US 20080135817A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2008/0135817 A1 Luly et al. (43) Pub. Date: Jun. 12, 2008

(54) GASEOUS WITH LOW (22) Filed: Dec. 12, 2006 GLOBAL WARMING POTENTIALS Publication Classi?cation (75) Inventors: Matthew H. Luly, Hamburg, NY (51) Int. Cl. (US); Robert G. Richard, H01B 3/20 (2006.01) Hamburg, NY (US) (52) U.S. Cl...... 252/571 Correspondence Address: (57) ABSTRACT Honeywell International Inc. Patent Services Department A gaseous compound which exhibits the following properties: a boiling point in the range between about —200 101 Columbia Road C. to about —2730 C.; non-ozone depleting; a GWP less than Morristown, NJ 07962 about 22,200; chemical stability, as measured by a negative standard enthalpy of formation (dHf<0); a toxicity level such (73) Assignee: Honeywell International Inc. that when the dielectric gas leaks, the effective diluted con centration does not exceed its PEL; and a (21) App1.No.: 11/637,657 greater than air. US 2008/0135817 A1 Jun. 12, 2008

GASEOUS DIELECTRICS WITH LOW —63.8° C., Which alloWs pressures of 400 kPa to 600 kPa (4 GLOBAL WARMING POTENTIALS to 6 atmospheres) to be employed in SF6-insulated equip ment. It is easily lique?ed under pressure at room temperature l. FIELD alloWing for compact storage in gas cylinders. It presents no handling problems, is readily available, and reasonably inex [0001] The present disclosure relates generally to a class of pensive. gaseous dielectric compounds having loW global Warming [0006] SP6 replaced air as a dielectric in gas insulated potentials (GWP). In particular, such gaseous dielectric com equipment based on characteristics such as insulation ability, pounds exhibits the folloWing properties: a boiling point in boiling point, compressibility, chemical stability and non the range betWeen about —200 C. to about —2730 C.; loW, toxicity. They have found that pure SP6, or SF6- preferably non-oZone depleting; a GWP less than about mixtures are the best gases to date. 22,200; chemical stability, as measured by a negative stan dard enthalpy of formation (dHf<0); a toxicity level such that [0007] HoWever, SP6 has some undesirable properties: it can form highly toxic and corrosive compounds When sub When the dielectric gas leaks, the effective diluted concentra jected to electrical discharges (e.g., 82F 10, SOF2); non-polar tion does not exceed its PEL, e.g., a PEL greater than about contaminants (e.g., air, CF4) are not easily removed from it; 0.3 ppm by volume (i.e., an Occupational Exposure Limit its is sensitive to Water vapor, conducting (OEL or TLV) of greater than about 0.3 ppm); and a dielectric particles, and conductor surface roughness; and it exhibits strength greater than air. These gaseous dielectric compounds non-ideal gas behavior at the loWest temperatures that can be are particularly useful as insulating-gases for use With elec encountered in the environment, i.e., in cold climatic condi trical equipment, such as gas-insulated circuit breakers and current-interruption equipment, gas-insulated transmission tions (about —50° C.), SP6 becomes partially lique?ed at normal operating pressures (400 kPa to 500 kPa). SP6 is also lines, gas-insulated , or gas-insulated substa an e?icient infrared (IR) absorber and due to its chemical tions. inertness, is not rapidly removed from the earth’ s atmosphere. Both of these latter properties make SP6 a potent greenhouse 2. BACKGROUND gas, although due to its chemical inertness (and the absence of [0002] hexa?uoride (SP6) has been used as a gas and bromine atoms in the SP6 molecule) it is benign eous dielectric () in equipment since the With regard to stratospheric oZone depletion. 1950s. It is noW knoWn that SP6 is a potent greenhouse [0008] That is, greenhouse gases are atmospheric gases Warming gas With one of the highest global Warming poten Which absorb a portion of the infrared radiation emitted by the tials (GWP) knoWn. Because of its high GWP, it is being earth and return it to earth by emitting it back. Potent green phased out of all frivolous applications. HoWever, there is house gases have strong infrared absorption in the Wavelength currently no knoWn substitute for SP6 in high voltage equip range from approximately 7 pm to 13 pm. They occur both ment. The electrical industry has taken steps to reduce the naturally in the environment (e.g., H2O, CO2, CH4, N20) and leak rates of equipment, monitor usage, increase recycling, as man-made gases that may be released (e.g., SP6; per?uori and reduce emissions to the atmosphere. HoWever, it Would nated compound (PFC); combustion products such as CO2, still be advantageous to ?nd a substitute for SP6 in electrical nitrogen, and sulfur oxides). The effective trapping of long dielectric applications. Wavelength infrared radiation from the earth by the naturally [0003] The basic physical and chemical properties of SP6, occurring greenhouse gases, and its reradiation back to earth, its behavior in various types of gas discharges, and its uses by results in an increase of the average temperature of the earth’ s the electric poWer industry have been broadly investigated. surface. Mans impact on climate change is an environmental [0004] In its normal state, SP6 is chemically inert, non issue that has prompted the implementation of the Kyoto toxic, non-?ammable, non-explosive, and thermally stable (it Protocol regulating the emissions of man made greenhouse does not decompose in the gas phase at temperatures less than gases in a number of countries. 500° C.). SP6 exhibits many properties that make it suitable [0009] SP6 is an e?icient absorber of infrared radiation, for equipment utiliZed in the transmission and distribution of particularly at Wavelengths near 10.5 um. Additionally, electric poWer. It is a strong electronegative (electron attach unlike most other naturally occurring green house gases (e. g., ing) gas both at room temperature and at temperatures Well CO2, CH4), SP6 is only sloWly decomposed; therefore its above ambient, Which principally accounts for its high dielec contribution to global Warming is expected to be cumulative tric strength and good arc-interruption properties. The break and long lasting. The strong infrared absorption of SP6 and its doWn voltage of SP6 is nearly three times higher than air at long lifetime in the environment are the reasons for its atmospheric pressure. Furthermore, it has good heat transfer extremely high Which for a 100 properties and it readily reforms itself When dissociated under year time horiZon is estimated to be approximately 22,200 high gas-pressure conditions in an electrical discharge or an times greater (per unit mass) than that of CO2, the predomi arc (i.e., it has a fast recovery and it is self-healing). Most of nant contributor to the greenhouse effect. The concern about its stable decomposition byproducts do not signi?cantly the presence of SP6 in the environment derives exclusively degrade its dielectric strength and are removable by ?ltering. from this very high value of its potency as a greenhouse gas. It produces no polymerization, carbon, or other conductive [0010] Accordingly, many in the electrical equipment deposits during arcing, and its is chemically compatible With industry have spent substantial time and effort seeking suit most solid insulating and conducting materials used in elec able replacement gases to reduce the use of SP6 in high volt trical equipment at temperatures up to about 2000 C. age electrical equipment. To date, the possible replacement [0005] Besides it good insulating and heat transfer proper gases have been identi?ed as (i) mixtures of SP6 and nitrogen ties, SP6 has a relatively high pressure When contained at for Which a large amount of research results are available; (ii) room temperature. The pres sure required to liquefy SP6 at 2 1 ° gases and mixtures (e. g., pure nitrogen, loW concentrations of C. is about 2100 kPa; its boiling point is reasonably loW, SP6 in N2, and SF6iHe mixtures) for Which a smaller yet US 2008/0135817 A1 Jun. 12, 2008

signi?cant amount of data is available; and (iii) potential tri?uoro -nitro so -ethene//Tri?uor-nitroso-aethen gases for Which little experimental data is available. [0011] Some replacements Which have been proposed have Tetra?uoroethene higher GWPs than SP6. For example, CF3SF5 falls into this [0017] 3,3,4,4-tetra?uoro-3,4-dihydro-[l,2]diaZete category. Because of fugitive emissions in the manufacture, transportation, ?lling and use of such chemicals, they should (Di?uoramino)di?uoracetonitril be avoided. Tetra?uorooxirane [0012] HoWever, the present inventors have determined that given the environmental dif?culty of SP6, it is necessary to relax certain of the requirements traditionally held as impor Per?uormethyl?uorformiat tant and accept as an alternative gas, compromise candidates With a loWer GWP. For example, gases Which are non-toxic [0018] tri?uoro -acetyl hypo?uorite are often inert With long atmospheric lifetimes Which can per?uoro-2-aZa-l -propene yield high GWP. By accepting a someWhat more reactive gas than SP6, the GWP can be greatly reduced. It may also be Per?uor-2 -aZa- l -propen (germ.) necessary to accept slightly more toxic materials in order to N-Fluor-tetra?uor-l -aethanimin (germ.) ?nd the best alternative in these applications. Such an increase in toxicity can be offset by reducing equipment leak [0019] 3 ,3 -di?uoro -2 -tri?uoromethyl-oxaZiridine rates or installing monitoring equipment. In some cases, the bis -tri?uoromethyl-diaZene//hexa?uoro -#ci s! -aZomethane gases discovered by the present inventors as suitable alterna tives to SP6 are shoW to be e?icient at loW levels and can be Fluoroxypenta?uoroethane mixed With nitrogen and/or another non-toxic gas to give dielectrics With greatly reduced toxicity and acceptably loW [0020] bis-tri?uoromethyl peroxide GWPs. [0013] The unique gaseous compounds discovered by the present inventors for use as substitutes for SP6 can be used in some existing electrical equipment, although they Would [0021] 3 -?uoro -3 #H ! -diaZirine-3 -carbonitrile preferably be used in speci?c electrical equipment optimiZed for them. The gaseous compounds of the present disclosure Ethyne are preferably used in pure form, but can also be used as part of an aZeotrope, or a mixture With an appropriate second gas, [0022] 1,2,2-tri?uoro-aziridine such as nitrogen, CO2 or N20. Ketene SUMMARY [0023] (di?uoro)vinylboran [0014] A dielectric gaseous compound Which exhibits the (Di?uor)vinylboran (germ.) folloWing properties: a boiling point in the range betWeen about —200 C. to about —2730 C.; loW, preferably non-oZone [0024] tri?uoro-vinyl-silane depleting; a GWP less than about 22,200; chemical stability, as measured by a negative standard enthalpy of formation Ethinylsilan (dHf<0); a toxicity level such that When the dielectric gas [0025] ethyl-di?uor-borane leaks, the effective diluted concentration does not exceed its PEL (i.e., an Occupational Exposure Limit (OEL or TLV) of Ethyl-di?uor-boran (germ.) at least about 0.3 ppm); and a dielectric strength greater than an. [0026] methyl -methylen-amine [0015] The dielectric gaseous compound is at least one compound selected from the group consisting of: Dimethyl ether [0027] vinyl-silane Arsenic penta?uoride Arsine Dimethylsilane Diboron tetra?uoride Chloroethyne [0028] ?uoroethyne//?uoro-acetylene Diborane Perchloric acid, 2-chloro-l,l,2,2-tetra?uoroethyl ester (9C1) Ethanedinitrile Perchloric acid, l,2,2-trichloro-l,2-di?uoroethyl ester [0029] tetra?uoropropyne// l ,3 ,3 ,3 -tetra?uoropropyne hexa?uoro-oxetane Tri?uoroacetyl chloride [0016] tri?uoromethylisocyanide (CF3-NC) Tri?uoro (tri?uoromethyl)oxirane tri?uoromethyl isocyanide

US 2008/0135817 A1 Jun. 12, 2008

methyl germane

Di?uorformimin Nitrogen oxide; and Tri?uoromethane Xenon [0096] tri?uoromethane thiol [0102] The dielectric gaseous compound is optionally form as an aZeotrope, Which imparts many advantages in handling Tri?uorrnethanthiol (germ.) the mixture. Preferred mixtures for dielectric gaseous com pound contain one additional gas selected from the group N,N, 1 ,1 -Tetra?uormethylamin consisting of: nitrogen, CO2 and N20. [0097] di?uoro dichlorosilane [0103] The present disclosure also includes an insulation gas for use in electrical equipment, Wherein said insulation Di?uordichlorsilan (germ.) gas is a dielectric gaseous compound Which exhibits the fol loWing properties: a boiling point in the range betWeen about [0098] di?uoro chlorosilane —200 C. to about —273° C.; loW, preferably non-oZone Di?uorchlorsilan (germ.) depleting; a GWP less than about 22,200; chemical stability, as measured by a negative standard enthalpy of formation Phosphorus chloride di?uoride (dHf<0); a toxicity level such that When the dielectric gas Chlorotri?uorosilane leaks, the effective diluted concentration does not exceed its PEL (i.e., Occupational Exposure Limit (OEL or TLV) of at chloride least about 0.3 ppm); and a dielectric strength greater than air. Chlorosilane [0104] Preferably, the electrical equipment is at least one selected from the group consisting of: gas-insulated circuit breakers and current-interruption equipment, gas-insulated transmission lines, gas-insulated transformers, and gas-insu lated substations. Carbonyl sul?de DETAILED DESCRIPTION OF THE PREFERRED Di?uoramine EMBODIMENT [0099] trans-Di?uorodiaZine cis-Di?uorodiaZine [0105] The compounds of the present disclosure are useful in gaseous phase for electrical insulation and for arc quench Thionyl ?uoride ing and current interruption equipment used in the transmis sion and distribution of electrical energy. Generally, there are Tri?uorosilane four major types of electrical equipment Which the gases of Nitrogen tri?uoride the present disclosure can be used for insulation and/or inter ruption purposes: (1) gas-insulated circuit breakers and cur Tri?uoramine oxide rent-interruption equipment, (2) gas-insulated transmission lines, (3) gas-insulated transformers, and (4) gas-insulated [0100] thiaZyl tri?uoride substations. Such gas-insulated equipment is a major compo nent of poWer transmission and distribution systems all over Phosphorus tri?uoride the World. It offers signi?cant savings in land use, is aestheti Germanium(IV) ?uoride cally acceptable, has relatively loW radio and audible noise emissions, and enables substations to be installed in popu Tetrafuorosilane lated areas close to the loads. Phosphorus penta?uoride [0106] Depending on the particular function of the gas insulated equipment, the gas properties Which are the most Selenium hexa?uoride signi?cant vary. Tellurium hexa?uoride [0107] For circuit breakers the excellent thermal conduc tivity and high dielectric strength of such gases, along With [0101] ?uorosilane the fast thermal and dielectric recovery (short time constant for increase in resistivity), are the main reasons for its high Nitro syl ?uoride interruption capability. These properties enable the gas to nitrate make a rapid transition betWeen the conducting (arc ) and the dielectric state of the arc, and to Withstand the rise of Hydrogen sul?de the recovery voltage. [0108] For gas-insulated transformers the cooling ability, compatibility With sold materials, and partial discharge char acteristics, added to the dielectric characteristics, make them Hydrogen iodide a desirable medium for use in this type of electrical equip ment. The compounds have distinct advantages over oil insu Krypton lation, including none of the ?re safety problems or environ Nitrogen mental problems related to oil, high reliability, ?exible layout, little maintenance, long service life, loWer noise, bet ter handling, and lighter equipment. US 2008/0135817 A1 Jun. 12, 2008

[0109] For gas-insulated transmission lines the dielectric [0114] Extrinsic properties are those Which describe hoW a strength of the gaseous medium under industrial conditions is gas may interact With its surroundings, or in response to of paramount importance, especially the behavior of the gas external in?uences, such as electrical breakdown and dis eous dielectric under metallic particle contamination, sWitch charges. To be used in electrical applications, a dielectric gas ing and lightning impulses, and fast transient electrical should: (undergo no extensive decomposition; lead to no stresses. These gases also have a high ef?ciency for transfer of polymeriZation; form no carbon or other deposits; and be heat from the conductor to the enclosure and are stable for non-corrosive and non-reactive to metals, insulators, spacers, long periods of time (e.g., 40 years). These gas-insulated and seals. In addition it should have: no byproduct With tox transmission lines offer distinct advantages: cost effective icity unacceptable for industrial applications; removable ness, high-carrying capacity, loW losses, availability at all byproducts; and a high recombination rate for reforming voltage ratings, no ?re risk, reliability, and a compact alter itself, especially for arc interruption. Finally, the gas must be native to overhead high voltage transmission lines in con environmentally friendly, e. g., it must not contribute to global gested areas that avoids public concerns With overhead trans Warming, must not deplete stratospheric oZone, and must not mission lines. persist in the environment for long periods of time. [0110] For gas-insulated substations, the entire substation [0115] Speci?c properties of the gas under discharge and (circuit breakers, disconnects, grounding sWitches, busbar, breakdoWn conditions include: a high breakdoWn voltage transformers, etc., are interconnected) is insulated With the under uniform and non-uniform electric ?elds; insensitivity gaseous dielectric medium of the present disclosure, and, to surface roughness or defects and freely moving conducting thus, all of the above-mentioned properties of the dielectric particles; good insulation properties under practical condi gas are signi?cant. tions; good insulator ?ashover characteristics; good heat [0111] The properties of a dielectric gas that are necessary transfer characteristics; good recovery (rate of voltage recov for its use in high voltage equipment are many and vary ery) and self-healing; no adverse reactions With moisture and depending on the particular application of the gas and the common impurities; and no adverse effects on equipment, equipment. especially on spacers and electrode surfaces. [0112] Intrinsic properties are those properties of a gas [0116] Speci?c properties of gaseous insulators for speci?c Which are inherent in the physical atomic or molecular struc electrical equipment is set forth beloW: ture of the gas. These properties are independent of the appli Circuit breakersiThe most signi?cant required gas proper cation or the environment in Which a gas is placed. One of the ties for arc interruption are: (i) high dielectric strength com desirable properties of a gaseous dielectric is high dielectric parable to that of SP6; (ii) high thermal conductivity; (iii) fast strength (higher, for instance than air). The gas properties that gas recovery; and (iv) self-healing/dielectric integrity. are principally responsible for high dielectric strength are Gas-insulated transmission linesiThe required properties those that reduce the number of electrons Which are present in include: (i) high dielectric strength; (ii) high vapor pressure at an electrically-stressed dielectric gas. To effect such a reduc operating and ambient temperature; (iii) chemical inertness; tion in the electron number densities, as gas should: (i) be (iv) high thermal conductivity; (v) no thermal aging; (vi) no electronegative (remove electrons by attachment over as Wide deposits; (vii) easily removable, non-harmful byproducts; an energy range as possible); it should preferably exhibit and (viii) no unacceptable level of haZards (?re, explosion, increased electron attachment With increasing electron toxicity, corrosion). energy and gas temperature since electrons have a broad Gas-insulated transformersiThe properties of the gas range of energies and the gas temperature in many applica required for this application include: (i) high dielectric tions is higher than ambient; (ii) have good electron sloWing strength at reasonable pressures (e.g., 500 kPa); (ii) loW boil doWn properties (sloW electrons doWn so that they can be ing point; (iii) acceptably loW toxicity; (iv) chemical inert captured e?iciently at loWer energies and be prevented from ness; (v) good thermal stability; (vi) non-?ammable; (vii) generating more electrons by electron impact ioniZation); and high cooling capability; (viii) good compatibility With solid (iii) have loW ioniZation cross section and high ioniZation materials; (ix) good partial discharge characteristics; (x) use onset (prevent ioniZation by electron impact). Besides the able over a range of temperatures; and (xi) safe, easy to above properties, there are a number of other basic properties handle, inexpensive and securely available. Which are necessary for the complete characterization of the [0117] The present inventors have discovered a unique dielectric gas behavior and its performance in practice, e.g., series of dielectric gases for use in electric equipment appli secondary processes such as electron emission from surfaces cations, Which exhibit many of the aforementioned proper by and photon impact; photoprocesses; absorption of ties, Which avoiding the greenhouse problems associated With photoioniZing radiation (this is a controlling factor in dis SP6. Such dielectric compounds exhibit at least one of the charge development in non-uniform ?elds); dissociation folloWing properties: under electron impact decomposition; ion-molecule reac [0118] A boiling point in the range betWeen about —20° tions; reactions With trace impurities; and reactions With sur C. to about —273° C. faces. [0119] LoW, preferably, Non-oZone depleting [0113] The dielectric gas must also have the folloWing [0120] A GWP less than about 22,200 chemical properties: high vapor pressure; high speci?c heat, [0121] Chemical stability, as measured by a negative high thermal conductivity for gas cooling; thermal stability standard enthalpy of formation (dHf<0) over long periods of time for temperatures greater than 4000 [0122] A toxicity level such that When the Working gas K; chemical stability and inertness With regard to conducting leaks from equipment at the manufacturer’s speci?ed and insulating materials; non-?ammable; toxicity acceptable maximum leak rate, the effective diluted concentration for industrial exposure; and non-explosive. When used in does not its PEL, i.e., does not exceed the PEL of that mixtures, it must have appropriate thermodynamic properties speci?c compound. In general With minimal ventilation for mixture uniformity, composition, and separation. PELs greater than about 0.3 ppm by volume are accept

US 2008/0135817A1 Jun. 12, 2008

TABLE 2-continued

Dielectric MY Compound Structure Name CAS MW BP(O C.)

ClF3Si SiClF3 Chlorotri?uorosilane 14049-3 6-6 120.53 —70.2 ClH HCl Hydrogen chloride 7647-01 —0 3 6.46 —85 .0 ClH3Si SiH3Cl Chlorosilane 13465-78-6 66.56 —30.3 CO CO Carbon monoxide 630-08-0 28.01 —191.5 C02 C02 Carbon dioxide 124-3 8-9 44.01 —78.4 COS OCS Carbonyl sul?de 463-58-1 60.07 —50.3 F2HN NHF2 Di?uoramine 10405 —27—3 53.01 —23 .2 F2N2 FNNF trans-Di?uorodiaZine 13776-62-0 66.01 —111.5 F2N2 FNNF cis-Di?uorodiaZine 13 812-43-6 66.01 — 105 .8 F2OS F2SO Thionyl ?uoride 7783-42-8 86.06 —43 .8 F3HSi SiHF3 Tri?uorosilane 13465-71-9 86.09 —95.2 F3N NF3 Nitrogen tri?uoride 7783-54-2 71.00 — 129.1 F3NO NOF3 Tri?uoramine oxide 13 847-65-9 87.00 —87.5 F3NS NSF3 thiaZyl tri?uoride 15930-75-3 103.07 —27.1 P3P PF3 Phosphorus tri?uoride 7783-55-3 87.97 —101.5 F4Ge GeF4 Germanium(IV) ?uoride 7783-58-6 148.58 —3 6.5 F4Si SiF4 Tetra?lorosilane 7783-61-1 104.08 —86.0 P5P PF5 Phosphorus penta?uoride 7647- 19-0 125.97 —84.5 F6Se SeF6 Selenium hexa?uoride 7783-79-1 192.95 —46.5 F6Te TeF6 Tellurium hexa?uoride 7783-80-4 241.59 —3 8.8 FH3Si SiH3F ?uorosilane 13537-33-2 50.11 —98.0 FNO Nitrosyl ?uoride 7789-25-5 49.00 —59.9 FNO3 Fluorine nitrate 7789-26-6 81.00 —46.2 H2S H2S Hydrogen sul?de 7783-06-4 34.08 —59.5 H3N NH3 Ammonia 7664-41-7 17.03 —33.3 He He Helium 7440-59-7 4.00 —268.9 HI HI Hyd.rogen iodide 10034-85-2 127.91 —35.6 Kr Kr Krypton 7439-90-9 83.80 —153.4 N2 N2 Nitrogen 7727-37-9 28.01 —195.8 N2O NON Nitrous oxide 10024-97-2 44.01 —88.5 Ne Ne Neon 7440-01-9 20.18 —246.1 NO NO Nitrogen oxide 10102-43-9 30.01 —151.8 Xe Xe Xenon 7440-63-3 131.29 —108.1

[0126] The aforementioned dielectric compounds may be EXAMPLE 1 used in pure form, but can also be used as part of an aZeotrope, or a mlxmre Wlth an aPPrOPnate Second gas, Le» nltl'ogen, [0138] Measurements of the dielectric strength of potential CO2 or N20. alternatives were determined using ASTM D2477 or obtained [0127] Particularly preferred non-electrical properties for from literature. These measurements were performed at 1 dielectric gases according to the present disclosure, include: atmosphere pressure across a 0.1 inch gap and at ambient [0128] Non-liquefying, e.g., Thol-Z less than —200 C. temperature. [0129] Chemically stableidecomposition temperature [0139] In the intended applications, the gas will not be at 1 must be higher than hot spot temperature in equipment, atmosphere pressure but at a higher pressure. In this example e.g., Tdec:200o C., and gas should not decompose in 5 atmospheres pressure is used as a maximum pressure. If the partial discharge spark (approximately 10000 K) gas lique?es at a lower pressure than that pressure was used. [0130] Low environmental impact, i.e., little to no These gases have higher dielectric strengths and break down destruction of ozone layer ODPIO; and low global Voltages than air. Using 5 atmospheres (73.5 psia) pressure as warming impact GWP less than SE6 the upper pressure (rating of the equipment). [0131] Acceptably low toxicity of gas and discharge byproducts [0132] Electrical equipment property requirements for Breakdown voltage at dielectric gases according to the present disclosure, include: Dielectric strength Pressure maximum pressure [0133] Insulation speci?c criteria include a critical ?eld Gas kV/0.1 inch gap (psia) (kV/0.1 inch gap) of Ecr, and no conducting decomposition products Air 4.75 73.5 23.75 should be generated by discharge R143a 5.8 73.5 29 [0134] Switching speci?c criteria include high critical R152a 5.9 73.5 29.5 ?eld of Ecr, arcing stability, i.e., a gas must recombine to R125 6.4 73.5 32 original molecular structure after being decomposed in R134a 6.6 73.5 33 R22 7.2 73.5 39.9 switching arc (Gibbs free energy of reaction is <0) R124 10.4 55.5 39.3 [0135] Speci?c thermal interruption performance, i.e., SP6 14.0 73.5 70 must be able to interrupt current ?ow at ac current Zero C318 16.0 45.3 49.3 R115 16.0 73.6 80 [0136] Arc erosion product from equipment and gas R114 17.0 31.1 36 must not form conduction deposits [0137] Low Velocity of sound US 2008/0135817 A1 Jun. 12, 2008

EXAMPLE 2 Ethinylsilan ethyl-di?uor-borane [0140] The dielectric strength of additional gases is mea Ethyl-di?uor-boran (germ.) sure at 1 atmosphere and at the maximum system pressure. methyl-methylen-amine Their breakdown voltages are found to be greater then air, Dimethyl ether Which alloWs smaller gaps and therefore smaller equipment vinyl-silane then Would be need if air Was used. Here the measurements Dimethylsilane Were performed on CTFE (Chlorotri?uoroethylene), HCl Chloroethyne (hydrogen chloride) and SiF4 (silicon tetra?uoride). [0141] Having described the invention in detail by refer Ethanedinitrile ence to the preferred embodiments and speci?c examples tetra?uoropropyne// l ,3 ,3 ,3 -tetra?uoropropyne thereof, it Will be apparent that modi?cations and variations hexa?uoro-oxetane are possible Without departing from the spirit and scope of the disclosure and claims. What is claimed is: 1,1,l,3,3,3-Hexa?uoropropanone 1. A dielectric gaseous compound Which exhibits the fol penta?uoro-propionyl ?uoride//per?uoropropionyl ?uo ride loWing properties: Tri?uoromethyl tri?uorovinyl ether a boiling point in the range betWeen about —200 C. to about 1 -Propyne —2730 C.; Cyclopropane loW non-oZone depleting; Propane a GWP less than about 22,200; Trimethylborane chemical stability, as measured by a negative standard cyanoketene enthalpy of formation (dHf<0); butatriene a toxicity level such that When the dielectric gas leaks, the effective diluted concentration does not exceed its PEL Cyano-bispenta?uorethyl-phosphin Trimethyl-l , l ,2,2-tetra?uorethylsilan in the Working environment; and methyl diborane a dielectric strength greater than air. Methyldiboran (germ.) 2. The dielectric gaseous compound according to claim 1, carbonyl bromide ?uoride Wherein said dielectric gaseous compound is at least one compound selected from the group consisting of: chloro-di?uoro-nitroso-methane//Chlor-di?uor-nitroso Arsenic penta?uoride methan Arsine chloroperoxytri?uoromethane Diboron tetra?uoride carbonylchlorid-?uorid Diborane Carbonychlorid?uorid (germ.) Perchloric acid, 2-chloro-l,l,2,2-tetra?uoroethyl ester di?uoro diaZomethane (9C1) Di?uordiaZomethan (germ.) Perchloric acid, l,2,2-trichloro-l ,2-di?uoroethyl ester Tri?uoroacetyl chloride Carbonyl ?uoride tri ?uoromethylisocyanide (CF3 -NC) Di?uordioxiran tri?uoromethyl isocyanide tri ?uoro -nitroso -ethene//Tri?uor-nitro so-aethen tri?uoromethylaZide Tetra?uoroethene Tri?uormethylaZid (germ.) tetra?uoro-diaZiridine 3,3,4,4-tetra?uoro -3 ,4-dihydro-[ l ,2] diaZete Fluorperoxytri?uormethan Tetra?uorooxirane Tri?uormethyl-phosphonyl?uorid Cyanogen ?uoride Per?uormethyl ?uorformi at Tri?uormethylphosphane (germ.) DiaZomethane per?uoro -2 -aZa- l -propene Per?uor-2-aZa-l -propen (germ.) formaldehyde//Formalin N-Fluor-tetra?uor- l -aethanimin (germ.) (methyl)di?uoroborane 3,3-di?uoro-2-tri?uoromethyl-oxaZiridine (Methyl)di?uorboran (germ.) Chloromethane bis-tri?uoromethyl-diaZene//hexa?uoro-#cis ! - aZomethane methylphosphonous acid di?uoride//di?uoro-methyl Fluoroxypenta?uoro ethane phosphine bis-tri?uoromethyl peroxide tri?uoro-methoxy-silane Methane 3-?uoro-3#H ! -diaZirine-3 -carbonitrile Methylsilane Ethyne #Si! -bromo-#Si! ,#Si!'-methanediyl-bis-silane l,2,2-tri?uoro-aZiridine Ketene Di?uormethylnitrit (di?uoro)vinylboran tri?uoromethanol (Di?uor)vinylboran (germ.) Formyl ?uoride tri?uoro -vinyl-silane Cyanic acid