IEC 61857-1:2008

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

IEC 61857-1:2008 specifies a general test procedure for the thermal evaluation and qualification of electrical insulation systems (EIS) and establishes a procedure that compares the performance of a candidate EIS to that of a reference EIS. This standard is applicable to existing or proposed EIS used in electrotechnical products with an input voltage of up to 1 000 V where the thermal factor is the dominating ageing factor. This third edition cancels and replaces the second edition published in 2004, and constitutes editorial revisions to make this standard compatible with Parts 21 and 22.

Systèmes d'isolation électrique - Procédures d'évaluation thermique - Partie 1: Exigences générales - Basse tension

La CEI 61857-1:2008 spécifie une procédure d'essai générale pour une évaluation thermique et une qualification des systèmes d'isolation électrique (SIE), et établit une procédure comparant la qualité de fonctionnement d'un SIE candidat à celle d'un SIE de référence. Cette norme s'applique aux SIE existants ou proposés, utilisés dans les produits électrotechniques dont la tension d'entrée monte jusqu'à 1 000 V pour lesquels le facteur thermique est le facteur de vieillissement prépondérant. Cette troisième édition annule et remplace la seconde édition publiée en 2004, et elle constitue une révision rédactionnelle pour rendre la présente norme compatible avec les Parties 21 et 22.

General Information

• Status: Published
• Publication Date: 25-Sep-2008
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.080.30 - Insulation systems
• Technical Committee: TC 112 - Evaluation and qualification of electrical insulating materials and systems
• Drafting Committee: WG 6 - TC 112/WG 6
• Current Stage: PPUB - Publication issued
• Start Date: 31-Oct-2008
• Completion Date: 26-Sep-2008

Relations

• Revises: IEC 61857-1:2004 - Electrical insulation systems - Procedures for thermal evaluation - Part 1: General requirements - Low-voltage
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 61857-1
Edition 3.0 2008-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical insulation systems – Procedures for thermal evaluation –
Part 1: General requirements – Low-voltage

Systèmes d'isolation électrique – Procédures d'évaluation thermique –
Partie 1: Exigences générales – Basse tension

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IEC 61857-1
Edition 3.0 2008-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical insulation systems – Procedures for thermal evaluation –
Part 1: General requirements – Low-voltage

Systèmes d'isolation électrique – Procédures d'évaluation thermique –
Partie 1: Exigences générales – Basse tension

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
P
CODE PRIX
ICS 29.080.30 ISBN 978-2-88910-581-6
– 2 – 61857-1 © IEC:2008
CONTENTS
FOREWORD.3
INTRODUCTION.5
Scope.6
2 Normative references.6
3 Terms and definitions .6
4 General information .8
4.1 Overview of test procedure .8
4.2 Basis of evaluation and qualification .8
4.3 Specific requirements .8
5 Test objects.9
5.1 General .9
5.2 Description .9
5.3 Number of test objects.9
6 Test procedures.9
6.1 General .9
6.2 Initial screening tests .9
6.3 Thermal ageing .10
6.4 Prediagnostic mechanical stress .11
6.5 Other prediagnostic conditioning .11
6.6 Moisture exposure .12
6.7 Dielectric diagnostic tests .12
6.8 Other diagnostic tests .12
7 Analyzing, reporting and classification.12
7.1 End-point criterion .12
7.2 Method of determining life.13
7.3 Extrapolation of data.13
7.4 Report of results .14
Bibliography .16

Figure 1 – Arrhenius graph for comparing a candidate system C with a reference
system R.15

Table 1 – Suggested ageing temperatures and ageing periods.10
Table 2 – Thermal class assignment .13

61857-1 © IEC:2008 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
ELECTRICAL INSULATION SYSTEMS –
PROCEDURES FOR THERMAL EVALUATION –

Part 1: General requirements – Low-voltage

FOREWORD
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International Standard IEC 61857-1 has been prepared by IEC technical committee 112:
Evaluation and qualification of electrical insulating materials and systems.
This third edition cancels and replaces the second edition published in 2004, and constitutes
editorial revisions to make this standard compatible with Parts 21 and 22.
The text of this standard is based on the following documents:
CDV Report on voting
112/92/CDV 112/102/RVC
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.

– 4 – 61857-1 © IEC:2008
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all the parts in the IEC 61857 series, under the general title Electrical insulation
systems – Procedures for thermal evaluation, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until the
maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
61857-1 © IEC:2008 – 5 –
INTRODUCTION
This International Standard establishes a standardized test procedure for estimating by
comparison the life expectancy of electrical insulation systems (EIS) in accordance with
IEC 60505.
An EIS contains many different components selected to withstand the varying electrical,
mechanical, and thermal stresses occurring in the different parts of the structure of an
electrotechnical product. The useful life of an EIS depends upon the way that its individual
components are arranged, their interactions upon each other, and the contribution of each
component to the electrical and mechanical integrity of the EIS. Therefore, it is impossible to
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