SIST EN 60216-6:2010

Electrical insulating materials - Thermal endurance properties - Part 6: Determination of thermal endurance indices (TI and RTE) of an insulating material using the fixed time frame method (IEC 60216-6:2006)

This part of IEC 60216 specifies the experimental and calculation procedures for deriving the thermal endurance characteristics, temperature index (TI) and relative thermal endurance index (RTE) of a material using the "fixed time frame method (FTFM)". In this protocol, the ageing takes place for a small number of fixed times, using the appropriate number of ageing temperatures throughout each time, the properties of the specimens being measured at the end of the relevant time interval. This differs from the procedure of IEC 60216-1, where ageing is conducted at a small number of fixed temperatures, property measurement taking place after ageing times dependent on the progress of ageing. The diagnostic tests employed in the fixed time frame method are restricted to destructive tests. The method has not as yet been applied to non-destructive or proof test procedures. Both the TI and the RTE determined according to the FTFM protocol are derived from experimental data obtained in accordance with the instructions of IEC 60216-1 and IEC 60216-2 as modified in this standard. The calculation procedures and statistical tests are modified from those of IEC 60216-3 and IEC 60216-5.

Elektroisolierstoffe - Eigenschaften hinsichtlich des thermischen Langzeitverhaltens - Teil 6: Bestimmung der thermischen Langzeitkennwerte (TI und RTE) eines Isolierstoffes unter Anwendung des Festzeitrahmenverfahrens (IEC 60216-6:2006)

Matériaux isolants électriques - Propriétés d'endurance thermique - Partie 6: Détermination des indices d'endurance thermique (TI et RTE) d'un matériau isolant en utilisant la méthode de trame de durées fixes (fixed time frame) (IEC 60216-6:2006)

La présente partie de la CEI 60216 spécifie les méthodes expérimentales et de calcul à utiliser pour en extraire les caractéristiques d'endurance thermique, l'indice de température (TI) et l'indice d'endurance thermique relatif (RTE) d'un matériau en utilisant la méthode de 'trame de durées fixes (fixed time frame)'.  Avec ce protocole, le vieillissement se produit après un petit nombre de durées déterminées, en utilisant le nombre approprié de températures de vieillissement tout au long de chaque durée pertinente, les propriétés des éprouvettes étant mesurées à la fin de chaque intervalle de temps. Cela diffère de la méthode de la CEI 60216-1, dans laquelle le vieillissement est effectué à un petit nombre de températures déterminées, la mesure des propriétés des éprouvettes se produisant après des durées de vieillissement variables en fonction de la progression du vieillissement. Les essais de diagnostic employés dans la méthode de trame de durées fixes sont limités aux essais destructifs. La méthode n'a pas encore été appliquée aux essais non destructifs ni aux procédures d'essais d'épreuves. Les deux indices d'endurance thermique TI et RTE déterminés selon le protocole FTFM (fixed time frame method), sont déduits des données expérimentales obtenues conformément aux instructions de la CEI 60216-1 et de la CEI 60216-2, et conformément aux modifications de la présente norme. Les méthodes de calcul et les essais statistiques sont différents de ceux de la CEI 60216-3 et de la CEI 60216-5. Par rapport à l'édition précédente, les modifications techniques majeures sont les suivantes. - Cette édition a été complétée par l'Annexe G et le logiciel correspondant.

Električno izolacijski materiali - Lastnosti v zvezi s toplotno vzdržljivostjo - 6. del: Ugotavljanje indeksov toplotne vzdržljivosti (TI - informacijska tehnologija in RTE - radijska in telekomunikacijska oprema) izolacijskega materiala z uporabo metode fiksnih časovnih okvirov (IEC 60216-6:2006)

Ta del IEC 60216 določa eksperimentalne in računske postopke za izpeljavo lastnosti toplotne vzdržljivosti, temperaturnih indeksov (TI) in relativnega indeksa toplotne vzdržljivosti (RTE) materiala z uporabo »metode fiksnih časovnih okvirov (FTFM)«. V tem protokolu staranje poteka pri majhnem številu fiksnih časov z uporabo ustreznega števila temperatur za staranje v vsakem času, lastnosti vzorcev pa se merijo na koncu ustreznega časovnega intervala. To se razlikuje od postopka v IEC 60216-1, kjer staranje poteka pri majhnem številu fiksnih temperatur, meritve lastnosti pa odvisno od napredovanja staranja potekajo po časih staranja.  Diagnostični preskusi, uporabljeni pri metodi s fiksnim časovnim okvirom, so omejeni na uničujoče preskuse. Metoda še ne velja za neuničujoče ali dokazne preskusne postopke. TI in RTE, ki se določita po protokolu FTFM, izhajata iz eksperimentalnih podatkov, pridobljenih v skladu z navodili IEC 60216-1 in IEC 60216-2, kot jih spreminja ta standard. Računski postopki in statistični preskusi so spremenjeni glede na tiste v IEC 60216-3 in IEC 60216-5.

General Information

• Status: Published
• Publication Date: 23-Dec-2009
• ICS: 29.035.01 - Insulating materials in general
• Technical Committee: IIZS - Insulating materials and systems
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 10-Dec-2009
• Due Date: 14-Feb-2010
• Completion Date: 24-Dec-2009
• Ref Project: EN 60216-6:2006 - Electrical insulating materials - Thermal endurance properties - Part 6: Determination of thermal endurance indices (TI and RTE) of an insulating material using the fixed time frame method

Relations

• Replaces: SIST EN 60216-6:2004 - Electrical insulating materials - Thermal endurance properties -- Part 6: Determination of thermal endurance indices (TI and RTE) of an insulating material using the fixed time frame method
• Effective Date: 06-May-2014

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 60216-6:2010
01-februar-2010
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SIST EN 60216-6:2004
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8JRWDYOMDQMHLQGHNVRYWRSORWQHY]GUåOMLYRVWL7,LQIRUPDFLMVNDWHKQRORJLMDLQ57(
UDGLMVNDLQWHOHNRPXQLNDFLMVNDRSUHPDL]RODFLMVNHJDPDWHULDOD]XSRUDERPHWRGH
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Electrical insulating materials - Thermal endurance properties - Part 6: Determination of
thermal endurance indices (TI and RTE) of an insulating material using the fixed time
frame method (IEC 60216-6:2006)
Elektroisolierstoffe - Eigenschaften hinsichtlich des thermischen Langzeitverhaltens - Teil
6: Bestimmung der thermischen Langzeitkennwerte (TI und RTE) eines Isolierstoffes
unter Anwendung des Festzeitrahmenverfahrens (IEC 60216-6:2006)
Matériaux isolants électriques - Propriétés d'endurance thermique - Partie 6:
Détermination des indices d'endurance thermique (TI et RTE) d'un matériau isolant en
utilisant la méthode de trame de durées fixes (fixed time frame) (IEC 60216-6:2006)
Ta slovenski standard je istoveten z: EN 60216-6:2006
ICS:
29.035.01 Izolacijski materiali na Insulating materials in
splošno general
SIST EN 60216-6:2010 en,fr
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 60216-6:2010

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SIST EN 60216-6:2010


EUROPEAN STANDARD
EN 60216-6

NORME EUROPÉENNE
November 2006
EUROPÄISCHE NORM

ICS 17.220.99; 29.035.01 Supersedes EN 60216-6:2004


English version


Electrical insulating materials -
Thermal endurance properties
Part 6: Determination of thermal endurance indices (TI and RTE)
of an insulating material using the fixed time frame method
(IEC 60216-6:2006)


Matériaux isolants électriques -  Elektroisolierstoffe -
Propriétés d'endurance thermique Eigenschaften hinsichtlich des
Partie 6: Détermination des indices thermischen Langzeitverhaltens
d'endurance thermique (TI et RTE) Teil 6: Bestimmung der thermischen
d'un matériau isolant en utilisant
Langzeitkennwerte (TI und RTE)
la méthode de "trame de durées fixes eines Isolierstoffes unter Anwendung
(fixed time frame)" des Festzeitrahmenverfahrens
(CEI 60216-6:2006) (IEC 60216-6:2006)




This European Standard was approved by CENELEC on 2006-09-01. 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, 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


© 2006 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60216-6:2006 E

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SIST EN 60216-6:2010
EN 60216-6:2006 - 2 -
Foreword
The text of document 112/28/FDIS, future edition 2 of IEC 60216-6, 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 60216-6 on 2006-09-01.
This European Standard supersedes EN 60216-6:2004.
The significant technical change with respect to EN 60216-6:2004 is as follows:
EN 60216-6:2006 has been supplemented by Annex G and the corresponding software.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
(dop) 2007-06-01
national standard or by endorsement
– latest date by which the national standards conflicting
(dow) 2009-09-01
with the EN have to be withdrawn
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 60216-6:2006 was approved by CENELEC as a European
Standard without any modification.
__________

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SIST EN 60216-6:2010
- 3 - EN 60216-6:2006
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

1) 2)
IEC 60212 - Standard conditions for use prior to and HD 437 S1 1984
during the testing of solid electrical insulating
materials


IEC 60216-1 2001 Electrical insulating materials - Properties of EN 60216-1 2001
thermal endurance
Part 1: Ageing procedures and evaluation of
test results


1) 2)
IEC 60216-2 - Electrical insulating materials - Thermal EN 60216-2 2005
endurance properties
Part 2: Determination of thermal endurance
properties of electrical insulating materials -
Choice of test criteria


3)
IEC 60216-3 2002 Electrical insulating materials - Thermal EN 60216-3 2002
  endurance properties
Part 3: Instructions for calculating thermal
endurance characteristics


1) 2)
IEC 60216-4-1 - Electrical insulating materials - Thermal EN 60216-4-1 2006
endurance properties
Part 4-1: Ageing ovens - Single-chamber
ovens


1) 2)
IEC 60216-4-2 - Electrical insulating materials - Thermal EN 60216-4-2 2000
endurance properties
Part 4-2: Ageing ovens - Precision ovens for
use up to 300 °C


1) 2)
IEC 60216-4-3 - Electrical insulating materials - Thermal EN 60216-4-3 2000
endurance properties
Part 4-3: Ageing ovens - Multi-chamber ovens


1) 2)
IEC 60216-5 - Electrical insulating materials - Thermal EN 60216-5 2003
endurance properties
Part 5: Determination of relative thermal
endurance index (RTE) of an insulating
material



1)
Undated reference.
2)
Valid edition at date of issue.
3)
EN 60216-3 is superseded by EN 60216-3:2006, which is based on IEC 60216-3:2006.

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SIST EN 60216-6:2010
EN 60216-6:2006 - 4 -
Publication Year Title EN/HD Year
IEC 60493-1 1974 Guide for the statistical analysis of ageing test - -
data
Part 1: Methods based on mean values of
normally distributed test results

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SIST EN 60216-6:2010
NORME CEI
INTERNATIONALE
IEC



60216-6
INTERNATIONAL


Deuxième édition
STANDARD

Second edition

2006-05


Matériaux isolants électriques –
Propriétés d'endurance thermique –
Partie 6:
Détermination des indices d'endurance
thermique (TI et RTE) d'un matériau isolant
en utilisant la méthode de «trame de durées
fixes (fixed time frame)»

Electrical insulating materials –
Thermal endurance properties –
Part 6:
Determination of thermal endurance indices
(TI and RTE) of an insulating material using
the fixed time frame method

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Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in any
utilisée sous quelque forme que ce soit et par aucun procédé, form or by any means, electronic or mechanical, including
électronique ou mécanique, y compris la photocopie et les photocopying and microfilm, without permission in writing from
microfilms, sans l'accord écrit de l'éditeur. the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: [phone] Telefax: [phone] E-mail: [e-mail] Web: www.iec.ch
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International Electrotechnical Commission
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Pour prix, voir catalogue en vigueur
For price, see current catalogue

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SIST EN 60216-6:2010
60216-6  IEC:2006 – 3 –
CONTENTS
FOREWORD.7

1 Scope.11
2 Normative references .11
3 Terms, definitions, symbols and abbreviated terms.13
3.1 Terms, abbreviations and definitions .13
3.2 Symbols and abbreviated terms.19
4 FTFM protocol .21
4.1 Principles and objectives.21
5 TI determination .23
5.1 Ageing procedures .23
5.2 Ageing times and temperatures .23
5.3 Test specimens .25
5.4 Diagnostic tests.27
5.5 Selection of end-points.27
5.6 Establishment of initial property value .29
5.7 Ageing conditions.29
5.8 Procedure for ageing.29
6 Calculation procedures.31
6.1 General principles .31
6.2 Precision of calculations.33
6.3 Derivation of temperatures equivalent to property values.33
6.4 Regression analysis (temperature on time).39
6.5 Statistical tests.43
6.6 Thermal endurance graph .47
7 Calculation and requirements for results.47
7.1 Calculation of thermal endurance characteristics.47
7.2 Reporting of results .49
8 Report .49
9 RTE determination.51
9.1 Objectives of RTE determination .51
10 Additional symbols .51
11 Experimental procedures .53
11.1 Selection of control material .53
11.2 Selection of diagnostic test for extent of ageing.53
11.3 Ageing procedures .53
12 Calculation procedures.53
12.1 General principles .53
12.2 Input data.55
12.3 RTE.55
12.4 Confidence limits.55
12.5 Extrapolation .59

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SIST EN 60216-6:2010
60216-6  IEC:2006 – 5 –
13 Results and report .59
13.1 Results of statistical and numerical tests .59
13.2 Result .59
13.3 Report .61

Annex A (normative) Decision flow chart.63
Annex B (normative) Decision table .65
Annex C (informative) Statistical tables.67
Annex D (informative) Suggested ageing times and temperatures.73
Annex E (informative) Figures.77
Annex F (normative) Statistical significance of the difference between two regression
estimates .83
Annex G (informative) Computer programs for IEC 60216-6.85


Figure E.1 – Property-temperature graph with regression line.77
Figure E.2 – Thermal endurance graph .77
Figure E.3 – Ageing times and temperatures in relation to thermal endurance graph .79
Figure E.4 – Ageing times and temperatures in relation to thermal endurance graph .79
Figure E.5 – Ageing times and temperatures in relation to thermal endurance graph .81
Figure G.1 − Thermal endurance graph .95

Table B.1 − Decision table .65
2
Table C.1 – χ -Function.67
Table C.2– t–Function.67
Table C.3 – F-function, P = 0,05 .69
Table C.4 – F-function, P = 0,005 .71

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SIST EN 60216-6:2010
60216-6  IEC:2006 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

ELECTRICAL INSULATING MATERIALS –
THERMAL ENDURANCE PROPERTIES –

Part 6: Determination of thermal endurance indices (TI and RTE)
of an insulating material using the fixed time frame method


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 60216-6 has been prepared by IEC technical committee 112:
Evaluation and qualification of electrical insulating materials and systems.
This second edition cancels and replaces the first edition, published in 2003. This edition
constitutes a technical revision.
The significant technical changes with respect to the previous edition are as follows.
− This new edition has been supplemented by Annex G and the corresponding software.

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SIST EN 60216-6:2010
60216-6  IEC:2006 – 9 –
The text of this standard is based on the following documents:
FDIS Report on voting
112/28/FDIS 112/32/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.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
IEC 60216, under the general title Electrical insulating materials – Thermal endurance
properties, consists of the following parts:
Part 1: Ageing procedures and evaluation of test results
Part 2: Determination of thermal endurance properties of electrical insulating materials –
Choice of test criteria
Part 3: Instructions for calculating thermal endurance characteristics
Part 4: Ageing ovens
Part 5: Determination of relative thermal endurance index (RTE) of an insulating material
Part 6: Determination of thermal endurance indices (TI and RTE) of an insulating material
using the fixed time frame protocol

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.

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SIST EN 60216-6:2010
60216-6  IEC:2006 – 11 –
ELECTRICAL INSULATING MATERIALS –
THERMAL ENDURANCE PROPERTIES –

Part 6: Determination of thermal endurance indices (TI and RTE)
of an insulating material using the fixed time frame method



1 Scope
This part of IEC 60216 specifies the experimental and calculation procedures for deriving the
thermal endurance characteristics, temperature index (TI) and relative thermal endurance
index (RTE) of a material using the “fixed time frame method (FTFM)”.
In this protocol, the ageing takes place for a small number of fixed times, using the appro-
priate number of ageing temperatures throughout each time, the properties of the specimens
being measured at the end of the relevant time interval. This differs from the procedure of
IEC 60216-1, where ageing is conducted at a small number of fixed temperatures, property
measurement taking place after ageing times dependent on the progress of ageing.
The diagnostic tests employed in the fixed time frame method are restricted to destructive
tests. The method has not as yet been applied to non-destructive or proof test procedures.
Both the TI and the RTE determined according to the FTFM protocol are derived from
experimental data obtained in accordance with the instructions of IEC 60216-1 and
IEC 60216-2 as modified in this standard. The calculation procedures and statistical tests are
modified from those of IEC 60216-3 and IEC 60216-5.
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 60212, Standard conditions for use prior to and during the testing of solid electrical
insulating materials
IEC 60216-1:2001, Electrical insulating materials – Properties of thermal endurance – Part 1:
Ageing procedures and evaluation of test results
IEC 60216-2, Electrical insulating materials – Thermal endurance properties – Part 2:
Determination of thermal endurance properties of electrical insulating materials – Choice of
test criteria
IEC 60216-3:2002, Electrical insulating materials – Thermal endurance properties – Part 3:
Instructions for calculating thermal endurance characteristics

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SIST EN 60216-6:2010
60216-6  IEC:2006 – 13 –
IEC 60216-4-1, Electrical insulating materials – Thermal endurance properties – Part 4-1:
Ageing ovens – Single-chamber ovens
IEC 60216-4-2, Electrical insulating materials – Thermal endurance properties – Part 4-2:
Ageing ovens – Precision ovens for use up to 300 °C
IEC 60216-4-3, Electrical insulating materials – Thermal endurance properties – Part 4-3:
Ageing ovens – Multi-chamber ovens
IEC 60216-5, Electrical insulating materials − Thermal endurance properties – Part 5:
Determination of relative thermal endurance index (RTE) of an insulating material
IEC 60493-1:1974, Guide for the statistical analysis of ageing test data – Part 1: Methods
based on mean values of normally distributed test results
3 Terms, definitions, symbols and abbreviated terms
For the purposes of this document, the following terms, definitions, symbols and abbreviations
apply.
3.1 Terms, abbreviations and definitions
3.1.1
assessed thermal endurance index
ATE
numerical value of the temperature in degrees Celsius, up to which the control material
possesses known, satisfactory service performance in the specified application
NOTE 1 The ATE of a specific material may vary between different applications of the material.
NOTE 2 ATE is sometimes referred to as “absolute” thermal endurance index.
3.1.2
ageing temperature
temperature in degrees Celsius at which a group of specimens is thermally aged
3.1.3
end-point temperature
temperature in degrees Celsius at which a specimen is considered to have reached end-point
after ageing for a specified time
3.1.4
candidate material
material for which an estimate of the thermal endurance is required to be determined
NOTE The determination is made by simultaneous thermal ageing of the material and a control material.
3.1.5
central second moment of a data group
sum of the squares of the differences between the data values and the value of the group
mean divided by the number of data in the group

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SIST EN 60216-6:2010
60216-6  IEC:2006 – 15 –
3.1.6
95 % confidence limit
statistical parameter, calculated from test data, which with 95 % confidence constitutes an
upper or lower limit for the true value of a quantity estimated by statistical analysis
NOTE 1 This implies that there is only 5 % probability that the true value of the quantity estimated is actually
larger (or smaller) than the upper (or lower) confidence limit.
NOTE 2 In other connections, confidence values other than 95 % may sometimes be used, e.g. in the linearity
test for destructive test data.
3.1.7
control material
material with known assessed thermal endurance index (ATE), preferably derived from
service experience, used as a reference for comparative tests with the candidate material
3.1.8
correlation coefficient
number expressing the completeness of the relation between members of two data sets, equal
to the covariance divided by the square root of the product of the variances of the sets
NOTE 1 The value of its square is between 0 (no correlation) and 1 (complete correlation).
NOTE 2 In this standard, the two data sets are the values of the independent variable and the means of the
corresponding dependent variable groups.
3.1.9
correlation time (RTE)
estimated time to end-point of the control material at a temperature equal to its ATE in
degrees Celsius
3.1.10
correlation time (TI)
hypothetical time to end-point used to calculate TI
NOTE Its usual value is 20 000 h.
3.1.11
covariance (of data sets)
for two sets of data with equal numbers of elements where each element in one set
corresponds to one in the other, sum of the products of the deviations of the corresponding
members from their set means, divided by the number of degrees of freedom
3.1.12
degrees of freedom
number of data values minus the number of parameter values
3.1.13
destructive test
diagnostic property test, where the test specimen is irreversibly changed by the property
measurement, in a way which precludes a repeated measurement on the same specimen
NOTE An example of a destructive test is measurement of electric strength. An example of a non-destructive test
is measurement of tg δ.
3.1.14
end-point line
line parallel to the temperature axis intercepting the property axis at the end-point value

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SIST EN 60216-6:2010
60216-6  IEC:2006 – 17 –
3.1.15
halving interval
HIC
numerical value of the temperature interval in kelvins which expresses the halving of the time
to end-point taken at a time equal to TI
3.1.16
regression analysis
process of deducing the best fit line expressing the relation of corresponding members of two
data groups by minimizing the sum of squares of deviations of members of one of the groups
from the line
3.1.17
regression coefficients
coefficients of the equation of the best fit lin
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