IEC TR 63025:2021

Insulating liquids - Quantitative determination of methanol and ethanol in insulating liquids

IEC TR 63025:2021(E) specifies two test methods for methanol and ethanol determination in insulating liquids.
Methanol (MeOH) and ethanol (EtOH) are two light alcohols generated during the degradation process of cellulosic materials. They are soluble in insulating liquids so they can be regarded as ageing tracers whose concentrations in oil reflect the degradation of insulating cellulosic materials in liquid-impregnated transformers.

General Information

• Status: Published
• Publication Date: 11-Jul-2021
• ICS: 29.040.10 - Insulating oils
• Technical Committee: TC 10 - Fluids for electrotechnical applications
• Drafting Committee: PT 63025 - TC 10/PT 63025
• Current Stage: PPUB - Publication issued
• Start Date: 12-Aug-2021
• Completion Date: 12-Jul-2021

Standards Content (Sample)

IEC TR 63025 ®
Edition 1.0 2021-07
TECHNICAL
REPORT
colour
inside
Insulating liquids – Quantitative determination of methanol and ethanol in
insulating liquids
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IEC TR 63025 ®
Edition 1.0 2021-07
TECHNICAL
REPORT
colour
inside
Insulating liquids – Quantitative determination of methanol and ethanol in

insulating liquids
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.040.10 ISBN 978-2-8322-9990-6

– 2 – IEC TR 63025:2021 © IEC 2021
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
4 Symbols and abbreviated terms . 9
5 Sampling . 10
6 Principle of the methods . 10
7 Method A – HS-GC-MS . 10
7.1 General . 10
7.2 Apparatus . 10
7.2.1 Analytical balance . 10
7.2.2 Headspace sampler . 10
7.2.3 Gas chromatograph coupled with mass spectrometry detector . 11
7.3 Reagents and materials . 11
7.3.1 Laboratory equipment and glassware . 11
7.3.2 Standard chemicals . 11
7.3.3 GC carrier gases . 12
7.4 Preparation of standard solutions . 12
7.4.1 General . 12
7.4.2 Degassed insulating liquid . 12
7.4.3 Internal standard stock solution . 12
7.4.4 Standard solutions of methanol and ethanol . 13
7.5 Sample preparation . 14
7.6 Headspace sampler parameters . 15
7.7 Gas chromatograph parameters . 15
7.7.1 Injector . 15
7.7.2 Carrier gas . 15
7.7.3 Temperature ramp . 15
7.8 Mass spectrometer parameters . 16
7.9 Analysis procedure . 16
7.10 Internal standard calibration . 17
7.10.1 General . 17
7.10.2 Response factor determination . 18
7.11 Expression of the results . 18
8 Method B – HS-GC-FID . 18
8.1 General . 18
8.2 Apparatus . 18
8.2.1 Analytical balance . 18
8.2.2 Headspace sampler . 18
8.2.3 Gas chromatograph with flame ionization detector . 19
8.3 Reagents and materials . 19
8.3.1 Laboratory equipment and glassware . 19
8.3.2 Standard chemicals . 19
8.3.3 GC carrier gases . 19
8.4 Preparation of standard solutions . 20

8.4.1 General . 20
8.4.2 Degassed insulating liquid . 20
8.4.3 Standard solutions of methanol and ethanol . 20
8.5 Sample preparation . 21
8.6 Headspace sampler parameters . 21
8.7 Gas chromatograph parameters . 22
8.7.1 Injector . 22
8.7.2 Carrier gas . 22
8.7.3 Temperature ramp . 22
8.7.4 FID parameters . 22
8.8 Analysis procedure . 22
8.9 Calibration . 23
8.10 Expression of the results . 23
9 Test report . 23
10 Precision . 24
10.1 Verification of the entire analytical system . 24
10.2 General . 24
10.3 Detection limits of Method A and Method B . 24
10.4 Repeatability . 24
10.5 Reproducibility . 25
Bibliography . 26

Figure 1 – Comparison of methanol and 2-furfural production in mineral oil versus
cellulose scission number . 7
Figure 2 –Typical chromatogram with selected ion (m/z = 31) mass spectrum . 17
Figure 3 – Typical GC-FID chromatogram . 23

Table 1 –Method A – Example of GC temperature ramp parameters . 16
Table 2 – Method A – m/z values of internal standard ions . 16
Table 3 – Method B – Examples of FID parameters reported in literature . 22
Table 4 – Detection limits of Method A and Method B, in mineral oil . 24
Table 5 – Repeatability (r) in % for Method A (HS-GC-MS), in mineral oil . 24
Table 6 – Reproducibility (R) in % for Method A (HS-GC-MS), in mineral oil . 25

– 4 – IEC TR 63025:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INSULATING LIQUIDS – QUANTITATIVE DETERMINATION OF
METHANOL AND ETHANOL IN INSULATING LIQUIDS

FOREWORD
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