IEC TR 62697-2:2018

IEC TR 62697-2 ®
Edition 1.0 2018-02
TECHNICAL
REPORT
Test methods for quantitative determination of corrosive sulfur compounds in
unused and used insulating liquids –
Part 2: Test method for quantitative determination of total corrosive sulfur (TCS)
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IEC TR 62697-2 ®
Edition1.0 2018-02
TECHNICAL
REPORT
Test methods for quantitative determination of corrosive sulfur compounds in

unused and used insulating liquids –

Part 2: Test method for quantitative determination of total corrosive sulfur (TCS)

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.040.10 ISBN 978-2-8322-5362-5

– 2 – IEC TR 62697-2:2018 © IEC 2018
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
4 Sampling . 9
5 Procedure . 9
5.1 Principle . 9
5.2 Significance and use . 9
5.3 Interferences. 9
5.3.1 General . 9
5.3.2 Interferences in turbidity measurements . 10
5.3.3 Interferences in ion chromatography measurements . 10
5.4 Apparatus . 10
5.4.1 Balance . 10
5.4.2 Hot plate with stirrer . 10
5.4.3 Heating block . 10
5.4.4 Turbidity monitor . 10
5.4.5 Ion chromatograph . 10
5.4.6 Data system . 10
5.5 Reagents and materials . 10
5.5.1 Purity of reagents . 10
5.5.2 Gases . 10
5.5.3 Solvents . 10
5.6 Standard materials . 11
5.6.1 Dibenzyl disulfide (DBDS) . 11
5.6.2 Blank oil . 11
5.6.3 Copper powder . 11
5.6.4 Potassium nitrate . 11
5.6.5 Hydrochloric acid . 11
5.6.6 Barium chloride . 11
5.7 Standard solutions . 11
5.7.1 Stock solution . 11
5.7.2 Internal standard (IS) solution . 11
6 Instrument set-up . 12
6.1 Turbidity monitor . 12
6.2 Ion chromatograph . 12
6.2.1 General . 12
6.2.2 Column . 12
6.2.3 Mobile phase . 12
6.2.4 Injector . 12
6.2.5 Suppressor . 12
6.2.6 Conductivity detector . 12
6.3 Corrosive chemistry . 13
6.3.1 Reaction of corrosive sulfur compounds with copper – formation of
Cu S . 13
6.3.2 Conversion of cuprous sulfide into cupric sulfate . 13
6.3.3 Quantification of cupric sulfate in solution . 14
6.3.4 Turbidity measurement . 14
6.3.5 Ion chromatography measurement . 14
6.4 Calibration . 14
6.4.1 General . 14
6.4.2 Calibration procedure . 14
6.4.3 Quantification of total corrosive sulfur (TCS) . 15
6.4.4 Quantification of total corrosive sulfur and DBDS equivalents (DBDS ) . 15
eq
6.5 Results . 15
7 Precision data . 15
7.1 Detection limit . 15
7.2 Repeatability . 16
7.3 Reproducibility . 16
8 Report . 16
Annex A (informative) Figures with typical chromatograms and results . 17
Annex B (informative) RRT results for quantitative determination of corrosive sulfur . 18
Bibliography . 18

Figure A.1 – Ion exchange chromatography detection DBDS as sulfate . 17
Figure A.2 – Photograph of turbidity meter cuvette containing BaSO suspension . 17
Table 1 – Repeatability limit . 16
Table 2 – Reproducibility limit . 16
Table B.1 – Turbidity and ion chromatography . 18
Table B.2 – RRT results for quantitative determination of DBDS (GC-ECD or GC-AED)
– Sample number 1 to 7 . 19
Table B.3 – RRT results for potentially corrosive sulfur according to IEC 62535 –
Sample number 1 to 7 . 19

– 4 – IEC TR 62697-2:2018 © IEC 2018
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
TEST METHODS FOR QUANTITATIVE DETERMINATION OF CORROSIVE
SULFUR COMPOUNDS IN UNUSED AND USED INSULATING LIQUIDS –

Part 2: Test method for quantitative determination
of total corrosive sulfur (TCS)

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