SIST EN IEC 61869-20:2025

SLOVENSKI STANDARD
01-julij-2025
Instrumentni transformatorji - 20. del: Varnostne zahteve za instrumentne
transformatorje za visokonapetostne aplikacije (IEC 61869-20:2025)
Instrument transformers - Part 20: Safety requirements of instrument transformers for
high voltage applications (IEC 61869-20:2025)
Sicherheitsanforderungen von Messwandlern für Hochspannungsanwendungen (IEC
61869-20:2025)
Transformateurs de mesure - Partie 20: Exigences de sécurité des transformateurs de
mesure pour applications à haute tension (IEC 61869-20:2025)
Ta slovenski standard je istoveten z: EN IEC 61869-20:2025
ICS:
17.220.20 Merjenje električnih in Measurement of electrical
magnetnih veličin and magnetic quantities
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 61869-20

NORME EUROPÉENNE
EUROPÄISCHE NORM May 2025
ICS 17.220.20
English Version
Instrument transformers - Part 20: Safety requirements of
instrument transformers for high voltage applications
(IEC 61869-20:2025)
Transformateurs de mesure - Partie 20 : Exigences de Messwandler - Teil20: Sicherheitsanforderungen von
sécurité des transformateurs de mesure pour applications à Messwandlern für Hochspannungsanwendungen
haute tension (IEC 61869-20:2025)
(IEC 61869-20:2025)
This European Standard was approved by CENELEC on 2025-05-21. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61869-20:2025 E

European foreword
The text of document 38/808/FDIS, future edition 1 of IEC 61869-20, prepared by TC 38 "Instrument
Transformers" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2026-05-31
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2028-05-31
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 61869-20:2025 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standard indicated:
IEC 60695-1-10 NOTE Approved as EN 60695-1-10
IEC 60695-1-11 NOTE Approved as EN 60695-1-11
IEC 60695-7-1 NOTE Approved as EN 60695-7-1
IEC 60947-2 NOTE Approved as EN IEC 60947-2
IEC 60947-7-1 NOTE Approved as EN 60947-7-1
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 60529 - Degrees of protection provided by EN 60529 -
enclosures (IP Code)
IEC/TS 60815-1 - Selection and dimensioning of high-voltage - -
insulators intended for use in polluted
conditions - Part 1: Definitions, information
and general principles
IEC 61869-1 - Instrument transformers - Part 1: General EN IEC 61869-1 -
requirements
IEC 61869-99 - Instrument transformers - Part 99: EN IEC 61869-99 -
Glossary
IEC 62262 - Degrees of protection provided by EN 62262 -
enclosures for electrical equipment against
external mechanical impacts (IK code)

IEC 61869-20 ®
Edition 1.0 2025-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Instrument transformers –
Part 20: Safety requirements of instrument transformers for high voltage

applications
Transformateurs de mesure –
Partie 20: Exigences de sécurité des transformateurs de mesure pour

applications à haute tension
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.220.20  ISBN 978-2-8327-0273-4

– 2 – IEC 61869-20:2025 © IEC 2025
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Protection against electric shock . 6
4.1 General . 6
4.2 Earthing of enclosure, terminals and connection to carrier-frequency
accessory . 6
4.2.1 General. 6
4.2.2 Earthing of high voltage circuit transformers (HV CTs) . 6
4.2.3 Earthing of high-voltage VTs (HV VTs) . 8
4.3 Access to secondary terminals . 12
4.3.1 General. 12
4.3.2 Indoor instrument transformers . 12
4.3.3 Outdoor instrument transformers . 12
4.3.4 Protection of equipment against mechanical impact under normal
service conditions . 13
4.4 Risk of open secondary terminals in CTs and shorted secondary terminals in VTs 13
4.4.1 General. 13
4.4.2 Protections against the risk of open secondary terminals in CTs . 13
4.4.3 Protections against the risk of shorted secondary terminals in VTs . 13
5 Protection against thermal and chemical hazards . 13
5.1 General . 13
5.2 Risk of fire . 13
5.3 Risk of internal arc . 14
5.4 Risk of leakage of oil or release of gases . 14
6 Protection against mechanical hazards . 14
6.1 General . 14
6.2 Hazards during mounting and dismounting . 14
Bibliography . 15

Figure 1 – Earthing of a CT with one secondary circuit (example) . 7
Figure 2 – Earthing of a CT with one secondary circuit having a tap (example) . 7
Figure 3 – Earthing of a CT with two secondary circuits (example) . 7
Figure 4 – Earthing terminal connected to the steel support structure . 8
Figure 5 – Earthing terminal connected to earth via an earthing conductor . 8
Figure 6 – Open delta earthing. 9
Figure 7 – Earthing of an earthed VT with one secondary circuit (example) . 9
Figure 8 – Earthing of an unearthed VT with one secondary circuit (example) . 10
Figure 9 – Earthing of an earthed VT with two secondary circuits (example) . 10
Figure 10 – Earthing of an earthed VT with a multi-tap secondary circuit (example) . 10
Figure 11 – Earthing of an earthed VT with carrier-frequency accessory (example) . 11
Figure 12 – Earthing terminal connected to the steel support structure . 11
Figure 13 – Earthing terminal connected to earth via an earthing conductor. 12

Table 1 – Fire hazard of electrotechnical products . 14

IEC 61869-20:2025 © IEC 2025 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INSTRUMENT TRANSFORMERS –
Part 20: Safety requirements of instrument transformers for high voltage
applications
FOREWORD
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