INSULATING GAS USED FOR ELECTRICAL INSULATION OR ARC EXTINGUISHING BY REPLACING SF6 GAS AND ELECTRICAL DEVICE USING SAME

Abstract

The present invention relates to an insulating gas used for electrical insulation or arc extinguishing of an electrical device, and an electrical device for insulating electricity using the same. The insulating gas of the present invention, which may replace SF.sub.6 gas, consists of a mixed gas of trifluoromethyl trifluorovinyl ether (CF.sub.3OCFCF.sub.2) and a carrier gas. The insulating gas of the present invention has the characteristics of a low boiling point, high dielectric strength, low toxicity, and a low global warming potential (GWP=1 or less), and thus may replace SF.sub.6, and the low global warming potential with no loss of high insulating capacity and arc extinguishing capability may reduce greenhouse gases.

Claims

1. An insulating gas used for electrical insulation or arc extinguishing of an electrical device, wherein the insulating gas is a mixed gas of trifluoromethyl trifluorovinyl ether (CF.sub.3OCFCF.sub.2) and a carrier gas.

2. The insulating gas of claim 1, wherein the mixed gas has: a GWP of less than 1; an acute inhalation toxicity (LC.sub.50 4 h) of 10,000 ppmv or greater; and a mixing ratio (k) such that a dielectric strength synergistic effect (C) defined by Equation 1 below is ?0.1 or greater, $\begin{array}{cc}C=\frac{k\left(\mathrm{Vm}-\mathrm{Va}\right)}{\left(1-k\right)\left(Vm-Vb\right)}& \left[\mathrm{Equation}1\right]\end{array}$ (wherein k is a mixing ratio (mol %) of the trifluoromethyl trifluorovinyl ether, V.sub.m is a dielectric breakdown voltage of the mixed gas, V.sub.a is a dielectric breakdown voltage of the trifluoromethyl trifluorovinyl ether, and V.sub.b is a dielectric breakdown voltage of the carrier gas).

3. The insulating gas of claim 1, wherein the carrier gas is CO.sub.2, and the mixed gas has CF.sub.3OCFCF.sub.2 in a mixing ratio of 1 to 60 mol %.

4. The insulating gas of claim 1, wherein the carrier gas is CO.sub.2 and O.sub.2, when the mol % of CF.sub.3OCFCF.sub.2 represented by x, the mol % of CO.sub.2 represented by y, and the mol % of O.sub.2 represented by z are expressed in a triangular diagram, (x, y, z) is outside a region surrounded by straight line AB, straight line BC, and straight line CA, and the straight line AB is a straight line connecting point A and point B, the straight line BC is a straight line connecting point B and point C, the straight line CA is a straight line connecting point C and point A, and in the point A, (x , y, z) is (50, 0, 50), in the point B, (x, y, z) is (5.1, 0, 94.9), and in the point C, (x, y, z) is (8.2, 80, 11.8).

5. The insulating gas of claim 1, wherein the carrier gas is CO.sub.2 and O.sub.2, and the mixed gas has CF.sub.3OCFCF.sub.2 in a mixing ratio of 1 to 60 mol %, O.sub.2 in a mixing ratio of 1 to 30 mol %, and CO.sub.2 as the balance.

6. An electric device configured to insulate electricity or extinguish arc through an insulating gas, wherein the insulating gas claim 1 is used.

7. The electric device of claim 6, comprising an insulating space filled with the insulating gas inside a housing, and a conductive member provided inside the housing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings are included to provide a further understanding of the present invention, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present invention and, together with the description, serve to explain principles of the present invention. In the drawings:

[0041] FIG. 1 shows a molecular structure of CF.sub.3OCFCF.sub.2 included in an insulating gas of the present invention;

[0042] FIG. 2 is a graph showing Paschen Curves of SF.sub.6, g.sup.3, a mixed gas of CO.sub.2 and O.sub.2, and CF.sub.3OCFCF.sub.2;

[0043] FIG. 3 is a graph showing a global warming potential of a mixed gas according to a mixing ratio of CF.sub.3OCFCF.sub.2;

[0044] FIG. 4 shows Paschen Curves obtained by measuring 50% discharge voltages of a mixed gas of CF.sub.3OCFCF.sub.2 and CO.sub.2 at different mixing ratios and SF.sub.6, and g.sup.3;

[0045] FIG. 5 is a graph showing a dielectric strength synergistic effect according to a mixing ratio of CF.sub.3OCFCF.sub.2;

[0046] FIG. 6 is a graph showing results of measuring 50% discharge voltages of a mixed gas of CF.sub.3OCFCF.sub.2 and CO.sub.2 at different mixing ratios, and SF.sub.6; and

[0047] FIG. 7 is a triangular diagram of CF.sub.3OCFCF.sub.2, CO.sub.2, and O.sub.2 as three components.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0049] In order to replace SF.sub.6 gas, a low boiling point (below ?25? C.), a high dielectric strength (80% or greater than SF.sub.6), a low toxicity (high toxic concentration (5000 ppmv or greater) and negative genetic modification), and a low global warming potential (GWP of 500 or less) are required and also chemical stability and affordable costs need to be satisfied.

[0050] As a candidate gas that satisfies the conditions described above, trifluoromethyl trifluorovinyl ether (CF.sub.3OCFCF.sub.2, CAS: 1187?93?5) was selected through a number of experiments.

[0051] As used herein, C.sub.3F.sub.6O may refer to CF.sub.3OCFCF.sub.2.

[0052] An insulating gas replacing SF.sub.6 gas according to an embodiment of the present invention includes CF.sub.3OCFCF.sub.2 having a molecular structure shown in FIG. 1.

[0053] Table 1 below compares the boiling point, vapor pressure, and global warming potential of CF.sub.3OCFCF.sub.2 with those of SF.sub.6 and (CF.sub.3).sub.2CFCN, and shows the following results.

TABLE-US-00001 TABLE 1 Characteristic comparison of SF.sub.6, (CF.sub.3).sub.2CFCN, and CF.sub.3OCFCF.sub.2 Boiling point Vapor pressure Acute inhalation Gas (? C.) [psia@](20? C.) GWP toxicity(LC.sub.50 4 h, ppmv) SF.sub.6 ?63.7 334 23,500 100,000~ (CF.sub.3).sub.2CFCN ?4.7 36.7 2,400 10,000~15,000 CF.sub.3OCFCF.sub.2 ?29 70.3 0.170 10,000~15,000

[0054] It is seen that CF.sub.3OCFCF.sub.2 has a very low GWP compared to (CF.sub.3).sub.2CFCN, which is the main component of SF.sub.6 and g.sup.3 gas, and has a lower boiling point than (CF.sub.3).sub.2CFCN, and has an equivalent level of acute inhalation toxicity (LC.sub.50 4 h, 10,000?15,000 ppmv). In order to test the insulation performance of CF.sub.3OCFCF.sub.2, a 50% discharge voltage was tested with respect to a population that a lighting impulse voltage within IEC 60060?1 was applied 30 times. After each test, gas collection and electrode cleaning were performed. In this case, the 50% discharge voltage indicates a voltage at which half of standard impulse voltage waveform repeatedly applied using a sphere-plane electrode flashovers and the other half does not flashover.

[0055] FIG. 2 shows Paschen Curves for each gas in which the 50% discharge voltage is measured for SF.sub.6, g3((CF.sub.3).sub.2CFCN), a mixed gas of CO.sub.2 (70.5 mol %) and O.sub.2 (29.5 mol %), and CF.sub.3OCFCF.sub.2. In this case, the Paschen Curve is a graph showing the 50% discharge voltage according to a pressure and distance between electrodes (sphere-plane electrode) to determine insulation performance.

[0056] The graph shows that CF.sub.3OCFCF.sub.2 has the same level of insulation performance as g.sup.3 gas. In addition, it is seen that CF.sub.3OCFCF.sub.2 is superior to the mixed gas of CO.sub.2 (70.5 mol %) and O.sub.2 (29.5 mol %) in the insulation performance.

[0057] Meanwhile, an insulating gas replacing SF.sub.6 gas according to another embodiment of the present invention may be used by mixing CF.sub.3OCFCF.sub.2 with CO.sub.2 and/or O.sub.2 as a carrier gas.

[0058] The mixed gas of the present invention may have a GWP of 1 or less, 0.9 or less, or 0.85 or less. In addition, the mixed gas of the present invention may have a GWP of 0.29 to 1, 0.29 to 0.9, or 0.29 to 0.85. Table 2 below shows GWP and acute inhalation toxicity (LC.sub.50, ppmv) according to a mixing ratio (mol %) of CF.sub.3OCFCF.sub.2 and CO.sub.2. In this case, a method for calculating GWP was based on Regulation (EU) NO 517/2014, and LC.sub.50, which represents lethal concentration 50% upon inhalation for 4 hours, was based one KS B ISO 10298: 2012.

TABLE-US-00002 TABLE 2 GWP and acute inhalation toxicity according to a mixing ratio (mol %) of CF.sub.3OCFCF.sub.2 and CO.sub.2 Mixture gas GWP LC.sub.50 4 h, ppmv C.sub.3F.sub.6O(100%) + CO.sub.2(0%) 0.170 15,000 C.sub.3F.sub.6O(90%) + CO.sub.2(10%) 0.190 16,529 C.sub.3F.sub.6O(80%) + CO.sub.2(20%) 0.220 18,405 C.sub.3F.sub.6O(70%) + CO.sub.2(30%) 0.250 20,761 C.sub.3F.sub.6O(60%) + CO.sub.2(40%) 0.290 23,810 C.sub.3F.sub.6O(50%) + CO.sub.2(50%) 0.340 27,907 C.sub.3F.sub.6O(40%) + CO.sub.2(60%) 0.410 33,708 C.sub.3F.sub.6O(30%) + CO.sub.2(70%) 0.490 42,553 C.sub.3F.sub.6O(20%) + CO.sub.2(80%) 0.600 57,692 C.sub.3F.sub.6O(10%) + CO.sub.2(90%) 0.750 89,552

[0059] Table 2 above shows that the mixed gas of CF.sub.3OCFCF.sub.2 and CO.sub.2 has a GWP of 0.190 to 0.750 when the mixing ratio of CF.sub.3OCFCF.sub.2 is 90 to 10 mol %, which is only about less than 0.003% compared to the GWP (23,500) of SF.sub.6. FIG. 3 is a graph showing a global warming potential of a mixed gas according to a mixing ratio of CF.sub.3OCFCF.sub.2. Meanwhile, KEPCO specifies the GWP standard as 500 or less in the case of a fluorine-based mixed gas, as a general purchase standard for eco-friendly gas insulated switchgear of 72.5 kV or higher. In order to satisfy the standard, the value of GWP needs to be reduced, and it is seen that the mixed gas of CF.sub.3OCFCF.sub.2 and CO.sub.2 is significantly lower than the standard described above.

[0060] In addition, the mixed gas of the present invention may have an acute inhalation toxicity ((LC.sub.50 4 h) of 10,000 ppmv or greater, 20,000 ppmv or greater, or 40,000 ppmv or greater, preferably 10,000 to 120,000 ppmv, 10,000 to 110,000 ppmv, or 10,000 to 100,000 ppmv. According to Table 2 above, the case in which the mixing ratio of CF.sub.3OCFCF.sub.2 is 70 mol % or less goes beyond the upper limit ((LC.sub.50?20,000 ppmv) of grade 4 acute inhalation toxicity with respect to the Globally Harmonized System of Classification and Labeling of Chemicals, and thus may be classified as toxicity grade 4 or higher.

[0061] In order to measure the dielectric strength according to the mixing ratio of the mixed gas of CF.sub.3OCFCF.sub.2 and CO.sub.2, the same insulation performance test method for CF.sub.3OCFCF.sub.2 was performed.

[0062] FIG. 4 shows a graph of test results obtained by measuring 50% discharge voltages of a mixed gas of CF.sub.3OCFCF.sub.2 and CO.sub.2 at different mixing ratios. In this case, 5 mm, 8 mm, and 11 mm indicate 50% discharge voltages when the distance between sphere and plane electrodes is 5 mm, 8 mm, and 11 mm, respectively, for the mixed gas of CF.sub.3OCFCF.sub.2 and CO.sub.2, and SF.sub.6 and g.sup.3 indicate 50% discharge voltages when the distance between sphere and plane electrodes is 5 mm. Accordingly, it is seen that the mixed gas of CF.sub.3OCFCF.sub.2 and CO.sub.2 showed a nonlinear pattern in the 50% discharge voltage according to the mixing ratio, and had 87% to 130% of dielectric strength compared to SF.sub.6.

[0063] Specifically, the mixed gas of CF.sub.3OCFCF.sub.2 and CO.sub.2 is superior to SF.sub.6 and g.sup.3 gases in the 50% discharge voltage regardless of the mixing ratio of CF.sub.3OCFCF.sub.2 when the distance between electrodes is 8 mm and 11 mm. In addition, it was found that the mixed gas of CF.sub.3OCFCF.sub.2 and CO.sub.2 was superior to SF.sub.6 and g.sup.3 gases in the 50% discharge voltage, except when the distance between electrodes was relatively small (5 mm) and the mixing ratio of CF.sub.3OCFCF.sub.2 was low (10 to 23 mol %). In particular, it is seen that when the mixing ratio of CF.sub.3OCFCF.sub.2 is 30 mol %, the 50% discharge voltage is 113% better than SF.sub.6 and 126% better than g.sup.3 gas.

[0064] FIG. 6 shows the results of a test (IEC 60060-1 lightning impulse test) measuring 50% discharge voltage of the mixed gas of CF.sub.3OCFCF.sub.2 and CO.sub.2 at different mixing ratios and SF.sub.6. As for a test electrode, the 50% discharge voltage was measured by applying Rogowski profile (field utilization factor of 0.94 to 1) and setting a distance between plane and plane electrodes to 5 mm, 8 mm, 11 mm, and 15 mm at atmospheric pressure.

[0065] The results of the experiment show that a mixed gas of 5% CF.sub.3OCFCF.sub.2 and 95% CO.sub.2 had a dielectric strength of 66% to 72% compared to SF.sub.6, and a mixed gas of 10% CF.sub.3OCFCF.sub.2 and 90% CO.sub.2 had a dielectric strength of 78% to 94% compared to SF.sub.6, indicating that the insulating gas of the present invention may replace SF.sub.6.

[0066] The insulating gas of the present invention may have a synergistic effect of ?0.1 or greater, ?0.08 or greater, or ?0.05 or greater. FIG. 5 is a graph showing a dielectric strength synergistic effect according to a mixing ratio of CF.sub.3OCFCF.sub.2. The dielectric strength synergistic effect (C) is obtained by Equation 1 below.

[00002]$\begin{array}{cc}C=\frac{k\left(\mathrm{Vm}-Va\right)}{\left(1-k\right)\left(\mathrm{Vm}-Vb\right)}& \left[\mathrm{Equation}1\right]\end{array}$

[0067] (wherein k is a mixing ratio (mol %) of the trifluoromethyl trifluorovinyl ether, V.sub.m is a dielectric breakdown voltage of the mixed gas, V.sub.a is a dielectric breakdown voltage of the trifluoromethyl trifluorovinyl ether, and V.sub.b is a dielectric breakdown voltage of the carrier gas)

[0068] Referring to FIG. 5, the dielectric strength synergistic effect shows a nonlinear pattern according to the mixing ratio of CF.sub.3OCFCF.sub.2 Specifically, the dielectric strength synergistic effect (C) is 0 or greater when the mixing ratio of CF.sub.3OCFCF.sub.2 is within the range of 25 to 58 mol %, the dielectric strength synergistic effect (C) value is ?0.05 or greater when the mixing ratio of CF.sub.3OCFCF.sub.2 is 20 to 60 mol %, and the dielectric strength synergistic effect (C) value is ?0.1 or greater when the mixing ratio of CF.sub.3OCFCF.sub.2 is 10 to 62 mol %. In addition, it is reasonably inferred that the dielectric strength synergistic effect value may be ?0.1 or greater or ?0.08 or greater for 10 mol % or less. In this case, even when the dielectric strength synergistic effect value corresponds to a (?) value, as shown in FIG. 4, it is seen that the 50% discharge voltage is higher than that of SF.sub.6 or g.sup.3 gas, except when the distance between electrodes is very small.

[0069] Meanwhile, insulating gases used in electric devices that insulate electricity or extinguish arc are not supposed to belong to the category of combustible gases. In accordance with KS B ISO 10156: 2017, standards for combustible gases are set as shown in the following table.

TABLE-US-00003 TABLE 3 Standards for combustible gas Category Standard 1 One of the following gases at 20? C. and a standard pressure of 101.3 kPa a) Ignitable when in a mixture having a volume fraction of less than 13% in air. or b) having a flammability range with air of at least 12% points regardless of lower flammability limit. 2 Gases having a flammability range when mixed with air at 20? C. and a standard pressure of 101.3 kPa, except for gases belonging to category 1.

[0070] The calculation results of the lower flammability limit (LFL) according to the mixing ratio of the mixed gas of CF.sub.3OCFCF.sub.2 and CO.sub.2 are shown in the following table. In this case, the lower flammability limit is a concentration range in which flame propagation may take place when a combustible gas is mixed with air and ignited, expressed in volume concentration (vol %), and refers to the lowest value in this volume concentration.

TABLE-US-00004 TABLE 4 Lower flammability limit according to the mixing ratio of CF.sub.3OCFCF.sub.2 of a mixed gas of CF.sub.3OCFCF.sub.2 of CO.sub.2 Mixing ratio 100 90 80 70 60 50 40 30 of CF.sub.3OCFCF.sub.2 Lower 7.5 8.37 9.47 10.9 12.84 15.61 19.89 27.36 flammability limit (LFL)

[0071] According to the experiment described above, it is seen that the case in which the mixing ratio of CF.sub.3OCFCF.sub.2 is 60% or less is out of the category of combustible gas category 1.

[0072] Meanwhile, preferably, the insulating gas does not react with electrodes or housings used in electrical devices for electrical insulation or arc extinguishing.

[0073] It was found that when CF.sub.3OCFCF.sub.2 was used alone as an insulating gas, CF.sub.3OCFCF.sub.2 reacted with electrodes at atmospheric pressure to form a carbon film, but when the mixing ratio of CF.sub.3OCFCF.sub.2 in the mixed gas of CF.sub.3OCFCF.sub.2 and CO.sub.2 was less than 70%, CF.sub.3OCFCF.sub.2 did not react with electrodes.

[0074] In this case, the reactivity test was to determine a reaction with electrodes upon testing dielectric strength for each mixing ratio of the insulating gases in an enclosed space where no external gas was not allowed to enter (insulation test chamber), at R.T. (room temperature), and at a standard atmospheric pressure of 1 atm. In this case, materials of a sphere electrode are CuCr and Wcu, and materials of a plane electrode are CuCr and SUS.

[0075] Accordingly, as for the mixed gas of CF.sub.3OCFCF.sub.2 and CO.sub.2, the mixing ratio of CF.sub.3OCFCF.sub.2 may be 1 to 60 mol %, 3 to 60 mol %, or 5 to 60 mol %, more preferably 1 to 20 mol %, 3 to 15 mol %, or 5 to 10 mol %, and the balance may be CO.sub.2. In the above range, the mixed gas had excellent global warming potential (GWP) and dielectric strength, had a low chance of flame propagation, and did not react to electrodes and SUS used in electric devices for electrical insulation or arc extinguishing, and thus it was found that the mixed gas was suitable as an alternative gas for SF.sub.6.

[0076] According to the present invention, the replacement of SF.sub.6 gas designated as a greenhouse gas with the mixed gas of CF.sub.3OCFCF.sub.2 and CO.sub.2 prevents loss of insulation performance compared to using SF.sub.6 gas, and allows a low global warming potential, thereby reducing harmful effects on the environment.

[0077] Meanwhile, it was found from the results of analyzing the components generated after arc extinguishing of CF.sub.3OCFCF.sub.2 that trifluoromethane (CHF.sub.3), hexafluoroethane (C.sub.2F.sub.6), tetrafluoroethane (C.sub.2F.sub.4), octafluoropropane (C.sub.3F.sub.8), hexafluoro ropropen (C.sub.3F.sub.6), and decafluorobutane (C.sub.4F.sub.10) were generated, and carbon compounds were generated from the substances.

[0078] Toxic by-products of the carbon compounds generated after arc extinguishing may be effectively reduced or avoided by using O.sub.2.

[0079] In this aspect, the carrier gas of the present invention may be CO.sub.2 and O.sub.2.

[0080] When the carrier gas of the insulating gas according to the present invention is CO.sub.2 and O.sub.2, when the mol % of CF.sub.3OCFCF.sub.2 represented by x, the mol % of CO.sub.2 represented by y, and the mol % of O.sub.2 represented by z are expressed in a triangular diagram with respect to a total amount of CF.sub.3OCFCF.sub.2, CO.sub.2, and O.sub.2, as shown in FIG. 7, (x, y, z) may be outside a region surrounded by straight line AB, straight line BC, and straight line CA. As shown in FIG. 7, this means that (x, y, z) is outside the Explosion region indicated by triangle ABC.

[0081] In this case, the straight line AB may be a straight line connecting point A and point B, the straight line BC may be a straight line connecting point B and point C, the straight line CA may be a straight line connecting point C and point A, and in the point A, (x , y, z) may be (50, 0, 50), in the point B, (x, y, z) may be (5.1, 0, 94.9), and in the point C, (x, y, z) may be (8.2, 80, 11.8). Unlike the case above, when (x, y, z) is present in the triangle ABC (explosion triangle) composed of the points A, B, and C, there may be an explosion hazard due to flammability.

[0082] In FIG. 7, the explosion limits indicate the explosion limit line, and is a line connecting the explosion limit points (filled square points). On the other hand, no ignition (hollow rectangle points) indicates a non-ignition point. Coordinates of the explosion limit points and non-ignition points are shown in Table 5 below.

TABLE-US-00005 TABLE 5 Gas composition in mol % C3F6O CO2 O2 Remarks 5.1 0.0 94.9 LEL 5.7 30.0 64.3 6.6 50.0 43.4 7.0 60.0 33.0 7.6 70.0 22.4 8.2 80.0 11.8 Point of tangency of ICR line 8.6 82.5 8.9 No ignition confirmed at 8.6% C3F6O 8.8 85.0 6.2 No ignition confirmed at 8.8% C3F6O

[0083] In addition, point A in the triangular diagram of FIG. 7 represents upper flammability limit (UFL), and when point A is connected to point C, which is an end point on the explosion limit line, a straight line AC, which is an expected explosion limit (expected line), is formed. Accordingly, it was found that the explosion triangle ABC would be formed by connecting the end points B and C, which are the end points on the explosion limit line, and the point A, and that non-flammability would be achieved when the composition of the insulating gas is present outside the explosion triangle. Meanwhile, the ICR line on the triangle diagram is tangent to the explosion triangle passing through 100% of O.sub.2, and the MXC value is 9.3% (C.sub.3F.sub.6O in CO.sub.2).

[0084] More specifically, the carrier gas is CO.sub.2 and O.sub.2, the mixed gas has CF.sub.3OCFCF.sub.2 in a mixing ratio of 1 to 60 mol % and O.sub.2 in a mixing ratio of 1 to 30 mol %, and the balance may be composed of CO.sub.2. More preferably in terms of insulation and stability, the mixed gas may have CF.sub.3OCFCF.sub.2 in a mixing ratio of 3 to 20 mol %, 4 to 16 mol %, or 5 to 10 mol %, O.sub.2 in a mixing ratio of 1 to 30 mol %, 1 to 25 mol %, 1 to 20 mol %, and CO.sub.2 as the balance.

[0085] When the mixing molar ratio of CF.sub.3OCFCF.sub.2 is greater than the above range, a synergistic effect or stability may be reduced, whereas when the mixing molar ratio of CF.sub.3OCFCF.sub.2 is less than the above range, insulation performance may be hardly effective. In addition, when the mixing molar ratio of O.sub.2 is greater than the above range, flammability may increase, whereas when the mixing molar ratio of O.sub.2 is less than the above range, the effect of reducing toxic by-products of the carbon compound may decrease.

[0086] In addition, when the carrier gas is CO.sub.2 and O.sub.2, the molar ratio of CO.sub.2 and O.sub.2 may be 70:30 to 99:1, 80:20 to 95:5, or 85:15 to 90:10. When the mixing molar ratio of O.sub.2 to CO.sub.2 is greater than the above range, flammability may increase, whereas when the mixing molar ratio of O2 is less than the above range, the effect of reducing toxic by-products of the carbon compound may decrease.

[0087] In addition, according to a preferred embodiment of the present invention, pure O.sub.2 and also a gas mixture containing O.sub.2, particularly air containing O.sub.2 may be used for the mixed gas of CF.sub.3OCFCF.sub.2 and CO.sub.2.

[0088] Meanwhile, an electric device corresponding to another aspect of the present invention is an electric device that insulates electricity or extinguishes arc through an insulating gas, and may insulate electricity or extinguish arc, using the insulating gas of the embodiment described above.

[0089] These electrical devices include gas transmission lines, gas insulated switchgear, Ring Main Unit (RMU), DC protection devices, and power distribution systems, and may be applicable to renewable energy such as solar and wind power, long-distance power transmission, and emergency power devices.

[0090] High voltage circuit breakers and gas insulated switchgears using the insulating gas of the present invention may be applicable to both a high voltage of 72.5 to 800 kV and a medium voltage of 1 to 72.5 kV, and are particularly suitable for high voltage areas.

[0091] The electric device (e.g., a high voltage circuit breaker or a gas insulated switchgear) of the present invention includes an insulating space filled with the insulating gas of the present invention inside a housing, and a conductive member provided inside the housing.

[0092] In this case, a temperature outside the housing may be ?35 to 55? C., ?30 to 50? C., or ?25 to 40? C., and an average temperature for 24 hours may be about 35? C. In addition, a pressure in the insulating space may be 1.5 MPaG, 1.2 MPaG, or 0.9 MPaG or less, and a voltage supplied to the conductive member may be 1 to 1100 kV, 1 to 1000 kV, or 1 to 800 kV.

[0093] Although the specific embodiments of the present invention are described with reference to the accompanying drawings, it should be apparent that the scopes of the present invention affect equivalents and modifications within the technical spirit as set forth in the claims.