IEC 60216-5:2022

IEC 60216-5 ®
Edition 4.0 2022-11
COMMENTED VERSION
INTERNATIONAL
STANDARD
colour
inside
Electrical insulating materials – Thermal endurance properties –
Part 5: Determination of relative temperature index (RTI) of an insulating material
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IEC 60216-5 ®
Edition 4.0 2022-11
COMMENTED VERSION
INTERNATIONAL
STANDARD
colour
inside
Electrical insulating materials – Thermal endurance properties –
Part 5: Determination of relative temperature index (RTI) of an insulating material
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 19.020; 29.020; 29.035.01 ISBN 978-2-8322-6112-5

– 2 – IEC 60216-5:2022 CMV © IEC 2022
CONTENTS
FOREWORD .4
1 Scope .6
2 Normative references .6
3 Terms, definitions, symbols and units and abbreviations.7
3.1 Terms, abbreviations, and definitions .7
3.2 Symbols and units .8
4 Objectives of RTE RTI determination . 10
5 Experimental procedures . 10
5.1 Selection of reference EIM . 10
5.2 Selection of diagnostic test for extent of ageing . 10
5.3 Ageing procedures. 10
6 Calculation procedures . 13
6.1 Thermal endurance data – Calculation of intermediate parameters . 13
6.2 Calculation of RTE RTI . 14
6.3 Statistical and numerical tests . 15
6.3.1 Tests of IEC 60216-3 . 15
6.3.2 Precision of correlation time . 15
6.3.3 Lower confidence interval of RTE RTI . 15
6.3.4 Extrapolation . 16
7 Results and report. 16
7.1 Results of statistical and numerical tests . 16
7.2 Results . 16
7.3 Report . 17
8 Material testing by short-term thermal ageing . 17
9 Insulation classification . 17
Annex A (informative) Repeatability of correlation time . 18
A.1 Overview . 18
A.2 F-test for equality of variances linearity . 18
A.3 Standard error of the difference of two means . 18
A.4 Student’s t-test for difference of two means . 19
A.5 Combination of data. 20
Annex B (informative) Thermal class assignment . 21
Annex C (informative) Computer program . 24
C.1 General . 24
C.1.1 Overview . 25
C.1.2 Convenience program execution . 26
C.2 Structure of data files used by the program . 27
C.3 Executing the calculation of RTI . 28
C.4 Output files and graph . 28
Annex D (informative) Selection of the reference EIM . 30
D.1 Overview . 30
D.2 Designation of reference EIM . 30
D.3 Reporting items for reference EIM . 30
Bibliography . 31
List of comments . 32

Figure 1 – Thermal endurance graphs . 12
Figure 2 – Unacceptable thermal endurance graphs . 13
Figure C.1 – Shortcut property dialog for program launch . 27
Figure C.2 – Thermal endurance graphs . 28
Figure C.3 – Example thermal endurance graphs . 29

Table 1 – Input parameters for the calculations concerning RTE RTI . 14
Table B.1 – Thermal class equivalents for insulating material . 21
Table B.2 – F– function; p = 0,05 . 22
Table B.3 – t–function . 23

– 4 – IEC 60216-5:2022 CMV © IEC 2022
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL INSULATING MATERIALS –
THERMAL ENDURANCE PROPERTIES –

Part 5: Determination of relative thermal endurance
index (RTE) relative temperature index (RTI) 1 of an insulating material

FOREWORD
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This commented version (CMV) of the official standard IEC 60216-5:2022 edition 4.0
allows the user to identify the changes made to the previous IEC 60216-5:2008
edition 3.0. Furthermore, comments from IEC TC 112 experts are provided to explain the
reasons of the most relevant changes, or to clarify any part of the content.
A vertical bar appears in the margin wherever a change has been made. Additions are in
green text, deletions are in strikethrough red text. Experts' comments are identified by a
blue-background number. Mouse over a number to display a pop-up note with the
comment.
This publication contains the CMV and the official standard. The full list of comments is
available at the end of the CMV.

IEC 60216-5 has been prepared by IEC technical committee 112: Evaluation and qualification
of electrical insulating materials and systems. It is an International Standard.
This fourth edition cancels and replaces the third edition published in 2008. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Annex C “Computer program” has been completely reworked;
b) in 3.1, the terms “ATE” and “RTE” were replaced by “ATI” and “RTI” to emphasize their
reference to an electrical insulating material (EIM).
This standard is to be read in conjunction with IEC 60216-1:2013, IEC 60216-2:2005 and
IE
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