SF6 Decomposition in Gas-Insulated Equipment

The increasing application of SF6 as an insulating gas has led to many studies on SF6 decomposition in gas-insulated equipment. In the presence-of an electric arc, spark or corona, SF6 decomposes to a wide variety of chemically active products which possess completely different properties from SF6. The accumulation of these decomposition products in the equipment has caused concerns regarding personnel safety and material compatibility problems. This paper reviews previous research in SF6 decomposition relating to the operation of gas-insulated switchgears, gas-insulated transmission lines, and electrostatic accelerators. Results on the qualitative and quantitative determination of the by-products and their formation ion rates in various modes of electrical discharges are summarized. The mechanisms leading to the formation of transient and stable products are described. In particular, the influence of discharge energies and impurities on the formation of SOF2 and SO2F2, the two dominant stable by-products, is discussed. The effects of the by-products on personnel safety and equipment ent dielectric integrity are presented. The application of SF6 gas analysis as a tool for diagnosing the internal condition of gas-insulated equipment is assessed. Based on the results of many phenomenological observations, future research activities are suggested to address the issues of safety, compatibility and equipment aging. More fundamental studies on electron, ion, and neutral reaction rates in an SF6 discharge are required to gain a better understanding of the decompositon mechanisms and the influence of the products on equipment operation.

[1]  G. L. Priest,et al.  Effect of High Voltage Electrical Discharges on Sulfur Hexafluoride , 1949 .

[2]  K. B. McAfee,et al.  Note on the Infrared Spectrum of Sulfur Hexafluoride , 1951 .

[3]  R. Lagemann,et al.  THE INFRARED SPECTRUM OF SULFUR HEXAFLUORIDE , 1951 .

[4]  H. Specht,et al.  Inhalation of sulfur hexafluoride. , 1951, Science.

[5]  G. Camilli,et al.  Gaseous insulation for high-voltage transformers , 1952, Electrical Engineering.

[6]  N. Hannay,et al.  The Formation of Negative Ions of Sulfur Hexafluoride , 1953 .

[7]  G. T. Kohman,et al.  Electrical Decomposition of Sulfur Hexafluoride , 1953 .

[8]  Permanent Dissociation of Sulphur Hexa-fluoride in Corona Discharges , 1955, Nature.

[9]  H. Bernstein,et al.  THE INFRARED AND RAMAN SPECTRA OF DISULPHUR DECAFLUORIDE (S2F10) , 1957 .

[10]  General Considerations on the Toxicity of Gaseous Dielectrics , 1957, Transactions of the American Institute of Electrical Engineers. Part III: Power Apparatus and Systems.

[11]  The use of SF6 for high-power arc quenching , 1957, Electrical Engineering.

[12]  NEGATIVE ION FORMATION AND ELECTRIC BREAKDOWN IN SOME HALOGENATED GASES , 1959 .

[13]  M. F. James,et al.  Sulphur Hexafluoride - Its Properities and Use as a Gaseous Insulator in Van De Graaff Acclerators , 1965 .

[14]  D. Rapp,et al.  Total Cross Sections for Ionization and Attachment in Gases by Electron Impact. I. Positive Ionization , 1965 .

[15]  J. W. Emsley,et al.  High Resolution Nuclear Magnetic Resonance Spectroscopy , 1965 .

[16]  Arc Stability of Electronegative Gases , 1967, IEEE Transactions on Electrical Insulation.

[17]  W. Frie,et al.  Berechnung der Gaszusammensetzung und der Materialfunktionen von SF6 , 1967 .

[18]  P. Swarbrick.  Composition and properties of a sulphur hexafluoride arc plasma , 1967 .

[19]  S. Benson,et al.  The kinetics and thermochemistry of S2F10 pyrolysis , 1969 .

[20]  R. Wilkins.  Thermodynamics of SF6 and Its Decomposition and Oxidation Products , 1969 .

[21]  T. A. Jacobs,et al.  Shock‐Tube Studies of Sulfur Hexafluoride , 1969 .

[22]  Current-Carrying and Short-Circuit Tests on EHV Cables Insulated with SF6 Gas , 1969 .

[23]  F. Fehsenfeld.  Electron Attachment to SF6 , 1970 .

[24]  K. Wray,et al.  Shock Tube Study of the Decomposition Kinetics of SO2F2 , 1971 .

[25]  Tsunero Ushio,et al.  Practical Problems on SF6 Gas Circuit Breakers , 1971 .

[26]  L. S. Frost,et al.  Composition and transport properties of SF 6 and their use in a simplified enthalpy flow arc model , 1971 .

[27]  H. Wittel,et al.  Investigations of the properties of SF 6 as an arc quenching medium , 1971 .

[28]  Predicted Arc Properties in Sulfur Hexafluoride , 1971 .

[29]  J. Lowke,et al.  Negligible Effect of Negative Ions on the Constriction of Arcs in SF6 , 1972 .

[30]  A. Modica.  Shock tube study of sulfur hexafluoride and sulfur chloride pentafluoride equilibium decomposition , 1973 .

[31]  D. Hildenbrand.  Mass spectrometric studies of some gaseous sulfur fluorides , 1973 .

[32]  K. Wray,et al.  The pyrolysis and subsequent oxidation of SF6 , 1973 .

[33]  Oscar Sala,et al.  The nuclear structure facility at the University of São Paulo , 1974 .

[34]  T. Dakin.  Application of Epoxy Resins in Electrical Apparatus , 1974, IEEE Transactions on Electrical Insulation.

[35]  D. Padma,et al.  Thermal decomposition of sulphur hexafluoride , 1975 .

[36]  Decomposition Products of SF6 Gas by High Current Arc and their Reaction Mechanism , 1975 .

[37]  B. C. O'Neill,et al.  Negative-ion/molecule reactions in sulphur hexafluoride , 1975 .

[38]  J. Lowke,et al.  Radiation emission coefficients for sulfur hexafluoride arc plasmas , 1976 .

[39]  A. Theoret,et al.  Occupational hazards and other problems related to the use of sulfur hexafluoride in metalclad substations , 1976, Canadian Electrical Engineering Journal.

[40]  R. E. Noftle,et al.  Argon matrix Raman and infrared spectra of SF5Cl, SF5Br, and S2F10 , 1976 .

[41]  R. R. Smardzewski,et al.  Vacuum ultraviolet photolysis of sulfur hexafluoride and its derivatives in argon matrices. The infrared spectrum of the SF5 radical , 1977 .

[42]  J. Lyman.  A model for unimolecular reaction of sulfur hexafluoride , 1977 .

[43]  H. Latour-Slowikowska,et al.  Some test results on the effect of SF6 decomposition products on superficial properties of epoxy resin compositions , 1978, 1978 IEEE International Conference on Electrical Insulation.

[44]  P. W. Reinhardt,et al.  Collisional ionization between fast alkali atoms and selected hexafluoride molecules , 1978 .

[45]  K. Brand,et al.  Particle densities in a decaying SF6 plasma , 1978 .

[46]  J. Kopainsky.  Influence of the Arc on Breakdown Phenomena in Circuit Breakers , 1978 .

[47]  H. Kuwahara,et al.  Factors Controlling Surface Flashover in SF6 Gas Insulated Systems , 1978, IEEE Transactions on Power Apparatus and Systems.

[48]  Arc degradation of SF6 in the presence of polymeric insulating materials , 1978, 1978 IEEE International Conference on Electrical Insulation.

[49]  Tetsuo Yoshimitsu,et al.  Degradation of insulating materials including SiO2 due to SF6 gas dissociation products , 1978, 1978 IEEE International Conference on Electrical Insulation.

[50]  M. Goldman,et al.  Chapter 4 – Corona Discharges , 1978 .

[51]  D. Airey.  Axial and radial heat transport in a high-temperature SF6 arc , 1979 .

[52]  D. K. Davies,et al.  Dielectric properties for SF6 and SF6 mixtures predicted from basic data , 1979 .

[53]  Y. Sakai,et al.  Boltzmann equation analysis of the electron swarm development in SF6 , 1979 .

[54]  Noise reduction in EPR discharge-flow studies. , 1979, The Review of scientific instruments.

[55]  Shotaro Tominaga,et al.  Influence of Arc-Decomposed SF6 Gas on Cast EPOXY Insulators for Gas Insulated Switchgears , 1979, IEEE Transactions on Power Apparatus and Systems.

[56]  P. J. Chantry,et al.  Photon‐enhanced dissociative electron attachment in SF6 and its isotopic selectivity , 1979 .

[57]  G. Bruno,et al.  Inorganic volatile fluorides obtained from electrical decomposition of sulfur hexafluoride in a quartz tube , 1979 .

[58]  H. Jungblut,et al.  IONIC AND ELECTRONIC PROCESSES IN SULFUR HEXAF LUORIDE , 1980 .

[59]  E. Schulz-Gulde.  Temperature determination for arcs in sulphur hexafluoride accounting for demixing , 1980 .

[60]  Kinetics of the arc decomposition of SF6 — Gas mixtures , 1980 .

[61]  THERMAL AGING OF DIELECTRIC GASES , 1980 .

[62]  Chikasa Uenosono,et al.  Spectroscopic Approach to the Analysis of High Current Arcs in SF6 , 1980, IEEE Transactions on Plasma Science.

[63]  Richard J. Van Brunt,et al.  Safety considerations for handling SF? used in electrical equipment , 1980 .

[64]  James M. Hanrahan,et al.  Adsorption-desorption gas chromatographic-infrared determination of trace disulfur decafluoride in sulfur hexafluoride , 1980 .

[65]  H. Mukae,et al.  Diagnostic Technique of Gas Insulated Substation by Partial Discharge Detection , 1980, IEEE Transactions on Power Apparatus and Systems.

[66]  P. Vouros,et al.  Study of arc by-products in gas-insulated equipment. Final report , 1980 .

[67]  R. V. Van Brunt,et al.  Mechanisms for inception of DC and 60 Hz AC corona in SF6 , 1981, Conference on Electrical Insulation & Dielectric Phenomena - Annual Report 1981.

[68]  L. Christophorou,et al.  Positive ions in spark breakdown of SF6 , 1981 .

[69]  A. Qureshi,et al.  Surface Flashover of Spacers in Compressed Gas Insulated Systems , 1981, IEEE Transactions on Electrical Insulation.

[70]  Hiroshi Kuwahara,et al.  SF6 Gas Analysis Technique and its Application for Evaluation of Internal Conditions in SF6 Gas Equipment , 1981, IEEE Transactions on Power Apparatus and Systems.

[71]  G. Streit,et al.  Ion–molecule reactions of SF6: Determination of I.P.(SF5), A.P.(SF5+/SF6), and D(SF5–F) , 1981 .

[72]  D. Flamm,et al.  Plasma etching of Si and SiO2 in SF6–O2 mixtures , 1981 .

[73]  C. Easterly,et al.  health effects of dielectric gases: preliminary report , 1982 .

[74]  Degradation Process of Grease Due to SF6 Gas Dissociation Products , 1982, IEEE Power Engineering Review.

[75]  S.A. Boggs,et al.  Disconnect Switch Induced Transients and Trapped Charge in Gas-Insulated Substations , 1982, IEEE Transactions on Power Apparatus and Systems.

[76]  F. Y. Chu,et al.  Fault analysis in gas-insulated equipment. Final report , 1982 .

[77]  A Solid State Gas Density Monitor for Gas Insulated Substation Equipment , 1982, IEEE Power Engineering Review.

[78]  K. Brand,et al.  Dielectric Strength, Boiling Point and Toxicity of Gases - Different Aspects of the Same Basic Molecular Properties , 1982, IEEE Transactions on Electrical Insulation.

[79]  G. Raju,et al.  Monte Carlo simulation of the motion of electrons in SF6 in uniform electric fields , 1983 .

[80]  L Niemeyer,et al.  Qualitative model of breakdown in SF6 in inhomogeneous gaps , 1983 .

[81]  D. J. Tedford,et al.  Modern research and development in SF6 switchgear , 1983 .

[82]  L. K. Fifield,et al.  Aspects of breakdown product contamination of sulphur hexafluoride in electrostatic accelerators , 1983 .

[83]  R. J. Brunt,et al.  Role of photodetachment in initiation of electric discharges in SF6 and O2 , 1983 .

[84]  F. Kneubühl,et al.  Mass spectrometry of high pressure arcs in air and SF6 , 1983 .

[85]  Clay E. Easterly,et al.  On the toxicity of sparked SF6 , 1983 .

[86]  H. Rodrigo,et al.  Recent Advances in Gaseous Dielectrics at Oak Ridge National Laboratory , 1984, IEEE Transactions on Electrical Insulation.

[87]  Characterization of degraded epoxy spacer surfaces by electron spectroscopy , 1984, Conference on Electrical Insulation & Dielectric Phenomena - Annual Report 1984.

[88]  C. Easterly,et al.  Cytotoxic activity of spark‐decomposed sulfur hexafluoride and analysis of cytotoxic contributions of individual spark decomposition products† , 1984 .

[89]  On the Toxicity of SF6 Insulating Gas , 1984 .

[90]  Decomposition of sparked SF/sub 6/ and cytotoxicity of SF/sub 6/ decomposition products , 1984 .

[91]  L. B. Gordon,et al.  Surface studies of dielectric materials used in spark gaps , 1984 .

[92]  T. Hirano.  Effects of high‐pressure SF6 gas dissolved in an insulating oil on dc conduction currents and ac partial discharges , 1984 .

[93]  L. Christophorou.  Electron-molecule Interactions and Their Applications, Volume 1 , 2013 .

[94]  Alan H. Cookson,et al.  Gas-Insulated Cables , 1985, IEEE Transactions on Electrical Insulation.

[95]  J. Laghari.  Spacer Flashover in Compressed Gases , 1985, IEEE Transactions on Electrical Insulation.

[96]  F. Chu,et al.  Degradation of Silica-Filled Epoxy Spacers By ARC Contaminated Gases in SF6-Insulated Equipment , 1985, IEEE Transactions on Power Apparatus and Systems.

[97]  A. Picard,et al.  Plasma etching of refractory metals (W, Mo, Ta) and silicon in SF6 and SF6-O2. An analysis of the reaction products , 1985 .

[98]  Mashikian,et al.  Gas-insulated substation reliability: present status and future trends. Final report , 1986 .

[99]  D. Sweet.  Registry of toxic effects of chemical substances , 1987 .