WO2024205069A1 - Insulating gas used for electrical insulation and electrical device using same - Google Patents

Abstract

The present invention relates to an insulating gas used for electrical insulation and an electrical device using same. The insulating gas according to the present invention has excellent insulating performance by having appropriate ranges of condensation temperature and breakdown voltage, and thus can be used for electrical insulation in place of sulfur hexafluoride (SF₆) gas. In addition, the insulating gas according to the present invention is used in electric power equipment in which arcs are not generated, and thus does not contain any oxygen (O₂), which is used by existing insulating gases to burn residual carbide, and as a result, the types of mixed gases are reduced and the mixing process can be omitted, thereby minimizing manufacturing costs. In addition, the insulating gas according to the present invention does not contain sulfur hexafluoride (SF₆) gas or carbon dioxide (CO₂) gas, which is a main cause of global warming, and thus is used as an eco-friendly insulating gas. Accordingly, the insulating gas according to the present invention has very high applicability to electrical devices that insulate electricity by using an insulating gas, especially electrical devices that do not generate arcs.

Description

Insulating gas used for electrical insulation and electrical devices using the same

The present invention relates to an insulating gas used for electrical insulation and an electrical device using the same.

Power equipment such as gas insulated sealing end (Europe/America), End-box gas (EBG, Japan) for general AC or DC, air termination for AC or DC (Outdoor/Indoor-termination (Europe/America), End-box air (EBA, Japan)), and test terminal for AC or DC use insulating gas as an insulator.

The most commonly used insulating gas in most power equipment to date is sulfur hexafluoride (SF ₆ ), which has excellent insulating performance and a low condensation temperature and has been used as an insulating medium in transmission and distribution power equipment for over 50 years.

However, in the case of sulfur hexafluoride (SF ₆ ) gas, the global warming potential (GWP), which indicates the degree to which other greenhouse gases contribute to global warming based on the effect of carbon dioxide on global warming, is very high at 23,900, and it is also a greenhouse gas with a very long atmospheric life of 3,200 years.

Efforts to reduce greenhouse gas emissions are being made on a large scale internationally, and through the 2015 Paris Agreement on Climate Change, each country allocated a reduction target for greenhouse gas emissions reduction. Korea submitted a greenhouse gas reduction target of 37% (56.4 million tons) compared to the projected greenhouse gas emissions (BAU, approximately 850 million tons) by 2030 to the UN Framework Convention on Climate Change Secretariat.

In this situation, it was necessary to develop an insulating gas that could reduce or replace the use of sulfur hexafluoride (SF ₆ ), which is an insulating gas used in power equipment and is also a greenhouse gas, and related technologies have been developed to meet this need.

First, technologies developed to reduce the amount of sulfur hexafluoride (SF ₆ ) gas used included technologies related to mixing sulfur hexafluoride (SF ₆ ) gas with dry air (a mixture of nitrogen and oxygen) or recycling sulfur hexafluoride (SF ₆ ) gas. However, these technologies inevitably entail the burden and risk of increasing the size of the applied power equipment or increasing the pressure of the insulating gas due to a decrease in the dielectric strength of the insulating gas, and therefore their introduction is currently being considered only for LV/MV with relatively low voltage.

As another method, there have been technologies to develop alternative eco-friendly insulating gases as a global trend.

For example, as in Patent Document 1, General Electric Technology GmbH (GE) of Switzerland launched an alternative insulating gas under the trade name g3 in 2014. g3 gas is a mixture of Novec ^TM 4710 (3 mol% to 10 mol%), CO ₂ (70 mol% to 97 mol%), and O ₂ (1 mol% to 25 mol%). It has a low condensation temperature of approximately -20°C or lower, and its insulation strength is approximately 81% to 106% of that of sulfur hexafluoride (SF ₆ ), making it an excellent insulating gas.

The aforementioned Novec ^TM 4710 is a gas specified as CAS 42532-60-5, and has a condensation temperature of -4.7℃ and a dielectric strength of 11㎸/㎜ (1 bar, 2.5㎜ gap between flat plate and flat plate electrodes), making it an insulating gas that cannot be used alone because its condensation temperature is too high.

Therefore, in the case of GE, the g3 insulating gas was developed by mixing _CO2 , which has a condensation temperature of -78.5℃, to lower the condensation temperature of the mixed insulating gas and by mixing oxygen to prevent breakdown due to carbide due to high-energy arc generation during switching, which is a characteristic of GIS equipment.

Additionally, even before GE's development of g3 insulating gas technology, there were efforts to develop alternative, environmentally friendly insulating gases.

In 2009, ABB successfully developed a 170kV GIS using Air-Plus insulating gas, which is a mixture of Novec ^TM 5110 and _CO2 . However, Novec ^TM 5110, which was used in the development of Air-Plus insulating gas, is heptafluoroisopropyl (trifluoromethyl) ketone (CAS 756-12-7), which has a global warming potential (GWP) of less than 1 but a very high condensation temperature of 26.9℃, so it can only be used in indoor power equipment.

Therefore, there is an urgent need for technology development for insulating gases used for electrical insulation and electrical devices using them through research and development of eco-friendly alternative insulating gases.

[Prior art literature]

[Patent Document]

Patent Document 1: International Publication No. WO2015/040069 (Published on March 26, 2015)

The present invention is intended to solve the above-mentioned problems, and provides an insulating gas used for electrical insulation and an electrical device using the same.

To solve the above-mentioned problems,

The present invention relates to an insulating gas used for electrical insulation of an electrical device,

The above insulating gas is a mixed gas containing heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN) and nitrogen (N ₂ ).

The above mixed gas provides an insulating gas satisfying both the following equations 1 and 2.

[Formula 1]

T _c = 17.263 × ln(M) A (67.666 ≤ A ≤ 77.326)

[Formula 2]

T _c ≤ 20 (unit: ℃)

In the above formulas 1 and 2, T _c means the condensation temperature of the mixed gas, and M means the mole percent concentration of heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN) contained in the mixed gas.

In addition, the present invention provides an insulating gas, characterized in that the mixed gas satisfies both of the following equations 3 and 4.

[Formula 3]

0.5874M + 10.762 ≤ V ≤ 0.7179M + 13.154

[Formula 4]

V ≤ 25 (unit: ㎸/㎜)

In the above formulas 3 and 4, V represents the breakdown voltage of the mixed gas, and M represents the mole percent concentration of heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN) contained in the mixed gas.

In addition, the present invention provides an insulating gas, characterized in that the mixed gas satisfies the following mathematical formula 5.

[Formula 5]

M ≤ 20 (unit: ㏖％)

In the above formula 5, M represents the mole percent concentration of heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN) contained in the mixed gas.

In addition, the present invention provides an insulating gas, characterized in that the insulating gas additionally contains at least one gas selected from the group consisting of helium (He), neon (Ne), and argon (Ar).

In addition, the present invention provides an insulating gas, characterized in that the mixed gas satisfies the following mathematical formula 6.

[Formula 6]

0.5 ≤ M (Unit: ㏖％)

In the above formula 6, M represents the mole percent concentration of heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN) contained in the mixed gas.

In addition, the present invention provides an electrical device that includes the insulating gas described above and insulates electricity by utilizing the insulating gas.

In addition, the present invention provides an electric device, characterized in that the electric device includes an insulating space, and the insulating space is filled with the insulating gas.

In addition, the present invention provides an electric device, characterized in that the pressure of the insulating gas filled in the insulating space is 0.2 MPa to 0.8 MPa.

In addition, the present invention provides an electric device, characterized in that the electric device is a gas terminal connection box for AC or DC.

In addition, the present invention provides an electric device, characterized in that the electric device is an air terminal connection box for AC or DC.

In addition, the present invention provides an electric device, characterized in that the electric device is a test terminal for AC or DC.

The insulating gas according to the present invention has excellent insulating performance by having an appropriate range of condensation temperature and breakdown voltage, and can be used for electrical insulation as a substitute for sulfur hexafluoride (SF ₆ ) gas.

In addition, since the insulating gas according to the present invention is used in power devices, etc., where arcs are not generated, it does not contain any oxygen (O ₂ ) that existing insulating gases use to burn residual carbides, and as a result, the types of mixed gases are reduced and the mixing process can be omitted, thereby minimizing the manufacturing cost.

In addition, the insulating gas according to the present invention does not contain carbon dioxide ( _CO2 ), a major cause of global warming, including sulfur hexafluoride ( _SF6 ) gas, and is thus utilized as an environmentally friendly insulating gas, and thus has a very high applicability to electrical devices that insulate electricity using insulating gas, particularly electrical devices that do not generate arcs.

The attached drawings are intended to explain the contents of the present invention in more detail to a person skilled in the art, but the technical idea of the present invention is not limited thereto.

FIG. 1 is a diagram showing a V-700 test terminal used for evaluating the performance of an HV air terminal block (EBA), which is a facility for testing the performance of an insulating gas used for electrical insulation according to the present invention and an electrical device using the same.

Figure 2 is a graph of the breakdown electric field according to pressure of an insulating gas used for electrical insulation according to the present invention.

Figure 3 is a graph showing the condensation temperature and breakdown electric field measured according to the mole percent concentration of heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN), an insulating gas used for electrical insulation according to the present invention.

Hereinafter, the insulating gas used for electrical insulation according to the present invention and the electrical device using the same will be described in detail, but the scope of the rights of the cable is not limited by the following description.

Throughout the specification, whenever a part is said to “include” a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise stated.

The present invention relates to an insulating gas used for electrical insulation.

The insulating gas may be in the form of a mixed gas. More specifically, the insulating gas may be a mixed gas containing heptafluoroisobutyronitrile and nitrogen (N ₂ ).

The above heptafluoroisobutyronitrile can be represented by the following chemical formula.

[chemical formula]

(CF ₃ ) ₂ CFCN

The above heptafluoroisobutyronitrile may correspond to 2,3,3,3-tetrafluoro-2-trifluoromethyl propanenitrile having a CAS number (Chemical Abstract Service Register Number) of "42532-60-5" and a boiling point of -3.9°C at 1 atm (1013 hPa) (the boiling point measured according to ASTM D1120-94 "Standard Test Method for Boiling Point of Engine Coolants").

The above heptafluoroisobutyronitrile has the characteristics of being non-toxic, non-corrosive and non-flammable, and exhibits a lower GWP than that of sulfur hexafluoride (SF ₆ ). In particular, when combined with a dilution gas, it can replace sulfur hexafluoride (SF ₆ ) gas as an insulating gas in high-voltage equipment, etc.

In the present invention, nitrogen (N ₂ ) is used as the dilution gas, and the heptafluoroisobutyronitrile is intended to be applied as an insulating gas in the form of a mixed gas. More specifically, in the case of the heptafluoroisobutyronitrile, since the condensation temperature is -4.7°C, which is higher than the required standard, and thus does not meet the operating temperature condition of -20°C for power equipment, it cannot be used as an insulating gas alone, and various gases such as Ar (-185°C), He (-268.9°C), O ₂ (-183°C), O ₂ (-78.5°C), and N ₂ (-195°C) with very low condensation temperatures must be mixed to lower the condensation temperature. Although Ar and He have low condensation temperatures, they are very expensive at more than twice that of N ₂ , and there is a problem that their supply is not smooth, so they have not been commercialized, and in the case of O ₂ , they are flammable gases and have a risk of explosion. In addition, CO ₂ is a greenhouse gas that is one of the main causes of global warming.

Accordingly, the present invention has developed an environmentally friendly mixed insulating gas as a result of studying a process of mixing nitrogen ( _N2 ), which is an inert gas, has a very low condensation temperature, is easy to supply, and is relatively inexpensive, with heptafluoroisobutyronitrile at an optimal ratio.

In particular, since the insulating gas according to the present invention is used in power devices that do not generate arcs, it has the advantage of reducing the types of mixed gases by not mixing oxygen (O ₂ ) and minimizing the manufacturing cost by omitting the mixing process.

In addition, the insulating gas according to the present invention has a very low GWP of 49 by using _nitrogen (N2) as a mixed gas, which is 0.2% lower than sulfur _hexafluoride ( _SF6 ) gas and 13% lower than g3 gas, compared to the existing GE's g3 gas which has a high GWP of 380 because its components are mostly composed of greenhouse gases (especially, it mixes in a high ratio (70 mol% or more) of CO2), and thus can be utilized as an environmentally friendly insulating gas.

With respect to the mixing ratio of heptafluoroisobutyronitrile and nitrogen, which are components of the above-described mixed gas, as can be confirmed in the examples described below, heptafluoroisobutyronitrile can be mixed at a mixing ratio of 20 mol% or less and 80 mol% or more of nitrogen in terms of mole percent (mol%) concentration, preferably, heptafluoroisobutyronitrile can be mixed at a mixing ratio of 0.5 mol% or more to 20 mol% or less and nitrogen can be mixed at a mixing ratio of 80 mol% or more to 99.5 mol% or less, and more preferably, heptafluoroisobutyronitrile can be mixed at a mixing ratio of 0.5 mol% or more to 17 mol% or less and nitrogen can be mixed at a mixing ratio of 83 mol% or more to 99.5 mol% or less.

In this case, as long as the above mixing ratio can be maintained, the nitrogen may be not only pure nitrogen but also a gas mixture containing nitrogen, particularly air containing nitrogen.

In one example, the mixed gas can satisfy both Equations 1 and 2 below.

[Formula 1]

T _c = 17.263 × ln(M) A (67.666 ≤ A ≤ 77.326)

[Formula 2]

T _c ≤ 20 (unit: ℃)

In the above formulas 1 and 2, T _c means the condensation temperature of the mixed gas, and M means the mole percent concentration of heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN)) contained in the mixed gas.

In the case of the mixed gas included in the insulating gas according to the present invention, by satisfying the above formulae 1 and 2, there is an advantage in that it can be used even in a lower cold environment.

In one example, the above mixed gas can satisfy both Equations 3 and 4 below.

[Formula 3]

0.5874M + 10.762 ≤ V ≤ 0.7179M + 13.154

[Formula 4]

V ≤ 25 (unit: ㎸/㎜)

In the above equations 3 and 4, V represents the breakdown voltage of the mixed gas, M represents the mole percent concentration of heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN)) contained in the mixed gas, and in the above equation 4, T _c represents the condensation temperature of the mixed gas.

In another example, the above mixed gas can satisfy the following equation 5.

[Formula 5]

M ≤ 20 (unit: ㏖％)

In the above formula 5, M means the mole percent concentration of heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN)) contained in the mixed gas.

In another example, the above mixed gas can satisfy the following equation 6.

[Formula 6]

0.5 ≤ M (Unit: ㏖％)

In the above formula 6, M represents the mole percent concentration of heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN) contained in the mixed gas.

In addition, if necessary, the insulating gas may be a mixed gas additionally including other gases within a range that does not hinder the implementation of the effects of the present invention.

Other gases that may be additionally included above are not particularly limited, but may be, for example, one or more gases selected from the group consisting of helium (He), neon (Ne), and argon (Ar).

The present invention also relates to an electrical device. More specifically, the present invention relates to an electrical device comprising the insulating gas described above and insulating electricity by utilizing the insulating gas.

In one example, the electrical device may include an insulating space, and the insulating space may be filled with the insulating gas.

The types of the above electrical devices may include gas insulated sealing end (Europe/America), End-box gas (EBG, Japan)) for AC or DC, air termination (Outdoor/Indoor-termination (Europe/America), End-box air (EBA, Japan)) for AC or DC, and test terminal (Test-termination) for AC or DC.

Although not specifically limited, the pressure used in the electric device can be charged and used within the range of 0.2 MPa to 0.8 MPa.

Hereinafter, the present invention will be described in more detail through specific experimental examples. However, these experimental examples are intended to exemplify the present invention, and the scope of the present invention is not limited to these experimental examples.

[Preparing for performance evaluation]

In order to test the performance of an insulating gas used for electrical insulation according to the present invention and an electric device using the same, the V-700 test terminal (see Fig. 1) used for evaluating the performance of HV power equipment was operated by filling the insulating gas according to the present invention at various pressures instead of sulfur hexafluoride (SF ₆ ) gas using the following method.

[Performance Evaluation]

The insulating gas used in the above performance evaluation was in the form of a mixed gas, containing heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN) and nitrogen (N ₂ ), and the mixing ratios were 15 mol% heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN) and 85 mol% nitrogen (N ₂ ) (Example 1), 9 mol% heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN) and 91 mol% nitrogen (N ₂ ) (Example 2), and 5 mol% heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN) and 95 mol% nitrogen (N ₂ ) (Example 3), and sulfur hexafluoride (SF ₆ ) gas was used as a control. The breakdown fields were measured and compared at different pressures (0.1 MPa, 0.3 MPa, 0.5 MPa, and 0.7 MPa).

Data on the measured breakdown field at different pressures are presented graphically in Fig. 2.

As shown in Fig. 2, when the insulating gas according to the present invention was used (Examples 1 to 3), the insulation strength was evaluated to be 22.8 kV/mm (based on 0.3 MPa), which is approximately 96% of that of SF ₆ gas (23.8 kV/mm, based on 0.3 MPa), and it was confirmed that the insulation strength changed in a proportional relationship depending on the pressure.

Additionally, in order to confirm the optimal mixing ratio of heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN) and nitrogen (N ₂ ) included in the insulating gas used for electrical insulation according to the present invention, the condensation temperature and breakdown electric field were measured according to the mole percent concentration of the heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN).

The measurement results are shown in Fig. 3.

As shown in Fig. 3, it was confirmed that the mixing ratio for maximum insulation strength while satisfying a condensation temperature of -20℃ or lower must be 20 mol% or less of heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN).

The above description of the present invention is for illustrative purposes only, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical idea or essential features of the present invention. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive. For example, each component described as a single component may be implemented in a distributed manner, and likewise, components described as distributed may be implemented in a combined manner.

The scope of the present application is indicated by the claims described below rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present application.

[Explanation of symbols]

10: V-700 Test Terminal

100: main tank

200: end tank

Claims (11)

As an insulating gas used for electrical insulation of electrical devices, The above insulating gas is a mixed gas containing heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN) and nitrogen (N ₂ ). The above mixed gas is an insulating gas satisfying both the following equations 1 and 2: [Formula 1] T _c = 17.263 × ln(M) A (67.666 ≤ A ≤77.326) [Formula 2] T _c ≤ 20 (unit: ℃) In the above formulas 1 and 2, T _c means the condensation temperature of the mixed gas, and M means the mole percent concentration of heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN) contained in the mixed gas. In paragraph 1, The above mixed gas is an insulating gas, characterized in that it satisfies both the following equations 3 and 4: [Formula 3] 0.5874M + 10.762 ≤ V ≤ 0.7179M + 13.154 [Formula 4] V ≤ 25 (unit: ㎸/㎜) In the above formulas 3 and 4, V represents the breakdown voltage of the mixed gas, and M represents the mole percent concentration of heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN) contained in the mixed gas. In paragraph 1, The above mixed gas is an insulating gas, characterized in that it satisfies the following equation 5: [Formula 5] M ≤ 20 (unit: ㏖％) In the above formula 5, M represents the mole percent concentration of heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN) contained in the mixed gas. In paragraph 1, An insulating gas, characterized in that the insulating gas additionally contains at least one gas selected from the group consisting of helium (He), neon (Ne), and argon (Ar). In the third paragraph, The above mixed gas is an insulating gas, characterized in that it satisfies the following equation 6: [Formula 6] 0.5 ≤ M (Unit: ㏖％) In the above formula 6, M represents the mole percent concentration of heptafluoroisobutyronitrile ((CF ₃ ) ₂ CFCN) contained in the mixed gas. Containing an insulating gas according to any one of claims 1 to 5, An electrical device that insulates electricity by utilizing the above insulating gas. In paragraph 6, The above electrical device comprises an insulating space, An electrical device, characterized in that the insulating space is filled with the insulating gas. In paragraph 7, An electrical device, characterized in that the pressure of the insulating gas filled in the insulating space is 0.2 MPa to 0.8 MPa. In paragraph 6, An electrical device, characterized in that the electrical device is a gas terminal connection box for AC or DC. In paragraph 6, An electrical device, characterized in that the electrical device is an air termination junction box for AC or DC. In paragraph 6, An electrical device, characterized in that the electrical device is a test terminal for AC or DC.

Images