IEC TR 60216-7-2:2016

IEC TR 60216-7-2 ®
Edition 1.0 2016-08
TECHNICAL
REPORT
colour
inside
Electrical insulating materials – Thermal endurance properties –
Part 7-2: Results of the round robin tests to validate procedures of
IEC TS 60216-7-1 by non-isothermal kinetic analysis of thermogravimetric data

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IEC TR 60216-7-2 ®
Edition 1.0 2016-08
TECHNICAL
REPORT
colour
inside
Electrical insulating materials – Thermal endurance properties –

Part 7-2: Results of the round robin tests to validate procedures of

IEC TS 60216-7-1 by non-isothermal kinetic analysis of thermogravimetric data

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 19.020; 29.020; 29.035.01 ISBN 978-2-8322-3606-2

– 2 – IEC TR 60216-7-2:2016 © IEC 2016
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references. 7
3 Terms and definitions . 7
4 Test specimens . 8
5 Test apparatus . 9
5.1 Thermogravimetric analyser (TGA) . 9
5.2 Purge gas supplied into the TGA furnace . 9
6 Test procedures . 9
6.1 General . 9
6.2 Preconditioning of test samples . 10
6.3 TGA tests with multiple heating rates . 10
6.4 Calculation of the activation energy (E ) . 10
a
6.5 Determination of thermal endurance using TGA . 11
6.5.1 General . 11
6.5.2 Determination of RTE by given degree of conversion from reference
A
material (Method A) . 11
6.5.3 Determination of TI by fixed degree of conversion at 0,05 (Method B) . 12
A
7 Round robin test results . 12
7.1 TGA test results . 12
7.2 Degree of conversion correlated to the activation energy from conventional
heat ageing data . 12
7.3 HIC determined by Method A and Method B . 13
A
7.4 RTE determined by Method A and TI by Method B . 14
A A
7.5 Difference between RTE and TI determined by the conventional heat
A
ageing tests . 16
8 Observations from the round robin test results . 17
8.1 General . 17
8.2 Sample weight variation . 18
8.3 Humidity and hydrolysis of the sample . 19
8.4 Consideration on repeatability of TGA curves. 20
8.5 Baseline drift and responsiveness to heating rates of TGA . 21
9 Conclusion and recommendation . 24
Bibliography . 26

Figure 1 – Fitting curve of plots between degree of conversion and activation energy
determined by ISO 11358-2 (example) . 11
Figure 2 – Correlation between the initial sample mass of sample A and the difference
of RTE (TI ) from TI . 19
A A
Figure 3 – Correlation between the initial sample mass of sample B and the difference
of RTE (TI ) from TI . 19
A A
Figure 4 – Overlay charts of TGA curves in multiple heating rates in multiple
laboratories (enlarged) . 22
Figure 5 – Logarithm plots for activation energy calculation . 23
Figure 6 – Fitting curves of degree of conversion vs. activation energy by TGA . 24

Table 1 – Heat ageing properties of the test specimens by the conventional procedure
described in IEC 60216-5 . 9
Table 2 – Degree of conversion identical to the activation energy of the conventional
heat ageing . 13
Table 3 – HIC determined by Method A and Method B for dielectric strength . 13
A
Table 4 – HIC determined by Method A and Method B for tensile strength . 14
A
Table 5 – HIC determined by Method A and Method B for impact strength . 14
A
Table 6 – RTE determined by Method A and TI by Method B for dielectric strength . 15
A A
Table 7 – RTE determined by Method A and TI by Method B for tensile strength . 15
A A
Table 8 – RTE determined by Method A and TI by Method B for impact strength . 16
A A
Table 9 – Difference between RTE or TI , and TI for dielectric strength . 16
A A
Table 10 – Difference between RTE or TI , and TI for tensile strength . 17
A A
Table 11 – Difference between RTE or TI , and TI for impact strength . 17
A A
Table 12 – Comparison of degree of conversion with original or rerun data at 8 K/min . 21

– 4 – IEC TR 60216-7-2:2016 © IEC 2016
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL INSULATING MATERIALS –
THERMAL ENDURANCE PROPERTIES –

Part 7-2: Results of the round robin tests to validate procedures
of IEC TS 60216-7-1 by non-isothermal kinetic analysis
of thermogravimetric data
FOREWORD
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IEC TR 60216-2-7, which is a Technical Report, has been prepared by IEC technical
committee 112: Evaluation and qualification of electrical insulating materials and systems.

The text of this Technical Report is based on the following documents:
Enquiry draft Report on voting
112/354/DTR 112/370/RVC
Full informatio
...