335 3164-09-027-preparation doc en-version_1_01

SF6 training documents For certification according to Regulation (EC) No. 842/2006 on certain fluorinated greenhouse gases, Regulation (EC) No. 305/2008 on the establishment of minimum requirements for the certification of personnel, and the German Chemical Climate Protection Ordinance (ChemKlimaschutzV)

PUBLICATION DETAILS SF6 training documents Published by: ZVEI - Zentralverband Elektrotechnik und Elektronikindustrie e.V. (German Electrical and Electronic Manufacturers' Association) Stresemannallee 19, D-60596 Frankfurt am Main, Germany BDEW Bundesverband der Energie- und Wasserwirtschaft e.V. (German Association of Energy and Water Industries) Reinhardtstr. 32, D-10117 Berlin, Germany Forum Netztechnik/Netzbetrieb im VDE (FNN) (Power Supply Technology/Power Supply Operation Forum of the VDE (German Association for Electrical, Electronic and Information Technologies)) Bismarckstr. 33, D-10625 Berlin, Germany Contacts: Johannes Stein, ZVEI Fachverband Energietechnik (Energy Technology Unit within ZVEI) Thoralf Bohn, Forum Netztechnik/Netzbetrieb im VDE Tel.: +49 69 6302-265 Fax: +49 69 6302-234 E-mail: [email protected] www.zvei.org www.sf6-energietechnik.de Editorial team: “SF6 Training and Certification” Peter Ball, ABB AG Andreas Lehmann, Vattenfall Europe Berlin Mario Prüfert, Siemens AG Bernd Drews, ABB AG Andreas Büscher, AREVA Energietechnik GmbH Sachsenwerk Paul Blumenthal, AREVA T&D AG Thoralf Bohn, Forum Netztechnik/Netzbetrieb im VDE Hayder Ali, DB Energie GmbH Michael Hippenstiel, DB Energie GmbH Ludwig Rieder, DILO Armaturen und Anlagen GmbH Martin Grote, Driescher-Wegberg Reinhold Haug, EnBW Regional AG Peter Pilzecker, G.A.S. Gesellschaft für analytische Sensorsystem mbH Andreas Reimüller, ABB AG Norbert Lambrecht, RWE Westfalen-Weser-Ems Netzservice GmbH Bernhard Tilwitz- von Keiser, Siemens AG Peter Jannick, SOLVAY FLUOR GmbH Johannes Stein, ZVEI Title image: Vattenfall Europe Berlin Despite 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 part of 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 of ZVEI/FNN. Edition: February 2009

mailto:[email protected]

http://www.zvei.org/

Contents

Contents

Requirements listed in the Annex to Regulation (EC) No. 305/2008 and the corresponding sections of this document 5

1 INTRODUCTION 6

2 BASIC KNOWLEDGE OF RELEVANT ENVIRONMENTAL ISSUES (T) 7 2.1 Greenhouse gases and the greenhouse effect 7 2.2 Impact of the anthropogenic greenhouse effect 9 2.3 The Kyoto Protocol 10 2.4 Global warming potential 11 2.5 The Voluntary Commitment on SF6 as an insulation and quenching gas 13 2.6 The European Regulation on certain fluorinated greenhouse gases 15 2.7 The national implementation regulation in Germany 25

3 SULPHUR HEXAFLUORIDE (SF6) 26 3.1 Physical, chemical and environmental characteristics of SF6 (T) 26 3.2 SF6 quality according to relevant industry standards (T) 27 3.3 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 29

4 CHECKING THE SF6 QUALITY 31 4.1 Introduction 31 4.2. Monitoring the gas quality 31

4.2.1 Moisture, air and CF4 31 4.2.2 By-products 34 4.2.3 Oil mist 39

4.3. Combination measuring devices 39

5 USE OF SF6 IN ELECTRIC POWER EQUIPMENT (INSULATION, ARC QUENCHING) (T) 41

6 UNDERSTANDING THE DESIGN OF ELECTRIC POWER EQUIPMENT (T) 48 6.2 Structure of switchgear systems 51 6.3 Structure of SF6-insulated medium-voltage switchgear systems 56

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Contents

7 RECOVERY OF SF6 AND SF6 MIXTURES AND PURIFICATION OF SF6 (P) 60 7.1 Practical structure of a process flow for the recovery of SF6 60 7.2 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 65

7.3 Provision of basic knowledge regarding the use of different filter types and adsorbents used in service devices or mobile prefilter units 65 7.4 Operation of SF6 recovery equipment (P) 66 7.4.1 Function: Extraction of SF6 gas 68 7.4.2 Deactivating the SF6 service equipment 74 7.5 Storage and transportation of SF6 (T) 80 7.6 Working on open SF6 compartments (P) 82 7.7 Neutralising SF6 by-products (T) 84 7.8 Operation of tight drilling systems, if necessary (P) 86

8 SF6 DATA RECORDING OBLIGATIONS 88

9 SOURCES AND REFERENCES 99 (P) Practical part of the training and examination (T) Theoretical part of the training and examination

Contents

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Requirements listed in the Annex to Regulation (EC) No. 305/2008 and the corresponding sections of this document

Topic No. in Annex to

305/2008 Section of this

training document

Basic knowledge of relevant environmental issues (climate change, Kyoto Protocol, Global Warming Potential), the relevant provisions of Regulation (EC) No. 842/2006 and of the relevant Regulations implementing the provisions of Regulation (EG) No. 842/2006

1. 2

Physical, chemical and environmental characteristics of SF6

2. 3.1

Use of SF6 in electric power equipment (insulation, arc quenching)

3. 5

SF6 quality, according to the relevant industrial standards

4. 3.2

Understanding the design of electric power equipment

5. 6

Checking the SF6 quality 6. 4

Recovery of SF6 and SF6 mixtures and purification of SF6

7. 7

Storage and transportation of SF6 8. 7.5

Operation of SF6 recovery equipment 9. 7.4

Operation of tight drilling systems, if necessary

10. 7.8

Re-use of SF6 and different re-use categories

11. 3.3

Working on open SF6 compartments 12. 7.6

Neutralising SF6 by-products 13. 7.7

Monitoring of SF6 and appropriate data recording obligations under national or community legislation or international agreements

14. 8

Introduction

1 Introduction

These training documents have been developed by colleagues working in an honorary capacity from the member companies of the BDEW, VIK and ZVEI associations and from the company Solvay. The associations, their member companies and Solvay are parties to the Voluntary Commitment on SF6.

The new German and European legislation sets down examination and certification requirements for the training of employees involved in the recovery of SF6 gas. These training documents are based on the Annex to Regulation (EC) No. 305/2008. They contain explanations aimed at harmonising the requirements and training contents in Germany and supporting both the training providers and the employees being trained.

The objective is to ensure that the training providers are in a position to issue the certification documents in agreement with the relevant regional authorities.

The legislative requirements are limited to the recovery of SF6 and the associated environmental protection aspects. In some areas, these training documents extend beyond this very limited scope to explore a number of supplementary issues and safety aspects. Not all these supplementary issues can be examined in depth here and, where appropriate, the training documents refer to additional sources of information.

This SF6 training document is intended as a training resource but also as a work of reference for trainers and trainees alike. From the highly detailed explanations in each section, extracts can be created individually for training purposes. Please note that, for each section, the training contents must always be at least aligned with the examination questions.

Basic knowledge of relevant environmental issues

2 Basic knowledge of relevant environmental issues (T)

2.1 Greenhouse gases and the greenhouse effect Sulphur hexafluoride (SF6) is a gas that has been used since around 1960 in electric power transmission and distribution equipment with voltages exceeding 1000 V. Its special physical characteristics make it ideal for use in various switching and insulation applications.

SF6 is an inert, non-flammable, non-toxic insulation medium. Although it is 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 the Kyoto Protocol. These are gases in the atmosphere that prevent long-wave infra-red radiation from being emitted directly from the Earth's surface into space. They behave like the glass panes of a greenhouse, causing the entire atmosphere to heat up. Natural greenhouse gases include 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 presence of greenhouse gases and water vapour in the atmosphere. The term originally came from the greenhouses used for gardening, in which the sun's rays warm the air behind the glass panes and thus heat the interior of the greenhouse. This warmth enables plants to germinate, bloom and bear 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 of the similarities between the mechanisms in real greenhouses and the mechanisms in the Earth's atmosphere, the accumulation in the Earth's atmosphere of heat from solar radiation is described as the "atmospheric greenhouse effect".

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Figure 1 Short-wave solar radiation enters the atmosphere and heats the surface of the Earth. Long-wave radiation is re-emitted from the Earth's surface and almost all of it is absorbed into the atmosphere. In the thermal equilibrium, half of the absorbed energy in the atmosphere is radiated downward to the Earth's surface, and the other half into space. The figures indicate the radiated energy in watts per square meter. 1

1The 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 Earth's atmosphere (or the glass panes of a greenhouse) because the atmosphere (or glass) is highly transparent. This short-wave radiation can therefore penetrate the Earth's atmosphere (or the greenhouse) almost unhindered.

3. However, the Earth's 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 Earth's 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 Earth's 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_effect

http://de.wikipedia.org/wiki/Treibhauseffekt


The gas that makes the biggest contribution to the greenhouse effect is water vapour. Water vapour produces around two thirds of the 33°C of heat generated in the Earth's surface by the natural greenhouse effect. The rest is generated by the trace gases carbon dioxide and methane and small amounts of other gases. The natural greenhouse effect is an essential prerequisite for life on Earth as we know it. The average temperature on the Earth's surface is +15°C; without the natural greenhouse effect, it would be -18°C! The gases in the Earth's atmosphere have an effect similar to that of the glass panes of a greenhouse.

However, mankind influences the natural greenhouse effect in a variety of ways, thus causing the temperature in the atmosphere to rise. The man-made greenhouse gases have a more intense effect, similar to that of the glass in a greenhouse. They cause the "barrier layer" in the atmosphere to become increasingly opaque for the long-wave infra-red radiation emitted from the Earth's surface. The radiation re-emitted from the Earth's surface is reflected against the barrier layer of gas in the atmosphere, thus increasing the temperature in the lower part of the Earth's atmosphere. The part of the artificial greenhouse effect that is caused by human activity is called the anthropogenic greenhouse effect. The term "greenhouse effect" is often used to mean just the anthropogenic greenhouse effect.

Mainly by burning fossil fuels such as coal, gas and oil, humans release large quantities of carbon dioxide (CO2) into the Earth's atmosphere. In addition, 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 CO2 emissions are then present in the atmosphere in gaseous form. This intensifies the natural greenhouse effect. As well as releasing CO2, mankind also influences the greenhouse effect by emitting further trace gases such as methane and artificially produced substances, above all CFCs (= chlorofluorocarbons, artificially produced gases or liquids) and HFCs (hydrofluorocarbons).

2.2 Impact of the anthropogenic greenhouse effect The average temperature of the Earth's surface has risen by around 0.6°C over the last 100 years. The steepest rise has been recorded within the last 30 years. At the present time, it is not possible to say for certain what the impact of the anthropogenic greenhouse effect will be. Today's climate models still contain too many uncertainties for the experts to make reliable forecasts. The greatest uncertainty factors are clouds and forests. Both have a decisive influence on the climate and involve complex relationships that defy simple description. Until now, it has been unclear whether climate change will be on a global scale or whether a number of different climate zones, each one stable within itself, will be formed. Neither do we yet know whether there is a critical CO2 concentration in the atmosphere above which climate changes will start to take effect within just a few years. We must

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assume, however, that a further increase in the average surface temperature will result in a drastic change in the Earth's 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 Alps

There is as yet no definitive proof that human activity has contributed to these effects. However, the fact that such significant changes have occurred within a very short space of time clearly supports this argument.

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 storms

Even if mankind's influence on the climate has not yet been proven beyond doubt, all the evidence currently available points to this conclusion.

2.3 The Kyoto Protocol The Kyoto Protocol (named after the location of the Kyōto Conference in Japan) was adopted on 11 December 1997. It is a supplementary protocol to the United Nations Framework Convention on Climate Change (UNFCC) aimed at protecting the climate. The Protocol, which entered into force in 2005 and will run until 2012, is the first treaty to set binding target values for emissions of greenhouse gases, which are the main cause of global warming. The gases regulated in the Protocol are: carbon dioxide (CO2, used as a reference value), methane (CH4), nitrous oxide (laughing gas, N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulphur hexafluoride (SF6). The Kyoto Protocol aims to achieve a 5.2% reduction, averaged over the period 2008-2012, in the annual greenhouse gas emissions of the industrialised nations compared to 1990 levels. However, there is no specific reduction target for each gas; instead, the gases are considered collectively as a "basket". A country can therefore reduce any one of these gases in order to achieve its reduction target. At the start of February 2005, 136

http://en.wikipedia.org/wiki/Kyoto_Protocol

http://en.wikipedia.org/wiki/Japan

http://en.wikipedia.org/wiki/UNFCCC

http://en.wikipedia.org/wiki/United_Nations

http://en.wikipedia.org/wiki/United_Nations

http://en.wikipedia.org/wiki/Climate_protection

http://en.wikipedia.org/wiki/Greenhouse_gas

http://en.wikipedia.org/wiki/Globale_warming

http://en.wikipedia.org/wiki/Carbon_dioxide

http://en.wikipedia.org/wiki/Reference_value

http://en.wikipedia.org/wiki/Methane

http://en.wikipedia.org/wiki/Nitrous_oxide

http://en.wikipedia.org/wiki/Nitrous_oxide

http://en.wikipedia.org/wiki/Hydrofluorocarbons

http://en.wikipedia.org/wiki/Hydrocarbons

http://en.wikipedia.org/wiki/Sulphur%20hexafluoride

http://www.umweltdatenbank.de/lexikon/reduktion.htm


states had ratified the Kyoto Protocol, covering 85% of the global population and 62% of global C02 emissions (the USA had not ratified at this time).

The UNFCCC resulted in the establishment of an Intergovernmental Panel on Climate Change (IPCC), which publishes corresponding Assessment Reports on the state of knowledge on climate change. Among other topics, Volume 3, Chapter 8 of the Fourth IPCC Assessment Report covers the use of SF6 in high-voltage switchgear. 2.4 Global warming potential

The (relative) global warming potential (GWP) or CO2 equivalent is a measure of how much a given mass of a greenhouse gas contributes to the greenhouse effect. Carbon dioxide is used as a comparison value, abbreviated to CO2e (equivalent). The value describes the average warming effect over a given period, usually 100 years.

For example: the CO2 equivalent for methane over a time horizon of 100 years is 25. This means that the contribution to the greenhouse effect of one kilogramme of methane is 25 times greater than that of one kilogramme of CO2.

However, the global warming potential is not the same as the actual contribution to global warming, as there is a strong variation in the emission volumes of the different gases. This concept enables a comparison of the different contributions of individual greenhouse gases based on known emission volumes.

In the first commitment period of the Kyoto Protocol, emission volumes are evaluated using the CO2 equivalents of the individual gases and weighted according to their global warming potential. This means, for example, that a reduction of one tonne of SF6 emissions is equivalent to a CO2 reduction of 22,200 tons because, in both cases, the reduction in emissions amounts to 22,200 tons of CO2 equivalent.

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http://en.wikipedia.org/wiki/Greenhouse_effect


Greenhouse gas Source Potential

(over 100

years)

Carbon dioxide CO2

Combustion of fossil fuels (coal, mineral oil and natural gas in transport and industry) and biomass (forest clearance/burning), cement production, volcanic activity

1

Methane CH4

Rice cultivation, livestock farming, sewage plants, landfill sites, coal-mining (mine gas), natural gas and mineral oil production, marine biology

25

Nitrous oxide N2O(laughing gas)

Nitrogen fertilisers in agriculture, combustion of biomass 298

Chlorofluorocarbons (CFCs)

A group of chemical compounds used as propellants in spray cans, freezing agents in refrigeration systems, anaesthetics, and filler gases in foams; banned in Germany since 1995

Up to 14,400

Hydrofluorocarbons (HFCs)

Propellants in spray cans, freezing agents in refrigeration systems, filler gases in foams

Up to 14,800

Tetrafluoroethane (R-134a, HFC-134a)

Freezing agent in refrigeration systems 1,430

Sulphur hexafluoride SF6

Used, for example, as a protective gas in the magnesium production process and as an arc-quenching and insulation gas in high-voltage switchgear

22,200


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 to the anthropogenic greenhouse effect as a petrol-driven mid-class car with a total mileage of around 120,000 km (emitting around 185 g CO2 per km).

According to an independent study conducted in 2005 (see ECOFYS Report [16]), SF6 emissions from electric power equipment in 2002 accounted for 0.05% of the total greenhouse gas emissions of the 15 EU member states. Assuming that further measures will be implemented Europe-wide, the SF6 emissions generated by the power transmission and distribution sector in Europe would seem to represent a negligible proportion of the total global warming potential of all greenhouse gases. This very low proportion is due to the high level of awareness and responsibility that was established in this sector in Germany very shortly after the greenhouse effect of SF6 became known. SF6 is used in a closed cycle in the power transmission and distribution sector. In this cycle, the emissions are minimised, and used SF6 is recovered (at the end of the SF6-filled equipment lifecycle, for example) and either re-used directly or first purified and then re-used (SF6 re-use concept).

2.5 The Voluntary Commitment on SF6 as an insulation and

quenching gas In the knowledge that SF6 has a very long lifetime in the atmosphere and is a highly effective greenhouse gas, the German operators and manufacturers of power transmission and distribution equipment with voltages exceeding 1 kV AC that use SF6, together with Solvay Fluor GmbH, a German manufacturer of SF6 gas, committed themselves to the first Voluntary Commitment, dated 1997, aimed at limiting and reducing SF6 emissions.

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In the 2005 version of the Voluntary Commitment of the SF6 producers and the manufacturers and operators of electric power equipment > 1 kV for electrical power transmission and distribution in the Federal Republic of Germany on SF6 as an insulation and quenching gas, the signatories have pledged to reduce SF6 emissions significantly 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 be taken by manufacturers and operators to limit emissions. Manufacturers and 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 have undertaken to implement all possible measures to reduce SF6 emissions during the development, manufacturing and installation phases and in the operation, maintenance, decommissioning and dismantling of equipment. This also applies to the manufacture, transport and storage of SF6 and all measures associated with the recovery, recycling, re-use or destruction of used SF6.

The "Criteria for selecting switchgear systems and devices for power transmission and distribution" provide decision-making support for the selection of SF6 technology or other equally proven technology (such as air-insulated, solid-insulated or oil-insulated equipment). The following criteria must considered:

• Technical/economic criteria • Factors that determine the lifecycle costs • Ecological criteria, sustainability • Public safety • Industrial health and safety

Based on 2003 data, the section on "Data and targets for the use of SF6 as an insulation and quenching gas in electric power transmission and distribution equipment > 1 kV" sets binding targets for Germany


concerning SF6 emission rates for different parts of the lifecycle of switchgear systems and devices.

To verify the implementation of the measures set out in the Voluntary Commitment on SF6, a detailed SF6 status report is issued each year. This data is made available each year by 31 March of the subsequent year, in an agreed form and via the associations, to the Federal Ministry for 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 cut emissions by over 55% since the comparison year 1995, despite a significant rise in the use of SF6 by manufacturers and in the inventories of the operators. For this reason, Germany's Voluntary Commitment on SF6 is cited by environmental politicians as exemplary, showing the way for other sectors as well as other countries.

2.6 The European Regulation on certain fluorinated greenhouse gases

While the "classic" greenhouse gases usually occur as unwanted by-products, most fluorinated greenhouse gases are produced intentionally and used as propellants, refrigerants or fire-extinguishing agents. Within the hydrofluorocarbons, a distinction is made between partially halogenated hydrofluorocarbons and fully halogenated hydrofluorocarbons. If HFCs are fully fluorinated - that is, they no longer contain any hydrogen atoms - they are also called perfluorocarbons (PFCs). Hydrofluorocarbons are now used in place of chlorofluorocarbons (CFCs), the use of which has been restricted since 1995. Because of their high global warming potential, fluorinated greenhouse 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 a maximum of 22,200.

Sulphur hexafluoride (SF6) has the highest known global warming potential of 22,200. However, its low total emission volume means that its contribution to the greenhouse effect is minimal. SF6 has an extremely small influence on global warming compared to the other greenhouse gases. SF6 emissions from electric power transmission and distribution equipment > 1 kV account for just 0.05% or so of Europe's entire global warming potential. However, it can take up to 3,000 years to break down in the atmosphere.

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The Regulation

In 2002, the European Union had already committed itself, in the Sixth Community Environment Action Programme and in the Kyoto Protocol, to achieving an 8% reduction in emissions of greenhouse gases compared to 1990 levels. It also recognized that, in the longer term, global emissions of greenhouse gases would need to be reduced by approximately 70% compared to 1990 levels. Due to the high global warming potential of fluorinated greenhouse gases,

Regulation (EC) No. 842/2006 of the European Parliament and of the Council

of 17 May 2006 on certain fluorinated greenhouse gases

was brought into force. Its primary objective is to reduce the emissions of the fluorinated greenhouse gases specified above and thus protect the 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, gas mixtures containing a fluorinated greenhouse gas, and products and equipment containing these fluorinated gases, as listed in Annex 1, Part 1 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 procedures that use fluorinated greenhouse gases, as well as "avoidable applications", such as windows, footwear, tyres, single-component foams and novelty aerosols.

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In the context of this Regulation, the term "high-voltage switchgear" means all electric equipment and systems for the transmission and distribution of electric energy at rated voltages above 1 kV [see Regulation (EC) No. 305/2008, Article 2 Definitions]:

Switching devices and their combination with associated control, measuring, protective and regulating equipment, and assemblies of such devices and equipment with associated interconnections, accessories, enclosures and supporting structures, intended for use in connection with generation, transmission, distribution and conversion of electric energy 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 gases applies without restriction to all member states of the European Union. Certain articles of this Regulation must be implemented in the member states without changes or additions. In other articles, the Regulation sets down minimum requirements and allows each member state to incorporate additional requirements into its national implementation regulation. However, any such additional national requirements may not impede the free movement of goods and the freedom of establishment within the European Union. Such articles include Article 5 Training and certification of Regulation (EC) No. 842/2006, which is implemented in the individual member states on the basis of the EU minimum requirements.

The text of the Regulation also has relevance to the European Economic Area (EEA). The EEA currently incorporates the member states of the European Union as well as Norway, Iceland and Liechtenstein.

Imports of products, equipment and services into the European Union are also subject to Regulation (EC) No. 842/2006.

Validity for the power transmission and distribution sector

The operation alone of SF6-insulated switchgear > 1 kV AC ("high-voltage switchgear") is not affected by this Regulation. Such equipment is not subject to any prohibitions or restrictions of use under Article 8 Control of use, Article 9 Placing on the market and Annex II of the Regulation.

The provisions of Article 3 Containment requiring operators to check for leakage apply to stationary applications in the form of refrigeration and air-conditioning systems, heat pumps and fire protection systems, but not to "high-voltage switchgear" (as defined above). However, a clear distinction must be drawn here and in all the following explanations between the purely environmental requirements of Regulation (EC) No. 842/2006 and the applicable technical or standard-based requirements.

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It is well known, for example, that the standard series IEC 62271/ EN 62271/VDE 0671 for equipment containing SF6 defines detailed gastightness requirements that are not covered by the statutory EU Regulation.

The following requirements and articles are of relevance to the power transmission and distribution sector in the practical implementation of Regulation (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 companies 2) Applies to manufacturers and service companies

Article 4 Recovery, Regulation (EC) No. 842/2006

Of particular relevance here are certain definitions given in Article 2 Definitions of Regulation (EC) No. 842/2006:

"Recovery" means collection and storage from, for example, machinery, equipment and containers.

Explanation: For SF6-filled equipment > 1 kV AC this is, for example, the extraction of SF6 using suitable equipment.

"Recycling" means the extraction of a recovered fluorinated greenhouse gas following a basic cleaning process.

Explanation: In many cases, used SF6 is filtered mechanically during the recovery process. If this SF6 gas then meets the requirements set down in IEC 60480/EN 60480 or IEC 62271-303, it is recycled (re-used).

"Treatment" means the reprocessing of a recovered fluorinated greenhouse gas in order to meet a specified standard of performance.

Explanation: The SF6 gas producer Solvay Fluor GmbH, for example, is implementing the 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 gas is permanently transformed or decomposed into one or more stable sustances which are not fluorinated greenhouse gases.


Explanation: Until 2006, 1% of the total volume of SF6 in Germany that was delivered to Solvay Fluor GmbH as part of the re-use programme was burned and thus destroyed in special processes because it had not been possible to reclaim the highly contaminated SF6 using the processes available at the time. Today, following extensive process improvements at Solvay Fluor GmbH, it is normal practice not to destroy any used SF6; in other words, 100% of the SF6 delivered to Solvay is now reclaimed. In other countries, 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

6 gas must be removed in accordance with proper

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 manufacturer's "re-use specification" in accordance with IEC 62271-303, it must be returned to the gas manufacturer for re-use processing.

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Article 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 Union shall give recognition to the certificates issued in another member state and shall not restrict the freedom to provide services or the freedom of establishment in accordance with this Regulation.

According to Article 5, the operator of the "high-voltage switchgear" shall ensure that the relevant personnel have obtained the necessary certification. 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 companies involved in carrying out the activities relating to the recovery, recycling, reclamation or destruction of SF6 in/from "high-voltage switchgear" shall only take delivery of SF6 if their relevant personnel hold the required certificates.

Explanation: This means that the relevant personnel must hold the required certificates by 4 July 2009 at the latest.

The detailed implementation of Article 5 Training and certification of Regulation (EC) No. 842/2006 specifically for "high-voltage switchgear" is defined in a separate Regulation of the European Commission entitled:

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.


This Regulation defines the minimum requirements for personnel and the conditions for the mutual recognition of the certificates issued. These minimum requirements form the basis for the mutual recognition of the certificates issued in the member states.

For our electric power transmission and distribution sector, Article 2 Definitions of Regulation (EC) No. 305/2008 for "high-voltage switchgear" is very important. The following definition is particularly relevant:

For the purposes of this Regulation, "high-voltage switchgear"

means switching devices and their combination with associated

control, measuring, protective and regulating equipment, and assemblies

of such devices and equipment with associated

interconnections, accessories, enclosures and supporting

structures, 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 SF6 mixtures used to generate, transmit, distribute and convert electric energy at voltages above > 1 kV.

As well as detailing the requirements relating to the certification and evaluation bodies, the Regulation also defines the minimum requirements for the certificates themselves. In this context, please also note that member states may require holders of certificates issued in another member state to provide a translation of the certificate in another official Community language.

Article 3 Certification of personnel also specifies conditions for employees who have already been carrying out the activities associated with SF6 for a longer period, as defined in the Regulation: for the transitional period up to 4 July 2009, the member states may decide that personnel with experience shall be deemed "certified".

Personnel undergoing training (in connection with the requirements of the F-Gas Regulation) may continue to carry out the SF6 activities without a certificate for up to one year, provided that they are supervised by a person holding a certificate.

The Annex to Regulation (EC) No. 305/2008 defines the theoretical and practical training and examination contents as minimum requirements for all affected personnel, with equal applicability to all member states. To ensure the continued comparability of the certificates based on the training and examination contents, the specified contents must be included in training courses and examinations, regardless of the area of activity of the person being trained.

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ANNEX

Minimum requirements as to the skills and knowledge to be covered by the evaluation bodies

The examination referred to in Articles 4(1) and 6(2) shall comprise the following:

a) a theoretical test with one or more questions testing that skill or knowledge, as indicated in the column "Test type" by "T";

b) a practical test where the applicant shall perform the corresponding task with the relevant material, tools and equipment, as indicated in the column "Test type" by "P".

No. Professional minimum knowledge and skills Test type

1 Basic knowledge of relevant environmental issues (climate change, Kyoto Protocol, Global Warming Potential), the relevant provisions ofRegulation(EC) No. 842/2006 and of the relevant Regulations implementing provisions of Regulation (EC) No. 842/2006

T

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 undernational or Community legislation, or international agreements

T

(1) for example IEC 60376 and IEC 60480


Article 6 Reporting, Regulation (EC) No. 842/2006

Regulation (EC) No. 842/2006 sets down requirements for SF6 reporting. This reporting is independent and must be implemented in addition to the national requirements (resulting from the Voluntary Commitment on SF6) for the reporting of information to the Federal Environmental Agency and the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety.

Within the meaning of the specified Regulation, the SF6 exported in loose cylinders or containers for use in "high-voltage switchgear" must be reported as an export from the European Union (EU). Similarly, the import of the corresponding SF6 in loose cylinders or containers must be reported as an import into the EU.

The implementation of the reporting requirements is subject to the following implementation regulation:


of 17 December 2007

establishing, 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 gases

By March 31 of any given year, every company that is independent under commercial law and is required to submit a report must issue a report directly to the entity designated by the European Commission concerning the quantities of SF6 gas exported and imported during the preceding year. The exported and imported SF6 gas quantities from several locations affiliated to a joint company under commercial law must be reported collectively for the national company concerned. A copy of the annual report to the entity designated by the European Commission is sent to the national body responsible in each country; in Germany, this is the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety.

The reporting requirements apply to national companies, independent under commercial law, that export or import more than one tonne of SF6 gas in loose cylinders or containers from or into the EU. The quantities of SF6 incorporated directly into products for export from or import into the EU should not be included in this report.

For the export of SF6 used in "high-voltage switchgear" and supplied by the producers/service companies of these systems, Regulation (EC) No. 1493/2007 requires the following forms to be used for reporting purposes:

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)

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Article 7 Labelling, Regulation (EC) No. 842/2006

From 1 April 2008, "high-voltage switchgear" containing SF6 or SF6 mixtures may not be placed on the market of the European Union unless the 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-filled compartments 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 information voluntarily.

For deliveries after 1 April 2008, the operating instructions supplied with the "high-voltage switchgear" must contain information on the SF6 or SF6 mixtures, including specification of the global warming potential.

In its national implementation regulation, each EU member state can specify the official EU language to be used for the labelling of equipment to be installed within its territory.

For further details on the implementation of Article 5 Labelling for "high-voltage switchgear", please refer to:


of 17 December 2007

establishing, 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. 842/2006

The EU member states have defined penalties and fines for infringements of Regulation (EC) No. 842/2006 and the associated implementation regulations. Germany has enacted the

Third Ordinance amending the

Ordinance on penalties and fines for chemical infringements

of 17 July 2007


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2.7 The national implementation regulation in Germany The implementation of Regulation (EC) No. 842/2006 and the associated European implementation regulations in Germany is set down 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 been incorporated into the German Chemical Climate Protection Ordinance without any additional national requirements.

Some details in the German Chemical Climate Protection Ordinance have been adapted in line with national circumstances and German linguistic usage, for example in

Article 5 Personal qualifications required for certain activities

The activities listed in the EU Regulation may be carried out only by persons holding a qualification certificate appropriate to the activity concerned or a corresponding certificate obtained in another EU member state.

The technical equipment required for the activity must be available and the persons concerned must be reliable.

A qualification certificate indicating competence to carry out the activity concerned shall be issued to persons who, in the case of "high-voltage switchgear", have successfully completed a theoretical and practical examination in accordance with Regulation (EC) No. 305/2008.

Article 7 Labelling in the German language

The labelling on the products and the SF6-specific information in the operating instructions shall be provided in the German language for "high-voltage switchgear" to be installed in Germany.

Article 8 Administrative offenses

This article sets out in detail the infringements of the requirements of the German Chemical Climate Protection Ordinance that are punishable by penalties or fines.

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 five times the density (heaviness) of air and can accumulate at ground level or in lower-level areas (risk of suffocation). Once SF6 has mixed with the room air, it can no longer be separated. SF6 becomes liquid when compressed at 50 bar and can then be stored and transported in pressurised gas containers as a gas in liquid form. Pure SF6 is chemically stable, inactive (inert), almost insoluble in water and 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 is available to ensure that emissions are avoided wherever possible. To ensure the safe handling of SF6 and used SF6, the trade association safety requirements must be observed (BGI 753 [5]) and IEC 62271-303 [3], EU safety data sheet as specified in Directive 2001/58/EC (available from Solvay Fluor on request).


3.2 SF6 quality according to relevant industry standards (T)

Table: SF6 gas qualities and relevant electrotechnical standards

Composition IEC 60376 (2005)

New SF6

(analysis from liquid phase)

IEC 60480 (2004)

Used SF6

IEC 62271-303 (2008)

Used SF6

SF6 re-use specification of gas producer,

e.g. Solvay Fluor

(1990)

SF6 99.55% by volume

Approx. 97.00% by volume

90.7% by volume

Air 2000 ppm by weight

(1% by volume)

3% by volume

< 30% by volume

(6% by weight)

CF4 2400 ppm by weight

(4000 ppm by volume)

< 5% by volume

(3% by weight)

H2O 25 ppm by weight (dew point approx.

-36°C)

(200 ppm by volume)

25…95 ppm by weight (dew point approx.

-36°C…-23°C)

(200…750 ppm by volume)

< 1000 ppm by weight (dew point approx. 5°C)

Mineral oil 10 ppm by weight

10 ppm by weight < 0.1% by weight

Acidity expressed in HF (hydrofluoric acid)

0.8 ppm by weight

(6 ppm by volume)

Total reactive gaseous by-products

50 ppm by volume in total

(12 ppm by volume for SO2 and SOF2 + 25 ppm by volume for HF)

< 1000 ppm by weight

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.

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To enable the gas to be returned to the re-use process, it must meet the gas quality specified in IEC 62271-303, e.g. the SF6 re-use specification of the gas producer. Within this specification, the used gas is considered as a product or raw material for the production of new SF6 and can be returned 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 using service 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 a number of intermediate steps via the SF6 re-use concept in order to save resources and energy. From an environmental perspective, this is necessary in order to restrict the release of SF6 into the atmosphere to the very low equipment leakage rate. The SF6 re-use concept is a closed-loop recycling system that aims to prevent SF6 emissions as far as possible during equipment servicing and decommissioning. The first step in the SF6 re-use concept is to assess the quality of the gas in the equipment. This is done either by using transportable measuring devices or by taking a gas sample for subsequent analysis in a laboratory (see Section 4). Based on the results of these analyses, a decision is made whether to reclaim and purify the gas on site or to regenerate the gas into new SF6 in accordance with IEC 60376. For each intermediate step in the gas handling procedure, corresponding packaging and service equipment is available (see Section 7 and [8]). The SF6 re-use concept is subdivided into three cases:

IEC 60376 VDE 0373-1

IEC 60480

IEC 62271-303

Figure: The SF6 re-use concept; according to the definitions of the Regulation No 842/2006 the case of inspection corresponds to the recycling. The case of recovery corresponds to the treatment and the case of disposal to the destruction.


3.3.1 Inspection – SF6 recovery and re-use on on site The impurities identified during inspection, such as dust, moisture, air, oil and SO2 compounds, are part of the normal aging process of the gas and are caused as a result of operation. The operator can remove these impurities on site. Solid by-products, such as dust and small particles of carbon, CuF2 and WOXFY, can be removed using solid filters (pore size 1µm), 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 service devices are equipped with the listed purification systems and are available as standard. The used SF6 must meet the requirements of the operator and the applicable IEC requirements, and can be re-used. If the treated material meets these requirements, the equipment being serviced can be refilled directly using an evacuation and filling system (service device). This is the procedure normally followed during assembly or inspection of the switchgear. New product quality, as defined in IEC 60376, is not achieved as a result of gas reclamation and purification.

3.3.2 Recovery – regeneration of SF6 to produce new gas in accordance with IEC 60376

If the used SF6 gas does not meet the requirements of the operator or IEC 60480 and it is no longer possible or desirable to purify the gas on site, it is sent directly to the gas producer to be regenerated into new gas. This is the case if the proportion of inert gas is too high2 or if high CF4 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 IEC 62271-303 or the re-use specification (see Section 3.2).

3.3.3 Disposal – incineration of SF6 If the inspection of the used SF6 on receipt in the plant reveals that the gas does not meet the requirements of IEC 62271-303 or the re-use specification and therefore cannot be re-used or regenerated into new gas, the gas must be disposed of at a licensed chemical waste incineration facility. Solvay Fluor is licensed to incinerate contaminated SF6 at the chemical waste incineration facility at its Frankfurt plant. However, the quantity of gas disposed of at the chemical waste incineration facility is negligible, and has been decreasing continuously over recent years. No SF6 gas is currently being incinerated. 2 as for instance nitrogen by a part of air in the SF6

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Assessment of the gas and categorisation as product or waste

Checking the SF6 quality

4 Checking the SF6 quality

4.1 Introduction Since the mid-1960s or so, sulphur hexafluoride (SF6) gas has been used increasingly as an insulation and quenching medium in gas-insulated switchgear (GIS) and circuit-breakers. The special, inert structure of the SF6 molecule means that its properties remain unchanged under optimum operating conditions throughout the entire lifecycle of the switchgear. This eliminates the need for the preventive replacement of SF6, helping to minimise emissions due to maintenance work.

Despite the high chemical inertness of SF6 gas, it is possible for faults to occur that can result in damage to the switchgear. Electric arcs that occur during normal operation of the circuit-breaker or the occurrence of partial discharges over a longer period cause the insulation gas SF6 to decompose, generating by-products that are in some cases toxic or highly corrosive. A number of these by-products can only be formed if reagents such as moisture and oxygen are present. It is therefore advisable to monitor the gas quality over the lifecycle of the electric power equipment.

In this context, please refer to the specifications provided by the manufacturer of the electric power equipment and measuring devices.

It is not normally necessary to conduct a gas analysis for equipment in which SF6 is used only for insulation purposes (e.g. medium-voltage GIS).

4.2. Monitoring the gas quality Measurements should be conducted to monitor the presence of the following foreign substances in SF6 gas. The threshold values for the foreign substances to be monitored in SF6 are listed in Section 3.

4.2.1 Moisture, air and CF4 Moisture 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 are subjected to discharge. High concentrations of these foreign substances reduce the insulating properties of the SF6 and the operating safety of the switchgear. In the case of discharges, air and/or moisture are the prerequisites for the generation of toxic and corrosive by-products.

The following methods can be used to measure the presence of moisture, air and CF4:

4.2.1.1. Moisture

4.2.1.1.1.Dewpoint mirror (physical measurement principle)

In chilled-mirror dewpoint hygrometers, the SF6 to be analysed is passed over a mirror that is cooled down to the dewpoint temperature of

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the SF6 gas by means of a Peltier element. Dewpoint hygrometers use an optoelectronic mechanism to detect the condensation on the basis of the reduction in intensity of the light reflected by the mirror. The electronic control mechanism modulates the power supply to the Peltier element so that the cooling of the mirror is directly dependent on the optically detected condensation, and controls the temperature of the mirror to maintain a dynamic equilibrium between evaporation and condensation on the mirror. In this continuously regulated state defined as the dewpoint temperature of a gas, an embedded temperature sensor measures the temperature on the surface of the mirror to a high level of accuracy.

Dewpoint hygrometer Source: G.A.S.

4.2.1.1.2 Electronic dewpoint hygrometer (capacitive)

An electronic dewpoint hygrometer measures the absorption of water molecules by a substance such as ceramic, aluminium oxide or polymer. Tiny quantities of water vapour accumulate in the substance, which functions as a dielectric in a condenser, and change the capacity of the condenser. This change is detected by an electronic evaluation mechanism and forwarded to a central processor, which converts it into a moisture value and outputs it.


Deckelelektrode (dampfdurchlässig)

Polymer

Grundelektrode + Kontaktfläche (Grundelektrode – Anschlussfläche – Draht)

Trägermaterial

Kontaktstelle(Deckelelektrode – Anschlussfläche – Draht)

Cover electrode (vapor permeable)

Contact spot (Cover electrode – connection area – wire)

Ground electrode + Contact area (Ground electrode – connection area – wire)

Base

C = f (%r.F.) Cges = C0 + C%r.F.

Source: CS Instruments

The graphic shows an example of a schematic diagram for a capacitive polymer sensor.

4.2.1.2 Air and CF4

The proportion of air and CF4 is determined indirectly according to the percentage of SF6 in the gas under analysis. The devices are generally calibrated to measure SF6-nitrogen mixtures. It is possible, however, to calibrate the measuring device to measure the percentage of SF6 in SF6-CF4 mixtures. The following measurement principles can be used to measure the percentage of SF6:

4.2.1.2.1 Measurement of the sound velocity

This measurement principle works by evaluating the different sound velocities 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. The sound velocity measured in the measurement cell is temperature-compensated and is converted into the percentage SF6 volume using a microprocessor.

4.2.1.2.2 Thermal conductivity detector

Thermal conductivity detectors (TCDs) continually measure the thermal conductivity of the SF6 using the heated-filament method.

The detector comprises a temperature-controlled metal block with two identical cells. A compensated comparison measurement is conducted as follows: the SF6 under analysis flows from the compartment into one cell, and the other comparison cell is filled with pure SF6. Both cells contain heated filaments of platinum or tungsten, which are connected together to form what is known as a wheatstone bridge circuit.

All filaments are heated by means of an electric current. The temperature of the filaments and thus their electric resistance depends on the thermal conductivity of the gases that flow through the cells. A change in the composition of the gas will cause a change in temperature, thus changing the resistance of the filaments in the measurement cells. The temperature of the heated filaments in the

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http://en.wikipedia.org/wiki/Thermal_conductivity


http://en.wikipedia.org/wiki/Platinum

http://en.wikipedia.org/wiki/Tungsten

http://en.wikipedia.org/wiki/Wheatstone_bridge_circuit

http://en.wikipedia.org/wiki/Electric_current

http://en.wikipedia.org/wiki/Temperature

http://en.wikipedia.org/wiki/Electrical_resistance


http://en.wikipedia.org/wiki/Gas

http://en.wikipedia.org/wiki/Temperature


comparison cell does not change. This temperature difference between the heated filaments in the measurement cell and the comparison cell produces a measurable voltage difference, which is converted into an SF6 percentage by an evaluation unit and displayed.

4.2.2 By-products Despite its excellent chemical stability, SF6 decomposes during discharge processes such as arcing, sparking or partial discharge activity.

The graphic illustrates the reaction sequence of the by-products. The discharge type also determines which by-products are produced in SF6. Partial discharges produce mainly SOF4, while spark discharges produce SOF2.

The decomposition of SF6 depends on the predominant gas pressure and the electrode and surface materials of the internal components. Despite the proven high reliability of these components of the power distribution network, faults may occur due to the SF6 aging described. Weak points in SF6-filled gas compartments are insulation materials such as epoxy resin supports (see graphic). Chemical reactions between by-products and the surfaces of insulation materials cause a change in the structure of the surface and reduce the surface stability. In the worst case, this can cause a flashover, resulting in damage to the equipment.

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 conductors due to by-products


The by-products, some of which are highly toxic (see table), can cause irritation and chemical burns to humans even in very small concentrations. Inhalation of the by-products can cause considerable damage to health.

The following table lists some of the physical and chemical properties of important by-products:

By-products Fp

/ °C

Sdp.

/ °C

Stability

in air

End products

MAK toxicity (ppmv)

Odour

SF4 sulphur tetrafluoride

-121

-38 Rapid decomposition

HF, SO2 3.6 Strongly acidic

S2F10 disulphur decafluoride

-53 30 Stable SF4, SF6 0.26

SOF2 thionylfluoride

-110

-44 Slow decomposition

HF, SO2 2.5 Rotten eggs

SOF4 silicon tetrafluoride

-107

-49 Rapid decomposition

SO2F2 0.5 Acidic

SO2F2 sulphurylfluoride

-120

-55 Stable 2.4 None

SO2 sulphur dioxide

-72.5

-10 Stable 0.5 Sharp

HF hydrofluoride

-83 19 Stable 1.0 Acidic

SiF4 tetrafluorosilane

-96 s.

Rapid decomposition

SiO2, HF

0.8 Acidic

The by-products can be detected as described below. The electrochemical sensors and the gas detector tubes quantify the main components SO2 and HF. Spectroscopic or chromatographic measurement 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 an electrolyte calibrated to detect the substance being measured.

SO2 sensor

The SF6 is diffused into the SO2 sensor, where it reacts with the measuring electrode in an oxidation process according to the following equation:

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Equation 1: Measurement process

Sulphur dioxide (SO2): SO2 + 2H2O = H2SO4 + 2H+ + 2e-

The counter-electrode attempts to equalise the reaction at the measuring electrode by reducing the oxygen, which causes water to be produced.

Equation 2: Equalising reaction: Oxygen reduction: ½ O2 + 2H+ + 2e- = H2O

Two reactions reflect the entire measurement cell reaction as follows:

SO2 + ½ O2 + H2O = H2SO4

If SO2 is present in the SF6 being measured, Equation 1 changes its electrochemical potential, with the result that electrons are given off. As a result, a voltage change is detected. This is converted into a concentration value (ppmv values) by means of an electronic evaluation mechanism.

SO2 measuring device (electrochemical) Source: Dilo

HF sensor

In an HF sensor, HF reacts with the electrolyte in the form of an electrocatalytic reduction that produces a pH change in the electrolyte. This change results in a potential change at the sensor's electrodes, which is converted into a concentration value (ppmv values) by means of an 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 ions are separated according to the different drift speeds, which will depend on the mass, charge and geometric structure of the ions.

Once they have drifted through the electric field, the ions reach a detector and return a time-dependent signal. By comparing the ion mobility spectrum of a pure SF6 gas (minimum quality 3.0) with that of an impure SF6 gas, it is possible to detect a deterioration in the SF6 gas mixture. The shift in the peak position is interpreted as a signal. The


example in the graphic clearly shows the peak position of the gas under analysis (originating from switchgear, for example), and its distance from the main peak of a comparison spectrum of pure SF6.

Peak shift

Sign

al /

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 the production of different by-products. The peak shift results from the formation of ions with different mobilities, while a widening of the peak indicates a wide variety of ions resulting from impurities in the gas. Comparison measurements using infra-red spectrometers were used as the basis for identifying a correlation between the total concentration of by-products and the maximum peak shift. Based on this correlation, it is possible to determine the quality of the SF6 and quantify the level of impurity.

4.2.2.3. Gas chromatography and infra-red spectrometry

To verify and quantify the individual concentrations of most by-products, laboratory analyses can be conducted using gas chromatography, mass spectrometry or infra-red spectrometry. All these methods are complicated, labour-intensive and relatively expensive, and must be carried out by qualified personnel. It is possible to take a sample of SF6 from the equipment using evaculated test cylinders, which must then be tested immediately using one of these methods. The by-products that are detectable using infra-red spectrometry are listed below:

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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 tubes

Gas detector tubes work according to the principle that a substance contained in the tube changes colour when a sample of SF6 is introduced.

Gas detector tubes are available for measuring the SO2 and HF content. The presence of one of these gases in the sample causes a colour change in the gas detector tube. The concentration of each by-product can be determined from the scale displayed on the gas detector tube and the extent of the colour change.

The following chemical reaction causes a colour change in an SO2 gas detector tube:

SO2 + I2 + 2H2O H2SO4 + 2 HI

The following reaction takes place in an HF gas detector tube:

HF + Zr(OH)4/chinalizarine [ZrF6]2- + chinalizarine


4.2.3 Oil mist Constituents of mineral oil can enter the gas compartment through the use of gas handling devices (pumps and compressors) that contain oil. The carbonisation of the oil on the inner surfaces can impair the equipment's 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 to check for the presence of oil.

The presence of oil mist in the SF6 gas compartment can be verified using gas detector tubes. The oil mist is deposited on the filter layer in the tube and, once sorption is complete, it is decomposed using concentrated sulphuric acid in the presence of a catalyst. The concentration of oil mist in the SF6 can then be determined from the colour intensity of the resulting dark-coloured reaction products.

4.3. Combination measuring devices As well as using individual measuring devices to determine the percentage of each foreign substance in the SF6, it is possible to use equipment that combines several sensors in one device. These combination measuring devices offer the advantage of comparatively low SF6 consumption and handling losses. They are easy to use and also save time.

The following combination measuring devices are currently available:

Two measurements in one device

1. Moisture (physical) and SF6 percentage

2. Moisture (electronic) and by-products (IMS, all by-products)

Three measurements in one device

1. Moisture (electronic), SF6 percentage (measurement of sound velocity) and by-products (electrochemical, SO2)

2. Moisture (electronic), SF6 percentage (measurement of sound velocity) and by-products (IMS, all by-products)

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Combination measuring device: moisture (electronic sensor), SF6 percentage (sound velocity) and by-products (electrochemical, SO2) Source: G.A.S.

Four measurements in one device

Moisture (electronic), SF6 percentage (TCD), oxygen (electrochemical) and by-products (electrochemical, HF)

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) with vacuum circuit-breakers, SF6 is used exclusively to insulate system parts and components carrying high voltages. In this context, the circuit-breaker performs the task of switching short-circuit and operating currents (in the vacuum).

SF6 gas

If a gas-insulated circuit-breaker is used, the switching of short-circuit and operating currents also takes place under SF6. In other words, the gas also acts as an arc-quenching medium. Arc quenching is performed by blasting SF6 into the electric arc.

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 Busbar

Figure: Medium-voltage switch bay with SF6 insulation and vacuum circuit-breaker Source: ABB

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

SF6 gas

Figure: High-voltage switch bay with SF6 insulation and gas-insulated circuit-breaker Source: Siemens

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The blast is generated by forcing the gas from a volume by means of volume reduction (blast piston) or by blasting the gas from a volume with a high pressure into a volume with a low pressure at the time of switching (dual-pressure switch). A method widely used today is the use of the arc heat itself to generate the corresponding quenching pressure at high currents (high energy). SF6 circuit-breakers are normally used in applications >52 kV.

circuit-breaker pole Source: ABB

Figure: Structure of a gas-insulated

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 contact


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 insulation and arc-quenching medium, as operating currents are interrupted by the switch-disconnector and short-circuit currents by a high-voltage fuse or a downstream circuit-breaker. SF6 is also used in applications involving the transmission of high currents, such as gas-insulated transmission lines (GIL), high-voltage cables and (high-)current busbars.

Figure: SF6-insulated busbar configurations

Source: Moser-Glaser

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Busbars comprise a copper or aluminium conductor within a contact-proof outer metal enclosure. High-voltage epoxy resin insulators are used to centre the conductor inside the metal housing. SF6 is used as an insulating gas between the external housing and the conductor.

Figure: Structure diagram of an SF6-insulated busbar with expansion elements (Source: pbp Preissinger)

Elongation resulting from thermal expansion, for example, can compromise the gastightness of the overall configuration. This is normally compensated for by fitting a series of independent expansion elements. Gas-insulated transmission lines (GIL) are constructed in a similar way to busbars:

2. Outer metal enclosure

3. Expansion element

4. Epoxy resin insulator

SF6 gas

1 Enclosure 2 Inner conductor 3 Conical insulator 4 Support insulator 5a Male sliding contact 5b Female sliding contact

1. Conductor

Figure: Schematic diagram of a GIL section Source: Siemens

Gas-insulated transmission lines are particularly suitable for transmitting high to maximum power ratings (up to 2000 MW) over long distances. The cables are insulated using a gas mixture (nitrogen and sulphur hexafluoride). GILs offer numerous advantages compared to conventional power lines, including lower ohmic losses and minimal


dielectric losses (thus reducing transmission losses and operating costs), no thermal or electrical aging of the insulation, and very weak electromagnetic fields outside the GIL. Because it is a non-toxic, non-flammable gas with good thermal conductivity, SF6 was originally also used in transformer construction. Although SF6 is no longer used in new transformer construction in Germany, existing SF6-filled transformers may still be in operation. Condensers incorporating sulphur hexafluoride as a dielectric are used in applications with high-frequency power ratings and voltages exceeding 10 kV. The capacity of these condensers can be adjusted by varying the inner gas pressure. In high-voltage and maximum-voltage technology, SF6 is being used increasingly as an insulation medium in instrument transformers (current/voltage).

Figure: Gas-insulated high-voltage current transformer Source: ABB

The use of SF6 to hermetically encapsulate all live components enables extremely high system voltages to be achieved, while at the same time reducing the occurrence of partial discharges.

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Leiter / Primärwicklung

Steuerelektrode

Durchführung

Kerne mit Sekundärwicklung

Sekundäranschluss

Innenelektrode

Grundplatte

Secondary terminal

Grading electrodInner electrodeConductor / primary wiCores with secondary windinBase plate

Bushing

housing

e

nding g

Current transformer Source: Siemens

SekundärwicklungSekundärwicklung

EisenkernEisenkern

DurchführungDurchführung

Primärwicklung

Secondary windin

Iron core

Primary winding

Bushing

g

Inductive voltage transformer Source: Siemens


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The tubular insulating body designed to enable a conductor to pass through an opening in an earthed wall is known as a bushing. To maintain the electrical operating and test conditions, the bushing must be sufficiently strong and must ensure an equal field distribution at the transition from one insulation medium to the other. Its excellent physical properties make SF6 ideal for use in this type of application.

VerbundisolatorPorzellan-Isolator

Composite insulator Porcelain insulator

BeBeispiel: Freiluft ispiel: Porzellandurchführunganschluss mit Verbundisolatoren Example: SF6/air termination with composite insulator Example: Pocelain insulator

Figure: Bushings with SF6 insulation Source: Siemens At the present stage of technological development, no other gas with the same optimum properties is available to replace SF6.


6 Understanding the design of electric power equipment (T)

6.1 Function and structure of the switching devices Circuit-breaker, switch-disconnector, earthing switch and combined fuse/switch-disconnector Key components of SF6-insulated switchgear are circuit-breakers, earthing switches (with or without interrupt capability), switch-disconnectors and combined fuse/switch-disconnectors. The detailed technical specifications vary for high-voltage and medium-voltage components. In the high-voltage range greater than 52 kV, these switching devices are either configured as individual devices or integrated into metal-encapsulated, gas-insulated switch bays (high-voltage GIS). In the medium-voltage range up to 52 kV, most switchgear in Germany is configured as gas-insulated switch bays/switchgear with integrated switching devices (medium-voltage GIS). SF6-insulated switching devices in the medium-voltage range up to 36 kV are used in air-insulated switchgear systems.

The following table lists the main functions of the individual switching devices:

Earthing switch

Circuit-breaker

Fuse/interrupter combination

Fuses

Switch-disconnector

Interrupter

Disconnector

Earthing + short-

circuiting Short-circuits

Current limitation

Circuit-break-

ing

Activa-tion

D e v i c e s

Functions of the switching devices in the electric power transmission and distribution network


Notes on differences between high and medium voltage: a. Disconnectors

In medium-voltage technology, so-called triple-position switches are often used in circuit-breaker bays. In this case, the disconnector has the following functions: Interrupt "on" – interrupt "off" – "ready-to-earth". In combinations incorporating downstream circuit-breakers, the cable to the corresponding medium-voltage GIS switch bay is earthed by setting the circuit-breaker to the "ready-to-earth" position. In this case, the high short-circuiting capability of the circuit-breaker is also used for the purpose of earthing. The de-earthing sequence is as follows: The activated circuit-breaker is deactivated and then the activated triple-position switch is reset from earthing "on" to earthing/interrupt "off". This procedure is known as "integral earthing", and is now being used increasingly in high-voltage switchgear combinations comprising circuit-breakers, disconnectors and current transformers.

b. Interrupters/switch-disconnectors, fuses and fuse/interrupter combinations In Germany, these switching devices are implemented almost exclusively in the medium-voltage range. Here, too, it is usual for triple-position switches combining the "interrupt + disconnect + earthing" functions to be used in SF6-insulated switchgear and as SF6-insulated switching devices. Most medium-voltage GIS systems are based on solutions comprising a shared gas compartment in which the SF6 acts as an insulation and arc-quenching medium. Also in use are solutions incorporating a separate SF6 compartment or vacuum switch chambers for the "interrupt" function and additional SF6 insulation.

c. Circuit-breakers Today's high-voltage circuit-breakers all use SF6. The SF6 acts as an insulation and arc-quenching medium. In high-voltage GIS switch bays, the SF6 circuit-breaker and all other necessary functional components are integrated into the SF6–insulated switch bay. In this context, it is particularly important to note that, in most cases, the SF6 pressure for the circuit-breaker is higher than the corresponding pressure in the other gas-filled compartments of the GIS switch bay. In medium-voltage GIS switch bays, the circuit-breaker is usually implemented as a vacuum circuit-breaker. Switching takes place in vacuum switch chambers that are integrated into gas-filled compartments insulated with SF6.

d. Earthing switches Earthing switches in high-voltage equipment insulated with SF6 are implemented either as makeproof or maintenance earthing switches. They perform the "earthing" and "short-circuiting" functions. Only makeproof earthing switches are used in medium-voltage GIS systems. The special case of earthing using triple-position (switch) disconnectors has already been covered in point a. above.

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Gas-filled compartments With regard to gas-filled compartments (containers) for SF6 equipment and devices, IEC 62271-1/VDE 0671-1 makes a distinction between two pressure systems that are relevant at the current stage of technological development.

Closed pressure system for gas

Sealed pressure system for gas High-voltage GIS and high-voltage switching devices and transformers are normally designed as closed pressure systems. Medium-voltage GIS and medium voltage switching devices insulated with SF6 are normally hermetically sealed pressure systems (sealed for life).

A closed pressure system for gas means: With regard to the gastightness, which must be specified by the manufacturer, the system must be designed to ensure minimum maintenance and inspection effort. Measures must be planned to ensure that the gas system can be refilled safely during operation. A sealed pressure system for gas means: The pressure system must be constructed in such a way that it does not need to be refilled with SF6 gas over its expected lifetime (see Section 6.3). However, this definition has no implications for the design of the SF6-insulated switchgear or switching devices. A closed pressure system does not necessarily have to be sealed hermetically by means of welding in its detailed design; it can also be constructed using sealed components. Both solutions are available on the market.

In addition to the difference described above, medium-voltage and high-voltage systems use different gas quantities and pressures. Due to the higher technical requirements, high-voltage switchgear systems are operated at higher pressure (400-800 kPa or 4-8 bar) and with larger quantities of SF6.

Medium-voltage applications use switchgear systems with only a low overpressure of 20 to 50 kPa (0.2 to 0.5 bar) compared to atmospheric pressure and a relatively small quantity of gas for each switchgear system (comprising several switch bays) of approximately 2 kg or more of SF6 for a 3-bay ring main unit (RMU). In switchgear systems for the lower and medium measurement data range, medium-voltage GIS systems are implemented with modules comprising a number of switch bays in a shared gas-filled compartment.


6.2 Structure of switchgear systems 6.2.1 SF6-insulated high-voltage switchgear (GIS) The structure of a high-voltage gas-insulated switchgear system (GIS) is characterized by its compactness. The use of SF6 (sulphur hexafluoride) as an insulation gas with three times the insulation capability of air (under atmospheric pressure) makes it possible to transmit high voltages of up to 800 kV safely in earthed, cast-aluminium enclosures. The corresponding gas pressure (density) must then be used when filling equipment in the different voltage ranges.

High-voltage gas-insulated switchgear

Source: Siemens

The structure of the individual switchgear systems will depend, among other factors, on the number of busbars to be incorporated (single or double).

Connected with this, it is then necessary to select the switching devices, such as disconnectors, earthing switches and circuit-breakers, that are required for the different switching operations. As shown in the cross-section diagram (see next page), all active switching devices have a separate gas compartment. Depending on the voltage range, these are then filled at a predefined gas pressure that, combined with the corresponding ambient temperature, produces the gas density required for insulation.

Density monitoring devices monitor this gas density to ensure safe operation. If any losses are detected, a signal is generated or the circuit-breaker is deactivated.

To ensure safe, low-maintenance operation, the different gas compartments are equipped with filter material according to their size. This filter material traps any moisture entering the compartment, ensuring that the insulation gas remains dry for up to 25 years.

To ensure safe, low-maintenance operation and a high degree of environmental compatibility, it is necessary to keep the leakage rate as low as possible.

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It is currently possible to achieve leakage rates of < 0.5% by using state-of-the-art machines to process the cast-aluminium enclosure.

1 Integrierter Ortssteuerschrank2 Stromwandler3 Sammelschiene I mit Trenn- und

Erdungsschalter4 Unterbrechereinheit des

Leistungsschalter 5 Sammelschiene II mit Trenn- und

Erdungsschalter

6 Federspeicherantrieb mit Leistungsschalter-Steuereinheit (1- oder 3-poliger Antrieb)

7 Spannungswandler8 Schnellerder9 Abgangsbaustein mit Trenn- und

Erdungsschalter10 Kabelendverschluss

1

2

3

4

5

6

7

89

10

1 Integrated l e ocal control cubicl

Current trans

with disconwitch

Circuit-breaker in

with disconnecting and witch

2 former

3 Busbar I necting and earthing s

4 terrupter unit

5 Busbar II earthing s

6 S w e or

pring-stored-energy operating mechanism ith circuit-break r control unit (common

single drive)

ake-proof earthing switch (high

g module earthing switch

7 Voltage transformer

8 M speed)

9 Outgoin with disconnecting and

10 Cable sealing end

3 5

2

8

10

M M

4

M 9

7

Source: Siemens

An important differentiating characteristic of high-voltage GIS is the design of the encapsulation for the gas-filled compartments:

a) Three-phase encapsulation: All three high-voltage conductors are integrated into a single encapsulation comprising the respective gas-filled compartments.

b) Single-phase encapsulation: Each individual high-voltage

conductor is integrated into a separate encapsulation comprising a gas-filled compartment. A three-phase system consists of three single-phase-encapsulated conductors.


High-voltage GIS with three-phase encapsulation Source: AREVA

High-voltage GIS with single-phase encapsulation Source: AREVA

Note: The three-phase and single-phase encapsulation variants differ with respect to the quantity of SF6 used in each gas-filled compartment. This must be borne in mind when providing SF6 maintenance equipment.

6.2.2 Conventional high-voltage outdoor switchgear SF6 circuit-breakers (high-voltage) Unlike encapsulated switchgear, only the main contacts of outdoor high-voltage switches are insulated with SF6. Outdoor switchgear uses air for insulation against the earth potential and between the switch poles (AIS, air-insulated switchgear). However, the use of SF6 makes it possible to achieve a greater switching capacity for each breakpoint, enabling equipment of this kind to be designed more compactly than switches with oil or air insulation.

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145kV SF6 outdoor circuit-breaker Source: AREVA Outdoor switchgear systems The switch bays in high-voltage outdoor switchgear systems contain a combination of the required equipment, such as disconnectors with earthing switches, circuit-breakers, current and voltage transformers, overvoltage arresters, transformers, insulators and, where required, cable sealing ends and bushings. On the high-voltage side, these units are interconnected by means of power lines or busbars. The busbar connections between the individual switch bays are power lines or tubular busbars.

Overvoltage arrester Frame

Transformer Instrument transformer

Circuit-breaker Disconnector Busbars

Power line

Structure diagram of a high-voltage outdoor switch bay Source: AREVA

For the last 20 years or so, high-voltage circuit-breakers have been implemented as SF6 circuit-breakers. They were previously implemented as either gas pressure switches or low-oil circuit-breakers.


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Other SF6-insulated components of high-voltage outdoor switchgear systems can be the instrument transformers and bushings (e.g. as omponents of SF6-insulated power equipment).

c

Outdoor switchgear with SF6 circuit-breakers

ource: AREVA S

Outdoor switchgear with SF6 circuit-breakers and SF6 current transformers

hoto: AREVA

SF6-insulated high-voltage GIS switch bays designed for outdoor use.

S designed for outdoor use Source: Siemens

P

In addition to the individual switching devices described above, high-voltage outdoor switchgear systems can also incorporate space-saving SF6-insulated switching devices with the combined functionality of a circuit-breaker, disconnector, earthing switch and transformer. Some outdoor systems even use complete

High-voltage GI


6.3 Structure of SF6-insulated medium-voltage switchgear systems A distinction is made between the primary and secondary distribution levels in relation to medium-voltage SF6-insulated switchgear (greater than 1 kV and up to and including 52 kV). At the primary distribution level, approximately 40% of today's new circuit-breaker systems are gas-insulated. Most medium-voltage circuit-breakers are equipped with vacuum switch chambers. At the secondary distribution level, gas-insulated switch-disconnector systems (RMUs = ring main units) are used for almost 80% of today's new systems. The SF6-insulated switch-disconnectors in these systems must switch load currents and are also used to disconnect operating and network components for maintenance purposes. The gas-insulated switching system technology commonly used at the secondary distribution level uses SF6 as a combined insulation and switching medium in a gas-filled compartment.

The "sealed for life" concept Medium-voltage systems are designed as closed pressure systems. The gas compartments are not designed to be accessed or refilled over their expected useful life (sealed for life).

At the primary distribution level, SF6-insulated circuit-breaker systems with vacuum circuit-breakers are used. These are used for switching short-circuit and load currents. Switchgear of this kind must meet extremely rigorous requirements. During the entire lifetime of the switchgear, which is approximately 40 years on average, the devices must be capable of interrupting even high short-circuit currents reliably in fractions of a second, and of repeating this process several times a second. In Germany, switching is usually implemented in vacuum switch chambers. The vacuum switch chambers, along with all other live components, are integrated into compartments filled with SF6 gas as the insulation medium.


Medium-voltage GIS with vacuum circuit-breaker (typical dual-busbar systems) Source: ABB, AREVA and SIEMENS

In these diagrams, the bay comprises the circuit-breaker compartment, two busbar compartments, the cable connection compartment, the pressure release compartment and the cable connection compartment. The circuit-breaker compartment and the busbar compartments are filled with gas. In the circuit-breaker systems pictured, no gas can circulate between the compartments or into adjacent bays. However, there are SF6-insulated circuit-breaker systems in use that allow gas to circulate between the different compartments. At the secondary distribution level, SF6 is used in encapsulated switchgear systems to quench the switching arc in the switch-disconnectors and as an insulation gas. Because the dielectric strength at atmospheric pressure is almost three times greater than in air, these switchgear systems can be designed much more compactly than air-insulated systems. Because they are encapsulated, the systems are highly climate-independent. The SF6 switchgear systems at the secondary distribution level are generally designed as blocks comprising a certain limited number of individual bays (RMUs = ring main units) or self-supporting individual bays that come in a wide range of configurations and can be welded together with a gas compartment to form a complete system.

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Source: Driescher Wegberg Source: Schneider Electric

Source: ABB Source:Siemens

The busbars are contained entirely within the encapsulation. As an alternative to the block design, the switchgear can also be extended directly via a busbar pickup using ready-made busbar connections and an external cone connection.


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Modular bays (Source: Driescher Wegberg)

The modular technology also enables individual bays or modules comprising several switchgear units to be combined into a complete switchgear system. These modular units are interlinked by means of proprietary busbar connections.

Modular circuit-breaker technology (Source: AREVA)

The gas-filled compartments of the SF6-insulated switch bays for the secondary distribution level are normally made from stainless steel sheet. The bay dimensions vary, depending on the design, installation and manufacturer. The structure and number of bays is an important point in terms of decommissioning. The gas volume varies, and it may be necessary to evacuate the gas-filled compartments individually. The compartments usually have gas-fill valves for extracting the SF6. For systems without a gas-fill valve, an alternative method must be used to extract the gas (see Section 7.8).

The gas pressure (overpressure) ranges between 20 and 50 kPa (200 and 500 mbar), depending on the design. The rating plate on the switchgear specifies the rated filling pressure as an absolute pressure in kPa or the overpressure in relation to 101.3 kPa (1013 mbar) normal air pressure at 20°C and the quantity of SF6 in kg.


7 Recovery of SF6 and SF6 mixtures and purification of SF6 (P)

7.1 Practical structure of a process flow for the recovery of SF6 During practical implementation, the operating instructions for the relevant devices must be followed.

Funktionsbild SF6-Service-GeräteFunction diagram for SF6 service equipment

internerFilter

SF t6-Wartungsgerä

SF6-Gasbehälter

Kompressor

Membran-Kompressor

Saug-Pumpe

Vakuum-Pumpe

Vorfilter

SF6 service unit BedieneinheitControl unit

Compressor

Membrane compressor

Suction pump

Vacuum pump

Internal filter

Prefilter

SF6 m /gefüllter RauBetriebsmittel /

Anlagenteil

SF6-filled compartment /

equipment / system

Atmosphäre

Source: RWE

The graphic shows a basic structure for the recovery of SF6. The gas compartment (system) to be evacuated is connected with the maintenance device via a prefilter. The maintenance device compresses the SF6 and fills it into an SF6 container or SF6 cylinder to be connected.

Atmosphere SF gas container

6


SF6 gas handling(recycling / disposal)

SF6 gasanalysis

No

Evacuation target reached (pressure, filled weight, mass

flow)

SF6 gas suitable for

re-use/ reclamation?

No Extract SF6 gas via

prefilter units

Transfer SF6 into specially labelled

containers (disposal)

Yes

No Yes SF6 gas analysis

(store)

Evacuation target reached(pressure, filledweight, mass

flow)

Extract (and filter)SF6 gas

Yes SF6 extraction

completed

Equipment or gas compartment

filled with SF6

Yes No Does gas

comply with IEC 60480?

Seal SF6 containersand label with

analysis values

Return SF6 gas to equipment

or gas compartment

SF6 extraction completed

Source: RWE The graphic explains the procedure for removing SF6 from a system, which involves measuring the quality of the SF6 gas and purifying the gas. The steps to be followed within the procedure depend on the gas quality.

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7.2 Measuring the gas quality Before a decision can be made as to whether the gas should be re-used or disposed of, it is necessary to analyse the SF6 or the SF6 gas mixture. For guidance on the re-use, reclamation or disposal of the gas, please refer to the manufacturer's specifications and/or the applicable standards, such as IEC. The minimum requirements for SF6 gas quality are listed in the SF6 gas quality table in Section 3.2.

Source: Vattenfall

During measurements, it is important to ensure that the gas is contained within a closed cycle where permitted by the measurement method used. In other words, steps must be taken to avoid releasing the gas required for the measurements into the atmosphere. The following information should be obtained during the measurement process:

Concentration of by-products

Moisture content

SF6 percentage

Concentration of oil mist, where relevant

When performing the measurements, it is important to follow the operating instructions for the relevant devices. The following points must be observed when performing the measurements, regardless of the device used:


7.2.1. Gas connection To avoid corrupting the measurement result, a suitable hose should be selected for the measurement. Ideally, a Teflon/PFA bend-proof (metal-sheathed) hose should be used (see image). The use of rubber hoses should be avoided (adsorption effects).

Source: G.A.S.

7.2.2. Measurement - Before conducting the measurement, care must be taken to ensure that any valves of the gas compartment are opened and that a gastight connection has been established between the gas compartment and the measuring device.

- The hose used should be flushed with the SF6 gas to be measured to ensure that the measuring device measures the gas from the compartment and not the gas from the hose or an SF6-air mixture (due to open connections).

- When connecting the measuring device, it is important to establish whether the measurement must be started manually, i.e. by opening an internal inlet valve in the measuring device, or whether the measuring device works as a "display device" and the SF6 from the compartment flows through the measuring device as soon as the measuring hose has been connected. With regard to the gas consumption and adherence to the measuring time, this point is particularly important for "display devices".

- If a high concentration of by-products is expected during measurement (resulting in an error), this should be determined before any other measuring devices are used. Electronic devices for measuring moisture are particularly prone to damage as a result of high percentages of by-products (chiefly HF; >500ppm).

- For comparability with older measurements and to enable the measurement result to be evaluated, it is important to know whether the measuring device used performed the measurement at ambient pressure or at the operating pressure of the equipment, and whether the sensor(s) is/are temperature-compensated in the device used. It may be necessary to convert the results (see operating instructions for the device).

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- To evaluate the measurement results, it is important to know whether the measuring device used displays the end result or whether according to operator’s judgement a stable end value will be achieved. In this case, it is important to note the specifications given in the operating instructions regarding the measuring time of the device used.

- The measurement results can be documented either electronically or manually (in writing). In this context, it is important to ensure the traceability of the measurement results by specifying the location (compartment/system), time and date. If the data is stored electronically, the data must be downloaded from the measuring device and archived appropriately.

- Depending on the measuring device used, either the results are interpreted automatically (and displayed on the device's screen; see diagram) or the operator makes a decision regarding the quality of the SF6. For guidance on the categorisation of the gas quality, please refer to the manufacturer's or operator's instructions or the applicable IEC standards (see Sections 3.2 and 7.2.4). For devices with automatic data interpretation, the threshold values for the individual sensors can be adjusted via the settings menus of the devices.

Source: G.A.S.

7.2.3. Collecting the measurement gas As already mentioned, it is important to minimise the amount of SF6 released into the atmosphere during measurement. Depending on the measuring device used, it is possible to pump the used gas directly back into the gas compartment after measurement or to collect it. However, this procedure is only possible if the gas quality in the collection containers meets the IEC requirements. The SF6 can be collected either in its gaseous state using a collection bag or as a liquid via a recycling system. For both alternatives, it is possible to pump out the used SF6 with a mobile service unit.


7.2.4. Evaluating the measurement against threshold values In order to evaluate the measurement results, it is necessary to know the target values for the gas quality. The target values for evaluating the measurement results are given in the manufacturer's specifications and in the applicable IEC standards (see Section 3.2).

IEC 60376: Specification of technical grade sulphur hexafluoride (SF6) IEC 60480 Guidelines for the checking and treatment of

sulphur hexafluoride (SF6) taken from electrical equipment

IEC 62271-303: Draft: Use and handling of SF6

Special separation equipment must be used to separate nitrogen or air (service provider or Solvay).

7.3 Provision of basic knowledge regarding the use of different filter types and adsorbents used in service devices or mobile prefilter units

For high levels of contamination (decomposed SF6), it is advisable to use separate equipment and prefilter units. The prefilter units must then be connected directly to the container to be emptied. The safety requirements set out in document BGI 753 of the German trade association for the electrical engineering, textile and precision mechanics industries (BGETF) must be observed [5].

When selecting the filters and adsorbents to be used in the service equipment or prefilter unit, please refer to the following table from Solvay's SF6 re-use concept [7].

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Table Section 7.3: Different filter types and adsorbents used in service equipment

Contaminants Filter type Function Properties

General contaminants:

oil, moisture, particles, reactive products, etc.

Prefilter Reduces the concentration of solid and gaseous contaminants in highly contaminated gas prior to the introduction of the gas into the purification unit

Pore size 10 μm

Residual moisture < 200 ppmv

Residual concentration of reactive products < 200 ppmv

Also traps oil

Dust/particles, carbon, switching dust:

CuF2, WOxFy,

Particle filter/ solid filter

Removes solid contaminants and other particles prior to the introduction of the gas into the purification unit

Pore size 1 μm

Moisture Moisture filter Removes moisture Alumina (Al2O3 / aluminium oxide)

Molecular sieves (pore size 4-5 Å)

Residual moisture < 100 ppmv

Gaseous by-products:

SF4, WF6, SOF4, SO2F2, SOF2, SO2, HF

Gas filter

Removes gaseous by-products

Activated carbon and zeolites

Also traps smaller particles

SO2+SOF2 < 12 ppmv

Oil Oil filter Removes oil Activated carbon, special filter with viewing panel at entry and exit

SO2, SOF2, SO2F2, HF

Detoxification filter

Reduces reactive by-products products to 200 ppmv to enable transport as non-toxic gas

As for prefilter


7.4 Operation of SF6 recovery equipment (P) The SF6 service equipment should have a sufficiently high suction capacity to evacuate as much gas as possible from the high-voltage and medium-voltage switchgear. The residual pressure in the gas-filled compartment should not exceed 20 mbar (Draft IEC 62271-303 Table 13, Section 8.1). In a small number of older systems, however, the minimum possible pressure may be limited by the design of the equipment (if in doubt, please contact the manufacturer). When extracting gas from power equipment > 52 kV, a final pressure of around 1 mbar should be aimed for, but may not always be achieved due to the shape of the gas compartment.

Source: Vattenfall The extraction of gas must be monitored. Vacuum monitoring can be performed only if the suction unit is disconnected, as the connected service equipment corrupts the measurement (e.g. close the valve and check the system pressure). The extracted SF6 volume can be measured using mass flow meters or weighing equipment. Setting up the connection between the gas extraction unit and the storage container: When setting up the closed recovery cycle, it is important to ensure that only the correct hoses, couplings and valves are used [8]. The instructions given in the manufacturers' specifications must also be observed!

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7.4.1 Function: Extraction of SF6 gas Key words for the practical training and examination General points Always perform a function check on the equipment before using it. Is it state-of-the-art equipment for SF6 recovery to at least 20 mbar?

If not, is an oil-free suction pump unit available for upstream

connection? Are the connection hoses sealed with self-closing couplings (e.g.

DILO), or is there air inside the hoses that must first be evacuated? Before starting the gas handling operations, it is necessary to

measure the gas quality. Determine the SF6 percentage, dew point and by-products and record the measurement results. A prefilter unit should be used if the SO2 concentration exceeds 100 ppm.

Check whether storage facilities are available for storing all the gas to be extracted, i.e. SF6 cylinders/containers.

Is the service equipment capable of liquefying SF6 gas in cylinders or containers?

Check whether the hose connector fits the connector on the gas compartment. If an adapter is fitted, ensure that no SF6 gas escapes into the atmosphere (draw off the gas from the hose and repeat the evacuation procedure).


The following images have been provided by DILO.

Schematic configuration

SF6 sevice unit Prefilter unit Switchgear

SF6 gas cylinder for storage

Economy series functional diagram – extraction of 6 gas Starting the gas handling operations Connect the gas handling equipment to the gas compartment.

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Connect gas compartment

If the coupling system is open, evacuate the connection hose. Open the ball valve to the storage tank or gas cylinder.


Open ball valve to storage container

Activate the electronic weighing equipment in case of liquid storage – record the initial weight

Set weight display to 0.0 kg

Start process of extraction (on different devices automatic process control). Bring ball valves on manual devices into position according to the operating instruction

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Select function

Start function: remove SF6 gas

Observe decrease of pressure at the manometer (vacuum

compressor or suction pump will be activated automatically from achievement of atmospheric pressure)


Extract < 1 mbar

Deactivate the extraction process manually once the final value has been reached (according to the reading on the vacuum meter): 50 mbar for compressors/vacuum compressors and <20 mbar for compressors/suction pumps.

Extraction completed

Close the ball valve to the storage tank or gas cylinder.

Close ball valve and cylinder valve

Disconnect the gas handling equipment from the gas compartment.

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Check the gas quality of the extracted gas and compare it with the initial values. If the values have not changed, this means that the filter cartridges were saturated and did not absorb any moisture or by-products.

The quantity of SF6 gas extracted is indicated on the weighing equipment (for liquid storage only). For storage in gaseous form, the quantity can be calculated according to the storage volume and the pressure in the storage tank.

Read off extracted gas quantity

The use of a mass flow meter is recommended for an accurate quantity indication.

Storing the recovered and/or purified SF6 The SF6 gas should be stored only in SF6 gas containers indicating the quality and pressure of the contents. The SF6 gas containers must be labelled with the values of the SF6 gas analysis. If the gas is not intended for immediate re-use, it is advisable to seal the container. Section 7.5 contains further guidance on storing and transporting SF6.

7.4.2 Deactivating the SF6 service equipment When extracting moist SF6, dry the residual gas in the pipe system of

the service equipment using the dry filter. Equalise the pressure in the equipment's pipe system. When transporting the service equipment by road, ensure that the

transport pressure does not exceed pe 2 bar (overpressure). Filling the container with SF6 (additional information not included in the certification training)


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Connect gas compartment


Schematic configuration

Open ball valve to SF6 cylinder


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Select function

Record initial weight

Fill with SF6 gas - Unscrew pressure regulator


Start function: fill with SF6 gas

Evaporator heats up -magnetic valve closed

Magnetic valve open - evaporator at operating temperature


Set filling pressure - turn pressure regulator to required filling pressure

Fill usingcompressor

Read off filled quantity

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7.5 Storage and transportation of SF6 (T) Transportation Sulphur hexafluoride is transported as a pressure-liquefied gas. In Germany, the Pressure Vessel Code (Druckgeräteverordnung) and the associated technical rules for pressure equipment (TRB) provide guidance on handling and safety measures. Because SF6 is normally classified as a product, the documentation and verification requirements for its transportation in Germany are limited to a simple delivery note procedure (delivery note indicating the SF6 quantity).

Storage SF6 is delivered as a pressure-liquefied gas in pressurised gas containers such as steel cylinders, large containers and mobile tanks (tube trailers). Used SF6 can be transported in special 40-litre steel cylinders and 600-litre large containers capable of withstanding the effects of any SF6 by-products that may be present. The containers are fitted with stainless steel valves and have a different connection thread and colour coding to prevent confusion with new gas containers.


The containers must be stored away from direct sunlight, and must be secured to prevent them from overturning and rolling away. Storage areas and workplaces must be properly ventilated. Ventilation must be particularly effective at ground level, as SF6 vapour is heavier than air. For storage in areas below ground level, sufficient forced ventilation must be ensured. When handling SF6, it is important to ensure that there are no naked flames (from welding operations, for example) and no hot metal surfaces (such as infra-red heating elements) in the work areas. No eating, drinking or smoking is permitted when working with SF6. Although pure SF6 does not in itself represent a physiological hazard, several precautions must be taken when handling it to ensure that it is used safely. The primary objective must always be to adhere to the workplace threshold values. If this is not possible, corresponding safety precautions must be taken in accordance with the extent of the possible hazard [5]. Figure: SF6 re-use containers

Source: Solvay

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Figure: SF6 valve for gas with new product quality (connector no. 6, W21.8 x 1/14“) and re-use quality (connector no. 8, 1“) Connectors for new gas and used gas

Source: Solvay

7.6 Working on open SF6 compartments (P) • Filling or evacuating SF6 gas compartments • Opening SF6 gas compartments and working on or in open SF6 gas

compartments • Type and scope of the tasks to be performed in the event of a fault,

such as checking, cleaning and repairing, which may involve entering SF gas compartments 6

• Selecting safety precautions • Selecting service and test equipment and the corresponding filling

equipment

7.6.1 Filling and evacuating SF6 gas compartments When filling or evacuating SF6 gas compartments, avoid releasing SF6 or by-products into the atmosphere. Service equipment must be used (see Section 7.4).

7.6.2 Opening SF6 gas compartments and working on or in open SF6 gas compartments SF6 gas compartments may not be opened until they have been fully evacuated (i.e. the pressure has been reduced to at least 20 mbar and equalised with the atmosphere). This also includes the use of service


equipment to evacuate the SF6 gas compartment, which is then ventilated until the pressure is equalised with the atmosphere (air)2. However, the service equipment may not be connected until the quality of the SF6 gas has been analysed using test equipment or unless the history of the gas is known. Once the service equipment has been connected to the gas compartment, the connectors must be checked to ensure a gastight seal and a firm connection.

7.6.3 Working on or in open SF6 gas compartments in the event of a fault Solid by-products in open SF6 gas compartments must be removed in accordance with proper procedures. Loose dust must be removed using industrial vacuum cleaners that correspond at least to dust class H (high) according to BGI 753. When opening SF6 gas compartments and working on or in open, contaminated SF6 gas compartments, it is forbidden to smoke, drink or eat or to store foodstuffs in the equipment room (German Ordinance on Hazardous Substances (Gefahrstoffverordnung)). Solid by-products, used cleaning fluids, cleaning agents, disposable clothing and used filters from SF6 switchgear, service equipment, industrial vacuum cleaners or respiratory protective equipment can be neutralised with a soda solution (soapy water) and disposed of in accordance with the local regulations, for example by means of collection in special, appropriately labelled containers for forwarding to a specialist waste disposal company.

7.6.4 Safety precautions The information leaflet

BGI 753 SF6 plant and equipment [5]

issued by the trade association contains health and safety information and recommendations to be observed when handling SF6 by-products. The information provided in BGI 753 regarding the hazard potential, the safety precautions and rules of conduct when handling SF6 by-products, and the neutralisation of the SF6 by-products is intended to avoid industrial accidents, occupational illnesses and work-related health hazards, and must be observed without fail in all cases.

The employer is responsible for providing the appropriate personal safety equipment to all employees involved in opening SF6 gas compartments and working on or in open, contaminated SF6 gas compartments and for maintaining this safety equipment in a fit state. The employees must wear the personal safety equipment provided.

2 For special service operations, the compartment can also be flooded with dry nitrogen.

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The following personal safety equipment may be required: Protective gloves Safety goggles Protective overalls Overshoes Respiratory protective equipment Skin protection

Before taking a break and after finishing work, employees must wash their face, neck, arms and hands thoroughly with plenty of water. Any dust that comes into contact with the skin or eyes must be removed immediately by rinsing with plenty of water.

7.7 Neutralising SF6 by-products (T)

Regulation (EC) No. 842/2006 on certain fluorinated greenhouse gases sets environmental targets for minimising emissions of these gases into the atmosphere. One environmental protection measure is the neutralisation of SF6 by-products, which can appear, for example, as solid deposits on the surfaces of the SF6 gas-filled compartments of high-voltage switchgear, in the filters and absorbers of the service equipment or, in the event of arcing faults, as gas leakages in the affected switchgear compartments.

Neutralise the objects/surfaces contaminated with SF6 by-products:

Sodium and calcium oxide in an aqueous solution: 3% soda solution (30 g of Na2CO3 to 1 litre of water).

o Put the solvent in a plastics case (5 measuring spoons are 30 g)

o Slow input of the mixture. Caution: Mixture heats and foams. During the process of neutralisation develops CO2.

o Leave the plastics case open at least 24 hours

o The solvent has to cover all objects which have to be neutralized

Rinse the cleaned parts/surfaces thoroughly with water.

Collect the cleaning agents/used cleaning liquids in specially labeled containers for forwarding to the specialist waste disposal company.


Waste codes

150202* for contaminated filter material, protective gloves, non-returnable protective overalls etc. with dangerous contaminations (solid SF6 by-products)

070101* for basic fluid detergents as for instance 3 percent soda solutions with neutralised by-products

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7.8 Operation of tight drilling systems, if necessary 3 (P)

Recycling SF6 from used switchgear For SF6 switchgear without a suitable filling valve, the SF6 gas can be recycled using a gastight drilling system.

This comprises mainly a gastight drilling attachment with a seal for drilling a hole in the gas vessel. Once the hole has been drilled, the gas flows through it into a compartment of the drilling system, from which it can be extracted using a standardised filling valve.

This drilling system is mounted on the gas compartment (gas vessel). Additional stays are welded on for this purpose.

The drilling system is attached to the SF6 service equipment. A hole is drilled into the vessel at the same time as the gas is being extracted.

The gas is extracted as described earlier (Section 7).

Once the SF6 gas has been extracted, the vessel can be opened and dismantled.

3 A practical examination is necessary only if special equipment is being used, and only for high-voltage equipment. For general training purposes, candidates must merely be aware of the possibility of operating gastight drilling systems. A practical examination is necessary only if special equipment is being used.


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Figure 1 Source: Driescher Wegberg Figure 2 Source: Siemens

Figure 3 Source: Siemens

Figure 1: Inlet connector (DILO valve) for extracting SF6

Figure 2: Welded inlet connector

Figure 3: Gastight drilling system with integrated suction connector for extracting SF6

SF6 data recording obligations

8 SF6 data recording obligations

Monitoring of SF6 and appropriate data recording obligations under national or Community legislation or international agreements The primary purpose of monitoring, reporting or data recording obligations is usually to monitor compliance with environmental policy targets, agreements or laws (such as the Kyoto Protocol). To enable the monitoring of its compliance with the Kyoto Protocol, Germany must send its emission data to the UNFCCC4 – including the data relating to SF6. The rules of the IPCC5 define how the emission data is to be recorded and collected. Conversion into CO2 equivalents enables the other greenhouse gas emissions, including SF6, to be evaluated in comparison to the more familiar variable of CO2 emissions. 1 kg of SF6 corresponds to 22,200 kg of CO2. The conversion factor is known as the global warming potential (GWP). Based on the general targets and requirements of the Kyoto Protocol, various reporting procedures have been introduced. These will now be introduced briefly and explored with respect to their practical implementation.

Level Basis Who supplies the data?

International Kyoto Protocol Signatory states send data to UNFCCC

European Union (EU)

Reporting requirements in Article 6 of Regulation (EC) 842/2006

and Regulation (EC) No. 1493/2007

Companies (see Section 1)

Germany Voluntary Commitment on SF6 in electric power equipment > 1 kV

BDEW, VIK and ZVEI (associations) and Solvay (company)

Companies report to the associations

Within the company

Association declarations, environ-mental management system or similar

Companies

International reporting Companies have no direct involvement in international reporting, although they may be required to provide data for inclusion in the declarations of individual member states.

4 UNFCCC: the United Nations Framework Convention on Climate Change http://unfccc.int/2860.php 5 IPCC: the UN Intergovernmental Panel on Climate Change http://www.ipcc.ch/

http://unfccc.int/2860.php

http://www.ipcc.ch/


Reporting requirements of Regulation (EC) No. 1493/2007 pursuant to Article 6 of Regulation (EC) No. 842/2006 Companies are required to report the quantities of SF6

produced in the EU, imported into the EU or exported from the EU

to the EU Commission subject to the following conditions:

The quantity exceeds 1 tonne/year/company. SF6 imported into or exported from the EU in loose cylinders or containers for

the purpose of filling equipment at the installation site must be declared (if the quantity exceeds 1 tonne/year/company).

Quantities of SF6 already contained in products - i.e. pre-charged medium-voltage switchgear - must not be declared.

The report must be submitted by 31 March for the preceding calendar year. The report for 2007 should have been submitted by 31 March 2008. For further details, including the format of the report and points of contact, please refer to Regulation (EC) No. 1493/2007 and the website of the EU Commission http://ec.europa.eu/environment/climat/fluor/index_en.htm. In practice, companies could be required to submit a report if they

export a total quantity > 1 tonne of SF6 for commissioning or service work,

import a total quantity > 1 tonne of used SF6 for reclamation and re-use purposes, or

import a total quantity > 1 tonne of SF6 for their own production purposes.

Germany – reporting in accordance with the Voluntary Commitment When the switchgear manufacturers and operators signed the first Voluntary Commitment in 1997, they agreed to comply with voluntary monitoring requirements (SF6 data recording).

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http://ec.europa.eu/environment/climat/fluor/index_en.htm


By the end of February each year, the operators and equipment manufacturers send the data from the preceding year to their associations (VDE FNN, VIK and ZVEI), which compile a summary report of the data submitted. In the working group for "SF6 in electric power transmission and distribution equipment >1 kV", the data from the associations is supplemented by information from Solvay, Germany's only SF6 manufacturer, and used to compile and evaluate a sector report. The data recorded for the Federal Republic of Germany is subdivided into medium-voltage and high-voltage switchgear and equipment. The monitoring procedure also records data from further applications such as transformers, condensers and bushings. Emissions Emissions are the "linchpin" of the monitoring procedure. Monitoring takes into account the SF6 emissions from all the different lifecycle phases:

1. Production of the electric power equipment (e.g. switchgear) 2. Commissioning and installation of the equipment 3. Operation and maintenance 4. Decommissioning and reclamation or destruction of the SF6

Recording requirements also include key figures In many areas, key figures have been introduced to make absolute variables more comparable. For example: car drivers express their petrol consumption as litres per 100 kilometres travelled. Similarly, the absolute SF6 emissions, taken on their own, say little about the quality of the processes. Manufacturers producing 10 kg of SF6 emissions may score well if they are processing 1000 kg, but may score badly if they are processing just 100 kg each year. Additional data is clearly needed in order to record the "petrol consumption" or, in this case, the rate of SF6 emissions. - Manufacturers: Development, test and production emissions are considered in relation to the annual consumption of SF6 (emissions resulting from the commissioning of equipment sold in Germany). - Operators: Emissions during operation are considered in relation to the total installed SF6 quantity (operating emissions/installed SF6 quantity in Germany). The emissions resulting from decommissioning are considered in relation to the SF6 quantity contained in the decommissioned equipment (decommissioning emissions/SF6 quantity in decommissioned equipment). It is therefore clear that the following data must be recorded in addition to the emissions: - Annual consumption of the equipment manufacturers6 - Quantity of SF6 contained in installed equipment - Decommissioned quantity

6 In this context, consumption should not be equated with emissions, because the term refers to the quantity used in production. The greatest proportion is used to fill the switchgear and equipment.


What are the internal rules for recording emissions? - Mass balancing and emission factors The mass balancing method is based on established practice in the field of business accounting: expressed simply, income is offset against expenses, taking into account any changes in inventory, and the result is the profit-and-loss statement. When used in the context of SF6 quantities and emissions, mass balancing is a theoretically simple and easy-to-follow concept. The SF6 entering the company is offset against the SF6 leaving the company, taking into account any change in the inventory levels of SF6. The resulting balance indicates the company's SF6 emissions. However, this method has been found to have a number of serious disadvantages when applied in practice7. Main problems: - Cash can be measured to the exact cent and without measurement tolerances.

This is not possible for SF6 gas. Significant technical effort is required to measure flow or weight in the lower percentage range. Emission rates today are typically between 1 and 2%, and this means that the measurement tolerance is in some cases higher than the emission rate itself. For this reason, the mass balancing method is no longer practicable.

- In our case, unfortunately, the equipment is widely distributed, and it would not be feasible to conduct a survey of all the equipment owners. However, because the affected equipment is not normally refilled and no gas handling is necessary during the entire equipment lifecycle, there is no real need to record the data for all equipment.

The problem has been solved by the introduction of emission factors. Let us now look again at our two previous examples:

- Manufacturers

Manufacturing emissions = Processed quantity x Emission factor

The equipment manufacturer can usually choose between the emission factor and mass balancing.

- Among the operators of high-voltage equipment, the use of the mass balancing method to determine emission rates is limited to just a small number of reference systems. The association applies these emission rates to the total quantity of SF6 in high-voltage switchgear as emission factors for estimating the actual emissions. The vast number of medium-voltage switchgear systems is not recorded in the operators' monitoring procedure. In this context, the manufacturers specify what quantities of SF6 were sold with the equipment in Germany. This gives the inventory of SF6 contained in medium-voltage systems. The current inventory level is updated with the new sales quantities each year as well as the decommissioning data submitted in the operators' questionnaires. Based on the medium-voltage inventory calculated in this way, the associations apply an emission factor of 0.1% to estimate the annual leakage losses during operation.

Medium-voltage operating emissions = Medium-voltage SF6 inventory x 0.1% High-voltage operating emissions = High-voltage SF6 inventory x Specific high-voltage emission factor

Explanation of terms: - Emission factor

We talk about emission factors when this factor is predefined and used to calculate emissions.

- Emission rate

7 Please refer to the detailed explanations in the IPCC Guidelines 2006

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An emission rate is calculated from the reported emission quantities in relation to a reference quantity (such as inventory or annual consumption). The emission rate can also be used for a qualitative comparison of the switchgear components (this is not possible using an absolute value because of the variation in the quantities used to fill the equipment).

Recording the emissions produced during development, manufacturing, testing and commissioning The recording of emissions by the equipment manufacturers is part of the ZVEI questionnaire and will not be explained in detail here [see 1, 12]:

- Development and testing

- Production

- Commissioning

Recording the operating emissions The operators of SF6 equipment are no longer required to record the emissions individually. However, they may find it useful to record this data for internal purposes or for the reference systems. Recording data individually for each item of equipment refilled It is necessary to measure the refill quantity for each system for recording purposes. This can be done by: a. Weighing the SF6 container before and after refilling b. Measuring the flow directly Modern service units for refilling containers and evacuating gas are already equipped with corresponding measuring devices or can be retrofitted. However, a simple measurement using good-quality weighing equipment can serve the same purpose. Identical conditions must be ensured for the before/after measurements (e.g. by ensuring that the lid is on the cylinder for both measurements). For example, when weighing: Emissions = (Weight of SF6 cylinder before - Weight of SF6 cylinder

after) for all refill operations

Caution: To calculate the emission rate of a system, it is necessary to distribute the calculated emissions over the years since the last refill. The emission rate is always specified in relation to one year. Example: The emission rate is calculated as follows for a refill quantity of 5 kg, a fill quantity of 110 kg and a period of 4 years since the last refill:

Emission rate 100*4*110

5== %13,1 1.13 %

If the operator subcontracts its gas handling tasks to manufacturers or service providers, the subcontracted company must indicate the SF6 refill quantity on the invoice so that the operator can determine its specific emission rates.


Recording the emissions during decommissioning Medium-voltage When decommissioning medium-voltage switchgear, the operator or manufacturer responsible for decommissioning must record only the rated fill quantity according to the rating plate. The quantity actually removed will be lower, but the previous losses due to leakage have already been taken into account in the annual emission factor. The handling losses and the residual quantity on evacuation (approx 20 mbar) are estimated using a clear arithmetic emission factor of 1.5% in the evaluation carried out by the associations. Manufacturers themselves are increasingly performing gas extraction from medium-voltage switchgear, whether because they have received an order for a new system that requires them to decommission the old system properly, or whether the operators send the system together with the gas to the manufacturer, who then extracts the gas. An agreement has been reached that operators will indicate decommissioning in the monitoring system if they have extracted the gas, and manufacturers will make the corresponding specification in the monitoring system if they extract the gas. To summarise: operators of medium-voltage switchgear who do not themselves extract the gas at the end of the equipment lifecycle are not subject to any monitoring requirements. They merely document the transfer of the gas-filled equipment in a delivery note or receive confirmation from the manufacturer or the subcontracted company that the equipment has been decommissioned and the gas extracted. High-voltage The emissions during decommissioning are calculated in the same way as for medium-voltage equipment. The operator must declare only the quantities that have been decommissioned.

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Additional requirements of the Voluntary Commitment The Voluntary Commitment defines targets based on policy discussions. Target achievement will be verifiable by means of monitoring. The recording of SF6 data makes it possible to verify whether the SF6 is actually contained within a closed cycle.

End of life, Recycling

End of life, Recycling

BetriebBetrieb InbetriebnahmeInbetriebnahme

EntwicklungPrüfung

EntwicklungPrüfungProduktionProduktionHerstellung SF6

Herstellung SF6SF6

manufacturingDevelopment

Testing Production

End of Life, recycling

Außerbetrieb-nahme

Außerbetrieb-nahme

De- commissioning Operation Commissioning

Once the switchgear has been decommissioned, the SF6 is removed and then: • re-used, e.g. in new equipment, if the gas contains only low

levels of contamination, or • forwarded to the company's internal SF6 stock for subsequent

refilling if the quality is good, • transported by the decommissioner (usually the manufacturer) for

re-use in production, or • returned to the SF6 producer for reclamation as new-quality SF6

within the re-use (recycling) concept, or • destroyed by the SF6 producer if the SF6 quality is too poor to

consider recycling. The quantities extracted and directly re-used by the operator during maintenance do not need to be recorded separately under the Voluntary Commitment. The operator has then met the stipulated monitoring requirements.


Overview: "Who supplies what data and how?" MB = the mass balancing method EF = the emission factor method DEC = Decommissioning

Data Medium-voltage High-voltage

Manufacturing emissions Manufacturer: EF or MB Manufacturer: EF or MB

Development/testing/test bay emissions

Manufacturer MB Manufacturer MB

Emissions during commissioning

ZVEI:

Manufacturer EF

ZVEI:

Manufacturer EF

Operating emissions ZVEI:

EF on inventory

Associations (VIK/FNN):

EF on inventory

Emissions during decommissioning

Associations:

EF on decommissioned SF6 quantity (as per rating plate)

Associations:

EF on decommissioned SF6 quantity (as per rating plate)

Manufacturer's annual consumption

Manufacturer Manufacturer

Quantity sold Manufacturer Manufacturer

Inventory (installed quantity)

ZVEI based on manufacturer's specifications for quantity sold and all DEC specifications

Operator (usually as per rating plate)

Decommissioned SF6 quantity

Manufacturer or operator: whichever extracts the gas

Operator

Quantity returned to SF6 producer (Solvay)

Operator and manufacturer

Quantity returned from inventory to third party (e.g. to manufacturer)

Operator

SF6 received from operators (returned to manufacturer)

Manufacturer

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Data Medium-voltage High-voltage

Quantity received from manufacturers

Solvay

Quantity received from operators

Solvay

Emission rates from destruction and re-use

Solvay

Emission rates from re-use and destruction

Solvay: EF on returned quantity, distributed over the different processes (re-use or destruction)

Emissions from re-use and destruction for DEC quantity

Solvay

based on the specifications from manufacturers and associations regarding the ratio of total SF6 to SF6 from

DEC


The data entry sheet to be filled in by the operator

The monitoring carried out to date has already documented significant reductions in emissions [1]. Internal Data recording procedures are organised independently within the company, supported by the questionnaires issued by the associations. It may be useful to record data over and above the mandatory requirements for the following reasons: - Companies can assess the effectiveness of their emission reduction measures. - They can compare their own emission key figures with the sector key figures.

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- They can identify possible emission sources more easily and thus eliminate or reduce them more effectively.

- SF6 refills cause operators, for example, to incur unnecessary costs in the form of SF6 deliveries and additional maintenance work.

- SF6 leakages can represent a criterion for assessing the state of the system. A low equipment leakage rate thus indicates greater system availability and better supply reliability. Manufacturers can also use the emission key figures to assess the quality of their manufacturing processes in comparison with other companies.

- Environmental awareness, social responsibility, etc. Particularly for the large companies in the sector, whether manufacturers or operators, a positive corporate image is of great importance - not only because a lack of compliance could become public knowledge, but because monitoring is the only way that companies can effectively disprove unfounded accusations. Companies can also publish their successes and positive key figures in the annual environmental report or similar documents.

Sources and references

9 Sources and references

[1] www.sf6-energietechnik.de [2] Regulation (EC) No. 842/2006 and subsequent regulations of

the EU Commission; see links under [1] [3] IEC standards 62271-303, 60480, 60376 [4] Voluntary Commitment; download from [1] [5] BGI 753: safety information sheet for SF6 plant and equipment [6] Solvay page containing information on SF6 [7] Solvay re-use brochure [8] Dilo service equipment www.dilo-gmbh.de [9] G.A.S. Gesellschaft für analytische Sensorsysteme mbH SF6-

Messtechnik http://www.gas-dortmund.de/ [10] Solvay Fluor GmbH http://www.solvay-fluor.com/ [11] www.zvei.org [12] www.vde.com/fnn [13] www.bdew.de [14] www.vik-online.de [15] EU safety data sheet in accordance with Directive 2001/58/EC [16] Operating instructions for gastight drilling systems???? [17] ECOFYS Report "REDUCTIONS OF SF6 EMISSIONS FROM

HIGH AND MEDIUM VOLTAGE ELECTRICAL EQUIPMENT IN EUROPE", 27 June 2005, Sina Wartmann and Jochen Harnisch, Ecofys GmbH, Germany Download from [1]

[18] Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU), Federal Environmental Agency (UBA) ????

[19] German Ordinance on climate protection against changes caused by release of certain fluorinated greenhouse gases (Chemikalien-KlimaschutzVerordnung; the national implementation of Regulation (EC) No. 842/2006 in Germany) http://bundesrecht.juris.de/chemklimaschutzv/index.html

[20] www.en.wikipedia.org

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http://www.sf6-energietechnik.de/

http://www.dilo-gmbh.de/

http://www.gas-dortmund.de/

http://www.solvay-fluor.com/

http://www.zvei.org/

http://www.vde.com/fnn

http://www.bdew.de/

http://www.vik-online.de/

http://bundesrecht.juris.de/chemklimaschutzv/index.html

http://www.wikipedia.de/

335 3164-09-027-preparation doc en-version_1_01

Business

structure of sf6

sf6 quality

sf6 mixtures

reuse of sf6

sf6 service equipment

recovery regeneration

contents7 recovery of

inspection sf6 reclamation