sf6 features and applications

Office Adress: Falkentaler Steig 76aD-13467 Berlin, Germany

[email protected] Phone: +49 30 404 35 30

Dipl. Ing. Wolfgang DegenSenior Technical Consultant High Voltage Substations, SF6Mobil: +49 171 550 1465

SF6 FeaturesArc extinguishing and

insulating Medium

Wolfgang Degen Senior Technical Consultant

Outlook

Properties of Sulphur Hexafluoride SF6SF6 and its Environmental Impact

Relevant documents for the use of SF6EU-Regulations

Use/Applications of SF6Mixtures and Replacements


Physical properties:

Properties of Sulphur Hexafluoride SF6

Excellent physical Characteristics for use in electricalEquipment

colourless, odourless and non-inflammable gasnon-toxic gaschemically inerttemperature-resistant (up to approx. 500 C)5 times heavier than air ( 6.08 g/l )speed of sound: approx. 1/3 compared to airhigh compression efficiencyhigh specific heat and heat transport capability


breakdown voltage: approx. 2.5 times higher than airhigh electron affinity (electron negativity) of the SF6 moleculeno severe drop of electric strength even with slight air mixturesexcellent arc quenching capability (100 times more effective than N2high speed of stabilization of the break

Electrical properties:

Excellent Characteristics for use in electrical Equipment

Properties of Sulphur Hexafluoride SF6


Use/Applications of SF6 in ElectricalEquipment

SF6-ReUse-ConceptA contribution on the sustainability of SF6


Negative Characteristics of SF6SF6-gas is a fluorinated greenhouse gas

SF6-gas is one of the six greenhouse gases besides: carbon dioxide, methane, nitrous oxide, HFCs, PFCs whichneed to be kept undercontrol according to the KyotoProtocol

SF6-gas has the highest global warming potential (22.900)

SF6-gas has a lifetime in the environment of 3.200 years

SF6 and its Environmental Impact

Due to its negative Environmental Impact SF6 isincreasingly in the focus of Interest


Greenhouse Effect

Courtesy: DOE. 2001.



Kyoto Protocoll

(effective as of February 2005)

The Kyoto Protocol was signed by 136 states = 85 %

of the worlds populationcovering 62 % of the total CO2

- emissions.

Objective:Reduction of global emissions of greenhouse gases by 5.2% calculated as average on the five-years period of 2008-2012compared to the emissions of the year 1990.


Kyoto Protocol (December 1997)

Kyoto Conference Protocol agreement:

6 major greenhousegasses included

3 Energy/ humanrelated CO2, CH4 and N2O

3 Industrial relatedHFCs, PFCs and SF6

empowered 2005-02 after 55 states incl. Russia signed the document

Reduction Increaseof greenhouse gases

Change from 2008 2012 in comparison to 1990


Kyoto Protocol - Requirements for each Party

Kyoto Protocol To have a National system for estimation of emissions,

by source, not later than 1 year prior to the start of thecommencement period 2007

To reduce average emissions of total of all gasses by5.2% below 1990 levels in period 2008-2012

To report annual inventory of emissions by source & removal by sinks

To establish stocks for base year 1990 (1995 for SF6) and estimate changes in stocks for subsequent years

On Behalf of CIGRE WG B3-18


Why is SF6 important?

From: Hansen et al., PNAS, 2001/EPA Conference 2006

Growth rate of climate forcing by well-mixed greenhouse gases (5-year mean, exept 3-year mean for 1999 and 1-year mean for 200) O3 and stratospheric H2O, which were not well measured,

are not included.


SF6 banked in electric equipment:

Until 1995 5) 27 000 tonsRate of banking in 1995 5) 2 000 tons / yEstimated rate of banking in 2005 1 200 tons / y

SF6 banked in 1999 ~30 000 tonsSF6 banked in 2010 45 000 tons

Electrical SF6 and environment

5) M. Maiss, C.A.M. Brenninkmeijer, Atmospheric SF6, trends, sources and prospects,Env. Sci. & Tech., vol. 32, N. 20, pp. 30773086, 1998


Man-made greenhouse emissions in 1999:

Electrical SF6 and environment

Emissions of electrical SF6 are negligible!

Greenhouse gas [tons/y] [Gtonseq/y]

CO2 26 60%CH4, N2O, CFCs, ... 16 40%FC and SF6 0.07 0.16%Total emissions ~40 100%

"Electrical" SF6 2200 0.05 0.1%

"Electrical" SF6 in 2010 1000 0.02 0.05%

39th CIGRE Session, Paris, 25th 30th August 2002


Source: EPA 2003

Annual Sales of SF6 by End-Use-Application


- 33%

- 15%

Total SF6 Sales by End Use from 1996 to 2003

Source: EPA 2003

appr. 55,000 tons


SF6 Sales by End Use of 2003

Electric Utilities (24%)

Orig. Equipment Manuf. (54%)

Magnesium Industry (4%)

Electronics Industry (13%)

SF6 Adiabatic Properties (0%)

All Other Uses (5%)

Source: EPA 2003


Use/Applications of SF6

Accelarator

AWACS Aircraft

Medical technology: Radiation unit

Semi-conductor industry


04.07.2007 04.07.2007

04.07.2007 04.07.2007

Magnesium die-casting forquantities >850 kg/year.

Consequences EC: Open SF6-Applications are prohibited and/or replaced!



Losses duringSF6-Handling

Recommendationacc. to Cigr:

SF6-Handling-Guide

SF6 leaks of SubstationsRecommendation acc. to

IEC 62271-303Leak rate:

HV: 0.5% / yearMV: 0.1% / year

70% to 90 % of the SF6-Emissions are caused byinadequate gas handling

SF6-Emissions in the Electrical Application


Handling Leakage


SF6 Emission Projection in Europe*

* Source: Reductions of SF6 emissions from electrical high and medium voltage equipment in Europe, Ecofys, 2005

Emission Projections 1995-2020 in the EU-25+3


Projected Development of SF6 Bankin Switchgear*

Medium voltage (up to 52 kV

High Voltage (above 52 kV)

*Source: Reductions of SF6 emissions from electrical high and medium voltage equipment in Europe, Ecofys, 2005

Projected Bank Development 1995-2020 in the EU-25+3


SF6 and Climate Change

Kyoto Target for the European Community (EU) 1990 2010:Reduction of all GHG Emissions by 8 % (Burden Sharing)

Source: EEA

Greenhouse Gas Emissions

Target Path 2010

I

n

d

e

x

(

b

a

s

e

y

e

a

r

=

1

0

0

)


SF6 and Climate Change

All SF6 in EU-15 contributes < 0,2 % to the total GHG EmissionsFraction of SF6 from Electrical Equipment: < 0,05 % (Gross)Closed Life Cycle Application

Source: -EEA, 2004-Ecofys 2005


Kyoto ProtocolSF6 as a Greenhouse Gas

Over a 100-year period, SF6 is 23,900 times more effective at trapping infrared radiation than an equivalent amount of carbon dioxideWith an atmospheric lifetime of 800 - 3,200 years, SF6 is also a very stable chemicalPresent contribution to global warming is 0.1% (and estimated at 0.01% in 100 years)Atmospheric concentration increasing 7-9% per year (space shuttle measurements) between 1985-94, showed that this was the largest increase of any greenhouse or ozone gas

Now development slowed down


0

100

200

300

400

500

600

1990 1995 2000 2005 2010Year

A

m

o

u

n

t

o

f

E

m

i

s

s

i

o

n

[

t

o

n

]

0

2000

4000

6000

8000

10000

12000

14000

16000

S

F

6

T

o

t

a

l

A

m

o

u

n

t

o

n

S

i

t

e

[

t

o

n

]

ManufacturersUtilitiesSF6 Total Amount on Site

Emission Reduction

Example: SF6 Emission in JapanManufacturers & Utilities


Conclusions of the Ecofys -Study*

There are no viable alternatives to SF6 due to its unique properties in electrical equipment for transmission and distribution of electricity available currently. SF6 is indispensable for sake of a secure electricity supply.SF6 emissions from electrical equipment contribute less than 0,05 % to the total European GHG effectVoluntary actions resulted in emissions reduction of 40% compared to 1995LCAs prove that SF6-technology can even relieve the overall balance of GHG emissionsRenewed increase of emissions caused by increasing bank can be prevented by consistent continued voluntary actions by 2020. By exhausting the reductions potentials emissions even can be further reduced

*Reductions of SF6 emissions from electrical high and medium voltage equipment in Europe, Ecofys, 2005


Ionization and Excitation

Ionization, the process of removing an electron from an atom or molecule

Excitation, the condition in which an electron moves to a higher, unstable energy level. Relaxation results in the electron returning to a stable energy level, releasing the excess energy as a photon

Photo ionizationNuclear particle impactElectron impactThermal ionizationFrictional or mechanical ionizationChemical


Photo Excitation

Electron raised to higher energy state, they returns to ground state, emitting a photon

Relaxation time


Electron Impact Ionization

Ionization:He He+ + e

HeHe+

Most important secondary process in breakdown of gasesElectron is accelerated in an electric field until its energy is equal to, or greater than the ionization potential of the molecule it strikes


Ions Vs Electrons

Mass of an electron vs. mass of SF6 1 to 125,000 (1500 lbs vs 95,000 tons)

vs.


Free Electrons in aNon-homogeneous Gap

Free electrons repelled from negative rod

Created by ionization processes Exist everywhereCreate radio noiseImpact us in many ways


Mean Free Path

Longest free way without collision


Accelerated Electron has Collisions


Higher Voltage (or longer path), Photo Excitation


Electron Avalanche by Impact of Electric Field

E

++

+

+

+

+

+

+

++

+

+

+

+

+

++

++

+

+

++

++

++

+ +


Many Collisions Produce Photons


Critical Field, Lightning Impulse

E kV/m

Distance

E critical

Process continues until the field strength cannot accelerate electrons to sufficient velocitiesWhen the critical field is at about 50% of the gap distance - flashover


Electrons and Ions, Comparing SF6and N2

Mass of an electron changes with velocity, at rest = 9 x 10-28 grams

Mass of a hydrogen atom = 1.7 x 10-24 grams euqals 1888 times the mass of e

Mass of nitrogen molecule = 2.32 x 10-23Mass of SF6 molecule = 1.16 x 10 -22

SF6 125,000 times the mass of eSF6 five times the mass of nitrogen

Ionization potential of Nitrogen 15.6 eVIonization potential of SF6 15.6 eV


Mean Free Path

Electrons require a certain distance to accelerate to sufficient velocity to have enough energy to cause ionization.The average distance between molecules is a function of the collision diameter and density (mean free path).Collision Diameter

N2 16.1 ASF6 36.5 A

Mean Free PathN2 6 x 10-8 mSF6 2.5 x 10-8 m


Quenching Capacity of SF6

SF6 Features


SF6 Features

50 Hz breakdown voltage in a hogeneous field as a function of the distance between electrodes at

various gas pressures (ETZ Supplement 3 [1966])


Summary, why is SF6 a Good Insulating Gas?

Molecule is large due to its affinity towards electronsFairly high ionization potential

The breakdown strength of air is dramatically increased by the addition of small quantities of SF6. In contrast, air has only a limited influence on the breakdown strength of sulfur hexafluoride. The addition of 10 % of air by volume reduces the breakdown voltage of SF6 by about 3 %, the addition of 30 % air by about 10 %.


SF6 Replacement

Gas Mixtures

First used in CBs for low temperature applications

Gas mixtures now being used on GIL applications

10% or 20% SF6 with Nitrogen is typical solution

Switching performance still limited

Special gas handling facilities required

For most applications mixtures are not attractive for GIS

Gas Mixtures

First used in CBs for low temperature applications

Gas mixtures now being used on GIL applications

10% or 20% SF6 with Nitrogen is typical solution

Switching performance still limited

Special gas handling facilities required

For most applications mixtures are not attractive for GIS


SF6 Replacements

Relationship between GWP and dielectric strength of various Gases


Air as Insulation Medium

Increasing the dielectric strength by using air and composite coating for insulation

Principle


100 % SF60,5 MPa

400 mm

Nitrogen for Insulation instead of SF6 ?

GIS-Dimensions based on approximated breakdown voltages (coax. cylinders, without additional effects)

20 % SF6 / 80 % N2 0,7 MPa

400 mm

100 % N2 2,0 MPa

400 mm

20 % SF6 / 80 % N20,5 MPa 560 mm

100 % N20,5 MPa

1600 mm

N2

?


Insulation Condition Monitoring Method

As there are significant market impediments to taking a substation out of service during the insulation assessment, the method had to be non-intrusive. This led to selection of the partial discharge (PD) method for detection of dielectric problems. These are based on detection of different signals produced by PD:

Ultra High Frequency (UHF) voltage signals

Acoustic Emissions

SF6 Chemical decomposition.


Electric Industry Germany: Voluntary Commitment on SF6Essentials SF6 emissions should be avoided wherever

possible Personnel dealing with SF6 has to be

informed and trained Maintenance work is carried out by qualified

personnel only Monitoring: Operators and manufactures

report on a yearly base on the used SF6 to the Federal Environmental Agency

Manufacturers of electrical equipment commit themselves to taking back equipment containing SF6 and to reclaim SF6 themselves or reclaimed the SF6 by a certified companyState-of-the-art maintenance equipment has to be used for SF6-gas handling


Comprehensiveprovisions lead

to furtherreduction of

SF6-emissions


Electric Industry in Germany reacts with: VoluntaryComittment on SF6


Targets on emission rates of

SF6 for switchgear

systems and switching devices:


Relevant documents for the use of SF6

< 1 < 1 ppmppm byby weightweightHydrolyzableHydrolyzablefluoridesfluorides termsterms of HFof HF

< 0.3 < 0.3 ppmppm byby weightweightAcidityAcidity, in , in termsterms of of HFHF

< 10 < 10 ppmppm byby weightweightMineral Mineral oiloil

< 15 < 15 ppmppm byby weightweight(0.012 % vol) (0.012 % vol) 4040CCHH22OO< 500 < 500 ppmppm byby weightweight(1.0 % vol)(1.0 % vol)

CFCF44

< 500 < 500 ppmppm byby weightweight(0.25 % vol)(0.25 % vol)

AirAir

IEC (International Electrotechnical Commission) is the worldwide leading organisation which defines and publishes international electro-technical standards. The IEC 60376- standard for new SF6is the respective basis for national standards.

Specification of technical grade SF6 for use in electrical equipmentThe standard stipulates among others:Properties of SF6Quality and limiting valuesEnvironmental aspectsGeneral procedure regarding transport and storage

Important: As soon as the gas is taken from the cylinder in which it has been deliveredin, it is considered to be used gas!



IEC 60480 refers to used SF6

The standard stipulates among others:

Handling of used SF6Precautions for maintenance workLimiting values for direct reuseEnvironmental aspectsGeneral procedure regarding transport andstorageRe-use

International Standard for used SF6

IEC 60480: Relevant Standard for Maintenance Staff of Substations


Relevant documents for the use of SF6Limits according to IEC 60480

Medium voltage

- 23 C dew point

High voltage

- 36 C dew point


International recommendation for SF6-HandlingCIGRE Handling GuideThe meaning of the French word CIGRE is Conseil International des Grands RseauxElectriques.

CIGRE is the international committee of the electrical energy supply and deals with both technical and environmental aspects worldwide

The Practical SF6 Handling Guide provides technically detailed recommendations on SF6:

CommissioningFillingGas qualityGas analysisReclaimingLife cycle



New: IEC 62271-303Use and handling of sulphurhexafluoride SF6

Replaces the IEC 61634 and Cigre Guide 276 Part 303

SF6 handling during installation, commissioning or recommissioningSF6 handling during normal service lifeSF6 recovering and reclaiming during maintenanceDismantling of SF6 electric power equipment at the end-of-lifeRecovery and reclaiming of SF6 at the end-of-life of sealed pressureDescription of SF6 handling equipmentPortable devices for gas measurement

Main content:



EU-Regulations

EG directive on Fluor gases 842/2006Valid for: Fluorinated greenhouse gases

- Fluorcarbon = HFC(quenching agents, cooling agents)

- Fluorcarbon PFC- SF6-gas

Aims: Limitation and reduction of emissions for fluorinated greenhouse gases, gradual abandoning of R134a cooling agent for air-conditioned cars

Purview: EU (25 countries) + Norway, Switzerland and IcelandEffective as of: 14th June 2006, directly valid after publication in

all member countries , no incorporation into national legislation required


EC Regulation No. 842/2006 on Certain Fluorinated Greenhouse Gases

Most important articles/content, applicable for high-voltage switchgear >1kV

Penalties13Promotion of alternatives11Review10Placing on the market9Control of use8Labelling7Reporting6

Minimum requirements

Training and Certification5Recovery4Containment3

EC Article 175(Minimum requirementsin EC regulation. National implementation in member states of EC)

EC Article 95(Internal EC market)

Title of the articleArticleno.

EU-Regulations


Art. 4) The gas must be reused and recycled in accordance with the correspondingregulations during gas recovery. The gas handling must be carried out from qualified personnel

Art. 5) Any gas work on devices or plants as well as reclaiming and treatment of gas is to be carried out by trained and authorized personnel only.

Art. 6) Companies producing, importing / exporting more than 1 ton of greenhouse gases per year must give a report to the EU commission.

Art. 7) On high voltage switchgear (> 1 kV) the utilization of the greenhouse gas used must be indicated.

Tasks for the implementation of the directive:Working out of labelling regulationsMinimum requirements for the training and certification of companies and their personnelDefinition of reportingRules on penalties. These penalties must be effective, proportionate and

dissuasive.

EG directive on Fluor gases 842/2006

EU-Regulations


Labelling of SF6-filled Equipment inside the manual

- Specification in VO Nr 842/2006, Article 7 (1):Die mitgelieferten Bedienungsanleitungen enthaltenInformationen ber die fluorierten Treibhausgase, einschlielichihres Treibhauspotenzials.

- Recommandation in implementation guide of T&D Europe for the Text inside the manual:

Das Betriebsmittel enthlt das vom Kyoto-Protokoll erfasste fluorierte Treibhausgas SF6 mit einem Treibhauspotenzial (GWP) 22 200. SF6 muss zurckgewonnen werden und darf nicht in die Atmosphre entlassen werden. Bei dem Umgang und der Handhabung mit SF6 ist IEC 62271-303: High-voltage switchgear and controlgear Part 303 Use and handling of sulphurhexafluoride (SF6) zu beachten.

DE

This equipment contains the fluorinated greenhouse gas SF6 covered by the Kyoto Protocoland with a global warming potential (GWP) 22 200. SF6 shall be recovered and not releasedinto the atmosphere.

For further information on use and handling of SF6 please refer to IEC 62271-303: High-voltage switchgear and controlgear Part 303 Use and handling of sulphur hexafluoride (SF6).

EN

EU-Regulations


Marking of electric switchgear with an additional labelpointing out that SF6 which is contained in the switchgear must be recycled and not released into the atmosphere.

On the one hand, reference to the use of SF6 and its environmental influence iscurrently made in the documents for switchgear

Gas monitoring diagram (information of SF6quantity and pressure per gas compartment)

EU-Regulations

Contents of Manual

Labelling art. 7 acc. 1494/2007Contents of the EU directive on F-gas- Labelling, article 7 -

Operating manual (information on the global warming potential of SF6)


Labelling art. 7 acc. 1494/2007Contents of the EU directive on F-gas- Labelling, article 7 -

and on the other hand directly on the GIS operating panel.

According to the directive on F-gas the SF6 switchgear shall beprovided with anoter label in addition to the already existinglabels. The final version still needs to be defined.

Name plate(with Closed pressure system note and information on SF6 quantity)

EU-Regulations

Contents of Operating Panel


Article 5 Training and Certification fluorinated greenhouse gases must be recovered by specially trained

personnel Proposal on the training programme made to the European Parliament

by 14th July 2007 at the latestIntroduction: July 2008 provisional certificatesMinimum requirements

Determination of who is authorized to train (companies and personnel evaluation body)

Determination of who is authorized to certify (certification body) Acceptance of certification programmes and certificates in other

member states

EU-Regulations

(1) A certification body as referred to in Article 5 shall issue a certificate to personnel who have passed a theoretical and practical examination organisedby an evaluation body as referred to in Article 6, covering the minimum skillsand knowledge set out in the Annex.

f Additional Commission Regulation (EC) No. 305/2008 Requirements in detail: Article 4 Issuance of certificates of personnel


f Additional Commission Regulation (EC) No 305/2008 Requirements in detail:

ANNEX

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

4 For instance IEC 60376 and IEC 60480

TSF6 quality, according to the relevant industrial standards44TUse of SF6 in electic power equipment (insulation, arcquenching)3TPhysical, chemical and environmental characteristics of SF62

TBasic 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 provisions of Regulation (EC) No. 842/2006.

1Test TypeMinimum Knowledge and SkillsNo.

EU-Regulations


f Additional Commission Regulation (EC) No 305/2008 Requirements in detail:

ANNEX


TRe-use of SF6 and different re-use categories11POperation of tight drilling systems, if necessary10POperation of SF6 recovery equipment9TStorage and transportation of SF68PRecovery of SF6 and SF6 mixtures and purification of SF67

PChecking the SF6 quality6

TUnderstanding of the design of electric power equipment5Test TypeMinimum Knowledge and SkillsNo.

EU-Regulations


f Additional Commission Regulation (EC) No. 305/2008 Requirements in detail:

ANNEX


TMonitoring of SF6 and appropriate data recording obligations undernational or Community legislation, or international agreements

14

TNeutralising SF6 by-products13

PWorking on open SF6 compartments12Test TypeMinimum Knowledge and SkillsNo.

EU-Regulations


f Additional Commission Regulation (EC) No305/2008 Requirements in detail: Article 4 Issuance of certificates of personnel

The certificate shall contain at least the following: the name of the certification body, the full name of the holder, certificate number, the date of expiry if any; the activity which the holder of the certificate is entitled to perform issuing date and issuer's signature.

EU-Regulations

Article 8 Conditions for mutual recognition

(1) Mutual recognition of certificates issuedin other Member States shall apply to certificates issued in accordance with Article 4.

(2) Member States may require holders ofcertificates issued in another MemberState to provide a translation of thecertificate in another official Community language.


Article 6 Reporting

Additional regulation no. 1493/2007Article 6 of the regulation no. 842/2006 stipulates that producers, importers and exporters of fluorinated greenhouse gases will have to submit annual reports on certain activities, starting as from 2008 (for 2007).

The following form is to be filled in by producers who produce, import or export more than one tonne of fluorinated greenhouse gases per year.

EU-RegulationsReporting- document within the EU


SF6-filled Equipment

GIT

GIS

AIS

MTS


Characteristics of SF6-filled Equipment

1. Introduced since the mid 60s2. Continuous improvement make them still state-of-art3. More compact design, in particular GIS and MTS4. Reduced space 1/7 of conventional air insulated

substations (AIS)5. Extended life time (approx. 30-40+ years )6. Very reliable equipment7. .

but little Experience when the End of Life Timeis reached !


Week Month Year 10 Years

F

a

u

l

t

F

r

e

q

u

e

n

c

y

FORECAST

Exchange

Repair0

Time of Operation

Stre

amer

Dev

elop

men

t?Pa

rtial

Dis

char

ges?

Sing

le P

artia

l Dis

char

ges

Putti

ng in

to o

pera

tion

Graph1 08.12.2005 13:24 J.I. Baumbach, Institut fr Spektrochemie und Angewandte Spektroskopie, ISAS, Dortmund

Lifetime with respect to FaultsBathtub Diagram

10 Years 20 Years 30 Years YearsCommissioning

Maintenance

Time of Operation

F

a

u

l

t

F

r

e

q

u

e

n

c

y


Different Type of Faults in SF6-filled Equipment

Insulating parts and Contacts


InsulationFailure57.3%

MechanismTrouble18.1%

Gas Leak12.4%

Others12.3%

CIGRE Task Force 23-102(1998)Three(3) Major Failures cover almost 90% of all GIS Failures

Statistics of GIS Major Failures in the World

Mayor Part of Insulation/Electrical Failures in GIS due to Discharges


Origin of SF6 Impurities

Air, H2O, HF, SO2, SOF2, SOF4, SO2F2, SF4, CF4Metal dusts, particles AlF3, FeF3 WO3 CuF2,

Melting & decomposition of materials

INTERNAL ARCMetal dusts, particlesMechanical erosion

H2O, HF, SO2, SOF2, SOF4, SO2F2,CuF2, SF4, WO3, CF4, AlF3

Switching arc erosion IN SWITCHING EQUIPMENT

HF, SO2, SOF2, SOF4, SO2F2

Partial Discharges : Corona and Sparking

INSULATING FUNCTION ONLY

Air, Oil, H2OLeaks and incomplete evacuationDesorption

DURING HANDLING AND IN SERVICE

POSSIBLE IMPURITIESSOURCES OF IMPURITIESSF6 SITUATION & USE

SF6 taken from electrical equipment in operation contains several kinds of impurities. Some of them were already present in the new gas, as a result of the manufacturing process. The nature of these impurities and the quantities admissible are

reported in the IEC 60376 and IEC 61634.


Study on the Influence of DecompositionProducts on Epoxy Resin

Experimental SetupSF6-filled Chamber

(Institute of High Voltage and Electrical Equipment, Dortmund)


Flushover at non-agedepoxy resin sample

Flushover at agedepoxy resin sample

Reduction of Surface Stabilitydue to By-Products

Sample before and after Experiment


Visible Inclusions of By-Products in Epoxy Resin Spacer


Is it possible to diagnose electrical faults by analysingthe SF6 Quality ?

Important Question forMaintenance Engineers


SF6-Decomposition Scheme

possible surfacereactions:


Necessary Precautions with used SF6

Under certain conditions, the SF6 gas used in electrical equipment can contain decomposition products with potential toxic properties. Decomposition can occur by two main routes: electrical discharges and heating.Electrical discharge decompositionAny form of electrical sparking in SF6 gas will tend to break the molecule down into its constituent parts. Following this chemical breakdown however, the vast majority of the breakdown products recombine to reform SF6.The presence of oxygen and water vapour (and metal surfaces), render other reaction paths possible. Some of these paths lead to the appearance of small quantities of by-products, which may have toxic properties.Thermal decompositionAbove about 500C SF6 gas begins to break down into its constituent elements. Such temperatures may result, for example, from fires,heating elements, cigarette smoking etc.The presence of metallic surfaces can enhance this effect through catalytic reactions.


CIGR Maximum Tolerable ImpurityLevels for SF6

SF6-PercentageDecompositionProductsMoisture

3%

< 2,000 ppmv

> -5C td

Maximum tolerable impurity level in

equipment

Recycling Guide: 23.10 Task Force, Page 20


Maximum Tolerable Impurity Levels forRe-Use of SF6

Recycling Guide: 23.10 Task Force, Page 20


The gases SO2 and SOF2 are particularly suitable..Their relative abundance isdetermined by stoichiometryof the reactions by which theyare created and is approx. (SO2+SOF2/HF = 1:2 to 1:4)Therefore if the sum of SO2+SOF2 is measured, thetotal concentration, incl. HF isabout 3 to 4 times higher

Calculation of Total By-Products usingSO2/SOF2-Residuals

Recycling Guide: 23.10 Task Force, Apendix 2.2, Page 50


Maximum acceptable Impurity Levelsfor Re-Use of SF6

Literature: Guide for the preparation of customised Practical SF6 Handling Instructions, CIGRE Task Force B3.02.01, August 2005, page 18

For use in HV equipment incomplete range of pressuresSimilar Values to CIGR SF6-Recycling Guide given by

IEC 60480


Determination of single By-Productsusing IR Spectra Analysis)

G.A.S. Laboratory instrumentation, qualified chemist needed!


DecompositionProducts > 1 Ln/h

SF6 - Percentage 10 Ln/h

Moisture 40 Ln/h

Todays Situation of Devices to check the SF6-Quality

Disadvantages single Devices: Very time- and SF6-consumption high !


Temperature/Density Distribution of SF6 in GIS

Temperature boundary conditionsCIGRE A3-105 Paris 2008 Thermal-Network Simulations and Computational Fluid Dynamics for Effective Gas Leakage Detection in SF6 Switchgear, Lukas GRABER* ETH Zurich Switzerland, Thomas THRONICKER TU Dresden, Germany


Early SF6 Leakage Detection Method

Thermal Network

Solar raditionAmbient temp.Load current

Model

CFD

GIS or Circuit-Breaker with monitoring

Thermal Network

Alternative: Measurement of Temperature Distribution

Leakage

Pmeasured

PfilteredPmodeled

SF6

The calculation of the transient gas temperature distribution is part of the Computational Fluid Dynamics

(CFD) model.


Early SF6 Leak Detection

Early detection of small gas leakages and accurate measurement of a yearly leakage rate is not an easy task. Sensors of necessary precision are available but the signal shows significant noise caused by sensitivity to mean gas temperature and to the exact distribution of temperature. A two-level model filters the signal from such deterministic disturbances.Such a model-based filter can reduce the density fluctuations at the position with highest fluctuation from originally 4.4 % to 0.7 %. This is expected to reduce the time to detect a leakage by around the same factor. A density measurement signal treated in this way also allows to measure more precisely the yearly leakage rate.


SO2- Determination as stable Decomposition Product

Electro-chemical SensorSO2/SOF2

- precise SO2- quantification- 1 year life time- used in SF6-Breaker-

Analyser- wide error of measurement- life time: one measurement

SO2-Detector tubes


3-in-1 Device: Decomposition Products via SO2/SOF2-content equivalent Moisture (C Dew Point / ppmv/ppmw) SF6-Percentage (%)

Automatic and immediate evaluation of resultsacc. to CIGR/IEC or company standards!

SF6-Breaker-Analyser to test the SF6-Quality


Main Advantages of the SF6-Breaker-Analyser

One gas connectionEasy one-click operationNo consumablesStorage of 150 measurementson memoryBattery operated (max. 8 hours)Internal mass flow controlModular System (operation with 1,2, or 3 sensors)Measurement within max. 7 minTotal gas consumption 0.4 Ln/min and 2.8 Ln per measurement

SF6-Breaker-Analyser fulfils maintenance staff requests !


Quick results on SF6-Quality and hence GCB Condition


Positive Impacts of SF6-Breaker-Analyser

Detect Electrical faults at early StageDetect Electrical faults at early Stage

Change Maintenance Strategy to CBMChange Maintenance Strategy to CBM

Prevent down timesPrevent down times

Increase asset LifetimeIncrease asset Lifetime

Reduce SF6-consumption and maintenancetime

Reduce SF6-consumption and maintenancetime


SF6 as a Greenhouse Gas

Over a 100-year period, SF6 is 23,900 times more effective at trapping infrared radiation than an equivalent amount of carbon dioxide.

With an atmospheric lifetime of 800 - 3,200 years, SF6 is also a very stable chemical.

Present contribution to Global Warming is 0.1% (and estimated at 0.01% in 100 years)

Atmospheric concentration increasing 7-9% per year (Space Shuttle measurements) between 1985-94,showed that this was the largest increase of any greenhouse or ozone gas

Now development slowed down


No legislation foreseenHandling Guidelines and Requirements defined

Corporate programsThe ReUse of SF6Life Cycle Assessment

Government programsUser Agreements

EPACAPIEL

What to do about the high GWP of SF6?

nrcsHighlight


New gasChecking the state of gas

SO2 decomposition products H2O Air Oil

Electricalapparatus

good

ProducerSOLVAY

ProducerSOLVAY

Incineration

SF6 servicing unit

SF6 servicing unit

Normal Case

Special Case

Exceptional Case

The SF6 ReUse Program

Principle Solvay, GERMANY


Product Specification and IEC 376 Specification for new SF6

Comparison of Solvay and IEC 376 product specification for new SF6, analysis of liquid phase


Determine gas qualityRemove SF6 from electrical enclosureFilter contaminantsRe-analyzeRe-introduce SF6 into enclosure

The SF6 ReUse Program Normal Case

Solvay, GERMANYDilo SF6 handling chart


Contact a supplier (e.g. Solvay company) to receive sampling kitGas is analyzed to determine suitability for reclaimingCompany sends used SF6 back to Solvay in specially marked cylindersWhen a sufficient quantity is obtained, used gas is to be sent back to Solvay Fluors production facility in GermanyUsed SF6 is fed back into virgin SF6production streamFulfills all requirements of virgin gas

The SF6 ReUse Program:Special Case

Solvay, GERMANY


Systemlength 1 km Palexpo, Swiss, 20% SF6/80% N2Undergound Part of a GIL / Overhead Line

GIL 300 kV Tunnel Installation


Provides comprehensive consideration of entire power supply system. Looks beyond the environmental view limited to the greenhouse potential of a unit of SF6

Life Cycle Assessment is directed to allrelevant environmental criteria

Life Cycle Assessment


LCA System study: Energy Supply without / with SF6-Technology

Object of the life-cycle assessment is the supply of electric power using different switchgear technologies. First, switchgear bays for the voltage levels 380 kV, 110 kV and 10/20 kV are studied. Based on this, a practical urban power supply system is assessed, the City of Wrzburg, Germany. The functional unit is the useful electrical energy per year. The studies are based on conditions in Germany. The technologies considered reflect the current state of the art. The power output in the various scenarios is equal; for this reason, its generation is ignored.


Example: Municipal Energy Supply City of Wrzburg/Germany

130.000 inhabitants40 km2 area

load density 0,2 ... 4,3 ... 20 MW/km2Demand of the first year 400 GWh

lifetime of 30 yearsload increase 1,5 % p.a.

LCA System study: Energy supply without / with SF6-Technology


AIS Technologyfour substations on outskirts

GIS TechnologyThree substations in the city

Alternativ with GIS

City of Wrzburg

LCA System study: Energy Supplywithout / with SF6-Technology -



PrimaryEnergy

Space Consumption

Global WarmingPotential

Acid Rain Potential

NutrificationPotential

- 27%

- 86%

- 21% - 19%- 29%

GIS reduces all potential environmental impacts studied



Conclusions: Use of SF6 leads to considerable environmental advantages To achieve any GHG benefits from using GIS will require a

very strict SF6 management maintaining very low emissions during service and maintenance of the equipment and recovery and reuse of the gas after decommisioning.

However, the results are not necessarily transferable. Other scenarios of power generation, extremely low

utilization of the capacity of the power supply system, extremely high SF6 losses, other switchgear technologies or power supply systems in rural areas may lead to different results.

Technical and logistical prerequisites for this effort already exist.


Responsible handling leads to the reduction of SF6 Emissions

Correct Disposal

Improved SF6 Handling Practices CIGRE SF6 Handling Guide

Reduction Potential

Re-use of SF6 SF6 Analysis

Effective quantative Leak Detection

On-site SF6 Leak Repair

Replacement of Old Equipment


Responsible use of SF6 Example: SF6-handling in operation

evacuate with a suction unit ...

or fill in a transport container for used SF6 for re-cycling

check SF6 qualityuse a mobile re-cycling

equipment

re-fill switchgear ...

Avoiding emissions by using proper equipment


Responsible use of SF6 (Development)

DILO, Germany

Mobilegascart

for collecting of used gas

Mobilegascart

for collecting of used gas


Responsible use of SF6 (Tightness testing)

TestingPressure and Gas Tightness

Routine Test with Helium


transportable SF6 maintenance

cart

transportable SF6 maintenance

cart

Responsible use of SF6(Reuse)

DILO, Germany


SF6 Handling Service Units

portable SF6 Service - Units

DILO, Germany


Regeneration of used SF6

Separator Station ( SF6 - N2 )DILO, Germany


Regeneration of used SF6

Cleaning Station ( SF6 decomposition products )

DILO, Germany


SF6 Handling Remaining SF6 Gas depending on Evacuation-Pressure

evacuation-pressure (mbar)

r

e

m

a

i

n

i

n

g

S

F

6

(

k

g

)

Example:3-phase CB

Volume:appr. 7000lNom. Pressure:

6,6 bar abs.SF6: appr. 300 kg

Density: 43g/l

When opening a 420kV 3-phase cicuit-breaker at evacuation-

pressure of 20 mbar appr. 1 kg SF6 would escape

1 mbar

20 mbar

50 mbar


Laboratory Analysis of Used SF6Because of the introduction of the SF6 ReUse - Concept, Solvay Fluor offers their customers an analysis service for used SF6 (analysis performed at a nominal fee). However used SF6 can not be specified according to IEC 376.The following impurities in used SF6 can be detected by Gas chromatographic analysis according to IEC 376

Impurity in Limit of detectionused SF6 in ppm by weight (LOD) (precision

+ / - 3 % rel.)

Oxygen (O2) 1Nitrogen (N2) 1Carbon Dioxid (CO2) 1Tetra Fluoro Methan(CF4) 1Thionyl Fluoride(SOF2) 1Sulphuryl Fluoride (SO2F2) 1Fluorinated Hydrocarbons, e.g. Oxifluorides 10


Generally recognized, that there are no suitable alternatives for SF6 in the short or medium termNo plans foreseen to legislate phase-out of SF6Government bodies and agencies have implemented a number of voluntary programs aimed at reducing SF6 emissions

- Europe - CIGRE- USA - EPA

User Agreements


Voluntary Agreement on the use of SF6 and on Measures for SF6 Emission Reduction in the

(national, regional) Electric Industry

Guiding principle to the agreement is:

avoid emissions of SF6 be wherever possible

CIGRE Working Group B3-02 Template Agreement


The EPAs SF6 Emissions Reduction Partnership for Electric Power Systems

The partnerships primary goal is to

achieve environmental and economic benefits by reducing SF6 emissions

United States Environmental Protection Agency


To become a partner, interested parties sign a Memorandum of Understanding (MOU)MOU is a voluntary agreement between EPA and industry partnersthat outlines the roles andresponsibilities of each party.

MOU commits partners to explore only the emissions abatement strategies that are both

technically and economically feasible, permitting individual partners to determine the best strategy

for their particular situation.

EPAs Memorandum of Understanding


Legislation and Prospects

Europe

Draft EU Regulation on F-Gases dated August 2003 in the legislation process. Adoption expected end of 2005/beginning 2006 after 2nd reading of the European Parliament

No bans, no use restrictions on SF6 switchgear above 1 kV !

General oibligations on F- Gases (including SF6)- Prevention/ minimization of emissions - Recovery: recycling; disposal- Training / Qualification of staff, handling with SF6- Reporting by member states


Legislation and Prospects

Conclusion:

There will be definitely no ban on SF6 switchgear !

No special and no uneconomical and unreasonable burden on manufacturers and users of SF6 switchgear to be expected from the F-gas-Regulation !

Voluntary agreements/ commitments and the exhaustion of the reduction potentials described Ecofys Study make sure that SF6 technology can be sustainably used and will be spared from further legal obligations in the future.


SF6 Handling Standards and Guidelines

IEC Standard 60376 Specification and acceptance of new sulfur hexafluorideIEC Standard 62271- 303 Handling of SF6 (former IEC Standard 60634)IEC Standard 60480 Guide to the Checking and Treatment of SF6 taken from electrical EquipmentUse and Handling of Sulfur Hexafluoride in High-voltage Switchgear and Control Gear IEC/TR2 61634Handling of SF6 and its Decomposition Products in Gas Insulated Switchgear (GIS) CIGRE Guide No. 276, transferred to IEEESF6 Recycling Guide CIGRE Guide No. 234Guide to the Checking of Sulfur Hexafluoride (SF6) taken from Electrical InstallationsPractical Guide to SF6 Handling Practices TR113933


Conclusion


Thank you for your attention.Vielen Dank fr Ihre Aufmerksamkeit.Remerciements pour votre attention.

Gracias por su tiempo y atencin

Office Adress: Falkentaler Steig 76aD-13467 Berlin, Germany

[email protected] Phone: +49 30 404 35 30

Dipl. Ing. Wolfgang DegenSenior Technical Consultant High Voltage Substations, SF6Mobil: +49 171 550 1465

sf6 features and applications

Documents