance to the field source
413 would be 20 cm considering a ratio of 4. More information about this topic can be found in IEC
414 61786.
415 5.3 Measurement procedures
416 If measurement procedures are used, one of the following methods shall be used: a) Hot spot
417 measurement procedure b) Isoline measurement procedure.
418 5.3.1 General
419 To consider equipment of all kinds of shape, a virtual envelope containing the equipment is
420 defined as the reference surface (RS); see Figure 2. The purpose of the RS is to integrate
421 irregularities and to eliminate abrupt changes in the measurement surface (MS). The MS is
422 defined outside the RS at 20 cm distance.
423 NOTE A measurement distance between 0,10 m and 0,20 m corresponds to the distance from the centre of a
424 person’s body to an accessible surface when a person is leaning against it. Taking into account the practical sizes
425 of field probes and the necessary clearance to avoid direct contact of the probe with the accessible surface, 0,20 m
426 IS considered the minimum measurement distance. Some national regulations as well as IEC 62110 take this
427 distance as their basis.
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428 Protruding elements (for example handles) shall be disregarded.

d
d
IEC  2040/09
430 Key
431 1 Equipment surface
432 2 Measurement surface (MS)
433 3 Reference surface (RS)
434 d Distance between equipment
435 and measurement surface (20 cm)
436 Figure 2 – Reference surface (RS) for equipment of irregular shape
438 5.3.2 Hot spot measurement procedure
439 5.3.2.1 Electric field
440 The maximum value(s) of the electric field over the accessible measurement surface shall be
441 found by first scanning on a coarse grid to find the regions of maximum field and then refining
442 the grid for the hot spot locations. See also Figure 3.
443 .
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Only if roof is accessible
d
sc
d d
sc sc
Standing
surface
Lateral view
d
sc
d d
sc sc
Only if roof
is accessible
d
sc
Top view
Reference surface (RS) of equipment
Scanning area
Measurement surface (MS)
d  Measurement distance from the RS (d = 20 cm)
sc
sc
IEC  2041/09
447 Figure 3 – Scanning areas to find the hot spots
448 The variation of the electric field shall be determined as a function of the distance from the
449 MS. Starting at each hot spot, the field values shall be measured along a line perpendicular to
450 the MS until the measured value is lower than 1/10 (–20 dB) of the hot spot value; see Figure
451 4. Additional measurements may be carried out to fulfil specific requirements (e.g. for a client
452 or country).
453 NOTE Significant electric fields are not expected for the equipment in the scope of this document. However, it is
454 the intention of this document to give guidance for the measurement of these fields where manufacturers and users
455 require them.
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d
1/10
E
Only if roof is accessible
B d
1/10
C
D
d
1/10
A
Standing
surface
Lateral view
Only if roof
is accessible
d
1/10
A
D
d
B 1/10
E
d
1/10
C
d
1/10
Top view
A
Hot spot location at distance d from the RS
sc
d
1/10
Series of measurements until the measured value
is lower than 1/10 (–20 dB) of the hot spot value
IEC  2042/09
458 Figure 4 – Determination of the field variation as a function of the distance
459 from the hot spot locations (perpendicular to the reference surface)
461 5.3.2.2 Magnetic field
462 The maximum value(s) of the magnetic field over the MS shall be found by first scanning on a
463 coarse grid to find the regions of maximum field and then refining the grid for the hot spot
464 locations. See also Figure 3.
466 The variation of the magnetic field shall be determined as a function of the distance from the
467 MS. Starting at each hot spot, the field values shall be measured along a line perpendicular to

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468 the MS until the measured value is lower than 1/10 (–20 dB) of the hot spot value; Figure 4.
469 Additional measurements may be carried out to fulfil specific requirements (e.g., for a client or
470 country).
471 5.3.2.3 Background fields
472 Immediately after the measurements, the equipment shall be switched off and the background
473 field level shall be measured and recorded.
474 By coarsely scanning the electric or magnetic field within the MV when voltage or current is
475 switched off, it shall be verified that the background field level is below 1/10 (–20 dB) of the
476 lowest value measured at any of the hot spots found during the live measurement.
477 Guidance on reducing the interfering background fields, caused by the external cables
478 connected to the test specimen, to a minimum, is given in 5.6.4.
479 5.3.2.4 Environmental factors
480 5.3.2.4.1 Electric field measurement
481 Environmental factors (e.g., humidity, temperature etc.) have no significant influence on the
482 electric field. However, the electric field measuring instrument can be influenced significantly
483 when the humidity is sufficient to cause condensation on the sensor and the supporting
484 structure. Thus, the environmental factors shall be measured to ensure that the measuring
485 instruments are used within their specified environmental limits. Special attention should be
486 paid to humidity.
487 Acceptable humidity limits for proper measurements are deemed to be
488 • 60 % relative humidity when using a normal tripod,
489 • 70 % relative humidity when using an offset tripod
490 (measuring instrument shifted by 0,50 m form the vertical axis of the tripod).
491 If those limits are exceeded, the measurements shall be considered as conservative, due to
492 the fact that the values measured in high humidity are higher than those in lower humidity for
493 the same equipment excited with the same voltages.
494 Likewise, electric field measurements in rain conditions are inappropriate.
495 5.3.2.4.2 Magnetic field measurement
496 Environmental factors (e.g., humidity, temperature etc.) have no significant influence on the
497 magnetic field. However, the environmental factors shall be measured to ensure that the
498 measuring instruments are being used within their specified environmental limits.
499 5.3.2.4.3 Other conditions
500 During electric field measurements, objects or persons shall be kept outside the influence
501 zone of the measuring device.
502 Only objects containing or consisting of high permeability materials can cause significant
503 distortions of the magnetic field. Persons do not influence the magnetic field, thus measuring
504 instruments may be directly held by persons when making measurements.
505 The presence of high permeability materials, which are not part of the equipment, in the
506 vicinity of the field source and/or the measuring instruments, shall be stated in the
507 measurement report.
508 All parts of the equipment intended to be earthed shall be earthed according to the
509 manufacturer’s instructions.

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510 5.3.3 Isoline measurement procedure
511 5.3.3.1 General
512 Th
...