Test method for quantitative determination of corrosive sulfur compounds in unused and used insulating liquids - Part 1: Test method for quantitative determination of dibenzyldisulfide (DBDS)

This part of IEC 62697 specifies a test method for the quantitative determination of corrosive sulfur compounds-dibenzyl disulfide (DBDS) in used and unused insulating liquids over a 5 - 600 mg kg-1 concentration range.

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Méthodes d'essai pour la déterminationquantitative des composés de soufre corrosif dans les liquides isolants usagés et neufs - Partie 1: Méthode d'essaipour la détermination quantitative du disulfure de dibenzyle (DBDS)

La CEI 62697-1:2012 spécifie une méthode d essai pour la détermination quantitative des composés de soufre corrosif disulfure de dibenzyle (DBDS) dans les liquides isolants usagés et neufs sur une plage de concentration comprise entre 5 mg kg-1 et 600 mg kg-1.

Preskusna metoda za kvantitativno določevanje korozivnih žveplovih spojin v nerabljenih in rabljenih izolacijskih tekočinah - 1. del: Preskusna metoda za kvantitativno določevanje dibenzil disulfidov (DBDS)

Ta del standarda IEC 62697 določa preskusno metodo za kvantitativno določevanje korozivnih žveplovih spojin – dibenzil disulfidov (DBDS) v rabljenih in nerabljenih izolacijskih tekočinah na območju koncentracije 5–600 mg/kg-1.

General Information

Status
Published
Publication Date
26-Nov-2012
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
21-Nov-2012
Due Date
26-Jan-2013
Completion Date
27-Nov-2012

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno./Méthodes d'essai pour la déterminationquantitative des composés de soufre corrosif dans les liquides isolants usagés et neufs - Partie 1: Méthode d'essaipour la détermination quantitative du disulfure de dibenzyle (DBDS)Test method for quantitative determination of corrosive sulfur compounds in unused and used insulating liquids - Part 1: Test method for quantitative determination of dibenzyldisulfide (DBDS)29.040.01Izolacijski fluidi na splošnoInsulating fluids in generalICS:Ta slovenski standard je istoveten z:EN 62697-1:2012SIST EN 62697-1:2013en01-januar-2013SIST EN 62697-1:2013SLOVENSKI

STANDARD
SIST EN 62697-1:2013
EUROPEAN STANDARD EN 62697-1 NORME EUROPÉENNE
EUROPÄISCHE NORM November 2012

CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung

Management Centre: Avenue Marnix 17, B - 1000 Brussels
© 2012 CENELEC -

All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 62697-1:2012 E
ICS 29.040
English version

Test methods for quantitative determination of corrosive sulfur compounds in unused and used insulating liquids -

Part 1: Test method for quantitative determination
of dibenzyldisulfide (DBDS) (IEC 62697-1:2012)

Méthodes d'essai pour la détermination quantitative des composés de soufre corrosif dans les liquides isolants

usagés et neufs -
Partie 1: Méthode d'essai
pour la détermination quantitative
du disulfure de dibenzyle (DBDS) (CEI 62697-1:2012)

Prüfverfahren zur quantitativen Bestimmung von Verbindungen korrosiven Schwefels in neuen und gebrauchten Isolierflüssigkeiten -

Teil 1: Prüfverfahren zur quantitativen Bestimmung von Dibenzyldisulfid (DBDS)(IEC 62697-1:2012)

This European Standard was approved by CENELEC on 2012-09-28. 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 CEN-CENELEC Management Centre 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 CEN-CENELEC Management Centre has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

SIST EN 62697-1:2013

EN 62697-1:2012 - 2 - Foreword The text of document 10/887/FDIS, future edition 1 of IEC 62697-1, prepared by IEC/TC 10 "Fluids for electrotechnical applications" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as EN 62697-1:2012. The following dates are fixed: • latest date by which the document has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2013-06-28 • latest date by which the national standards conflicting with the document have to be withdrawn (dow) 2015-09-28

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent rights.

Endorsement notice The text of the International Standard IEC 62697-1:2012 was approved by CENELEC as a European Standard without any modification. In the official version, for Bibliography, the following notes have to be added for the standards indicated:

IEC 60296 NOTE Harmonised as EN 60296. IEC 60422 NOTE Harmonised as EN 60422. IEC 60567 NOTE Harmonised as EN 60567.

SIST EN 62697-1:2013
- 3 - EN 62697-1:2012 Annex ZA
(normative)

Normative references to international publications with their corresponding European publications

The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. 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
IEC 60475 - Method of sampling insulating liquids EN 60475 -
IEC 62535 2008 Insulating liquids - Test method
for detection of potentially corrosive
sulphur in used and unused insulating oil EN 62535 2009
SIST EN 62697-1:2013
SIST EN 62697-1:2013

IEC 62697-1 Edition 1.0 2012-08 INTERNATIONAL STANDARD NORME INTERNATIONALE Test methods for quantitative determination of corrosive sulfur compounds in unused and used insulating liquids –

Part 1: Test method for quantitative determination of dibenzyldisulfide (DBDS)

Méthodes d’essai pour la détermination quantitative des composés de soufre corrosif dans les liquides isolants usagés et neufs –

Partie 1: Méthode d’essai pour la détermination quantitative du disulfure de dibenzyle (DBDS)

INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE V ICS 29.040 PRICE CODE CODE PRIX ISBN 978-2-83220-305-7

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale ®

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé. SIST EN 62697-1:2013 colourinside

– 2 – 62697-1 © IEC:2012 CONTENTS FOREWORD ........................................................................................................................... 5 INTRODUCTION ..................................................................................................................... 7 1 Scope ............................................................................................................................... 9 2 Normative references ....................................................................................................... 9 3 Terms, definitions and abbreviations ................................................................................ 9 3.1 Terms and definitions .............................................................................................. 9 3.2 Abbreviations ........................................................................................................ 13 4 Sampling ........................................................................................................................ 13 5 Procedure ...................................................................................................................... 13 5.1 Principle ................................................................................................................ 13 5.2 Significance and use ............................................................................................. 13 5.3 Interferences ......................................................................................................... 14 5.3.1 Co-eluting compounds ............................................................................... 14 5.3.2 Electron capture detector (ECD) ................................................................ 14 5.3.3 Atomic emission detector (AED) ................................................................ 14 5.3.4 Mass spectrometer (MS) ............................................................................ 14 5.3.5 MS/MS ...................................................................................................... 14 5.3.6 Interference from the matrix ....................................................................... 14 5.4 Apparatus .............................................................................................................. 15 5.4.1 Balance ..................................................................................................... 15 5.4.2 Gas chromatography system ..................................................................... 15 5.4.3 Data system .............................................................................................. 16 5.5 Reagents and materials ......................................................................................... 16 5.5.1 Purity of reagents ...................................................................................... 16 5.5.2 Gases ........................................................................................................ 16 5.5.3 Solvents .................................................................................................... 16 5.6 Standard materials ................................................................................................ 16 5.6.1 Dibenzyl disulfide (DBDS) ......................................................................... 16 5.6.2 Diphenyl disulfide (DPDS) ......................................................................... 16 5.6.3 Blank oil .................................................................................................... 16 5.7 Standard solutions ................................................................................................ 17 5.7.1 Stock solution ............................................................................................ 17 5.7.2 Internal standard (IS) solution.................................................................... 17 6 Instrument set-up ........................................................................................................... 17 6.1 Gas chromatograph ............................................................................................... 17 6.1.1 General ..................................................................................................... 17 6.1.2 Carrier gas ................................................................................................ 17 6.1.3 Injector ...................................................................................................... 17 6.1.4 Separation parameters .............................................................................. 17 6.1.5 ECD detection ........................................................................................... 18 6.1.6 AED detection ........................................................................................... 18 6.1.7 MS detection ............................................................................................. 18 6.1.8 MS/MS detection ....................................................................................... 18 6.2 Calibration ............................................................................................................. 19 6.2.1 General ..................................................................................................... 19 6.2.2 Calibration procedure ................................................................................ 19 SIST EN 62697-1:2013

62697-1 © IEC:2012 – 3 – 6.2.3 Response factor determination (ECD and AED) ......................................... 19 6.2.4 Response factor determination (MS) .......................................................... 19 6.2.5 Response factor determination (MS/MS) .................................................... 20 6.3 Analysis ................................................................................................................ 20 6.3.1 Sample pre-treatment ................................................................................ 20 6.3.2 Sample injection ........................................................................................ 20 6.3.3 Chromatographic run ................................................................................. 20 6.3.4 Peak integration ........................................................................................ 20 6.4 Calculations .......................................................................................................... 21 6.4.1 ECD and AED ............................................................................................ 21 6.4.2 Mass spectrometer (MS) ............................................................................ 21 6.4.3 MS/MS ...................................................................................................... 21 6.5 Results .................................................................................................................. 21 7 Precision data ................................................................................................................ 21 7.1 Detection limit ....................................................................................................... 21 7.2 Repeatability ......................................................................................................... 22 7.3 Reproducibility ...................................................................................................... 22 8 Report ............................................................................................................................ 22 Annex A (informative)

Figures with typical chromatograms and results ................................ 23 Annex B (informative)

Operating parameters for other suitable detectors ............................. 30 Bibliography .......................................................................................................................... 31

Figure A.1 – GC-ECD chromatogram of 2 mg kg–1 DBDS and DPDS (IS) in white mineral oil ............................................................................................................................. 23 Figure A.2 – GC-ECD chromatogram of 200 mg kg–1 DBDS and DPDS (IS) in white mineral oil ............................................................................................................................. 24 Figure A.3 – GC-ECD chromatogram of commercial mineral insulating oil with a known DBDS contamination ............................................................................................................. 24 Figure A.4 – GC-ECD chromatogram of commercial mineral insulating oil with no known DBDS contamination .................................................................................................. 25 Figure A.5 – GC-ECD chromatogram of commercial mineral insulating oil with known DBDS contamination fortified with acommercial polychlorinated biphenyls (PCBs) formulation............................................................................................................................ 25 Figure A.6 – Carbon and sulfur (C-S) oil finger prints of a commercial mineral insulating oil with known DBDS contamination obtained with GC-AED .................................. 26 Figure A.7 – C-S oil fingerprints of a commercial mineral insulating oil

with no known DBDS contamination obtained with GC-AED ......................................................................... 26 Figure A.8 – C-S oil fingerprints of a commercial mineral insulating oil with known DBDS contamination obtained with GC-AED ......................................................................... 27 Figure A.9 – Extracted ion chromatograms of DPDS (IS) molecular ion m/z 218 and DBDS molecular ion m/z 246 in white mineral fortified with DBDS, concentration 4 mg kg–1 ............................................................................................................................. 27 Figure A.10 – Extracted ion chromatograms DPDS (IS) molecular ion m/z 218 and DBDS molecular ion m/z 246 in commercial mineral insulating oil with known DBDS contamination ....................................................................................................................... 28 Figure A.11 – Extracted ion chromatograms m/z 109 derived from CID of DPDS (IS) molecular ion m/z 218 and m/z 91 derived from CID of DBDS molecular ion m/z 246 in white mineral fortified with DBDS (4 mg/kg) .......................................................................... 28 SIST EN 62697-1:2013

– 4 – 62697-1 © IEC:2012 Figure A.12 – Extracted ion chromatograms m/z 109 derived from CID of DPDS (IS) molecular ion m/z 218 and m/z 91 derived from CID of DBDS molecular ion m/z 246 in a commercial mineral oil with known DBDS contamination .................................................... 29

Table 1 – Column oven temperature programming parameters ............................................. 18 Table 2 – Mass spectrometer parameters ............................................................................. 18 Table 3 – Repeatability limit .................................................................................................. 22 Table 4 – Reproducibility limit ............................................................................................... 22

SIST EN 62697-1:2013
62697-1 © IEC:2012 – 5 – INTERNATIONAL ELECTROTECHNICAL COMMISSION ____________
TEST METHODS FOR QUANTITATIVE DETERMINATION
OF CORROSIVE SULFUR COMPOUNDS IN UNUSED
AND USED INSULATING LIQUIDS –
Part 1: Test method for quantitative determination
of dibenzyldisulfide (DBDS)

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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any services carried out by independent certification bodies. 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 62697-1 has been prepared by IEC technical committee 10: Fluids for electrotechnical applications. The text of this standard is based on the following documents: FDIS Report on voting 10/887/FDIS 10/891/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. SIST EN 62697-1:2013

– 6 – 62697-1 © IEC:2012 The committee has decided that the contents of this publication will remain unchanged until the stability 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.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates that it contains colours which are considered to be useful for the correct understanding of its contents. Users should therefore print this document using a colour printer.

SIST EN 62697-1:2013

62697-1 © IEC:2012 – 7 – INTRODUCTION Sulfur can be present in insulating liquids in various forms, including elemental sulfur, inorganic sulfur compounds and organic sulfur compounds. The number of diverse sulfur species comprised of different isomers and homologous can run into hundreds. The total sulfur(TS) concentration in insulating liquids depends on the origin of the liquid, refining processes and the degree of refining and formulation including addition of additives to the base oils. Base oils include mineral based paraffinic and naphthenic oils, synthetic iso- paraffins obtained through gas to liquid conversion process (GTL-Fischer-Tropsch), esters, poly alpha olefins, poly alkylene glycols, etc. Additives can be comprised of electrostatic discharge depressants, metal deactivators, metal passivators, phenolic and sulfur containing antioxidants such as the polysulfides, disulfides, dibenzyl disulfide (DBDS), etc.

Certain sulfur compounds present in the insulating liquids exhibit antioxidant and metal deactivating properties without being corrosive, whereas other sulfur compounds have been known to react with metal surfaces. Specifically, sulfur compounds such as mercaptans are very corrosive to metallic components of electrical devices. Presence of these corrosive sulfur species has been linked to failures of electrical equipment used in generation, transmission and distribution of electrical energy for several decades. Therefore, the IEC standard for mineral insulating oils states that corrosive sulfur compounds shall not be present in unused and used insulating liquids (see IEC 60296) [5]1. Recently, the serious detrimental impact of corrosive sulfur has been linked to the presence of a specific highly corrosive sulfur compound, DBDS. This compound has been found in certain mineral insulating oils [1, 14, 15, 16]; presence of this compound has been shown to result in copper sulfide formation on the surfaces of copper conductors under normal operating conditions of transformers [2]. Current standard test methods for detection of corrosive sulfur (ASTM D1275, methods A and B, and DIN 51353) and potentially corrosive sulfur in used and unused insulating oil (IEC 62535) are empirical and qualitative. These methods rely on visual and subjective perception of colour profiles. The methods do not yield quantitative results in regard to the concentration of DBDS or other corrosive sulfur compounds present in insulating liquids.

Furthermore, methods for corrosive sulfur and potentially corrosive sulfur in insulating liquids (ASTM D1275, method B and IEC 62535) are applicable only to mineral insulating oils that do not contain a metal passivator additive, the methods otherwise can yield negative results even when corrosive sulfur compounds are present in the insulating liquids – thus providing a false negative test result. On the other hand, the test method when used with aged insulating oils (e.g. those with relative high acidity), may give ambiguous results and lead to a false positive test result. Further analysis of insulating liquids is stipulated, e.g. IEC 62535 specifies that if there are any doubts in the interpretation of the results of inspection of paper, the composition of precipitate should be analyzed by other

methods (for example by SEM-EDX). For this reason, IEC TC 10 WG 37 was set up to prepare test methods for the unambiguous quantitative determination of corrosive sulfur compounds in unused and used insulating liquids. Because of the complexity of such determinations, the test methods are divided into three parts: Part 1 – Test method for quantitative determination of dibenzyldisulfide (DBDS). Part 2 – Test methods for quantitative determination of total corrosive sulfur (TCS). Part 3 – Test methods for quantitative determination of total mercaptans and disulfides (TMD) and other targeted corrosive sulfur species. ___________ 1 Figures in square brackets refer to the bibliography. SIST EN 62697-1:2013

– 8 – 62697-1 © IEC:2012 Health and safety This part of IEC 62697 does not purport to address all the safety problems associated with its use. It is the responsibility of the user of the standard to establish appropriate health and safety practices and determine the applicability of regulatory limitations prior to use. The insulating liquids which are the subject of this standard should be handled with due regard to personal hygiene. Direct contact with eyes may cause slight irritation. In the case of eye contact, irrigation with copious quantities of clean running water should be carried out and medical advice sought. Some of the tests specified in this standard involve the use of processes that could lead to a hazardous situation. Attention is drawn to the relevant standard for guidance. Environment This standard involves mineral insulating oils, natural ester insulating liquids, chemicals and used sample containers. The disposal of these items should be carried out in accordance with current national legislation with regard to the impact on the environment. Every precaution should be taken to prevent the release of chemicals used during the test into the environment. SIST EN 62697-1:2013

62697-1 © IEC:2012 – 9 – TEST METHODS FOR QUANTITATIVE DETERMINATION
OF CORROSIVE SULFUR COMPOUNDS IN UNUSED
AND USED INSULATING LIQUIDS –
Part 1: Test method for quantitative determination
of dibenzyldisulfide (DBDS)

1 Scope This part of IEC 62697 specifies a test method for the quantitative determination of corrosive sulfur compounds-dibenzyl disulfide (DBDS) in used and unused insulating liquids over a 5 – 600 mg kg–1 concentration range. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60475, Method of sampling liquid dielectrics IEC 62535:2008, Insulating liquids – Test method for detection of potentially corrosive sulfur in used and unused insulating oil 3 Terms, definitions and abbreviations For the purposes of this document, the following terms, definitions and abbreviations apply. 3.1 Terms and definitions 3.1.1

accuracy closeness of agreement between test result and the accepted reference value 3.1.2

additive a suitable chemical substance that is deliberately added to insulating liquid in order to improve certain characteristics Note 1 to entry: Examples include antioxidants, pour-point depressants, electrostatic charging tendency depressant such as benzotriazol (BTA) metal passivator or deactivators, antifoam agent, refining process improver, etc. 3.1.3

atomic emission detector AED simultaneously monitors emissions of radiation resulting from atomic species excited in a microwave-induced plasma and permits quantitative determination of selected heteroatoms in compounds that elute from a GC column Note 1 to entry: AED thus provides heteroatom profiles, i.e. “fingerprints” of complex samples such as insulating liquids. SIST EN 62697-1:2013

– 10 – 62697-1 © IEC:2012 3.1.4

contaminants foreign substances or materials in an insulating liquid or gas which usually has a deleterious effect on one or

more properties [SOURCE: IEC 60050-212:2010, 212-17-27, modified] 3.1.5

corrosion disintegration of a metal due to chemical reactions with sulfur and other chemical species in insulating liquids 3.1.6

corrosive sulfur free sulfur and corrosive sulfur compounds detected by subjecting metals such as copper to contact with an insulating liquid under standardized conditions [SOURCE: IEC 60050-212:2010, 212-18-20] 3.1.7

dibenzyl disulfide DBDS aromatic disulfide containing two benzyl functionalities with a molecular

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