Electrical insulation systems - Procedures for thermal evaluation - Part 31: Applications with a designed life of 5 000 h or less

IEC 61857-31:2017 establishes an EIS evaluation for applications with a designed life of 5 000 h or less. This test method follows the procedures of IEC 60505 and is modified based on the range of designed life.

Systèmes d'isolation électrique - Procédures d'évaluation thermique - Partie 31: Applications avec une durée de vie de conception maximale de 5 000 h

L'IEC 61857-31:2017 établit une évaluation SIE pour les applications dont la durée de vie de conception maximale est de 5 000 h. Cette méthode d'essai suit les procédures de l'IEC 60505 et est modifiée en fonction de la plage de durée de vie de conception.

General Information

Status
Published
Publication Date
23-Jan-2017
Current Stage
PPUB - Publication issued
Completion Date
24-Jan-2017
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IEC 61857-31
Edition 1.0 2017-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical insulation systems – Procedures for thermal evaluation –
Part 31: Applications with a designed life of 5 000 h or less
Systèmes d'isolation électrique – Procédures d'évaluation thermique –
Partie 31: Applications avec une durée de vie de conception maximale de 5 000 h
IEC 61857-31:2017-01(en-fr)
---------------------- Page: 1 ----------------------
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IEC 61857-31
Edition 1.0 2017-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical insulation systems – Procedures for thermal evaluation –
Part 31: Applications with a designed life of 5 000 h or less
Systèmes d'isolation électrique – Procédures d'évaluation thermique –
Partie 31: Applications avec une durée de vie de conception maximale de 5 000 h
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.080.30 ISBN 978-2-8322-5287-1

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC 61857-31:2017 © IEC 2017
CONTENTS

FOREWORD ........................................................................................................................... 3

INTRODUCTION ..................................................................................................................... 5

1 Scope .............................................................................................................................. 6

2 Normative references ...................................................................................................... 6

3 Terms and definitions ...................................................................................................... 6

4 EIS evaluation ................................................................................................................. 7

5 Test objects ..................................................................................................................... 7

6 Test procedures .............................................................................................................. 7

6.1 Procedure A: Establishing a TE for applications with a designed life of

1 500 h or less: one-temperature ageing ................................................................. 7

6.2 Procedure B: Establishing a TE rating for applications with a designed life of

5 000 h or less: one-temperature ageing ................................................................. 8

6.3 Procedure C: Establishing a TE rating for applications with a designed life of

5 000 h or less: two-temperature ageing ................................................................. 8

7 Data analysis ................................................................................................................... 8

7.1 Analysis – Test Procedures A and B (See 6.1 and 6.2) ........................................... 8

7.2 Analysis – Test Procedure C (See 6.3) ................................................................... 9

8 Test report ....................................................................................................................... 9

Bibliography .......................................................................................................................... 10

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IEC 61857-31:2017 © IEC 2017 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL INSULATION SYSTEMS – PROCEDURES
FOR THERMAL EVALUATION –
Part 31: Applications with a designed life of 5 000 h or less
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

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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 61857-31 has been prepared by IEC technical committee 112:

Evaluation and qualification of electrical insulating materials and systems.

This bilingual version (2018-01) corresponds to the monolingual English version, published in

2017-01.
The text of this International Standard is based on the following documents:
CDV Report on voting
112/356/CDV 112/375/RVC

Full information on the voting for the approval of this International Standard can be found in

the report on voting indicated in the above table.
---------------------- Page: 5 ----------------------
– 4 – IEC 61857-31:2017 © IEC 2017
The French version of this standard has not been voted upon.

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

A list of all parts in the IEC 61857 series, published 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 document will remain unchanged until the

stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to

the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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IEC 61857-31:2017 © IEC 2017 – 5 –
INTRODUCTION

IEC 61857-1 provides the general structure to be followed for an electrical insulation system

(EIS) evaluation and classification.

IEC TR 61857-2 provides guidelines to identify the application and to select the preferred test

method based on the application.

This part of IEC 61857 provides a test method for EIS applications, such as the automotive

industry, when the designed life is 5 000 h or less.
The selection of this test method can be decided by the end product application.
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– 6 – IEC 61857-31:2017 © IEC 2017
ELECTRICAL INSULATION SYSTEMS – PROCEDURES
FOR THERMAL EVALUATION –
Part 31: Applications with a designed life of 5 000 h or less
1 Scope

This part of IEC 61857 establishes an EIS evaluation for applications with a designed life of

5 000 h or less. This test method follows the procedures of IEC 60505 and is modified based

on the range of designed life.
2 Normative references

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.
IEC 60505, Evaluation and qualification of electrical insulation systems

IEC 61857-1, Electrical insulation systems – Procedures for thermal evaluation – Part 1:

General requirements – Low-voltage

IEC TR 61857-2, Electrical insulation systems – Procedures for thermal evaluation – Part 2:

Selection of the appropriate test method for evaluation and classification of electrical

insulation systems

IEC 61857-21, Electrical insulation systems – Procedures for thermal evaluation – Part 21:

Specific requirements for general-purpose models – Wire-wound applications

IEC 61857-22, Electrical insulation systems – Procedures for thermal evaluation – Part 22:

Specific requirements for encapsulated-coil model – Wire-wound electrical insulation system

(EIS)
3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 61857-1 and the

following apply.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
designed life

expected application time which is proposed or decided by an end user, an industrial

manufacturer, etc., regardless of the duty cycle, continual or intermittent
---------------------- Page: 8 ----------------------
IEC 61857-31:2017 © IEC 2017 – 7 –
3.2
thermal endurance
maximum designed temperature for the selected time coordinate
3.3
average life
mean value of life
4 EIS evaluation

Procedure A (see Clause 6) is intended for EIS with a designed life of 1 500 h or less,

subjecting one set of test objects to one-temperature ageing at 10 K above the maximum

design temperature. The average life of the set under evaluation shall be at least 1 500 h.

Procedure B (see Clause 6) is intended for EIS with a designed life of 5 000 h or less,

subjecting one set of test objects to one-temperature ageing at 10 K above the maximum

design temperature. The ageing time in Procedure A may be increased up to 5 000 h to

correspond to the designed life of the EIS. The average life of the set under evaluation shall

be at least 1 500 h.

Procedure C (see Clause 6) is intended for EIS with a designed life of 5 000 h or less,

subjecting two sets of test objects to two-temperature ageing at 20 K to 30 K and 30 K to 35 K

above the maximum design temperature.

The test results determined by either Procedure A, Procedure B or Procedure C described in

Clause 6 can be expanded to larger full thermal evaluations in accordance with IEC 61857 (all

parts), if the additional thermal ageing is started prior to the completion of the thermal ageing

according to this document. When expanded to a full thermal ageing, the work undertaken

according to this document is referred to as a screening test portion of the full thermal ageing.

Also, IEC 61857-1 and IEC TR 61857-2 may require a reference EIS to be included in the

evaluation for establishing a relative thermal endurance (RTE) rating. When expansion is

needed, an evaluation with regard to other applications shall require the addition of a

reference EIS in accordance with an EIS method selected from IEC TR 61857-2.
5 Test objects

The test objects and test equipment shall be in accordance with the appropriate test method

selected from IEC TR 61857-2.
6 Test procedures

6.1 Procedure A: Establishing a TE for applications with a designed life of 1 500 h or

less: one-temperature ageing

Follow the procedures of the selected test method. For the selected test method, one test

cycle consists of:
– thermal ageing subcycle according to IEC 60505,
– conditioning subcycle according to IEC TR 61857-2, for example IEC 61857-21 or
IEC 61857-22, and

– diagnostic testing in accordance with the procedures of the test method selected from

IEC TR 61857-2. The selected ageing temperature shall be 10 K above the maximum
design temperature.
---------------------- Page: 9 ----------------------
– 8 – IEC 61857-31:2017 © IEC 2017
The average life of the set under evaluation shall be at least 1 500 h.

To accumulate at least 1 500 h prior to the breakdown of the EIS the ageing cycle shall be

168 h.

NOTE 168 hours (one week) is used for accumulating more than 1 500 ageing hours in nine ageing cycles.

If the set of test objects exceeds the original test time of 1 500 h the test may be terminated

as the target was achieved or the thermal ageing may be continued to achieve an expanded

goal.

6.2 Procedure B: Establishing a TE rating for applications with a designed life of

5 000 h or less: one-temperature ageing

The one-temperature ageing described in Procedure A can be extended to accumulate

additional hours. The set undergoing thermal evaluation under Procedure A can be extended

to a time coordinate of up to 5 000 h.

6.3 Procedure C: Establishing a TE rating for applications with a designed life of

5 000 h or less: two-temperature ageing

For these two-temperature ageing applications, the recommendation is for two sets of the

candidate EIS test objects to undergo test cycles at each of two elevated ageing
temperatures. One test cycle consists of
– thermal ageing subcycle according to IEC 60505,
– conditioning subcycle, and

– diagnostic testing in accordance with the procedures of the test method selected from

IEC TR 61857-2 with the following selected ageing temperatures:

• the lower temperature shall be 20 K to 30 K above the expected thermal class value,

and

• the higher ageing temperature shall be 30 K to 35 K above the expected thermal class

value.
7 Data analysis
7.1 Analysis – Test Procedures A and B (See 6.1 and 6.2)

The thermal classification is evaluated and established when there are no failed test objects

and no breakdown of the EIS prior to accumulating the specific number of hours. No

projection is needed or made with the accumulated single data point. The application

expected life is reached prior to the failure of the EIS undergoing the thermal ageing

exposure.

If any specimens have a failure of the EIS prior to accumulation of the selected number of

hours, the TE shall be established by using the average life (AL) of the set of test objects. The

AL is calculated in accordance with the procedure given in IEC 61857-1.
The EIS TE value assigned to the candidate EIS is defined as EIS TE x/y where
x is the established thermal class (expressed in ºC),
y is the specified time interval for this ratin
...

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