EN 61857-1:2005

SLOVENSKI SIST EN 61857-1:2005

STANDARD
julij 2005
Sistemi električne izolacije – Postopki za toplotno vrednotenje – 1. del:
Splošne zahteve – Nizka napetost
Electrical insulation systems – Procedures for thermal evaluation – Part 1: General
requirements – Low-voltage
ICS 29.080.30 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

EUROPEAN STANDARD EN 61857-1
NORME EUROPÉENNE
EUROPÄISCHE NORM March 2005
ICS 29.080.30 Supersedes EN 61857-1:1999

English version
Electrical insulation systems –
Procedures for thermal evaluation
Part 1: General requirements –
Low-voltage
(IEC 61857-1:2004)
Systèmes d'isolation électrique - Elektrische Isoliersysteme –
Procédures d'évaluation thermique Verfahren zur thermischen Bewertung –
Partie 1: Exigences générales – Teil 1: Allgemeine Anforderungen -
Basse tension Niederspannung
(CEI 61857-1:2004) (IEC 61857-1:2004)

This European Standard was approved by CENELEC on 2005-02-01. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden,
Switzerland and United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2005 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 61857-1:2005 E
Foreword
The text of document 98/222/FDIS, future edition 2 of IEC 61857-1, prepared by IEC TC 98, Electrical
insulation systems (EIS), was submitted to the IEC-CENELEC parallel vote and was approved by
CENELEC as EN 61857-1 on 2005-02-01.
This European Standard supersedes EN 61857-1:1999.
It constitutes a technical revision which makes this basic standard compatible with parts 21 and 22.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2005-11-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2008-02-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61857-1:2004 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 standards indicated:
IEC 60034-18-1 NOTE Harmonized as EN 60034-18-1:1994 (not modified).
IEC 60034-18-21 NOTE Harmonized as EN 60034-18-21:1994 (not modified).
IEC 60034-18-31 NOTE Harmonized as EN 60034-18-31:1994 (not modified).
IEC 62114 NOTE Harmonized as EN 62114:2001 (not modified).
__________
- 3 - EN 61857-1:2005
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
NOTE Where an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
Publication Year Title EN/HD Year
1) 2)
IEC 60216-4-1 - Guide for the determination of thermal HD 611.4.1 S1 1992
endurance properties of electrical
insulating materials
Part 4: Ageing ovens –
Section 1: Single-chamber ovens

1) 2)
IEC 60216-5 - Part 5: Determination of relative thermal EN 60216-5 2003
endurance index (RTE) of an insulating
material
1)
IEC 60493-1 - Guide for the statistical analysis of ageing - -
test data
Part 1: Methods based on mean values of
normally distributed test results

1) 2)
IEC 60505 - Evaluation and qualification of electrical EN 60505 2004
insulation systems
1)
Undated reference.
2)
Valid edition at date of issue.

NORME CEI
INTERNATIONALE
IEC
61857-1
INTERNATIONAL
Deuxième édition
STANDARD
Second edition
2004-11
Systèmes d'isolation électrique –
Procédures d'évaluation thermique –
Partie 1:
Exigences générales – Basse tension

Electrical insulation systems –
Procedures for thermal evaluation –
Part 1:
General requirements – Low-voltage

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61857-1 © IEC:2004 – 3 –
CONTENTS
FOREWORD.3
INTRODUCTION.9

1 Scope.11
2 Normative references.11
3 Terms and definitions .11
4 General information .15
4.1 Overview of test procedure .15
4.2 Basis of evaluation and qualification .15
4.3 Specific requirements .15
5 Test objects.17
5.1 General .17
5.2 Description .17
5.3 Number of test objects.17
6 Test procedures.19
6.1 General .19
6.2 Initial screening tests .19
6.3 Thermal ageing .19
6.4 Prediagnostic mechanical stress .23
6.5 Other prediagnostic conditioning .23
6.6 Moisture exposure .23
6.7 Dielectric diagnostic tests .23
6.8 Other diagnostic tests .25
7 Analyzing, reporting, and classification.25
7.1 End-point criterion .25
7.2 Method of determining life.25
7.3 Extrapolation of data.27
7.4 Report of results .27

Bibliography .33

Figure 1 – Arrhenius graph for comparing a candidate system C with a reference
system R.31

Table 1 – Suggested ageing temperatures and ageing periods.19
Table 2 – Thermal class assignment .27

61857-1 © IEC:2004 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
ELECTRICAL INSULATION SYSTEMS –
PROCEDURES FOR THERMAL EVALUATION –

Part 1: General requirements – Low-voltage

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61857-1 has been prepared by IEC technical committee 98:
Electrical insulation systems (EIS).
This second edition cancels and replaces the first edition published in 1998, and constitutes a
technical revision to make this basic standard compatible with parts 21 and 22.
The text of this standard is based on the following documents:
FDIS Report on voting
98/222/FDIS 98/228/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.

61857-1 © IEC:2004 – 7 –
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
IEC 61857 consists of the following parts, under the general title Electrical insulation systems –
Procedures for thermal evaluation
Part 1: General requirements – Low-voltage
Part 2
...