SIST EN 61858:2008

Electrical insulation systems - Thermal evaluation of modifications to an established wire-wound EIS (IEC 61858:2008)

This International Standard lists the required test procedures for qualification of modifications of an established electrical insulation system (EIS) with respect to its thermal classification. This standard is applicable to EIS used in wire-wound electrotechnical devices. The test procedures are comparative in that the performance of a candidate EIS is compared to that of a reference EIS, which has proven service experience in accordance with IEC 60505 or has been evaluated by one of the procedures given in the IEC 61857 series.

Elektrische Isoliersysteme - Thermische Bewertung von Veränderungen an einem erprobten, drahtgewickelten EIS (IEC 61858:2008)

Systèmes d’isolation électrique - Evaluation thermique des modifications apportées à un système d’isolation électrique éprouvé à enroulements à fil (CEI 61858:2008)

La CEI 61858:2008 indique les procédures d'essai requises pour la qualification des modifications qui ont été apportées à un système d'isolation électrique éprouvé (SIE), pour ce qui concerne sa classification thermique. Cette norme s'applique aux systèmes d'isolation électrique existant dans les dispositifs électrotechniques à enroulements à fils. Les procédures d'essai se font par comparaison des performances d'un système d'isolation électrique candidat avec celles d'un système d'isolation électrique de référence dont l'expérience en service a été démontrée conformément à la CEI 60505, ou qui a été évalué par une des procédures décrites dans la série 61857. Cette troisième édition annule et remplace la seconde édition, publiée en 2004 par le comité d'études 98 de la CEI: Systèmes d'isolation électrique (SIE). Elle constitue une révision rédactionnelle.

Sistemi električne izolacije - Toplotno vrednotenje sprememb preverjenega sistema električne izolacije z žičnim navitjem (IEC 61858:2008)

General Information

• Status: Withdrawn
• Publication Date: 22-Oct-2008
• Withdrawal Date: 07-Mar-2017
• ICS: 29.080.30 - Insulation systems
• Technical Committee: IIZS - Insulating materials and systems
• Current Stage: 9900 - Withdrawal (Adopted Project)
• Start Date: 08-Mar-2017
• Due Date: 31-Mar-2017
• Completion Date: 08-Mar-2017
• Ref Project: EN 61858:2008 - Electrical insulation systems - Thermal evaluation of modifications to an established wire-wound EIS

Relations

• Replaced By: SIST EN 61858-1:2014 - Electrical insulation systems - Thermal evaluation of modifications to an established EIS - Part 1: Wire-wound winding EIS
• Effective Date: 15-Apr-2014
• Replaced By: SIST EN 61858-1:2014 - Electrical insulation systems - Thermal evaluation of modifications to an established EIS - Part 1: Wire-wound winding EIS
• Effective Date: 28-Jan-2023
• Revised: SIST EN 61858:2005 - Electrical insulation systems - Thermal evaluation of modifications to an established wire-wound EIS
• Effective Date: 06-Sep-2011
• Replaces: SIST EN 61858:2005 - Electrical insulation systems - Thermal evaluation of modifications to an established wire-wound EIS
• Effective Date: 29-Jan-2023
• Replaces: SIST EN 61858:2005 - Electrical insulation systems - Thermal evaluation of modifications to an established wire-wound EIS
• Effective Date: 07-Jun-2022

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 61858:2008
01-december-2008
1DGRPHãþD
SIST EN 61858:2005
6LVWHPLHOHNWULþQHL]RODFLMH7RSORWQRYUHGQRWHQMHVSUHPHPESUHYHUMHQHJD
VLVWHPDHOHNWULþQHL]RODFLMH]åLþQLPQDYLWMHP,(&
Electrical insulation systems - Thermal evaluation of modifications to an established wire-
wound EIS (IEC 61858:2008)
Elektrische Isoliersysteme - Thermische Bewertung von Veränderungen an einem
erprobten, drahtgewickelten EIS (IEC 61858:2008)
Systèmes d’isolation électrique - Evaluation thermique des modifications apportées à un
système d’isolation électrique éprouvé à enroulements à fil (CEI 61858:2008)
Ta slovenski standard je istoveten z: EN 61858:2008
ICS:
29.080.30 Izolacijski sistemi Insulation systems
SIST EN 61858:2008 en,fr
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

SIST EN 61858:2008

---------------------- Page: 2 ----------------------

SIST EN 61858:2008

EUROPEAN STANDARD
EN 61858

NORME EUROPÉENNE
October 2008
EUROPÄISCHE NORM

ICS 29.080.30 Supersedes EN 61858:2005


English version


Electrical insulation systems -
Thermal evaluation of modifications to an established wire-wound EIS
(IEC 61858:2008)


Systèmes d’isolation électriques -  Elektrische Isoliersysteme -
Evaluation thermique des modifications Thermische Bewertung
apportées à un système d’isolation von Veränderungen an einem erprobten,
électrique éprouvé à enroulements à fil drahtgewickelten EIS
(CEI 61858:2008) (IEC 61858:2008)




This European Standard was approved by CENELEC on 2008-09-01. 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, Bulgaria, Cyprus, the
Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the 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


© 2008 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61858:2008 E

---------------------- Page: 3 ----------------------

SIST EN 61858:2008
EN 61858:2008 - 2 -
Foreword
The text of document 112/90/CDV, future edition 3 of IEC 61858, prepared by IEC TC 112, Evaluation
and qualification of electrical insulating materials and systems, was submitted to the IEC-CENELEC
parallel vote and was approved by CENELEC as EN 61858 on 2008-09-01.
This European Standard supersedes EN 61858:2005.
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) 2009-06-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2011-09-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61858:2008 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following note has to be added for the standard indicated:
IEC 60317-24 NOTE  Harmonized as EN 60317-24:1995 (not modified).
__________

---------------------- Page: 4 ----------------------

SIST EN 61858:2008
- 3 - EN 61858:2008
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  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.

Publication Year Title EN/HD Year

IEC 60085 2007 Electrical insulation - Thermal evaluation and EN 60085 2008
designation


1) 2)
IEC 60172 - Test procedure for the determination of the EN 60172 1994
temperature index of enamelled winding wires


1) 2)
IEC 60216-5 - Electrical insulating materials - Thermal EN 60216-5 2008
endurance properties -
Part 5: Determination of relative thermal
endurance index (RTE) of an insulating
material


1)
IEC 60317-3 - Specifications for particular types of winding - -
wires -
Part 3: Polyester enamelled round copper
wire, class 155


1) 2)
IEC 60317-4 - Specifications for particular types of winding EN 60317-4 1994
wires -
Part 4: Solderable polyurethane enamelled
round copper wire, class 130


1) 2)
IEC 60317-7 - Specifications for particular types of winding HD 555.7 S2 1992
wires -
Part 7: Polyimide enamelled round copper
wire, class 220


1) 2)
IEC 60317-8 - Specifications for particular types of winding EN 60317-8 1994
wires -
Part 8: Polyesterimide enamelled round
copper wire, class 180


1) 2)
IEC 60317-13 - Specifications for particular types of winding EN 60317-13 1994
wires -
Part 13: Polyester or polyesterimide
overcoated with polyamide-imide enamelled
round copper wire, class 200


1) 2)
IEC 60317-15 - Specifications for particular types of winding EN 60317-15 2004
wires -
Part 15: Polyesterimide enamelled round
aluminium wire, class 180


1) 2)
IEC 60317-16 - Specifications for particular types of winding HD 555.16 S2 1992
wires -
Part 16: Polyester enamelled rectangular
copper wire, class 155



1)
Undated reference.
2)
Valid edition at date of issue.

---------------------- Page: 5 ----------------------

SIST EN 61858:2008
EN 61858:2008 - 4 -
Publication Year Title EN/HD Year

1) 2)
IEC 60317-19 - Specifications for particular types of winding EN 60317-19 1995
wires -
Part 19: Solderable polyurethane enamelled
round copper wire overcoated with polyamide,
class 130


1) 2)
IEC 60317-20 - Specifications for particular types of winding EN 60317-20 1995
wires -
Part 20: Solderable polyurethane enamelled
round copper wire, class 155


1) 2)
IEC 60317-21 - Specifications for particular types of winding EN 60317-21 1995
wires -
Part 21: Solderable polyurethane enamelled
round copper wire overcoated with polyamide,
class 155


1) 2)
IEC 60317-22 - Specifications for particular types of winding EN 60317-22 2004
wires -
Part 22 : Polyester or polyesterimide
enamelled round copper wire overcoated with
polyamide, class 180


1) 2)
IEC 60317-23 - Specifications for particular types of winding EN 60317-23 1995
wires -
Part 23: Solderable polyesterimide enamelled
round copper wire, class 180


1) 2)
IEC 60317-25 - Specifications for particular types of winding EN 60317-25 1996
wires -
Part 25: Polyester or polyesterimide
overcoated with polyamide-imide enamelled
round aluminium wire, class 200


1) 2)
IEC 60317-29 - Specifications for particular types of winding EN 60317-29 1996
wires -
Part 29: Polyester or polyesterimide
overcoated with polyamide-imide enamelled
rectangular copper wire, class 200


1) 2)
IEC 60317-30 - Specifications for particular types of winding EN 60317-30 1996
wires -
Part 30: Polyimide enamelled rectangular
copper wire, class 220


1)
IEC 60317-34 - Specifications for particular types of winding - -
wires -
Part 34: Polyester enamelled round copper
wire, class 130 L


1) 2)
IEC 60317-42 - Specifications for particular types of winding EN 60317-42 1997
wires -
Part 42: Polyester-amide-imide enamelled
round copper wire, class 200


1) 2)
IEC 60317-46 - Specifications for particular types of winding EN 60317-46 1997
wires -
Part 46: Aromatic polyimide enamelled round
copper wire, class 240


1) 2)
IEC 60317-47 - Specifications for particular types of winding EN 60317-47 1997
wires -
Part 47: Aromatic polyimide enamelled
rectangular copper wire, class 240

---------------------- Page: 6 ----------------------

SIST EN 61858:2008
- 5 - EN 61858:2008
Publication Year Title EN/HD Year

1) 2)
IEC 60317-51 - Specifications for particular types of winding EN 60317-51 2001
wires -
Part 51: Solderable polyurethane enamelled
round copper wire, class 180


1) 2)
IEC 60505 - Evaluation and qualification of electrical EN 60505 2004
insulation systems


1) 2)
IEC 61033 - Test methods for the determination of bond EN 61033 2006
strength of impregnating agents to an
enamelled wire substrate


IEC 61857 Series Electrical insulation systems - Procedures for EN 61857 Series
thermal evaluation


1) 2)
IEC 61857-1 - Electrical insulation systems - Procedures for EN 61857-1 2005
thermal evaluation -
Part 1: General requirements - Low-voltage

---------------------- Page: 7 ----------------------

SIST EN 61858:2008

---------------------- Page: 8 ----------------------

SIST EN 61858:2008
IEC 61858
Edition 3.0 2008-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE


Electrical insulation systems – Thermal evaluation of modifications to an
established wire-wound EIS

Systèmes d’isolation électriques – Evaluation thermique des modifications
apportées à un système d’isolation électrique éprouvé à enroulements à fil

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
R
CODE PRIX
ICS 29.080.30 ISBN 2-8318-9946-X
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

---------------------- Page: 9 ----------------------

SIST EN 61858:2008
– 2 – 61858 © IEC:2008
CONTENTS
FOREWORD.3
INTRODUCTION.5
1 Scope.6
2 Normative references .6
3 Terms and definitions .7
4 General considerations.8
5 Evaluation of the change of thickness of an EIM.10
5.1 Samples .10
5.2 Acceptance .10
6 Substitution of winding wire .10
6.1 General .10
6.2 Substitution of enamel.10
6.3 Substitution of conductor material .10
6.4 Alternate winding wire .10
7 Substitution of impregnating resin/varnish .11
7.1 Thermal class determination.11
7.2 Evaluation .11
7.2.1 Thermal classes equal or better.11
7.2.2 One thermal class lower .11
7.2.3 Other criteria .11
8 Substitution with other EIM.11
8.1 Technically equivalent materials.11
8.2 Previous evaluation .12
8.3 Other.12
9 Evaluation of additions .12
9.1 Addition of an impregnating resin/varnish .12
9.2 Addition of other components .12
10 Single-point thermal ageing test .12
10.1 Test objects.12
10.2 Establishing the EIS relative thermal endurance index (EIS RTE).12
10.3 Interpretation of results .13
Annex A (normative) Classes of winding wire.14
Annex B (normative) Compatibility test procedure.15
Bibliography.18

Figure 1 – Overview of evaluation methods.9

Table 1 – Thermal ageing test methods for resin/varnishes.11
Table A.1 – Winding wire types.14

---------------------- Page: 10 ----------------------

SIST EN 61858:2008
61858 © IEC:2008 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

ELECTRICAL INSULATION SYSTEMS –
THERMAL EVALUATION OF MODIFICATIONS TO
AN ESTABLISHED WIRE-WOUND EIS


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
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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 61858 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 by IEC TC 98:
Electrical insulation systems (EIS). It constitutes an editorial revision.
The text of this standard is based on the following documents:
CDV Report on voting
112/90/CDV 112/98/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.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

---------------------- Page: 11 ----------------------

SIST EN 61858:2008
– 4 – 61858 © IEC:2008
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.

---------------------- Page: 12 ----------------------

SIST EN 61858:2008
61858 © IEC:2008 – 5 –
INTRODUCTION
This International Standard describes procedures for the evaluation of changes to an
established electrical insulation system (EIS) for wire-wound electrotechnical devices and the
effect of these changes on the thermal classification of the established EIS.
General principles for evaluation and qualification of EIS can be found in IEC 60505. Unless
the procedures of this standard indicate otherwise, the principles of IEC 60505 should be
followed.
The thermal classification of an EIS is established either by known service life, in accordance
with IEC 60505, or evaluated in accordance with IEC 61857 (all parts).

---------------------- Page: 13 ----------------------

SIST EN 61858:2008
– 6 – 61858 © IEC:2008
ELECTRICAL INSULATION SYSTEMS –
THERMAL EVALUATION OF MODIFICATIONS TO
AN ESTABLISHED WIRE-WOUND EIS



1 Scope
This International Standard lists the required test procedures for qualification of modifications
of an established electrical insulation system (EIS) with respect to its thermal classification.
This standard is applicable to EIS used in wire-wound electrotechnical devices. The test
procedures are comparative in that the performance of a candidate EIS is compared to that of
a reference EIS, which has proven service experience in accordance with IEC 60505 or has
been evaluated by one of the procedures given in the IEC 61857 series.
2 Normative references
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.
IEC 60085:2007, Electrical insulation – Thermal evaluation and designation
IEC 60172, Test procedure for the determination of the temperature index of enamelled
winding wires
IEC 60216-5, Electrical insulating materials – Thermal endurance properties – Part 5:
Determination of relative thermal endurance index (RTE) of an insulating material
IEC 60317-3, Specifications for particular types of winding wires – Part 3: Polyester
enamelled round aluminium wire, class 155
IEC 60317-4, Specifications for particular types of winding wires – Part 4: Solderable
polyurethane enamelled round copper wire, class 130
IEC 60317-7, Specifications for particular types of winding wires – Part 7: Polyimide
enamelled round copper wire, class 220
IEC 60317-8, Specifications for particular types of winding wires – Part 8: Polyesterimide
enamelled round copper wire, class 180
IEC 60317-13, Specifications for particular types of winding wires – Part 13: Polyester or
polyesterimide overcoated with polyamide-imide enamelled round copper wire, class 200
IEC 60317-15, Specifications for particular types of winding wires – Part 15: Polyesterimide
enamelled round aluminium wire, class 180
IEC 60317-16, Specifications for particular types of winding wires – Part 16: Polyester
enamelled rectangular copper wire, class 155
IEC 60317-19, Specifications for particular types of winding wires – Part 19: Solderable
polyurethane enamelled round copper wire, overcoated with polyamide, class 130

---------------------- Page: 14 ----------------------

SIST EN 61858:2008
61858 © IEC:2008 – 7 –
IEC 60317-20, Specifications for particular types of winding wires – Part 20: Solderable
polyurethane enamelled round copper wire, class 155
IEC 60317-21, Specifications for particular types of winding wires – Part 21: Solderable
polyurethane enamelled round copper wire overcoated with polyamide, class 155
IEC 60317-22, Specifications for particular types of winding wires – Part 22: Polyester or
polyesterimide enamelled round copper wire overcoated with polyamide, class 180
IEC 60317-23, Specifications for particular types of winding wires – Part 23: Solderable
polyesterimide enamelled round copper wire, class 180
IEC 60317-25, Specifications for particular types of winding wires – Part 25: Polyester or
polyesterimide overcoated with polyamide-imide enamelled round aluminium wire, class 200
IEC 60317-29, Specifications for particular types of winding wires – Part 29: Polyester or
polyesterimide overcoated with polyamide-imide enamelled rectangular copper wire, class 200
IEC 60317-30, Specifications for particular types of winding wires – Part 30: Polyimide
enamelled rectangular copper wire, class 220
IEC 60317-34, Specifications for particular types of winding wires – Part 34: Polyester
enamelled round copper wire, class 130 L
IEC 60317-42, Specifications for particular types of winding wires – Part 42: Polyester-amide-
imide enamelled round copper wire, class 200
IEC 60317-46, Specifications for particular types of winding wires – Part 46: Aromatic
polyimide enamelled round copper wire, class 240
IEC 60317-47, Specifications for particular types of winding wires – Part 47: Aromatic
polyimide enamelled rectangular copper wire, class 240
IEC 60317-51, Specifications for particular types of winding wires – Part 51: Solderable
polyurethane enamelled round copper wire, class 180
IEC 60505, Evaluation and qualification of electrical insulation systems
IEC 61033, Test methods for the determination of bond strength of impregnating agents to an
enamelled wire substrate
IEC 61857 (all parts), Electrical insulation systems – Procedures for thermal evaluation
IEC 61857-1, Electrical insulation systems – Procedures for thermal evaluation – Part 1:
General requirements – Low voltage
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
electrical insulation system
EIS
insulating structure containing one or more electrical insulating materials (EIM) together with
associated conducting parts employed in an electrotechnical device

---------------------- Page: 15 ----------------------

SIST EN 61858:2008
– 8 – 61858 © IEC:2008
3.2
electrical insulating material
EIM
material with negligibly low electric conductivity, used to separate conducting parts at different
electrical potentials
3.3
candidate EIS
EIS under evaluation to determine its service capability (thermal)
3.4
reference EIS
established EIS evaluated on the basis of either a known service experience record or a
known comparative functional evaluation
3.5
EIS assessed thermal endurance index
EIS ATE
numerical value of temperature in degrees Celsius for the reference EIS as derived from
known service experience or a known comparative functional evaluation
3.6
EIS relative thermal endurance index
EIS RTE
numerical value of the temperature in degrees Celsius of the candidate EIS which is relative
to the known EIS ATE of a reference EIS, when both EIS are subjected to the same ageing
and diagnostic procedures in a comparative test
4 General considerations
This standard provides relatively low cost and short-time methods by which the user can
make modifications to an established EIS by evaluating
a) the impact on the thermal life of the EIS if the thickness of an EIM is changed,
b) the compatibility, under thermal stress, of a substituted EIM,
c) the compatibility, under thermal stress, of other components used in intimate contact with
an established EIS.
EIM having different temperature indices (ATE/RTE) according to IEC 60216-5, may be
combined to form an EIS having a thermal class that may be higher or lower than that of any
of the individual components according to IEC 60505.
There may be more than one EIS in a particular apparatus. These EIS may have different
thermal classes.
The following overview (Figure 1) is a flow chart for guidance in selecting the proper clauses
for evaluation.

---------------------- Page: 16 ----------------------

SIST EN 61858:2008
61858 © IEC:2008 – 9 –

Established EIS per IEC 60791
or IEC 61857-1
EIM modification of established EIS Evaluation of additions to
established EIS
Addition of Addition
Change of
Substitution of EIM component
impregnating resin/ of other
thickness
varnish components
(5)
(9.1) (9.2)
Impregnating
Winding
resin/varnish Other EIM(8)
Wire (6)
(7)
Compare Substitution Substitution Substitution
thermal allowed? (8.2) allowed? (8.1) allowed? (6.1)
classes (7.1)
    Yes No
  No
   Yes
Yes Acceptable?
 No
per IEC 60172
Equal or
greater than?
   Yes
No
   Yes
     No
Test per
Test per Annex B
Annex B
Acceptable
results?
No
  Yes
Single temperature Acceptable
aging test results?
(10)
  No
Yes
Acceptable
Can use in Can not use
results?
EIS in EIS
     No
  Yes
Modified EIS is acceptable
Test as new EIS according to IEC 61857-1
IEC  1473/04

Figure 1 – Overview of evaluation methods

---------------------- Page: 17 ----------------------

SIST EN 61858:2008
– 10 – 61858 © IEC:2008
5 Evaluation of the change of thickness of an EIM
5.1 Samples
Representative samples of the established EIS (the reference EIS) and of the EIS with
reduced EIM thickness(es) (the candidate EIS) shall be evaluated in accordance with
Clause 10.
5.2 Acceptance
A candidate EIS that meets the acceptance criteria according to Clause 10 shall be assigned
the same thermal class as the established EIS.
If the results of the candidate EIS testing are outside the acceptance criteria according to
Clause 10, then full thermal ageing in accordance with IEC 61857-1 shall be conducted in
order to establish its thermal class.
NOTE Full thermal ageing may be accomplished by testing at additional temperatures, according to IEC 61857-1.
6 Substitution of winding wire
6.1 General
Substitution of a winding wire evaluated in the established EIS can be made without additional
testing when one or more of the following conditions have been met:
a) the winding wire conforms to an IEC 60317 specification having the same chemical
composition, according to the Annex A groupings, as the winding wire evaluated in the
established EIS but is of a different size or shape;
b) the winding wire conforms to an IEC 60317 specification having the same chemical
composition, according to the Annex A groupings, as
...