Design Method and System for Enhancing Post-Arc Recombination Properties of C4F7N Environmentally Friendly Mixed Gas

Abstract

This invention provides a design method and system for C4F7N environmentally friendly mixed gas to enhance the post-arc recombination performance of plasma. By conducting a breaking test on a circuit breaker filled with C4F7N environmentally friendly mixed gas under a first preset current, a binary C4F7N mixed gas is selected. The volume percentage of C4F7N is determined based on the applicable ambient temperature of the equipment. Furthermore, an appropriate amount of O2 is added to the C4F7N binary mixed gas to inhibit carbon precipitation and deposition, as well as the decomposition or reaction of C4F7N gas. A breaking test is then conducted on the circuit breaker under a second preset current to determine the volume percentage of O2, thereby improving the recombination and reduction capabilities of the decomposition products after the C4F7N mixed gas breaks the arc. Finally, a ternary C4F7N mixed gas is selected to ensure successful high-capacity breaking of the circuit breaker.

Description

Technical Field

[0001] This invention relates to the field of environmentally friendly gas-insulated power transmission and distribution equipment technology, and more specifically, to a design method and system for C4F7N environmentally friendly mixed gas that enhances the post-arc recombination performance of plasma. Background Technology

[0002] Sulfur hexafluoride (SF6) gas is widely used in electrical equipment as an excellent insulating and arc-quenching medium. However, SF6 has a greenhouse effect 24,300 times that of CO2 and a lifespan in the atmosphere of up to 3,200 years, posing a significant adverse impact on the environment. Domestic and international research indicates that perfluoroisobutyronitrile (C4F7N) environmentally friendly gas, when mixed with CO2, O2, N2, or air, exhibits high insulation strength and a low greenhouse effect, making it considered a superior environmentally friendly alternative to SF6. Compared to SF6, C4F7N environmentally friendly mixed gas generates high-temperature arc plasma under equipment breaking conditions, resulting in significant decomposition or mutual reactions. This leads to poor gas recombination performance after arc breaking, severely limiting its high-capacity breaking capacity. Therefore, improving the recombination and insulation recovery performance of C4F7N environmentally friendly mixed gas arc plasma is particularly urgent for guiding the development of C4F7N environmentally friendly gas circuit breakers. Summary of the Invention

[0003] In view of this, the present invention proposes a design method and system for C4F7N environmentally friendly mixed gas to enhance the plasma post-arc recombination performance, aiming to solve the problem of poor recombination and reduction capabilities of existing C4F7N mixed gas decomposition products after arc breaking.

[0004] This invention proposes a design method for an environmentally friendly C4F7N mixed gas to enhance plasma post-arc recombination performance, comprising the following steps:

[0005] Three binary C4F7N mixtures, each consisting of a predetermined volume ratio of C4F7N and one of the buffer gases CO2, N2, or CF4, were selected as test gases under a first atmospheric pressure. These test gases were then introduced into the circuit breaker, and a breaking test was conducted at a first predetermined current. The gas composition in the circuit breaker after the breaking test was measured, and the total content of newly generated gases (excluding C4F7N, CO2, N2, or CF4) was determined. The binary C4F7N mixture with the lowest total content of newly generated gases was selected as the C4F7N environmentally friendly mixture with superior recombination capability after arc breaking, and this mixture was designated as the C4F7N environmentally friendly mixture. 4f ;

[0006] The C4F7N environmentally friendly mixed gas C was determined. 4f The volume percentage K of C4F7N in C4 The maximum value K C4m ;

[0007] In the C4F7N environmentally friendly mixed gas C 4f Adding a predetermined volume percentage of O2 to form a C4F7N ternary gas mixture. 4t To enhance the recombination capability after arc breaking; wherein, the volume percentage of O2 is less than or equal to 33%;

[0008] Under a second preset pressure, various combinations of C4F7N ternary gas mixtures were selected based on the volume percentage ranges of C4F7N and one of CO2, N2 or CF4, and O2. 4t Each of the C4F7N ternary gas mixtures (C4t) was charged into a circuit breaker, and a breaking test was conducted under a second preset current. The change in the volume percentage of C4F7N before and after the circuit breaker broke was measured, and the C4F7N mixture with the smallest change in volume percentage was selected. 4t C4F7N is an environmentally friendly mixed gas with the best recombination capability after arc breaking.

[0009] Furthermore, in the above-mentioned design method for C4F7N environmentally friendly mixed gas to enhance plasma post-arc recombination performance, the current value of the first preset current is less than or equal to 5kA.

[0010] Furthermore, in the above-mentioned design method for C4F7N environmentally friendly mixed gas to enhance plasma post-arc recombination performance, the volume ratio of C4F7N in the C4F7N binary mixed gas is 10-20%.

[0011] Furthermore, in the above-mentioned design method for C4F7N environmentally friendly mixed gas to enhance plasma post-arc recombination performance, the C4F7N environmentally friendly mixed gas C 4f The volume percentage of C4F7N in the sample includes:

[0012] Calculate the relationship between the gas pressure and temperature of C4F7N gas;

[0013] Based on the relationship between the gas pressure and temperature of C4F7N gas and the C4F7N environmentally friendly mixed gas used in circuit breakers... 4f The minimum applicable ambient temperature is required to calculate the C4F7N environmentally friendly mixed gas C. 4f The maximum volume fraction K of C4F7N C4m .

[0014] Furthermore, the design of the aforementioned environmentally friendly C4F7N mixed gas to enhance plasma post-arc recombination performance...

[0015] In this method, the relationship between the gas pressure and temperature of C4F7N gas is calculated according to the following formula:

[0016]

[0017]

[0018] In the formula, p is the pressure; T is the thermodynamic temperature; V m R is the gas molar volume; α is the gas pressure correction factor; β is the gas volume correction factor; T c It is the critical temperature of C4F7N gas; p c It is the critical pressure of C4F7N gas;

[0019] Based on the liquefaction temperature T of C4F7N gas at standard atmospheric pressure being -4.7℃, substituting this into equation (1) yields V. m Then V m Substituting into equation (1) yields the relationship between the gas pressure and temperature of C4F7N gas.

[0020] Furthermore, in the above-mentioned design method for C4F7N environmentally friendly mixed gas to enhance plasma post-arc recombination performance, the C4F7N environmentally friendly mixed gas C 4f The maximum volume fraction K of C4F7N C4m The calculation method is as follows:

[0021] Let K be the volume percentage of C4F7N. C4 Then the partial voltage p1 of C4F7N is P 总 ·K C4 P 总 C4F7N environmentally friendly mixed gas C 4f The air pressure, T is the pressure of the circuit breaker C. 4f The minimum applicable ambient temperature is calculated using equation (1) to determine the maximum volume fraction K of C4F7N. C4m It should satisfy 3% ≤ K C4 ≤K C4m .

[0022] Furthermore, in the above-mentioned design method for C4F7N environmentally friendly mixed gas to enhance plasma post-arc recombination performance, when the C4F7N ternary mixed gas C 4t When the gas is a mixture of C4F7N / CO2 / O2, K should be satisfied. O2 ≥9 / 4K C4 When the C4F7N ternary gas mixture C 4t When the gas is a C4F7N / N2 / O2 mixture, K should be satisfied. O2 ≥7 / 2K C4 When the C4F7N ternary gas mixture C 4t When the gas is a mixture of C4F7N / CF4 / O2, K should be satisfied. O2 ≥9 / 4K C4 .

[0023] Furthermore, in the above-mentioned design method for C4F7N environmentally friendly mixed gas to enhance plasma post-arc recombination performance, the current value of the second preset current is 10kA to 30kA.

[0024] Furthermore, in the above-mentioned design method for C4F7N environmentally friendly mixed gas to enhance plasma post-arc recombination performance, the volume percentage K of C4F7N is determined according to... C4 The range of values ​​for K and the volume percentage of O2 O2 Multiple volume percentage data are selected at equal intervals within the range of values ​​to combine mixed gases with different volume percentages, forming at least two C4F7N ternary mixed gases.

[0025] This invention also provides a design system for an environmentally friendly C4F7N mixed gas to enhance plasma post-arc recombination performance, comprising:

[0026] The binary mixed gas screening module is used to charge circuit breakers with three C4F7N binary mixed gases (composed of C4F7N in a preset volume ratio and one of the buffer gases CO2, N2, or CF4) under a first gas pressure. A breaking test is then conducted at a first preset current, and the gas composition in the circuit breaker after the breaking test is detected. The total content of newly generated gases other than C4F7N, CO2, N2, or CF4 is obtained. The C4F7N binary mixed gas with the lowest total content of newly generated gases is selected as the C4F7N environmentally friendly mixed gas with superior recombination ability after arc breaking, and this gas is designated as the C4F7N environmentally friendly mixed gas. 4f ;

[0027] Environmentally friendly mixed gas C 4f The volume percentage K of C4F7N in C4 The maximum value K C4m The determination module is used to determine the liquefaction temperature of C4F7N gas and the C4F7N environmentally friendly mixed gas used in circuit breakers. 4f The minimum applicable ambient temperature is required to determine the C4F7N environmentally friendly mixed gas C 4f The volume percentage K of C4F7N in C4 The maximum value K C4m ;

[0028] The O2 volume percentage determination module is used to control the C4F7N environmentally friendly mixed gas C 4f The volume percentage of O2 in the circuit breaker is adjusted to enhance its post-arc recombination capability; wherein, the volume percentage of O2 is less than or equal to 33%.

[0029] Three-way gas mixture C 4t The optimal proportion determination module is used to select, under a second preset gas pressure, various combinations of volume proportions of C4F7N ternary gas mixtures based on the volume proportion ranges of C4F7N and O2. 4tEach of the C4F7N ternary mixed gases C 4t The circuit breakers were charged separately, and a breaking test was conducted at the second preset current. The change in the volume ratio of C4F7N before and after the circuit breaker breaking was measured. The circuit breaker with the smallest change in volume ratio of C4F7N was selected. 4t C4F7N is an environmentally friendly mixed gas with the best recombination capability after arc breaking.

[0030] The present invention discloses a design method for an environmentally friendly C4F7N mixed gas to enhance plasma post-arc recombination performance. This method involves conducting breaking tests on circuit breakers filled with the C4F7N mixed gas to select a binary C4F7N gas. Based on the applicable ambient temperature of the equipment, the volume percentage of C4F7N is determined. Furthermore, an appropriate amount of O2 is added to the C4F7N binary mixed gas to inhibit carbon precipitation and deposition, as well as the decomposition or reaction of C4F7N. Breaking tests are then conducted on circuit breakers to determine the volume percentage of O2. Finally, the C4F7N mixed gas with the smallest change in volume percentage is selected. 4t As the environmentally friendly mixed gas with the best recombination capability after arc breaking, C4F7N can improve the recombination and reduction capabilities of the decomposition products after arc breaking, providing a basis for the research and development of C4F7N environmentally friendly gas circuit breakers and effectively ensuring the successful large-capacity breaking of circuit breakers. Attached Figure Description

[0031] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0032] Figure 1 A schematic flowchart illustrating the design method of C4F7N environmentally friendly mixed gas for enhancing plasma post-arc recombination performance provided in an embodiment of the present invention. Detailed Implementation

[0033] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0034] In existing technologies, the arc-quenching performance of C4F7N mixed with CO2, N2, or CF4, as well as key parameters such as the amount of O2 added to inhibit gas decomposition, are unknown. These parameters are mostly determined through preliminary breaking tests. However, the high cost of large-capacity breaking tests limits the number and conditions of these tests. Therefore, this invention conducts fewer simulation tests to detect changes in gas composition and volume ratio before and after the tests. Combined with theoretical analysis, it determines the composition of the C4F7N environmentally friendly mixed gas and core parameters such as the volume ratio of C4F7N and O2. This provides suitable insulation and arc-quenching gases for C4F7N environmentally friendly gas circuit breakers, offering a basis for their development.

[0035] See Figure 1 The design method of C4F7N environmentally friendly mixed gas for enhancing plasma post-arc recombination performance according to embodiments of the present invention includes the following steps:

[0036] Step S1: Under a first gas pressure, three binary C4F7N mixed gases, each consisting of a predetermined volume ratio of C4F7N and one of the buffer gases CO2, N2, or CF4, are respectively introduced into the circuit breaker. A breaking test is conducted under a first predetermined current, and the gas composition in the circuit breaker after the breaking test is detected. The total content of newly generated gases, excluding C4F7N, CO2, N2, or CF4, is obtained. The binary C4F7N mixed gas with the lowest total content of newly generated gases is selected as the C4F7N environmentally friendly mixed gas with superior recombination ability after arc breaking, and this is determined as the C4F7N mixed gas. 4f .

[0037] Specifically, each combination of C4F7N environmentally friendly mixed gas can be divided into multiple groups with varying volume percentages to ensure that the selected C4F7N binary mixed gas has the lowest total content of newly generated gas after the interruption test. 4f This refers to a mixture of C4F7N and CO2, a mixture of C4F7N and N2, or a mixture of C4F7N and CF4. The volume percentage of C4F7N in the binary gas mixture can be 10-20%, for example, 10%. In this step, to preliminarily determine the composition of the binary gas mixture, the breaking current does not need to be too large. Preferably, the first preset current value is less than or equal to 5kA; for example, a 100A breaking test can be conducted. The first gas pressure can be 0.8MPa, which can be selected according to different equipment.

[0038] In practice, various C4F7N environmentally friendly mixed gases are charged into a 126kV single-phase self-energized circuit breaker. In accordance with the requirements of GB1984-2014 "High Voltage AC Circuit Breakers", five breaking tests with a current of less than or equal to 5kA are carried out. Gas chromatography or gas chromatography-mass spectrometry is used to detect the gas composition of the circuit breaker after breaking. The total content of new gases generated during breaking, excluding C4F7N, CO2, N2 or CF4, is analyzed (the total amount of new gases for each mixed gas refers to the sum of new gases generated in the five sets of breaking tests).

[0039] Step S2, based on the liquefaction temperature of C4F7N gas and the C4F7N environmentally friendly mixed gas C used in the circuit breaker... 4f The minimum applicable ambient temperature is required to determine the C4F7N environmentally friendly mixed gas C 4f The volume percentage K of C4F7N in C4 The maximum value K C4m .

[0040] Specifically, the volume fraction K of C4F7N is determined according to the following method. C4 The maximum value K C4m Calculation:

[0041] (1) Calculate the relationship between the gas pressure and temperature of C4F7N gas.

[0042] In practical implementation, the relationship between the gas pressure and temperature of C4F7N gas is calculated according to the following formula:

[0043]

[0044]

[0045] In the formula: p is pressure, in MPa; T is thermodynamic temperature, in K; V m This refers to the molar volume of a gas, with units of m³. 3 / mol; R is a gas parameter, 8.3147 J·molK. -1 α is the gas pressure correction factor; β is the gas volume correction factor; T c It is the critical temperature of C4F7N gas, 385.928 K; p c It is the critical pressure of C4F7N gas, 2.5028 MPa.

[0046] Based on the liquefaction temperature T of C4F7N gas at standard atmospheric pressure being -4.7℃, substituting this into equation (1) yields V. m Then V m Substituting into equation (1) yields the relationship between the gas pressure and temperature of C4F7N gas.

[0047] (2) Based on the relationship between the gas pressure and temperature of C4F7N gas and the C4F7N environmentally friendly mixed gas used in circuit breakers... 4f The minimum applicable ambient temperature is required to calculate the C4F7N environmentally friendly mixed gas C. 4f The volume percentage K of C4F7N in C4 The maximum value K C4m .

[0048] In practical implementation, due to the environmentally friendly mixed gas C 4f The liquefaction temperatures of buffer gases CO2 (-78.3℃), N2 (-195.8℃), and CF4 (-128.1℃) are all significantly lower than the liquefaction temperature of C4F7N (-4.7℃). Therefore, the environmentally friendly mixed gas C... 4f The liquefaction temperature is determined solely by the partial pressure of C4F7N gas. Let K be the volume percentage of C4F7N. C4 Then the voltage divider p1 of the C4F7N circuit breaker is P 总 ·K C4 P 总 For environmentally friendly mixed gas C 4f The air pressure, T is the pressure of the circuit breaker C. 4f The minimum applicable ambient temperature is given by setting p1 = P. 总 ·K C4 Substitute into equation (1) to calculate K C4 The maximum value K C4m It should satisfy 3% ≤ K C4 ≤K C4m .

[0049] Step S3, in the C4F7N environmentally friendly mixed gas C 4f Adding a predetermined volume percentage of O2 to form a C4F7N ternary gas mixture. 4t To enhance the post-arc recombination capability of plasma during circuit breaker breaking tests; among which, for C4F7N / CO2 / O2, C4F7N / N2 / O2 and C4F7N / CF4 / O2 mixed gases, the test results showed that the O2 content was below 33% and did not support the combustion of the mixed gas. Therefore, preferably, the volume percentage of O2 is less than or equal to 33%.

[0050] In specific implementation, when the C4F7N ternary gas mixture C 4t When the gas is a mixture of C4F7N / CO2 / O2, K should be satisfied. O2 ≥9 / 4K C4 When the C4F7N ternary gas mixture C 4t When the gas is a C4F7N / N2 / O2 mixture, K should be satisfied. O2 ≥7 / 2K C4 When the C4F7N ternary gas mixture C 4tWhen the gas is a mixture of C4F7N / CF4 / O2, K should be satisfied. O2 ≥9 / 4K C4 .

[0051] Step S4: Under the second preset pressure, select various combinations of C4F7N ternary mixed gas C4F7N based on the volume ratio range of C4F7N and O2. 4t Each of the C4F7N ternary mixed gases C 4t The circuit breakers were charged separately, and a breaking test was conducted at the second preset current. The change in the volume ratio of C4F7N before and after the circuit breaker breaking was measured. The circuit breaker with the smallest change in volume ratio of C4F7N was selected. 4t C4F7N is an environmentally friendly mixed gas with the best recombination capability after arc breaking.

[0052] Specifically, the current value of the second preset current is 10kA to 30kA. After determining the volume ratio of two gases in the ternary gas mixture, the volume ratio of the third gas can be determined. Therefore, in this embodiment, it is only necessary to select ternary gas mixtures with different volume ratio combinations based on the volume ratio range of C4F7N and O2.

[0053] Preferably, based on the volume percentage K of C4F7N respectively C4 The range of values ​​for K and the volume percentage of O2 O2 Multiple volume percentage data are selected at equal intervals within the range of values ​​to combine mixed gases with different volume percentages, forming at least two C4F7N ternary mixed gases.

[0054] More specifically, it can be based on the volume percentage range K of C4F7N. C4 Two C4F7N volume percentages were selected at equal intervals, and the O2 volume percentage range K was determined. O2 Six C4F7N ternary mixed gases were formed by selecting three O2 volume percentages at equal intervals.

[0055] In specific implementation, each C4F7N ternary gas mixture C 4t A 126kV single-phase self-energized circuit breaker was charged, and in accordance with the requirements of GB1984-2014 "High Voltage AC Circuit Breakers", 10 breaking tests with currents of 10-30kA were carried out respectively. The volume ratio K of the circuit breaker after breaking was measured. C4 Analyze its relationship with K before the experiment C4 Change in amount. Preferably, in this embodiment, multiple switching tests are conducted under a second preset current to more accurately test the effect of O2 in inhibiting carbon precipitation and deposition and C4F7N gas decomposition.

[0056] In this embodiment, the first preset air pressure and the second preset air pressure can be equal, for example, both are 0.8MPa.

[0057] In this embodiment, the numbering of the steps should not be interpreted as a limitation on the order of the steps. For example, the order of steps S2 and S3 can be selected according to the specific situation.

[0058] This invention also provides a design system for an environmentally friendly C4F7N mixed gas to enhance plasma post-arc recombination performance. The system includes a binary mixed gas screening module, used to separately charge three C4F7N binary mixed gases (composed of C4F7N in a preset volume ratio and one of the buffer gases CO2, N2, or CF4) into a circuit breaker under a first gas pressure. A breaking test is conducted under a first preset current, and the gas composition in the circuit breaker after the breaking test is detected. The total content of newly generated gases other than C4F7N, CO2, N2, or CF4 is obtained. The C4F7N binary mixed gas with the lowest total content of newly generated gases is selected as the C4F7N environmentally friendly mixed gas with superior post-arc recombination performance, and this gas is determined as the C4F7N environmentally friendly mixed gas. 4f ;

[0059] Environmentally friendly mixed gas C 4f The volume percentage K of C4F7N in C4 The maximum value K C4m The determination module is used to determine the liquefaction temperature of C4F7N gas and the C4F7N environmentally friendly mixed gas used in circuit breakers. 4f The minimum applicable ambient temperature is required to determine the C4F7N environmentally friendly mixed gas C 4f The volume percentage K of C4F7N in C4 The maximum value K C4m ;

[0060] The O2 volume percentage determination module is used to control the C4F7N environmentally friendly mixed gas C 4f The volume percentage of O2 in the circuit breaker is increased to enhance its post-arc recombination capability.

[0061] Three-way gas mixture C 4t The optimal proportion determination module is used to select, under a second preset gas pressure, various combinations of volume proportions of C4F7N ternary gas mixtures based on the volume proportion ranges of C4F7N and O2. 4t Each of the C4F7N ternary mixed gases C 4t The circuit breakers were charged separately, and a breaking test was conducted at the second preset current. The change in the volume ratio of C4F7N before and after the circuit breaker breaking was measured. The circuit breaker with the smallest change in volume ratio of C4F7N was selected. 4t C4F7N is an environmentally friendly mixed gas with the best recombination capability after arc breaking.

[0062] The system implementation is based on the same principle as the method implementation described above, and the relevant parts can be referred to each other, which will not be repeated here.

[0063] In summary, this invention conducts a breaking test on a circuit breaker filled with a pre-set volume ratio of C4F7N environmentally friendly mixed gas under a first pre-set current. The C4F7N binary mixed gas with superior recombination capability after arc breaking is selected. The maximum volume ratio of C4F7N is determined by considering the liquefaction temperature of C4F7N and the applicable ambient temperature of the equipment. Based on this, an appropriate amount of O2 is added to the C4F7N binary mixed gas to inhibit carbon precipitation and deposition, as well as the decomposition or reaction of C4F7N gas. A breaking test is then conducted on the circuit breaker under a second pre-set current to determine the volume ratio of O2. The optimal C4F7N ternary mixed gas composition is selected, improving the recombination and reduction capability of the decomposition products after arc breaking of the C4F7N mixed gas, thus ensuring successful high-capacity breaking of the circuit breaker.

[0064] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A design method for an environmentally friendly C4F7N mixed gas to enhance plasma post-arc recombination performance, characterized in that, Includes the following steps: The three kinds of C4F7N binary mixed gases composed of the preset volume ratio of C4F7N and one of the buffer gases CO2, N2 or CF4 under the first gas pressure are respectively filled into the circuit breaker, the breaking test is carried out under the first preset current, and the gas composition in the circuit breaker after the breaking test is detected, the total content of the newly generated gas except C4F7N, CO2, N2 or CF4 is obtained, the C4F7N binary mixed gas with the lowest total content of the newly generated gas is selected as the C4F7N environmental protection mixed gas with relatively optimal post-breaking arc recombination ability, and is determined as C 4f ​ Based on the liquefaction temperature of C4F7N gas and the C4F7N environmentally friendly mixed gas used in circuit breakers... 4f The minimum applicable ambient temperature is required to determine the C4F7N environmentally friendly mixed gas C 4f The volume percentage K of C4F7N in C4 The maximum value K C4m ; In the C4F7N environmentally friendly mixed gas C 4f Adding a predetermined volume percentage of O2 to form a C4F7N ternary gas mixture. 4t To enhance the recombination capability after arc breaking; wherein, the volume percentage of O2 is less than or equal to 33%; Under a second preset pressure, various combinations of C4F7N ternary mixed gas C4F7N with different volume ratios were selected based on the volume ratio ranges of C4F7N and O2. 4t Each of the C4F7N ternary mixed gases C 4t The circuit breakers were charged separately, and a breaking test was conducted at the second preset current. The change in the volume ratio of C4F7N before and after the circuit breaker breaking was measured. The circuit breaker with the smallest change in volume ratio of C4F7N was selected. 4t C4F7N is an environmentally friendly mixed gas with the best recombination capability after arc breaking.

2. The design method for enhancing the post-arc recombination performance of C4F7N environmentally friendly mixed gas according to claim 1, characterized in that, The current value of the first preset current is less than or equal to 5kA.

3. The design method for C4F7N environmentally friendly mixed gas to enhance plasma post-arc recombination performance according to claim 1, characterized in that, The volume percentage of C4F7N in the C4F7N binary gas mixture is 10-20%.

4. The design method for C4F7N environmentally friendly mixed gas to enhance plasma post-arc recombination performance according to claim 1, characterized in that, The C4F7N environmentally friendly mixed gas C was determined. 4f The volume percentage K of C4F7N in C4 The maximum value K C4m include: Calculate the relationship between the gas pressure and temperature of C4F7N gas; Based on the relationship between the gas pressure and temperature of C4F7N gas and the C4F7N environmentally friendly mixed gas used in circuit breakers... 4f The minimum applicable ambient temperature is required to calculate the C4F7N environmentally friendly mixed gas C. 4f The volume percentage K of C4F7N in C4 The maximum value K C4m .

5. The design method for C4F7N environmentally friendly mixed gas to enhance plasma post-arc recombination performance according to claim 4, characterized in that, The relationship between the gas pressure and temperature of C4F7N gas can be calculated using the following formula: In the formula, p is the pressure; T is the thermodynamic temperature; V m R is the molar volume of the gas; R is the gas parameter; α is the gas pressure correction factor. β is the gas volume correction factor; T c It is the critical temperature of C4F7N gas; p c It is the critical pressure of C4F7N gas; Based on the liquefaction temperature T of C4F7N gas at standard atmospheric pressure being -4.7℃, substituting this into equation (1) yields V. m Then V m Substituting into equation (1) yields the relationship between the gas pressure and temperature of C4F7N gas.

6. The design method for C4F7N environmentally friendly mixed gas to enhance plasma post-arc recombination performance according to claim 5, characterized in that, The C4F7N environmentally friendly mixed gas C 4f The volume percentage K of C4F7N C4 The maximum value K C4m The calculation method is as follows: The voltage divider p1 of C4F7N is P 总 ·K C4 P 总 For environmentally friendly mixed gas C 4f The air pressure, T is the pressure of the circuit breaker C. 4f The minimum applicable ambient temperature K is calculated from equation (1) above. C4 The maximum value K C4m It should satisfy 3% ≤ K C4 ≤K C4m .

7. The design method of C4F7N environmentally friendly mixed gas to enhance plasma post-arc recombination performance according to claim 1, characterized in that, When the C4F7N ternary gas mixture C 4t When the gas is a mixture of C4F7N / CO2 / O2, K should be satisfied. O2 ≥9 / 4K C4 When the C4F7N ternary gas mixture C 4t When the gas is a C4F7N / N2 / O2 mixture, K should be satisfied. O2 ≥7 / 2K C4 When the C4F7N ternary gas mixture C 4t When the gas is a mixture of C4F7N / CF4 / O2, K should be satisfied. O2 ≥9 / 4K C4 .

8. The design method of C4F7N environmentally friendly mixed gas to enhance plasma post-arc recombination performance according to claim 1, characterized in that, The second preset current has a current value of 10kA-30kA.

9. The design method of C4F7N environmentally friendly mixed gas to enhance plasma post-arc recombination performance according to claim 1, characterized in that, Based on the volume percentage K of C4F7N respectively C4 The range of values ​​for K and the volume percentage of O2 O2 Multiple volume percentage data are selected at equal intervals within the range of values ​​to combine mixed gases with different volume percentages, forming at least two C4F7N ternary mixed gases.

10. A design system for an environmentally friendly C4F7N mixed gas to enhance plasma post-arc recombination performance, characterized in that, include: The binary mixed gas screening module is used to charge circuit breakers with three C4F7N binary mixed gases (composed of C4F7N in a preset volume ratio and one of the buffer gases CO2, N2, or CF4) under a first gas pressure. A breaking test is then conducted at a first preset current, and the gas composition in the circuit breaker after the breaking test is detected. The total content of newly generated gases other than C4F7N, CO2, N2, or CF4 is obtained. The C4F7N binary mixed gas with the lowest total content of newly generated gases is selected as the C4F7N environmentally friendly mixed gas with superior recombination ability after arc breaking, and this gas is designated as the C4F7N environmentally friendly mixed gas. 4f ; Environmentally friendly mixed gas C 4f The volume percentage K of C4F7N in C4 The maximum value K C4m The determination module is used to determine the liquefaction temperature of C4F7N gas and the C4F7N environmentally friendly mixed gas used in circuit breakers. 4f The minimum applicable ambient temperature is required to determine the C4F7N environmentally friendly mixed gas C 4f The volume percentage K of C4F7N in C4 The maximum value K C4m ; The O2 volume percentage determination module is used to control the C4F7N environmentally friendly mixed gas C 4f The volume percentage of O2 in the circuit breaker is adjusted to enhance its post-arc recombination capability; wherein, the volume percentage of O2 is less than or equal to 33%. Three-way gas mixture C 4t The optimal proportion determination module is used to select, under a second preset gas pressure, various combinations of volume proportions of C4F7N ternary gas mixtures based on the volume proportion ranges of C4F7N and O2. 4t Each of the C4F7N ternary mixed gases C 4t The circuit breakers were charged separately, and a breaking test was conducted at the second preset current. The change in the volume ratio of C4F7N before and after the circuit breaker breaking was measured. The circuit breaker with the smallest change in volume ratio of C4F7N was selected. 4t C4F7N is an environmentally friendly mixed gas with the best recombination capability after arc breaking.

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