SF6 training documentsFor certification according to Regulation (EC) No. 842/2006 on certainfluorinated greenhouse gases, ...
PUBLICATION DETAILSSF6 training documentsPublished by:ZVEI - Zentralverband Elektrotechnik und Elektronikindustrie e.V.(Ge...
ContentsContentsRequirements listed in the Annex to Regulation (EC) No. 305/2008 andthe corresponding sections of this doc...
Contents7     RECOVERY OF SF6 AND SF6 MIXTURES AND PURIFICATION      OF SF6 (P)                                        607...
ContentsRequirements listed in the Annex to Regulation (EC) No. 305/2008      and the corresponding sections of this docum...
Introduction    1    IntroductionThese training documents have been developed by colleagues workingin an honorary capacity...
Basic knowledge of relevant environmental issues      2   Basic knowledge of relevant environmental issues (T)2.1       Gr...
Basic knowledge of relevant environmental issuesFigure 1 Short-wave solar radiation enters the atmosphereand heats the sur...
Basic knowledge of relevant environmental issuesThe gas that makes the biggest contribution to the greenhouse effect iswat...
Basic knowledge of relevant environmental issuesassume, however, that a further increase in the average surfacetemperature...
Basic knowledge of relevant environmental issuesstates had ratified the Kyoto Protocol, covering 85% of the globalpopulati...
Basic knowledge of relevant environmental issues                                                                        Po...
Basic knowledge of relevant environmental issues                                                                    Potent...
Basic knowledge of relevant environmental issuesIn the 2005 version of the VoluntaryCommitment of the SF6 producersand the...
Basic knowledge of relevant environmental issuesconcerning SF6 emission rates for different parts of the lifecycle ofswitc...
Basic knowledge of relevant environmental issuesThe RegulationIn 2002, the European Union had alreadycommitted itself, in ...
Basic knowledge of relevant environmental issuesIn the context of this Regulation, the term "high-voltage switchgear"means...
Basic knowledge of relevant environmental issuesIt is well known, for example, that the standard series IEC 62271/EN 62271...
Basic knowledge of relevant environmental issuesExplanation:Until 2006, 1% of the total volume of SF6 in Germany that was ...
Basic knowledge of relevant environmental issuesArticle 5 Training and certification defines deadlines and procedures for ...
Basic knowledge of relevant environmental issuesThis Regulation defines the minimum requirements for personnel andthe cond...
Basic knowledge of relevant environmental issues                                        ANNEX       Minimum requirements a...
Basic knowledge of relevant environmental issuesArticle 6 Reporting, Regulation (EC) No. 842/2006Regulation (EC) No. 842/2...
Basic knowledge of relevant environmental issuesArticle 7 Labelling, Regulation (EC) No. 842/2006From 1 April 2008, "high-...
Basic knowledge of relevant environmental issues2.7    The national implementation regulation in GermanyThe implementation...
Sulphur hexafluoride (SF6)      3   Sulphur hexafluoride (SF6)3.1       Physical, chemical and environmental characteristi...
Sulphur hexafluoride (SF6)  3.2         SF6 quality according to relevant industry standards (T)  Table: SF6 gas qualities...
Sulphur hexafluoride (SF6)To enable the gas to be returned to the re-use process, it must meet thegas quality specified in...
Sulphur hexafluoride (SF6)3.3.1 Inspection – SF6 recovery and re-use on on siteThe impurities identified during inspection...
Sulphur hexafluoride (SF6)Assessment of the gas and categorisation as product or wastePage 30
Checking the SF6 quality      4   Checking the SF6 quality4.1       IntroductionSince the mid-1960s or so, sulphur hexaflu...
Checking the SF6 qualitythe SF6 gas by means of a Peltier element. Dewpoint hygrometers usean optoelectronic mechanism to ...
Checking the SF6 quality                                         Deckelelektrode                                         C...
Checking the SF6 qualitycomparison cell does not change. This temperature difference betweenthe heated filaments in the me...
Checking the SF6 qualityThe by-products, some of which are highly toxic (see table), can causeirritation and chemical burn...
Checking the SF6 qualityEquation 1: Measurement processSulphur dioxide (SO2):           SO2 + 2H2O = H2SO4 + 2H+ + 2e-The ...
Checking the SF6 qualityexample in the graphic clearly shows the peak position of the gas underanalysis (originating from ...
Checking the SF6 quality             By-product             Sulphur dioxide (SO2)             Hydrofluoride (HF)          ...
Checking the SF6 quality4.2.3 Oil mistConstituents of mineral oil can enter the gas compartment through theuse of gas hand...
Checking the SF6 qualityCombination measuring device: moisture (electronic sensor), SF6 percentage (soundvelocity) and by-...
Use of SF6 in electric power equipment    5    Use of SF6 in electric power equipment (insulation, arc         quenching) ...
Use of SF6 in electric power equipmentThe blast is generated by forcing the gas from a volume by means ofvolume reduction ...
Use of SF6 in electric power equipment      Circuit-breaker               Main contact               Arcing contact       ...
Use of SF6 in electric power equipmentBusbars comprise a copper or aluminium conductor within a contact-proof outer metal ...
Use of SF6 in electric power equipmentdielectric losses (thus reducing transmission losses and operatingcosts), no thermal...
Use of SF6 in electric power equipment                                     Sekundäranschluss                              ...
Use of SF6 in electric power equipmentThe tubular insulating body designed to enable a conductor to passthrough an opening...
Understanding the design of electric power equipment   6    Understanding the design of electric power equipment        (T...
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  1. 1. SF6 training documentsFor certification according to Regulation (EC) No. 842/2006 on certainfluorinated greenhouse gases, Regulation (EC) No. 305/2008 on theestablishment of minimum requirements for the certification ofpersonnel, and the German Chemical Climate Protection Ordinance(ChemKlimaschutzV)
  2. 2. PUBLICATION DETAILSSF6 training documentsPublished by:ZVEI - Zentralverband Elektrotechnik und Elektronikindustrie e.V.(German Electrical and Electronic Manufacturers Association)Stresemannallee 19, D-60596 Frankfurt am Main, GermanyBDEW Bundesverband der Energie- und Wasserwirtschaft e.V.(German Association of Energy and Water Industries)Reinhardtstr. 32, D-10117 Berlin, GermanyForum Netztechnik/Netzbetrieb im VDE (FNN)(Power Supply Technology/Power Supply Operation Forum of the VDE (German Association forElectrical, Electronic and Information Technologies))Bismarckstr. 33, D-10625 Berlin, GermanyContacts:Johannes Stein, ZVEI Fachverband Energietechnik (Energy Technology Unit within ZVEI)Thoralf Bohn, Forum Netztechnik/Netzbetrieb im VDETel.: +49 69 6302-265Fax: +49 69 6302-234E-mail: etechnik@zvei.orgwww.zvei.orgwww.sf6-energietechnik.deEditorial team:“SF6 Training and Certification”Peter Ball, ABB AGAndreas Lehmann, Vattenfall Europe BerlinMario Prüfert, Siemens AGBernd Drews, ABB AGAndreas Büscher, AREVA Energietechnik GmbH SachsenwerkPaul Blumenthal, AREVA T&D AGThoralf Bohn, Forum Netztechnik/Netzbetrieb im VDEHayder Ali, DB Energie GmbHMichael Hippenstiel, DB Energie GmbHLudwig Rieder, DILO Armaturen und Anlagen GmbHMartin Grote, Driescher-WegbergReinhold Haug, EnBW Regional AGPeter Pilzecker, G.A.S. Gesellschaft für analytische Sensorsystem mbHAndreas Reimüller, ABB AGNorbert Lambrecht, RWE Westfalen-Weser-Ems Netzservice GmbHBernhard Tilwitz- von Keiser, Siemens AGPeter Jannick, SOLVAY FLUOR GmbHJohannes Stein, ZVEITitle image: Vattenfall Europe BerlinDespite exercising the utmost care, the publisher accepts no liability for the contents.All rights, in particular the right to copy, distribute and translate this document, are reserved. No partof this document may be reproduced in any form (print, photocopy, microfilm or other) or stored,processed, copied or distributed by means of electronic systems without the written permission ofZVEI/FNN.Edition: February 2009
  3. 3. ContentsContentsRequirements listed in the Annex to Regulation (EC) No. 305/2008 andthe corresponding sections of this document 51 INTRODUCTION 62 BASIC KNOWLEDGE OF RELEVANT ENVIRONMENTAL ISSUES (T) 72.1 Greenhouse gases and the greenhouse effect 72.2 Impact of the anthropogenic greenhouse effect 92.3 The Kyoto Protocol 102.4 Global warming potential 112.5 The Voluntary Commitment on SF6 as an insulation and quenching gas 132.6 The European Regulation on certain fluorinated greenhouse gases 152.7 The national implementation regulation in Germany 253 SULPHUR HEXAFLUORIDE (SF6) 263.1 Physical, chemical and environmental characteristics of SF6 (T) 263.2 SF6 quality according to relevant industry standards (T) 273.3 Re-use of SF6 and the different re-use categories (T) 28 3.3.1 Inspection – SF6 reclamation and purification on site 29 3.3.2 Recovery – regeneration of SF6 to produce new gas in accordance with IEC 60376 29 3.3.3 Disposal – incineration of SF6 294 CHECKING THE SF6 QUALITY 314.1 Introduction 314.2. Monitoring the gas quality 31 4.2.1 Moisture, air and CF4 31 4.2.2 By-products 34 4.2.3 Oil mist 394.3. Combination measuring devices 395 USE OF SF6 IN ELECTRIC POWER EQUIPMENT (INSULATION, ARC QUENCHING) (T) 416 UNDERSTANDING THE DESIGN OF ELECTRIC POWER EQUIPMENT (T) 486.2 Structure of switchgear systems 516.3 Structure of SF6-insulated medium-voltage switchgear systems 56Page 3 / 99
  4. 4. Contents7 RECOVERY OF SF6 AND SF6 MIXTURES AND PURIFICATION OF SF6 (P) 607.1 Practical structure of a process flow for the recovery of SF6 607.2 Measuring the gas quality 62 7.2.1. Gas connection 63 7.2.2. Measurement 63 7.2.3. Collecting the measurement gas 64 7.2.4. Evaluating the measurement against threshold values 657.3 Provision of basic knowledge regarding the use of different filter types and adsorbents used in service devices or mobile prefilter units 657.4 Operation of SF6 recovery equipment (P) 667.4.1 Function: Extraction of SF6 gas 687.4.2 Deactivating the SF6 service equipment 747.5 Storage and transportation of SF6 (T) 807.6 Working on open SF6 compartments (P) 827.7 Neutralising SF6 by-products (T) 847.8 Operation of tight drilling systems, if necessary (P) 868 SF6 DATA RECORDING OBLIGATIONS 889 SOURCES AND REFERENCES 99(P) Practical part of the training and examination(T) Theoretical part of the training and examinationPage 4
  5. 5. ContentsRequirements listed in the Annex to Regulation (EC) No. 305/2008 and the corresponding sections of this document Topic No. in Annex to Section of this 305/2008 training documentBasic knowledge of relevant 1. 2environmental issues (climatechange, Kyoto Protocol, GlobalWarming Potential), the relevantprovisions of Regulation (EC) No.842/2006 and of the relevantRegulations implementing theprovisions of Regulation (EG) No.842/2006Physical, chemical and environmental 2. 3.1characteristics of SF6Use of SF6 in electric power 3. 5equipment (insulation, arc quenching)SF6 quality, according to the relevant 4. 3.2industrial standardsUnderstanding the design of electric 5. 6power equipmentChecking the SF6 quality 6. 4Recovery of SF6 and SF6 mixtures 7. 7and purification of SF6Storage and transportation of SF6 8. 7.5Operation of SF6 recovery equipment 9. 7.4Operation of tight drilling systems, if 10. 7.8necessaryRe-use of SF6 and different re-use 11. 3.3categoriesWorking on open SF6 compartments 12. 7.6Neutralising SF6 by-products 13. 7.7Monitoring of SF6 and appropriate 14. 8data recording obligations undernational or community legislation orinternational agreementsPage 5 / 99
  6. 6. Introduction 1 IntroductionThese training documents have been developed by colleagues workingin an honorary capacity from the member companies of the BDEW, VIKand ZVEI associations and from the company Solvay. The associations,their member companies and Solvay are parties to the VoluntaryCommitment on SF6.The new German and European legislation sets down examination andcertification requirements for the training of employees involved in therecovery of SF6 gas. These training documents are based on the Annexto Regulation (EC) No. 305/2008. They contain explanations aimed atharmonising the requirements and training contents in Germany andsupporting both the training providers and the employees being trained.The objective is to ensure that the training providers are in a position toissue the certification documents in agreement with the relevant regionalauthorities.The legislative requirements are limited to the recovery of SF6 and theassociated environmental protection aspects. In some areas, thesetraining documents extend beyond this very limited scope to explore anumber of supplementary issues and safety aspects. Not all thesesupplementary issues can be examined in depth here and, whereappropriate, the training documents refer to additional sources ofinformation.This SF6 training document is intended as a training resource but also asa work of reference for trainers and trainees alike. From the highlydetailed explanations in each section, extracts can be createdindividually for training purposes. Please note that, for each section, thetraining contents must always be at least aligned with the examinationquestions.Page 6
  7. 7. Basic knowledge of relevant environmental issues 2 Basic knowledge of relevant environmental issues (T)2.1 Greenhouse gases and the greenhouse effectSulphur hexafluoride (SF6) is a gas that has been used since around1960 in electric power transmission and distribution equipment withvoltages exceeding 1000 V. Its special physical characteristics make itideal for use in various switching and insulation applications.SF6 is an inert, non-flammable, non-toxic insulation medium. Although itis a relatively ozone-friendly gas, it has a high global warming potential.For this reason, SF6 is one of the six greenhouse gases regulated by theKyoto Protocol. These are gases in the atmosphere that prevent long-wave infra-red radiation from being emitted directly from the Earthssurface into space. They behave like the glass panes of a greenhouse,causing the entire atmosphere to heat up. Natural greenhouse gasesinclude water vapour, carbon dioxide, ozone, methane and nitrous oxide.Man-made greenhouse gases are HFCs, PFCs, CFCs and SF6.The greenhouse effect causes the Earth to heat up due to the presenceof greenhouse gases and water vapour in the atmosphere. The termoriginally came from the greenhouses used for gardening, in which thesuns rays warm the air behind the glass panes and thus heat the interiorof the greenhouse. This warmth enables plants to germinate, bloom andbear fruit earlier than normal. This is a highly specific use of the term"greenhouse effect".Today, however, we use the term in a much wider sense. Because ofthe similarities between the mechanisms in real greenhouses and themechanisms in the Earths atmosphere, the accumulation in the Earthsatmosphere of heat from solar radiation is described as the "atmosphericgreenhouse effect".Page 7 / 99
  8. 8. Basic knowledge of relevant environmental issuesFigure 1 Short-wave solar radiation enters the atmosphereand heats the surface of the Earth. Long-wave radiation is re-emitted from the Earths surface and almost all of it isabsorbed into the atmosphere. In the thermal equilibrium, halfof the absorbed energy in the atmosphere is radiateddownward to the Earths surface, and the other half into space.The figures indicate the radiated energy in watts per squaremeter.11 The greenhouse effect is based on just a few steps:1. The Sun radiates a huge amount of energy to the Earth in the form of electromagnetic waves. As a result, the surface of the Sun is cooled (radiation cooling).2. Most of the short-wave, visible light from the Sun is not absorbed by the Earths atmosphere (or the glass panes of a greenhouse) because the atmosphere (or glass) is highly transparent. This short- wave radiation can therefore penetrate the Earths atmosphere (or the greenhouse) almost unhindered.3. However, the Earths surface (like the objects in the greenhouse) absorbs the short-wave light from the Sun and this causes it to heat up.4. The heated objects re-emit electromagnetic waves. The light that they re-emit, however, is long-wave (infra-red) radiation.5. The Earths atmosphere (like the glass of the greenhouse) becomes increasingly opaque, making it difficult for this re-emitted long-wave radiation to escape into space. The result of this lack of radiation cooling is that the Earths atmosphere (like the objects in the greenhouse) heats up more intensively than would be expected on the basis of the radiation equilibrium.1 The following explanations are based in part on the information available at:http://en.wikipedia.org/wiki/Greenhouse_effectPage 8
  9. 9. Basic knowledge of relevant environmental issuesThe gas that makes the biggest contribution to the greenhouse effect iswater vapour. Water vapour produces around two thirds of the 33°C ofheat generated in the Earths surface by the natural greenhouse effect.The rest is generated by the trace gases carbon dioxide and methaneand small amounts of other gases.The natural greenhouse effect is an essential prerequisite for life onEarth as we know it. The average temperature on the Earths surface is+15°C; without the natural greenhouse effect, it would be -18°C! Thegases in the Earths atmosphere have an effect similar to that of theglass panes of a greenhouse.However, mankind influences the natural greenhouse effect in a varietyof ways, thus causing the temperature in the atmosphere to rise. Theman-made greenhouse gases have a more intense effect, similar to thatof the glass in a greenhouse. They cause the "barrier layer" in theatmosphere to become increasingly opaque for the long-wave infra-redradiation emitted from the Earths surface. The radiation re-emitted fromthe Earths surface is reflected against the barrier layer of gas in theatmosphere, thus increasing the temperature in the lower part of theEarths atmosphere. The part of the artificial greenhouse effect that iscaused by human activity is called the anthropogenic greenhouse effect.The term "greenhouse effect" is often used to mean just theanthropogenic greenhouse effect.Mainly by burning fossil fuels such as coal, gas and oil, humans releaselarge quantities of carbon dioxide (CO2) into the Earths atmosphere. Inaddition, large amounts of bound carbon dioxide are released"artificially" via exhaust emissions or as a result of deforestation,particularly the burning of the rainforests. The additional man-made CO2emissions are then present in the atmosphere in gaseous form. Thisintensifies the natural greenhouse effect. As well as releasing CO2,mankind also influences the greenhouse effect by emitting further tracegases such as methane and artificially produced substances, above allCFCs (= chlorofluorocarbons, artificially produced gases or liquids) andHFCs (hydrofluorocarbons).2.2 Impact of the anthropogenic greenhouse effectThe average temperature of the Earths surface has risen by around0.6°C over the last 100 years. The steepest rise has been recordedwithin the last 30 years. At the present time, it is not possible to say forcertain what the impact of the anthropogenic greenhouse effect will be.Todays climate models still contain too many uncertainties for theexperts to make reliable forecasts. The greatest uncertainty factors areclouds and forests. Both have a decisive influence on the climate andinvolve complex relationships that defy simple description.Until now, it has been unclear whether climate change will be on a globalscale or whether a number of different climate zones, each one stablewithin itself, will be formed. Neither do we yet know whether there is acritical CO2 concentration in the atmosphere above which climatechanges will start to take effect within just a few years. We mustPage 9 / 99
  10. 10. Basic knowledge of relevant environmental issuesassume, however, that a further increase in the average surfacetemperature will result in a drastic change in the Earths climate.The following climate changes have already been recorded: An unusually long warm phase in the "El Nino" (ocean current) between 1990 and 1995 A rise of between 10 and 25 cm in sea levels within the last 100 years, due mainly to the increased volume of water produced by the rise in air temperature A 2 - 4°C rise in the surface temperature in Alaska Increased atmospheric humidity in the Tropics Increased cloud cover over land The shrinkage of the snow mantle in the AlpsThere is as yet no definitive proof that human activity has contributed tothese effects. However, the fact that such significant changes haveoccurred within a very short space of time clearly supports thisargument.Possible effects in the future are: The melting of the polar ice caps A further rise in sea levels Increased occurrence of extreme events such as drought and flooding The displacement of ocean currents (such as the Gulf Stream), resulting in extreme regional climate changes Increased occurrence of hurricanes and stormsEven if mankinds influence on the climate has not yet been provenbeyond doubt, all the evidence currently available points to thisconclusion.2.3 The Kyoto ProtocolThe Kyoto Protocol (named after the location of the Kyōto Conference inJapan) was adopted on 11 December 1997. It is a supplementaryprotocol to the United Nations Framework Convention on ClimateChange (UNFCC) aimed at protecting the climate. The Protocol, whichentered into force in 2005 and will run until 2012, is the first treaty to setbinding target values for emissions of greenhouse gases, which are themain cause of global warming. The gases regulated in the Protocol are:carbon dioxide (CO2, used as a reference value), methane (CH4), nitrousoxide (laughing gas, N2O), hydrofluorocarbons (HFCs), perfluorocarbons(PFCs) and sulphur hexafluoride (SF6). The Kyoto Protocol aims toachieve a 5.2% reduction, averaged over the period 2008-2012, in theannual greenhouse gas emissions of the industrialised nationscompared to 1990 levels. However, there is no specific reduction targetfor each gas; instead, the gases are considered collectively as a"basket". A country can therefore reduce any one of these gases inorder to achieve its reduction target. At the start of February 2005, 136Page 10
  11. 11. Basic knowledge of relevant environmental issuesstates had ratified the Kyoto Protocol, covering 85% of the globalpopulation and 62% of global C02 emissions (the USA had not ratified atthis time).The UNFCCC resulted in the establishment of an IntergovernmentalPanel on Climate Change (IPCC), which publishes correspondingAssessment Reports on the state of knowledge on climate change.Among other topics, Volume 3, Chapter 8 of the Fourth IPCCAssessment Report covers the use of SF6 in high-voltageswitchgear.2.4 Global warming potentialThe (relative) global warming potential (GWP) or CO2 equivalent is ameasure of how much a given mass of a greenhouse gas contributes tothe greenhouse effect. Carbon dioxide is used as a comparison value,abbreviated to CO2e (equivalent). The value describes the averagewarming effect over a given period, usually 100 years.For example: the CO2 equivalent for methane over a time horizon of 100years is 25. This means that the contribution to the greenhouse effect ofone kilogramme of methane is 25 times greater than that of onekilogramme of CO2.However, the global warming potential is not the same as the actualcontribution to global warming, as there is a strong variation in theemission volumes of the different gases. This concept enables acomparison of the different contributions of individual greenhouse gasesbased on known emission volumes.In the first commitment period of the Kyoto Protocol, emission volumesare evaluated using the CO2 equivalents of the individual gases andweighted according to their global warming potential. This means, forexample, that a reduction of one tonne of SF6 emissions is equivalent toa CO2 reduction of 22,200 tons because, in both cases, the reduction inemissions amounts to 22,200 tons of CO2 equivalent.Page 11 / 99
  12. 12. Basic knowledge of relevant environmental issues Potential (over Greenhouse gas Source 100 years) Combustion of fossil fuels (coal, mineral oil and natural gasCarbon dioxide CO2 in transport and industry) and 1 biomass (forest clearance/burning), cement production, volcanic activity Rice cultivation, livestock farming, sewage plants, landfill sites, coal-Methane CH4 mining (mine gas), 25 natural gas and mineral oil production, marine biologyNitrous oxide N2O Nitrogen fertilisers in agriculture, 298(laughing gas) combustion of biomass A group of chemical compounds used as propellants in spray cans,Chlorofluorocarbons freezing agents in refrigeration Up to(CFCs) systems, anaesthetics, and 14,400 filler gases in foams; banned in Germany since 1995 Propellants in spray cans, freezingHydrofluorocarbons Up to agents in refrigeration systems,(HFCs) 14,800 filler gases in foamsTetrafluoroethane Freezing agent in refrigeration 1,430(R-134a, HFC-134a) systems Used, for example, as a protective gas in the magnesium productionSulphur hexafluoride SF6 process and as an arc-quenching 22,200 and insulation gas in high-voltage switchgearPage 12
  13. 13. Basic knowledge of relevant environmental issues Potential (over Greenhouse gas Source 100 years) SF6 was previously also used in the manufacture of windows, footwear and tyres, but this was banned by the F-Gas Regulation.Comparison of SF6 emissions:1 kg SF6 released into the atmosphere makes the same contribution tothe anthropogenic greenhouse effect as a petrol-driven mid-class carwith a total mileage of around 120,000 km (emitting around 185 g CO2per km).According to an independent study conducted in 2005 (see ECOFYSReport [16]), SF6 emissions from electric power equipment in 2002accounted for 0.05% of the total greenhouse gas emissions of the 15 EUmember states. Assuming that further measures will be implementedEurope-wide, the SF6 emissions generated by the power transmissionand distribution sector in Europe would seem to represent a negligibleproportion of the total global warming potential of all greenhouse gases.This very low proportion is due to the high level of awareness andresponsibility that was established in this sector in Germany very shortlyafter the greenhouse effect of SF6 became known. SF6 is used in aclosed cycle in the power transmission and distribution sector. In thiscycle, the emissions are minimised, and used SF6 is recovered (at theend of the SF6-filled equipment lifecycle, for example) and either re-useddirectly or first purified and then re-used (SF6 re-use concept).2.5 The Voluntary Commitment on SF6 as an insulation and quenching gasIn the knowledge that SF6 has a very long lifetime in the atmosphere andis a highly effective greenhouse gas, the German operators andmanufacturers of power transmission and distribution equipment withvoltages exceeding 1 kV AC that use SF6, together with Solvay FluorGmbH, a German manufacturer of SF6 gas, committed themselves tothe first Voluntary Commitment, dated 1997, aimed at limiting andreducing SF6 emissions.Page 13 / 99
  14. 14. Basic knowledge of relevant environmental issuesIn the 2005 version of the VoluntaryCommitment of the SF6 producersand the manufacturers and operatorsof electric power equipment > 1 kVfor electrical power transmission anddistribution in the Federal Republic ofGermany on SF6 as an insulation andquenching gas, the signatories havepledged to reduce SF6 emissionssignificantly in• the manufacture of electric power equipment,• its commissioning and operation, and in the• recovery,• recycling (including re-use) and• disposal of SF6.The Voluntary Commitment on SF6 defines detailed measures to betaken by manufacturers and operators to limit emissions. Manufacturersand operators work according to the following principles: SF6 emissions should be avoided wherever possible. Quantities of SF6 required to fulfill specific functions should be minimised.The equipment operators and manufacturers and the SF6 producer haveundertaken to implement all possible measures to reduce SF6 emissionsduring the development, manufacturing and installation phases and inthe operation, maintenance, decommissioning and dismantling ofequipment. This also applies to the manufacture, transport and storageof SF6 and all measures associated with the recovery, recycling, re-useor destruction of used SF6.The "Criteria for selecting switchgear systems and devices for powertransmission and distribution" provide decision-making support for theselection of SF6 technology or other equally proven technology (such asair-insulated, solid-insulated or oil-insulated equipment). The followingcriteria must considered:• Technical/economic criteria• Factors that determine the lifecycle costs• Ecological criteria, sustainability• Public safety• Industrial health and safetyBased on 2003 data, the section on "Data and targets for the use of SF6as an insulation and quenching gas in electric power transmission anddistribution equipment > 1 kV" sets binding targets for GermanyPage 14
  15. 15. Basic knowledge of relevant environmental issuesconcerning SF6 emission rates for different parts of the lifecycle ofswitchgear systems and devices.To verify the implementation of the measures set out in the VoluntaryCommitment on SF6, a detailed SF6 status report is issued each year.This data is made available each year by 31 March of the subsequentyear, in an agreed form and via the associations, to the Federal Ministryfor the Environment, Nature Conservation and Nuclear Safety (BMU)and the Federal Environmental Agency (UBA).The measures set down in the Voluntary Commitment on SF6 have cutemissions by over 55% since the comparison year 1995, despite asignificant rise in the use of SF6 by manufacturers and in the inventoriesof the operators. For this reason, Germanys Voluntary Commitment onSF6 is cited by environmental politicians as exemplary, showing the wayfor other sectors as well as other countries.2.6 The European Regulation on certain fluorinated greenhouse gasesWhile the "classic" greenhouse gases usually occur as unwanted by-products, most fluorinated greenhouse gases are produced intentionallyand used as propellants, refrigerants or fire-extinguishing agents. Withinthe hydrofluorocarbons, a distinction is made between partiallyhalogenated hydrofluorocarbons and fully halogenatedhydrofluorocarbons. If HFCs are fully fluorinated - that is, they no longercontain any hydrogen atoms - they are also called perfluorocarbons(PFCs). Hydrofluorocarbons are now used in place ofchlorofluorocarbons (CFCs), the use of which has been restricted since1995. Because of their high global warming potential, fluorinatedgreenhouse gases have become a focal point of environmental policy.The family of fluorinated greenhouse gases includes:• hydrofluorocarbons (HFCs),• perfluorocarbons (PFCs) and• sulphur hexafluoride (SF6)with a global warming potential (GWP) ranging from around 100 to amaximum of 22,200.Sulphur hexafluoride (SF6) has the highest known global warmingpotential of 22,200. However, its low total emission volume means thatits contribution to the greenhouse effect is minimal. SF6 has anextremely small influence on global warming compared to the othergreenhouse gases. SF6 emissions from electric power transmission anddistribution equipment > 1 kV account for just 0.05% or so of Europesentire global warming potential. However, it can take up to 3,000 yearsto break down in the atmosphere.Page 15 / 99
  16. 16. Basic knowledge of relevant environmental issuesThe RegulationIn 2002, the European Union had alreadycommitted itself, in the Sixth CommunityEnvironment Action Programme and in the KyotoProtocol, to achieving an 8% reduction inemissions of greenhouse gases compared to 1990levels. It also recognized that, in the longer term, global emissions ofgreenhouse gases would need to be reduced by approximately 70%compared to 1990 levels. Due to the high global warming potential offluorinated greenhouse gases, Regulation (EC) No. 842/2006 of the European Parliament and of the Council of 17 May 2006 on certain fluorinated greenhouse gaseswas brought into force. Its primary objective is to reduce the emissionsof the fluorinated greenhouse gases specified above and thus protectthe environment.This Regulation covers• the reduction of emissions,• the use of the specified fluorinated gases (F-gases),• the recovery, recycling, reclamation and destruction of the F-gases,• the labelling and disposal of products and equipment containing these F-gases,• the reporting requirements for these gases (monitoring/recording of SF6 imported into and exported from the EU and used in production),• the control of uses of products and equipment containing the affected gases, and restrictions on the placing of such products and equipment on the market, and• the training and certification of personnel involved in activities provided for by this Regulation.This Regulation applies to certain fluorinated greenhouse gases, gasmixtures containing a fluorinated greenhouse gas, and products andequipment containing these fluorinated gases, as listed in Annex 1, Part1 of the Regulation:• refrigeration systems,• air-conditioning systems,• heat pumps,• fire protection systems and fire-extinguishers,• equipment containing solvents based on fluorinated greenhouse gases, and• high-voltage switchgear.The Regulation also covers processes and manufacturing proceduresthat use fluorinated greenhouse gases, as well as "avoidableapplications", such as windows, footwear, tyres, single-componentfoams and novelty aerosols.Page 16
  17. 17. Basic knowledge of relevant environmental issuesIn the context of this Regulation, the term "high-voltage switchgear"means all electric equipment and systems for the transmission anddistribution of electric energy at rated voltages above 1 kV [seeRegulation (EC) No. 305/2008, Article 2 Definitions]:Switching devices and their combination with associated control,measuring, protective and regulating equipment, and assemblies of suchdevices and equipment with associated interconnections, accessories,enclosures and supporting structures, intended for use in connectionwith generation, transmission, distribution and conversion of electricenergy at rated voltages above 1,000 V.Which countries are bound by the F-Gas Regulation?Regulation (EC) No. 842/2006 on certain fluorinated greenhouse gasesapplies without restriction to all member states of the European Union.Certain articles of this Regulation mustbe implemented in the member stateswithout changes or additions. In otherarticles, the Regulation sets downminimum requirements and allowseach member state to incorporateadditional requirements into itsnational implementation regulation.However, any such additional nationalrequirements may not impede the freemovement of goods and the freedomof establishment within the EuropeanUnion. Such articles include Article 5 Training and certification ofRegulation (EC) No. 842/2006, which is implemented in the individualmember states on the basis of the EU minimum requirements.The text of the Regulation also has relevance to the European EconomicArea (EEA). The EEA currently incorporates the member states of theEuropean Union as well as Norway, Iceland and Liechtenstein.Imports of products, equipment and services into the European Unionare also subject to Regulation (EC) No. 842/2006.Validity for the power transmission and distribution sectorThe operation alone of SF6-insulated switchgear > 1 kV AC ("high-voltage switchgear") is not affected by this Regulation. Such equipmentis not subject to any prohibitions or restrictions of use under Article 8Control of use, Article 9 Placing on the market and Annex II of theRegulation.The provisions of Article 3 Containment requiring operators to check forleakage apply to stationary applications in the form of refrigeration andair-conditioning systems, heat pumps and fire protection systems, butnot to "high-voltage switchgear" (as defined above). However, a cleardistinction must be drawn here and in all the following explanationsbetween the purely environmental requirements of Regulation (EC) No.842/2006 and the applicable technical or standard-based requirements.Page 17 / 99
  18. 18. Basic knowledge of relevant environmental issuesIt is well known, for example, that the standard series IEC 62271/EN 62271/VDE 0671 for equipment containing SF6 defines detailedgastightness requirements that are not covered by the statutory EURegulation.The following requirements and articles are of relevance to the powertransmission and distribution sector in the practical implementation ofRegulation (EC) No. 842/2006:• Article 4 Recovery 1)• Article 5 Training and certification 1)• Article 6 Reporting 2)• Article 7 Labelling 2)1) Applies to operators, manufacturers and service companies2) Applies to manufacturers and service companiesArticle 4 Recovery, Regulation (EC) No. 842/2006Of particular relevance here are certain definitions given in Article 2Definitions of Regulation (EC) No. 842/2006:"Recovery"means collection and storage from, for example, machinery, equipmentand containers.Explanation:For SF6-filled equipment > 1 kV AC this is, for example, the extraction ofSF6 using suitable equipment."Recycling"means the extraction of a recovered fluorinated greenhouse gasfollowing a basic cleaning process.Explanation:In many cases, used SF6 is filtered mechanically during the recoveryprocess. If this SF6 gas then meets the requirements set down in IEC60480/EN 60480 or IEC 62271-303, it is recycled (re-used)."Treatment"means the reprocessing of a recovered fluorinated greenhouse gas inorder to meet a specified standard of performance.Explanation:The SF6 gas producer Solvay Fluor GmbH, for example, is implementingthe reclamation of used and recovered SF6 as part of its re-use concept.See also IEC 62271-303."Destruction"means the process by which all or most of a fluorinated greenhouse gasis permanently transformed or decomposed into one or more stablesustances which are not fluorinated greenhouse gases.Page 18
  19. 19. Basic knowledge of relevant environmental issuesExplanation:Until 2006, 1% of the total volume of SF6 in Germany that was deliveredto Solvay Fluor GmbH as part of the re-use programme was burned andthus destroyed in special processes because it had not been possible toreclaim the highly contaminated SF6 using the processes available at thetime. Today, following extensive process improvements at Solvay FluorGmbH, it is normal practice not to destroy any used SF6; in other words,100% of the SF6 delivered to Solvay is now reclaimed. In othercountries, however, the destruction of used SF6 is still commonplace.The provisions of Article 4 Recovery apply as follows to "high-voltage switchgear": (1) Operators shall be responsible for putting in place arrangements for the proper recovery by certified personnel, who comply with the requirements of Article 5 Training and certification, of fluorinated greenhouse gases to ensure their recycling, reclamation or destruction. Explanation: The term "operator" is somewhat misleading in this context. Commission Regulation (EC) No. 305/2008, which establishes minimum requirements for the certification of personnel, refers not just to the term "operator" but to "personnel recovering certain fluorinated greenhouse gases from high- voltage switchgear". In reality, the certification requirements apply to all persons involved in activities of this kind - including all those involved in the recovery of SF6. (2) When a loose SF6 cylinder or container reaches the end of its life, the person using the cylinder or container for transport or storage purposes shall be responsible for putting in place arrangements for the proper recovery of any residual SF6 gas it contains to ensure its recycling, reclamation or destruction. (3) Recovery, for the purpose of recycling, treatment or destruction of SF6, shall take place before the final disposal of the affected equipment and, when appropriate, during its servicing and maintenance. Explanation: Once the equipment has reached the end of its life, the used SF gas must be removed in accordance with proper 6 procedures. If it meets the IEC 60480 standard for used SF6, it can be re-used directly as a product. If it meets the gas manufacturers "re-use specification" in accordance with IEC 62271-303, it must be returned to the gas manufacturer for re- use processing.Page 19 / 99
  20. 20. Basic knowledge of relevant environmental issuesArticle 5 Training and certification defines deadlines and procedures for the minimum requirements and conditions for mutual recognition in respect of training programmes and certification as well as for the personnel involved in activities relating to the recovery, reclamation, recycling or destruction of SF6 in/from "high-voltage switchgear".Article 5 also stipulates that the member states of the European Unionshall give recognition to the certificates issued in another member stateand shall not restrict the freedom to provide services or the freedom ofestablishment in accordance with this Regulation.According to Article 5, the operator of the "high-voltage switchgear" shallensure that the relevant personnel have obtained the necessarycertification. This implies: appropriate knowledge of the applicable regulations and standards, as well as the necessary competence in emission prevention and the recovery of SF6 and the safe handling of SF6 maintenance and testing equipment of the relevant type and size.This is the objective of this training programme.By 4 July 2009, the member states shall ensure that the companiesinvolved in carrying out the activities relating to the recovery, recycling,reclamation or destruction of SF6 in/from "high-voltage switchgear" shallonly take delivery of SF6 if their relevant personnel hold the requiredcertificates.Explanation: This means that the relevant personnel must hold therequired certificates by 4 July 2009 at the latest.The detailed implementation of Article 5 Training and certification ofRegulation (EC) No. 842/2006 specifically for "high-voltage switchgear"is defined in a separate Regulation of the European Commissionentitled: COMMISSION REGULATION (EC) No. 305/2008 of 2 April 2008 — pursuant to Regulation (EC) No. 842/2006 of the European Parliament and of the Council — establishing minimum requirements and the conditions for mutual recognition for the certification of personnel recovering certain fluorinated greenhouse gases from high-voltage switchgear.Page 20
  21. 21. Basic knowledge of relevant environmental issuesThis Regulation defines the minimum requirements for personnel andthe conditions for the mutual recognition of the certificates issued. Theseminimum requirements form the basis for the mutual recognition of thecertificates issued in the member states.For our electric power transmission and distribution sector, Article 2Definitions of Regulation (EC) No. 305/2008 for "high-voltageswitchgear" is very important. The following definition is particularlyrelevant: For the purposes of this Regulation, "high-voltage switchgear" means switching devices and their combination with associatedcontrol, measuring, protective and regulating equipment, and assemblies of such devices and equipment with associated interconnections, accessories, enclosures and supportingstructures, intended for use in connection with generation, transmission, distribution and conversion of electric energy at rated voltages above 1,000 V.The Regulation therefore covers all equipment filled with SF6 or SF6mixtures used to generate, transmit, distribute and convert electricenergy at voltages above > 1 kV.As well as detailing the requirements relating to the certification andevaluation bodies, the Regulation also defines the minimumrequirements for the certificates themselves. In this context, please alsonote that member states may require holders of certificates issued inanother member state to provide a translation of the certificate inanother official Community language.Article 3 Certification of personnel also specifies conditions foremployees who have already been carrying out the activities associatedwith SF6 for a longer period, as defined in the Regulation: for thetransitional period up to 4 July 2009, the member states may decide thatpersonnel with experience shall be deemed "certified".Personnel undergoing training (in connection with the requirements ofthe F-Gas Regulation) may continue to carry out the SF6 activitieswithout a certificate for up to one year, provided that they are supervisedby a person holding a certificate.The Annex to Regulation (EC) No. 305/2008 defines the theoretical andpractical training and examination contents as minimum requirements forall affected personnel, with equal applicability to all member states. Toensure the continued comparability of the certificates based on thetraining and examination contents, the specified contents must beincluded in training courses and examinations, regardless of the area ofactivity of the person being trained.Page 21 / 99
  22. 22. Basic knowledge of relevant environmental issues ANNEX Minimum requirements as to the skills and knowledge to be covered by the evaluation bodiesThe examination referred to in Articles 4(1) and 6(2) shall comprise thefollowing:a) a theoretical test with one or more questions testing that skill orknowledge, as indicated in the column "Test type" by "T";b) a practical test where the applicant shall perform the correspondingtask with the relevant material, tools and equipment, as indicated in thecolumn "Test type" by "P". No. Professional minimum knowledge and skills Test type 1 Basic knowledge of relevant environmental issues (climate change, T Kyoto Protocol, Global Warming Potential), the relevant provisions of Regulation(EC) No. 842/2006 and of the relevant Regulations implementing provisions of Regulation (EC) No. 842/2006 2 Physical, chemical and environmental characteristics of SF6 T 3 Use of SF6 in elctric power equipment (insulation, arc quenching) T 4 SF6 quality, according to the relevant industrial standards (1) T 5 Understanding of the design of electric power equipment T 6 Checking of the SF6 quality P 7 Recovery of SF6 and SF6 mixtures and purification of SF6 P 8 Storage and transportation of SF6 T 9 Operation of a SF6 recovery equipment P 10 Operation of tight drilling systems, if necessary P 11 Re-use of SF6 and different re-use categories T 12 Working on open SF6 compartments P 13 Neutralizing SF6 by-products T 14 Monitoring of SF6 and appropriate data recording obligations under T national or Community legislation, or international agreements (1) for example IEC 60376 and IEC 60480Page 22
  23. 23. Basic knowledge of relevant environmental issuesArticle 6 Reporting, Regulation (EC) No. 842/2006Regulation (EC) No. 842/2006 sets down requirements for SF6 reporting.This reporting is independent and must be implemented in addition tothe national requirements (resulting from the Voluntary Commitment onSF6) for the reporting of information to the Federal EnvironmentalAgency and the Federal Ministry for the Environment, NatureConservation and Nuclear Safety.Within the meaning of the specified Regulation, the SF6 exported inloose cylinders or containers for use in "high-voltage switchgear" mustbe reported as an export from the European Union (EU). Similarly, theimport of the corresponding SF6 in loose cylinders or containers must bereported as an import into the EU.The implementation of the reporting requirements is subject to thefollowing implementation regulation: COMMISSION REGULATION (EC) No. 1493/2007 of 17 December 2007establishing, pursuant to Regulation (EC) No. 842/2006 of the European Parliament and of the Council, the format for the report to be submitted by producers, importers and exporters of certain fluorinated greenhouse gasesBy March 31 of any given year, every company that is independentunder commercial law and is required to submit a report must issue areport directly to the entity designated by the European Commissionconcerning the quantities of SF6 gas exported and imported during thepreceding year. The exported and imported SF6 gas quantities fromseveral locations affiliated to a joint company under commercial lawmust be reported collectively for the national company concerned. Acopy of the annual report to the entity designated by the EuropeanCommission is sent to the national body responsible in each country; inGermany, this is the Federal Ministry for the Environment, NatureConservation and Nuclear Safety.The reporting requirements apply to national companies, independentunder commercial law, that export or import more than one tonne of SF6gas in loose cylinders or containers from or into the EU. The quantitiesof SF6 incorporated directly into products for export from or import intothe EU should not be included in this report.For the export of SF6 used in "high-voltage switchgear" and supplied bythe producers/service companies of these systems, Regulation (EC) No.1493/2007 requires the following forms to be used for reportingpurposes: Part 3: Company contact information Part 7: Exporter Form (all fluorinated greenhouse gas types) for export from the EU Part 5: Producer and Importer Form for import into the EU (may be relevant to the return of used SF6)Page 23 / 99
  24. 24. Basic knowledge of relevant environmental issuesArticle 7 Labelling, Regulation (EC) No. 842/2006From 1 April 2008, "high-voltage switchgear" containing SF6 or SF6mixtures may not be placed on the market of the European Union unlessthe equipment involved is labelled as follows:• Specification of "SF6" or exact specification of the SF6 gas mixture contained in the equipment• Specification of the quantity of the SF6 or the SF6 gas mixture in kilogrammes, abbreviated to "kg", contained in the equipment concerned• The text "Contains fluorinated greenhouse gases covered by the Kyoto Protocol", in the official language of the respective EU member state. The language of the respective installation site is also recommended.Specification of the relevant technical pressure system for gas-filledcompartments of "high-voltage switchgear" (as defined in IEC 62271-1/EN 62271-1/VDE 0671-1) is not required by Regulation (EC) No.842/2006, although manufacturers may supply this informationvoluntarily.For deliveries after 1 April 2008, the operating instructions supplied withthe "high-voltage switchgear" must contain information on the SF6 or SF6mixtures, including specification of the global warming potential.In its national implementation regulation, each EU member state canspecify the official EU language to be used for the labelling of equipmentto be installed within its territory.For further details on the implementation of Article 5 Labelling for "high-voltage switchgear", please refer to: COMMISSION REGULATION (EC) No. 1494/2007 of 17 December 2007establishing, pursuant to Regulation (EC) No. 842/2006 of the European Parliament and of the Council, the form of labels and additional labelling requirements as regards products and equipment containing certain fluorinated greenhouse gases.Article 13 Penalties, Regulation (EC) No. 842/2006The EU member states have defined penalties and fines forinfringements of Regulation (EC) No. 842/2006 and the associatedimplementation regulations. Germany has enacted the Third Ordinance amending the Ordinance on penalties and fines for chemical infringements of 17 July 2007Page 24
  25. 25. Basic knowledge of relevant environmental issues2.7 The national implementation regulation in GermanyThe implementation of Regulation (EC) No. 842/2006 and theassociated European implementation regulations in Germany is setdown in the Ordinance on climate protection against changes caused by release of certain fluorinated greenhouse gases(German Chemical Climate Protection Ordinance, ChemKlimaschutzV).The requirements of the EU Regulations described above have beenincorporated into the German Chemical Climate Protection Ordinancewithout any additional national requirements.Some details in the German Chemical Climate Protection Ordinancehave been adapted in line with national circumstances and Germanlinguistic usage, for example inArticle 5 Personal qualifications required for certain activitiesThe activities listed in the EU Regulation may be carried out only bypersons holding a qualification certificate appropriate to the activityconcerned or a corresponding certificate obtained in another EUmember state.The technical equipment required for the activity must be available andthe persons concerned must be reliable.A qualification certificate indicating competence to carry out the activityconcerned shall be issued to persons who, in the case of "high-voltageswitchgear", have successfully completed a theoretical and practicalexamination in accordance with Regulation (EC) No. 305/2008.Article 7 Labelling in the German languageThe labelling on the products and the SF6-specific information in theoperating instructions shall be provided in the German language for"high-voltage switchgear" to be installed in Germany.Article 8 Administrative offensesThis article sets out in detail the infringements of the requirements of theGerman Chemical Climate Protection Ordinance that are punishable bypenalties or fines.Page 25 / 99
  26. 26. Sulphur hexafluoride (SF6) 3 Sulphur hexafluoride (SF6)3.1 Physical, chemical and environmental characteristics of SF6 (T)Sulphur hexafluoride (SF6) is a colourless, odourless gas.It has a density of 6.07 g/l at 20°C and 1013 hPa. It has around fivetimes the density (heaviness) of air and can accumulate at ground levelor in lower-level areas (risk of suffocation). Once SF6 has mixed with theroom air, it can no longer be separated. SF6 becomes liquid whencompressed at 50 bar and can then be stored and transported inpressurised gas containers as a gas in liquid form.Pure SF6 is chemically stable, inactive (inert), almost insoluble in waterand non-flammable. SF6 has a high degree of dielectric stability and excellent arc-quenching properties that make it ideal for use as an insulation and quenching medium in medium-voltage and high- voltage circuit-breakers and switchgear. SF6 has a global warming potential of 22,200 and should therefore be used only in closed systems such as high-voltage and medium-voltage switchgear.After use, a recycling programme such as the SF6 re-use concept isavailable to ensure that emissions are avoided wherever possible.To ensure the safe handling of SF6 and used SF6, the trade associationsafety requirements must be observed (BGI 753 [5]) and IEC 62271-303[3], EU safety data sheet as specified in Directive 2001/58/EC (availablefrom Solvay Fluor on request).Page 26
  27. 27. Sulphur hexafluoride (SF6) 3.2 SF6 quality according to relevant industry standards (T) Table: SF6 gas qualities and relevant electrotechnical standardsComposition IEC 60376 IEC 60480 (2004) IEC 62271-303 (2008) (2005) Used SF6 Used SF6 New SF6 SF6 re-use specification (analysis from of gas producer, liquid phase) e.g. Solvay Fluor (1990)SF6 99.55% by Approx. 97.00% by 90.7% by volume volume volumeAir 2000 ppm by < 30% by volume weight 3% by volume (6% by weight) (1% by volume)CF4 2400 ppm by < 5% by volume weight (3% by weight) (4000 ppm by volume)H2O 25 ppm by 25…95 ppm by weight < 1000 ppm by weight weight (dew (dew point approx. (dew point approx. 5°C) point approx. -36°C…-23°C) -36°C) (200…750 ppm by (200 ppm by volume) volume)Mineral oil 10 ppm by 10 ppm by weight < 0.1% by weight weightAcidity expressed 0.8 ppm by Total reactive gaseous < 1000 ppm by weightin HF weight by-products(hydrofluoric acid) (6 ppm by 50 ppm by volume in volume) total (12 ppm by volume for SO2 and SOF2 + 25 ppm by volume for HF) New, unused SF6 must meet the gas quality specified in IEC 60376. Once it has been removed from the electric power equipment, the SF6 gas must meet the gas quality specified in IEC 60480 in order to be re- used in the equipment. Page 27 / 99
  28. 28. Sulphur hexafluoride (SF6)To enable the gas to be returned to the re-use process, it must meet thegas quality specified in IEC 62271-303, e.g. the SF6 re-use specificationof the gas producer. Within this specification, the used gas is consideredas a product or raw material for the production of new SF6 and can bereturned to the gas producer (delivery note procedure: see Section 7.5).Otherwise, the gas is disposed of (see Section 3.3.3).3.3 Re-use of SF6 and the different re-use categories (T)In most cases, the used SF6 can be reclaimed and purified on site usingservice equipment. If reclamation and purification is no longer possible,the SF6 obtained during the servicing or decommissioning of gas-insulated switchgear can be reintegrated into the economic cycle in anumber of intermediate steps via the SF6 re-use concept in order to saveresources and energy.From an environmental perspective, this is necessary in order to restrictthe release of SF6 into the atmosphere to the very low equipmentleakage rate. The SF6 re-use concept is a closed-loop recycling systemthat aims to prevent SF6 emissions as far as possible during equipmentservicing and decommissioning.The first step in the SF6 re-use concept is to assess the quality of thegas in the equipment. This is done either by using transportablemeasuring devices or by taking a gas sample for subsequent analysis ina laboratory (see Section 4). Based on the results of these analyses, adecision is made whether to reclaim and purify the gas on site or toregenerate the gas into new SF6 in accordance with IEC 60376. Foreach intermediate step in the gas handling procedure, correspondingpackaging and service equipment is available (see Section 7 and [8]).The SF6 re-use concept is subdivided into three cases: IEC 60376 IEC 60480VDE 0373-1 IEC 62271-303Figure: The SF6 re-use concept; according to the definitions of theRegulation No 842/2006 the case of inspection corresponds to therecycling. The case of recovery corresponds to the treatment and thecase of disposal to the destruction.Page 28
  29. 29. Sulphur hexafluoride (SF6)3.3.1 Inspection – SF6 recovery and re-use on on siteThe impurities identified during inspection, such as dust, moisture, air, oiland SO2 compounds, are part of the normal aging process of the gasand are caused as a result of operation. The operator can remove theseimpurities on site. Solid by-products, such as dust and small particles ofcarbon, CuF2 and WOXFY, can be removed using solid filters (pore size1µm), moisture using alumina (Al2O3) or molecular sieves (pore size 4-5Å), and gaseous by-products such as SF4, WF6, SOF4, SO2F2, SOF2,SO2 and HF using activated carbon and zeolites. Corresponding servicedevices are equipped with the listed purification systems and areavailable as standard. The used SF6 must meet the requirements of theoperator and the applicable IEC requirements, and can be re-used.If the treated material meets these requirements, the equipment beingserviced can be refilled directly using an evacuation and filling system(service device). This is the procedure normally followed duringassembly or inspection of the switchgear. New product quality, asdefined in IEC 60376, is not achieved as a result of gas reclamation andpurification.3.3.2 Recovery – regeneration of SF6 to produce new gas in accordance with IEC 60376If the used SF6 gas does not meet the requirements of the operator orIEC 60480 and it is no longer possible or desirable to purify the gas onsite, it is sent directly to the gas producer to be regenerated into newgas. This is the case if the proportion of inert gas is too high2 or if highCF4 concentrations and toxic by-products are detected.For the reclamation procedure used in practice (e.g. by Solvay Fluor),the product supplied must meet certain conditions set down in IEC62271-303 or the re-use specification (see Section 3.2).3.3.3 Disposal – incineration of SF6If the inspection of the used SF6 on receipt in the plant reveals that thegas does not meet the requirements of IEC 62271-303 or the re-usespecification and therefore cannot be re-used or regenerated into newgas, the gas must be disposed of at a licensed chemical wasteincineration facility.Solvay Fluor is licensed to incinerate contaminated SF6 at the chemicalwaste incineration facility at its Frankfurt plant.However, the quantity of gas disposed of at the chemical wasteincineration facility is negligible, and has been decreasing continuouslyover recent years. No SF6 gas is currently being incinerated.2 as for instance nitrogen by a part of air in the SF6Page 29 / 99
  30. 30. Sulphur hexafluoride (SF6)Assessment of the gas and categorisation as product or wastePage 30
  31. 31. Checking the SF6 quality 4 Checking the SF6 quality4.1 IntroductionSince the mid-1960s or so, sulphur hexafluoride (SF6) gas has beenused increasingly as an insulation and quenching medium in gas-insulated switchgear (GIS) and circuit-breakers. The special, inertstructure of the SF6 molecule means that its properties remainunchanged under optimum operating conditions throughout the entirelifecycle of the switchgear. This eliminates the need for the preventivereplacement of SF6, helping to minimise emissions due to maintenancework.Despite the high chemical inertness of SF6 gas, it is possible for faults tooccur that can result in damage to the switchgear. Electric arcs thatoccur during normal operation of the circuit-breaker or the occurrence ofpartial discharges over a longer period cause the insulation gas SF6 todecompose, generating by-products that are in some cases toxic orhighly corrosive. A number of these by-products can only be formed ifreagents such as moisture and oxygen are present. It is thereforeadvisable to monitor the gas quality over the lifecycle of the electricpower equipment.In this context, please refer to the specifications provided by themanufacturer of the electric power equipment and measuring devices.It is not normally necessary to conduct a gas analysis for equipment inwhich SF6 is used only for insulation purposes (e.g. medium-voltageGIS).4.2. Monitoring the gas qualityMeasurements should be conducted to monitor the presence of thefollowing foreign substances in SF6 gas. The threshold values for theforeign substances to be monitored in SF6 are listed in Section 3.4.2.1 Moisture, air and CF4Moisture and air can enter the gas compartment as a result of leakage,incomplete evacuation and operating errors when filling the equipment.CF4 (tetrafluoromethane) is produced when organic materials aresubjected to discharge. High concentrations of these foreign substancesreduce the insulating properties of the SF6 and the operating safety ofthe switchgear. In the case of discharges, air and/or moisture are theprerequisites for the generation of toxic and corrosive by-products.The following methods can be used to measure the presence ofmoisture, air and CF4:4.2.1.1. Moisture4.2.1.1.1.Dewpoint mirror (physical measurement principle)In chilled-mirror dewpoint hygrometers, the SF6 to be analysed ispassed over a mirror that is cooled down to the dewpoint temperature ofPage 31 / 99
  32. 32. Checking the SF6 qualitythe SF6 gas by means of a Peltier element. Dewpoint hygrometers usean optoelectronic mechanism to detect the condensation on the basis ofthe reduction in intensity of the light reflected by the mirror. Theelectronic control mechanism modulates the power supply to the Peltierelement so that the cooling of the mirror is directly dependent on theoptically detected condensation, and controls the temperature of themirror to maintain a dynamic equilibrium between evaporation andcondensation on the mirror. In this continuously regulated state definedas the dewpoint temperature of a gas, an embedded temperaturesensor measures the temperature on the surface of the mirror to a highlevel of accuracy.Dewpoint hygrometerSource: G.A.S.4.2.1.1.2 Electronic dewpoint hygrometer (capacitive)An electronic dewpoint hygrometer measures the absorption of watermolecules by a substance such as ceramic, aluminium oxide or polymer.Tiny quantities of water vapour accumulate in the substance, whichfunctions as a dielectric in a condenser, and change the capacity of thecondenser. This change is detected by an electronic evaluationmechanism and forwarded to a central processor, which converts it intoa moisture value and outputs it.Page 32
  33. 33. Checking the SF6 quality Deckelelektrode Cover electrode (dampfdurchlässig) (vapor permeable) Polymer Kontaktstelle Contact spot (Cover electrode – connection area – Draht) (Deckelelektrode – Anschlussfläche – wire) Grundelektrode Ground electrode + Contact area + Kontaktfläche (Ground electrode Anschlussfläche – Draht) (Grundelektrode – – connection area – wire) Trägermaterial Base C = f (%r.F.) Cges = C0 + C%r.F.Source: CS InstrumentsThe graphic shows an example of a schematic diagram for a capacitivepolymer sensor.4.2.1.2 Air and CF4The proportion of air and CF4 is determined indirectly according to thepercentage of SF6 in the gas under analysis. The devices are generallycalibrated to measure SF6-nitrogen mixtures. It is possible, however, tocalibrate the measuring device to measure the percentage of SF6 in SF6-CF4 mixtures. The following measurement principles can be used tomeasure the percentage of SF6:4.2.1.2.1 Measurement of the sound velocityThis measurement principle works by evaluating the different soundvelocities of gases. The sound velocity in air is normally around 330 m/s,but only around 130 m/s in an atmosphere comprising purely SF6. Thesound velocity measured in the measurement cell is temperature-compensated and is converted into the percentage SF6 volume using amicroprocessor.4.2.1.2.2 Thermal conductivity detectorThermal conductivity detectors (TCDs) continually measure the thermalconductivity of the SF6 using the heated-filament method.The detector comprises a temperature-controlled metal block with twoidentical cells. A compensated comparison measurement is conductedas follows: the SF6 under analysis flows from the compartment into onecell, and the other comparison cell is filled with pure SF6. Both cellscontain heated filaments of platinum or tungsten, which are connectedtogether to form what is known as a wheatstone bridge circuit.All filaments are heated by means of an electric current. Thetemperature of the filaments and thus their electric resistance dependson the thermal conductivity of the gases that flow through the cells. Achange in the composition of the gas will cause a change intemperature, thus changing the resistance of the filaments in themeasurement cells. The temperature of the heated filaments in thePage 33 / 99
  34. 34. Checking the SF6 qualitycomparison cell does not change. This temperature difference betweenthe heated filaments in the measurement cell and the comparison cellproduces a measurable voltage difference, which is converted into anSF6 percentage by an evaluation unit and displayed.4.2.2 By-productsDespite its excellent chemical stability, SF6 decomposes duringdischarge processes such as arcing, sparking or partial dischargeactivity. The graphic illustrates thereaction sequence of the by-products. The discharge type alsodetermines which by-products are produced in SF6. Partial dischargesproduce mainly SOF4, while spark discharges produce SOF2.The decomposition of SF6 depends on the predominant gas pressureand the electrode and surface materials of the internal components.Despite the proven high reliability of these components of the powerdistribution network, faults may occur due to the SF6 aging described.Weak points in SF6-filled gas compartments are insulation materialssuch as epoxy resin supports (see graphic). Chemical reactionsbetween by-products and the surfaces of insulation materials cause achange in the structure of the surface and reduce the surface stability. Inthe worst case, this can cause a flashover, resulting in damage to theequipment.The by-products have a corrosive effect on metal surfaces (see graphic)and reduce the operating safety of the equipment.Source: G.A.S.Figure: Damage to epoxy resin insulated supports and inner conductorsdue to by-productsPage 34
  35. 35. Checking the SF6 qualityThe by-products, some of which are highly toxic (see table), can causeirritation and chemical burns to humans even in very smallconcentrations. Inhalation of the by-products can cause considerabledamage to health.The following table lists some of the physical and chemicalproperties of important by-products:By-products Fp Sdp. Stability End MAK Odour products toxicity / °C / °C in air (ppmv)SF4 - -38 Rapid HF, SO2 3.6 Stronglysulphur 121 decomposition acidictetrafluorideS2F10 -53 30 Stable SF4, SF6 0.26disulphurdecafluorideSOF2 - -44 Slow HF, SO2 2.5 Rottenthionylfluoride 110 decomposition eggsSOF4 - -49 Rapid SO2F2 0.5 Acidicsilicon tetrafluoride 107 decompositionSO2F2 - -55 Stable 2.4 Nonesulphurylfluoride 120SO2 - -10 Stable 0.5 Sharpsulphur dioxide 72.5HF -83 19 Stable 1.0 AcidichydrofluorideSiF4 -96 Rapid SiO2, 0.8 Acidictetrafluorosilane s. decomposition HFThe by-products can be detected as described below. Theelectrochemical sensors and the gas detector tubes quantify the maincomponents SO2 and HF. Spectroscopic or chromatographicmeasurement procedures can quantify the full range of by-products.4.2.2.1. Electrochemical sensors (SO2 and HF)An electrochemical sensor is based on an electrode system and anelectrolyte calibrated to detect the substance being measured.SO2 sensorThe SF6 is diffused into the SO2 sensor, where it reacts with themeasuring electrode in an oxidation process according to the followingequation:Page 35 / 99
  36. 36. Checking the SF6 qualityEquation 1: Measurement processSulphur dioxide (SO2): SO2 + 2H2O = H2SO4 + 2H+ + 2e-The counter-electrode attempts to equalise the reaction at themeasuring electrode by reducing the oxygen, which causes water to beproduced.Equation 2: Equalising reaction:Oxygen reduction: ½ O2 + 2H+ + 2e- = H2OTwo reactions reflect the entire measurement cell reaction as follows: SO2 + ½ O2 + H2O = H2SO4If SO2 is present in the SF6 being measured, Equation 1 changes itselectrochemical potential, with the result that electrons are given off. Asa result, a voltage change is detected. This is converted into aconcentration value (ppmv values) by means of an electronic evaluationmechanism.SO2 measuring device (electrochemical)Source: DiloHF sensorIn an HF sensor, HF reacts with the electrolyte in the form of anelectrocatalytic reduction that produces a pH change in the electrolyte.This change results in a potential change at the sensors electrodes,which is converted into a concentration value (ppmv values) by means ofan electronic evaluation mechanism.4.2.2.2. Ion mobility spectrometry (IMS)IMS works by measuring the speed at which charged gas molecules(ions) move (drift) in an electric field at atmospheric pressure. The ionsare separated according to the different drift speeds, which will dependon the mass, charge and geometric structure of the ions.Once they have drifted through the electric field, the ions reach adetector and return a time-dependent signal. By comparing the ionmobility spectrum of a pure SF6 gas (minimum quality 3.0) with that ofan impure SF6 gas, it is possible to detect a deterioration in the SF6 gasmixture. The shift in the peak position is interpreted as a signal. ThePage 36
  37. 37. Checking the SF6 qualityexample in the graphic clearly shows the peak position of the gas underanalysis (originating from switchgear, for example), and its distance fromthe main peak of a comparison spectrum of pure SF6. Peak shift Signal / a. u. *   ) (> 1000 ppm By-products) Drift time [ms]  *) arbitrary units Source: G.A.S.The visible peak shift toward longer drift times corresponds to theproduction of different by-products. The peak shift results from theformation of ions with different mobilities, while a widening of the peakindicates a wide variety of ions resulting from impurities in the gas.Comparison measurements using infra-red spectrometers were used asthe basis for identifying a correlation between the total concentration ofby-products and the maximum peak shift. Based on this correlation, it ispossible to determine the quality of the SF6 and quantify the level ofimpurity.4.2.2.3. Gas chromatography and infra-red spectrometryTo verify and quantify the individual concentrations of most by-products,laboratory analyses can be conducted using gas chromatography, massspectrometry or infra-red spectrometry. All these methods arecomplicated, labour-intensive and relatively expensive, and must becarried out by qualified personnel. It is possible to take a sample of SF6from the equipment using evaculated test cylinders, which must then betested immediately using one of these methods. The by-products thatare detectable using infra-red spectrometry are listed below:Page 37 / 99
  38. 38. Checking the SF6 quality By-product Sulphur dioxide (SO2) Hydrofluoride (HF) Sulphur tetrafluoride (SF4) Thionylfluoride (SOF2) Tetrafluorosilane (SOF4) Sulphurylfluoride (SO2F2) Disulphur decafluoride (S2F10) Silicon tetrafluoride (SiF4) Tetrafluoromethane (CF4) The following substances can also be analysed: H2O, CO2 and CO.4.2.2.4. Gas detector tubesGas detector tubes work according to the principle that a substancecontained in the tube changes colour when a sample of SF6 isintroduced.Gas detector tubes are available for measuring the SO2 and HF content.The presence of one of these gases in the sample causes a colourchange in the gas detector tube. The concentration of each by-productcan be determined from the scale displayed on the gas detector tubeand the extent of the colour change.The following chemical reaction causes a colour change in an SO2 gasdetector tube: SO2 + I2 + 2H2O H2SO4 + 2 HIThe following reaction takes place in an HF gas detector tube: HF + Zr(OH)4/chinalizarine [ZrF6]2- + chinalizarinePage 38
  39. 39. Checking the SF6 quality4.2.3 Oil mistConstituents of mineral oil can enter the gas compartment through theuse of gas handling devices (pumps and compressors) that contain oil.The carbonisation of the oil on the inner surfaces can impair theequipments insulating properties.If only oil-free compressors and pumps were used during the filling,vacuum extraction and evacuation of the equipment, there is no need tocheck for the presence of oil.The presence of oil mist in the SF6 gas compartment can be verifiedusing gas detector tubes. The oil mist is deposited on the filter layer inthe tube and, once sorption is complete, it is decomposed usingconcentrated sulphuric acid in the presence of a catalyst. Theconcentration of oil mist in the SF6 can then be determined from thecolour intensity of the resulting dark-coloured reaction products.4.3. Combination measuring devicesAs well as using individual measuring devices to determine thepercentage of each foreign substance in the SF6, it is possible to useequipment that combines several sensors in one device. Thesecombination measuring devices offer the advantage of comparativelylow SF6 consumption and handling losses. They are easy to use andalso save time.The following combination measuring devices are currently available:Two measurements in one device1. Moisture (physical) and SF6 percentage2. Moisture (electronic) and by-products (IMS, all by-products)Three measurements in one device1. Moisture (electronic), SF6 percentage (measurement of soundvelocity) and by-products (electrochemical, SO2)2. Moisture (electronic), SF6 percentage (measurement of soundvelocity) and by-products (IMS, all by-products)Page 39 / 99
  40. 40. Checking the SF6 qualityCombination measuring device: moisture (electronic sensor), SF6 percentage (soundvelocity) and by-products (electrochemical, SO2)Source: G.A.S.Four measurements in one deviceMoisture (electronic), SF6 percentage (TCD), oxygen (electrochemical)and by-products (electrochemical, HF)Page 40
  41. 41. Use of SF6 in electric power equipment 5 Use of SF6 in electric power equipment (insulation, arc quenching) (T)In gas-insulated medium-voltage switchgear systems (1kV to 52kV) withvacuum circuit-breakers, SF6 is used exclusively to insulate systemparts and components carrying high voltages. In this context, the circuit-breaker performs the task of switching short-circuit and operatingcurrents (in the vacuum). SF6 gas 1 Control unit of the multifunctional protection and control unit 2 Triple-position circuit-breaker drive mechanism 3 Triple-position circuit-breaker 4 Pressure sensor (temperature-compensated) 5 Power switch drive mechanism 6 Sec. outlet for current signals 7 Cable plug socket 8 Cable plug 9 Central unit of the multifunctional protection and control unit 10 Voltage transformer 11 Plug and test socket 12 Pressure release valve 13 Current transformer 14 Pressure release channel 15 Circuit-breaker 16 Test sockets for capacitive voltage display system 17 BusbarFigure: Medium-voltage switch bay with SF6 insulation and vacuumcircuit-breakerSource: ABBIf a gas-insulated circuit-breaker is used, the switching of short-circuitand operating currents also takes place under SF6. In other words, thegas also acts as an arc-quenching medium. Arc quenching is performedby blasting SF6 into the electric arc. SF6 gas 1. Circuit-breaker interrupter unit 2. Spring-stored energy mechanism 3. Busbar disconnecting switch I 4. Busbar I 5. Busbar disconnecting switch II 6. Busbar II 7. Outgoing feeder disconnecting switch 8. Earthing switch (work-in-progress) 9. Earthing switch (work-in-progress) 10. Make-proof earthing switch (high speed) 11. Current transformer 12. Voltage transformer Figure: High-voltage switch bay with SF6 insulation and gas- insulated circuit-breaker Source: SiemensPage 41 / 99
  42. 42. Use of SF6 in electric power equipmentThe blast is generated by forcing the gas from a volume by means ofvolume reduction (blast piston) or by blasting the gas from a volume witha high pressure into a volume with a low pressure at the time ofswitching (dual-pressure switch). A method widely used today is the useof the arc heat itself to generate the corresponding quenching pressureat high currents (high energy). SF6 circuit-breakers are normally used inapplications >52 kV. Figure: Structure of a gas-insulated circuit-breaker pole Source: ABB 1 Terminal 6 Fixed arcing contact 2 Insulating case 7 Fixed main contact 3 Blasting nozzle 8 Insulating tie-rod 4 Moving arcing contact 9 Anti-explosition valve 5 Main moving contactPage 42
  43. 43. Use of SF6 in electric power equipment Circuit-breaker Main contact Arcing contact Circuit-breaker closed separation separation open Main contact separation No electric arc strikes as the current flows through the arcing contacts. During its run downwards, the moving part compresses the gas contained in the lower chamber. The compressed gas flows out of the lower chamber into the upper chamber, taking them both to the same pressure. Arcing contact separation The current flows thanks to the electric arc which has struck between the arcing contacts. The gas cannot get out through the nozzle because the hole is still closed by the fixed arcing contact and cannot get out through the inside of the moving arcing contact either because the electric arc closes this (clogging effect). - with low currents, when the current passes through natural zero and the arc is quenched, the gas flows through the contacts. The low pressure reached cannot chop the current and the modest amount of compressed gas is sufficient to restore dielectric resistance between the two contacts, preventing restricting on the rising front of the return voltage. - with the short-circuit currents, the pressure wave generated by the electric arc closes the valve between the two chambers so that the circuit-breaker starts to operate as a “ pure self-blast”. The Pressure increases in the upper volume thanks to heating of the gas and molecular disassociation due to the high temperature. The increase in pressure generated is proportional to the arc current and ensures quenching on the first passage through current zero. Circuit-breaker open The arc has been interrupted, the self-generated pressure in the upper volume is reduced because the gas is flowing through the contacts. The valve re-opens and so a new flow of fresh gas comes into the breaking chamber. The apparatus is therefore immediately ready to close and trip again up to its maximum breaking capacity.If switch-disconnector systems are used, SF6 is used as an insulationand arc-quenching medium, as operating currents are interrupted by theswitch-disconnector and short-circuit currents by a high-voltage fuse or adownstream circuit-breaker.SF6 is also used in applications involving the transmission of highcurrents, such as gas-insulated transmission lines (GIL), high-voltagecables and (high-)current busbars.Figure: SF6-insulated busbar configurations Source: Moser-GlaserPage 43 / 99
  44. 44. Use of SF6 in electric power equipmentBusbars comprise a copper or aluminium conductor within a contact-proof outer metal enclosure. High-voltage epoxy resin insulators areused to centre the conductor inside the metal housing. SF6 is used asan insulating gas between the external housing and the conductor. Figure: Structure diagram of an SF6- insulated busbar with expansion elements (Source: pbp Preissinger) 1. Conductor 2. Outer metal enclosure 3. Expansion element 4. Epoxy resin insulatorElongation resulting from thermal expansion, for example, cancompromise the gastightness of the overall configuration. This isnormally compensated for by fitting a series of independent expansionelements.Gas-insulated transmission lines (GIL) are constructed in a similar wayto busbars: 1 Enclosure 2 Inner conductor 3 Conical insulator 4 Support insulator 5a Male sliding contact 5b Female sliding contact SF6 gasFigure: Schematic diagram of a GIL section Source: SiemensGas-insulated transmission lines are particularly suitable for transmittinghigh to maximum power ratings (up to 2000 MW) over long distances.The cables are insulated using a gas mixture (nitrogen and sulphurhexafluoride). GILs offer numerous advantages compared toconventional power lines, including lower ohmic losses and minimalPage 44
  45. 45. Use of SF6 in electric power equipmentdielectric losses (thus reducing transmission losses and operatingcosts), no thermal or electrical aging of the insulation, and very weakelectromagnetic fields outside the GIL.Because it is a non-toxic, non-flammable gas with good thermalconductivity, SF6 was originally also used in transformer construction.Although SF6 is no longer used in new transformer construction inGermany, existing SF6-filled transformers may still be in operation.Condensers incorporating sulphur hexafluoride as a dielectric are usedin applications with high-frequency power ratings and voltagesexceeding 10 kV. The capacity of these condensers can be adjusted byvarying the inner gas pressure.In high-voltage and maximum-voltage technology, SF6 is being usedincreasingly as an insulation medium in instrument transformers(current/voltage). Figure: Gas-insulated high-voltage current transformer Source: ABBThe use of SF6 to hermetically encapsulate all live components enablesextremely high system voltages to be achieved, while at the same timereducing the occurrence of partial discharges.Page 45 / 99
  46. 46. Use of SF6 in electric power equipment Sekundäranschluss Secondary terminal housing Steuerelektrode e Grading electrod Innenelektrode Inner electrode Leiter / Primärwicklung Conductor / primary winding Kerne mit Sekundärwicklungg Cores with secondary windin Grundplatte Base plate Durchführung BushingCurrent transformerSource: Siemens Sekundärwicklung Secondary winding Eisenkern Iron core Primärwicklung Primary winding Durchführung BushingInductive voltage transformerSource: SiemensPage 46
  47. 47. Use of SF6 in electric power equipmentThe tubular insulating body designed to enable a conductor to passthrough an opening in an earthed wall is known as a bushing. Tomaintain the electrical operating and test conditions, the bushing mustbe sufficiently strong and must ensure an equal field distribution at thetransition from one insulation medium to the other. Its excellent physicalproperties make SF6 ideal for use in this type of application. Verbundisolator Composite insulator Porzellan-Isolator Porcelain insulatorBeispiel: Freiluftanschluss mit VerbundisolatorenExample: SF6/air termination with composite insulator Beispiel: Porzellandurchführung Example: Pocelain insulatorFigure: Bushings with SF6 insulationSource: SiemensAt the present stage of technological development, no other gas with thesame optimum properties is available to replace SF6.Page 47 / 99
  48. 48. Understanding the design of electric power equipment 6 Understanding the design of electric power equipment (T)6.1 Function and structure of the switching devicesCircuit-breaker, switch-disconnector, earthing switch andcombined fuse/switch-disconnectorKey components of SF6-insulated switchgear are circuit-breakers,earthing switches (with or without interrupt capability), switch-disconnectors and combined fuse/switch-disconnectors. The detailedtechnical specifications vary for high-voltage and medium-voltagecomponents. In the high-voltage range greater than 52 kV, theseswitching devices are either configured as individual devices orintegrated into metal-encapsulated, gas-insulated switch bays (high-voltage GIS). In the medium-voltage range up to 52 kV, most switchgearin Germany is configured as gas-insulated switch bays/switchgear withintegrated switching devices (medium-voltage GIS). SF6-insulatedswitching devices in the medium-voltage range up to 36 kV are used inair-insulated switchgear systems.The following table lists the main functions of the individual switchingdevices: Earthing + Activa- Circuit- Current Short-circuits short- tion break- limitation circuiting ing D Disconnector e v Interrupter i Switch-disconnector c e s Fuses Fuse/interrupter combination Circuit-breaker Earthing switchFunctions of the switching devices in the electric power transmission anddistribution networkPage 48

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