An alternating output SF 6 / CF 4 Method for correcting the inflation ratio of a mixed gas inflation device

Abstract

A method for correcting the charging ratio of an alternating output SF6 / CF4 mixed gas charging device, belonging to the technical field of insulating and arc extinguishing media, which solves the problems of incomplete mixing of the SF6 / CF4 mixed gas charged into the gas chamber and inaccurate mixing ratio of the SF6 / CF4 mixed gas in the prior art; the technical solution of the present invention only uses one mass flow controller to alternately output SF6 and CF4 gases in different time periods, stores the alternately output SF6 and CF4 gases in a buffer tank, and at the same time judges whether the gas chamber pressure value meets the conditions after each charging cycle, and corrects the charging ratio of the last charging cycle according to the judgment conditions, achieving the requirement of fast mixing of the mixed gas, improving the accuracy of the mixing ratio, and reducing the cost of the device.

Description

Technical Field

[0001] The invention belongs to the technical field of insulation and arc extinguishing media, and relates to a method for correcting the gas filling ratio of an alternatingly output SF6 / CF4 mixed gas filling device. Background Art

[0002] So far, SF6 gas is still the most ideal insulation and arc extinguishing medium. However, the greenhouse effect of SF6 gas is 23,900 times that of CO2. It is one of the six greenhouse gases that are prohibited from being emitted in the Kyoto Protocol of the United Nations Framework Convention on Climate Change. Therefore, it needs to be strictly controlled during use. In order to adapt to the new international environmental protection requirements and reduce greenhouse gas emissions, mixed insulating gas has begun to be used to replace pure SF6 insulating gas at home and abroad to reduce the amount of SF6 gas.

[0003] In order to reduce the harm to the environment, my country's power grid has begun to try to promote hybrid electrical equipment. Relevant research shows that when the proportion of SF6 in the SF6 / CF4 mixed gas is between 40% and 60%, it has certain insulation and arc extinguishing capabilities, and has the characteristics of not being easy to liquefy, and is widely used in high-altitude cold areas. When the mixed gas inflation equipment is inflated for the first time or after a long period of operation, it needs to be inflated and replenished with gas. At present, there are two main methods for filling and replenishing mixed gases: the traditional partial pressure method and the new dynamic gas distribution method. The traditional partial pressure method is to fill the two gases in sequence, and use the partial pressure method to control the inflation volume and inflation speed to achieve the target ratio of the mixed gas. Although the method is simple, the two gases need to diffuse naturally in the gas chamber for a long time before they can be mixed. At the same time, the partial pressure method gas distribution is roughly estimated by measuring the absolute pressure in the chamber to be inflated, resulting in a large deviation between the actual inflation ratio and the ideal setting ratio.

[0004] The dynamic gas distribution method has made some improvements on the traditional partial pressure method. According to the required mixed gas ratio, two mass flow controllers (MFCs) are selected to adjust the flow of SF6 and CF4 respectively, and then directly fill them into the electrical equipment. The gas distribution accuracy (mixing ratio) and mixing degree are good. Affected by the reliability of MFC, although the same model of MFC is used, the actual errors of different MFCs manufactured in the same batch will also be different. For MFC, its marked accuracy is the maximum deviation range of the instrument of this model, such as ±1%, but because the manufacturing process and materials cannot be exactly the same, some MFCs may have errors that are mainly positive deviations, and the other part may be negative deviations. Therefore, when two MFCs of the same model are selected, the actual errors may be different, and the errors of the mixed gas mixing ratio may increase after the errors are superimposed on each other. For example, for the same model MFC with an accuracy of 1.0FS, the gas flow deviation of one gas tends to be +0.7%, and the gas flow deviation of the other gas tends to be -0.7%, and the final gas distribution error under this superposition will exceed the MFC gas distribution accuracy level.

[0005] In the prior art, the Chinese invention patent application document "A mixed gas replenishment device for high-voltage electrical equipment in extremely cold regions" with an application publication date of March 2, 2018 and application publication number CN107747678A uses a single-chip microcomputer to obtain the signal of a mass flow controller (MFC), controls the opening of the electromagnetic valve according to a preset value of the gas inflation ratio, and replenishes gas when the mixed gas ratio and pressure in the mixing bottle reach the optimal value; however, the document uses multiple mass flow controllers, which has a high probability of failure, and multiple mass flow controllers will also increase costs. Summary of the invention

[0006] The technical solution of the present invention is used to solve the problems of error and high cost of using multiple mass flow controllers in the dynamic gas distribution method in the prior art.

[0007] The present invention solves the above technical problems through the following technical solutions:

[0008] A method for correcting the inflation ratio of an inflation device that alternately outputs SF6 / CF4 mixed gas, the inflation device comprising: an SF6 gas circuit, a CF4 gas circuit, a mass flow controller (30), a buffer tank (31), an inflation pipeline, and a second pressure sensor (38); the output end of the SF6 gas circuit, the output end of the CF4 gas circuit, and the input end of the mass flow controller (30) are connected via a three-way pipeline, the output end of the mass flow controller (30) is connected to the input end of the buffer tank (31) via a pipeline, the output end of the buffer tank (31) is connected to the input end of the inflation pipeline via a pipeline, the output end of the inflation pipeline is connected to an air chamber, and the second pressure sensor (38) is installed between the output end of the inflation pipeline and the air chamber;

[0009] The inflation ratio correction method is as follows:

[0010] (1) Setting the mixed gas ratio to SF6:CF4=a:b, wherein a is the proportion of SF6 gas in each charging cycle T, b is the proportion of CF4 gas in each charging cycle T, and a+b=1; setting the single charging cycle of the mass flow controller (30) to T, the output flow rate to be constant to Q, opening the SF6 gas line to charge the buffer tank (31) with SF6 gas for aT time, then closing the SF6 gas line, opening the CF4 gas line and switching the mass flow controller (30), charging the buffer tank (31) with CF4 gas for bT time, and then closing the CF4 gas line, and controlling the mass flow controller (30) to alternately output SF6 and CF4 in each charging cycle;

[0011] (2) Before inflating the air chamber, the pressure value in the air chamber is measured by the second pressure sensor (38) as P0, the inflation pipeline is opened to inflate the air chamber, and after the second inflation cycle is completed, the inflation pipeline is closed, and the pressure value of the air chamber after the second inflation cycle is measured by the second pressure sensor (38) as P2. The average value of the pressure increase of the air chamber in a single inflation cycle is calculated as:

[0012]

[0013] Among them, △P T The average value of the pressure increase in the air chamber for a single inflation cycle;

[0014] Starting from the third inflation cycle, after each inflation cycle, the inflation pipeline is closed, and the pressure value in the air chamber is measured by the second pressure sensor (38) to obtain a value P C , and determine whether the following formula is satisfied:

[0015]

[0016] Among them, P M Indicates the rated pressure of the gas chamber;

[0017] If not, continue to inflate. If satisfied, correct the inflation ratio by the following formula:

[0018]

[0019]

[0020] Wherein, a′ represents the corrected SF6 gas charging ratio in the last charging cycle T, and b′ represents the corrected CF4 gas charging ratio in the last charging cycle T.

[0021] Furthermore, the SF6 gas circuit comprises: an SF6 steel cylinder (10), a first pressure reducing valve (11), a first heat exchanger (12), and a first solenoid valve (13); the output end of the SF6 steel cylinder (10) is connected to the input end of the first pressure reducing valve (11) via a pipeline; the output end of the first pressure reducing valve (11) is connected to the input end of the first heat exchanger (12) via a pipeline; the output end of the first heat exchanger (12) is connected to the input end of the first solenoid valve (13) via a pipeline; and the output end of the first solenoid valve (13) serves as the output end of the SF6 gas circuit.

[0022] Furthermore, the CF4 gas circuit comprises: a CF4 cylinder (20), a second pressure reducing valve (21), a second heat exchanger (22), and a second solenoid valve (23); the output end of the CF4 cylinder (20) is connected to the input end of the second pressure reducing valve (21) via a pipeline; the output end of the second pressure reducing valve (21) is connected to the input end of the second heat exchanger (22) via a pipeline; the output end of the second heat exchanger (22) is connected to the input end of the second solenoid valve (23) via a pipeline; and the output end of the second solenoid valve (23) serves as the output end of the CF4 gas circuit.

[0023] Furthermore, the inflation pipeline comprises: a compressor (32) and a third solenoid valve (33); the input end of the compressor (32) is connected to the output end of the buffer tank (31) via a pipeline; the output end of the compressor (32) is connected to the input end of the third solenoid valve (33) via a pipeline; the output end of the third solenoid valve (33) serves as an inflation port for connecting to the air chamber.

[0024] Furthermore, the inflation device further comprises: a first pressure sensor (36) and a temperature sensor (37), wherein the first pressure sensor (36) and the temperature sensor (37) are respectively sealed and mounted on the buffer tank (31).

[0025] Furthermore, the inflation device also includes a vacuum pumping pipeline, which includes: a fourth solenoid valve (34), a vacuum pump (35), and a vacuum gauge (39); the input end of the fourth solenoid valve (34) is connected between the output end of the buffer tank (31) and the input end of the compressor (32), the output end of the fourth solenoid valve (34) is connected to the input end of the vacuum pump (35) through a pipeline, the output end of the vacuum pump (35) serves as the exhaust port of the device, and the vacuum gauge (39) is sealed and installed between the fourth solenoid valve (34) and the vacuum pump (35).

[0026] Furthermore, the working process of the vacuum pumping pipeline is as follows: open the fourth solenoid valve (34), the first solenoid valve (13) and the second solenoid valve (23), start the vacuum pump (35) to vacuum the device, and after the vacuum pumping is completed, close the fourth solenoid valve (34), the first solenoid valve (13) and the second solenoid valve (23).

[0027] The advantages of the present invention are:

[0028] The technical solution of the present invention uses only one mass flow controller (30) to alternately output SF6 and CF4 gases in time periods, stores the alternately output SF6 and CF4 gases in a buffer tank (31), and simultaneously judges whether the value of the gas chamber pressure after each inflation cycle meets a condition, and corrects the inflation ratio of the last inflation cycle according to the judgment condition, thereby reducing the error of the gas distribution process, improving the accuracy of the mixing ratio, and reducing the cost of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic structural diagram of an SF6 / CF4 mixed gas charging device that alternately outputs gas according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific embodiments:

[0032] Embodiment 1

[0033] like Figure 1 As shown, the alternate output SF6 / CF4 mixed gas charging device of this embodiment includes: an SF6 cylinder (10), a first pressure reducing valve (11), a first heat exchanger (12), a first solenoid valve (13), a CF4 cylinder (20), a second pressure reducing valve (21), a second heat exchanger (22), a second solenoid valve (23), a mass flow controller (30), a buffer tank (31), a compressor (32), a third solenoid valve (33), a fourth solenoid valve (34), a vacuum pump (35), a first pressure sensor (36), a temperature sensor (37), a second pressure sensor (38), and a vacuum gauge (39).

[0034] The output end of the SF6 steel cylinder (10) is connected to the input end of the first pressure reducing valve (11) through a pipeline, the output end of the first pressure reducing valve (11) is connected to the input end of the first heat exchanger (12) through a pipeline, and the output end of the first heat exchanger (12) is connected to the input end of the first solenoid valve (13) through a pipeline; the output end of the CF4 steel cylinder (20) is connected to the input end of the second pressure reducing valve (21) through a pipeline, the output end of the second pressure reducing valve (21) is connected to the input end of the second heat exchanger (22) through a pipeline, and the output end of the second heat exchanger (22) is connected to the input end of the second solenoid valve (23) through a pipeline; the output end of the first solenoid valve (13), the output end of the second solenoid valve (23) and the input end of the mass flow controller (30) are connected through a three-way pipeline; the output end of the mass flow controller (30) is connected to the output end of the buffer tank (31). The first pressure sensor (36) and the temperature sensor (37) are respectively installed in a sealed manner on the buffer tank (31); the output end of the buffer tank (31), the input end of the compressor (32) and the input end of the fourth solenoid valve (34) are connected through a three-way pipeline; the output end of the compressor (32) and the input end of the third solenoid valve (33) are connected through a pipeline; the output end of the third solenoid valve (33) is used as an air filling port for connecting to the air chamber; the second pressure sensor (38) is installed in a sealed manner on the output end of the third solenoid valve (33); the output end of the fourth solenoid valve (34) is connected to the input end of the vacuum pump (35) through a pipeline; the output end of the vacuum pump (35) is used as the exhaust port of the device; the vacuum gauge (39) is installed in a sealed manner between the fourth solenoid valve (34) and the vacuum pump (35); all pipeline connections are sealed.

[0035] The working process of the alternate output SF6 / CF4 mixed gas charging device of this embodiment is as follows:

[0036] (1) Vacuuming the device

[0037] Open the fourth solenoid valve (34), the first solenoid valve (13) and the second solenoid valve (23), start the vacuum pump (35) to evacuate the device to 133 Pa, turn off the vacuum pump (35), read the vacuum value A of the vacuum gauge (39) after standing for 30 minutes, and read the vacuum value B of the vacuum gauge (39) after standing for 5 hours. The difference (BA) should not exceed 67 Pa. After the vacuuming is completed, close the fourth solenoid valve (34), the first solenoid valve (13) and the second solenoid valve (23);

[0038] (2) SF6 gas and CF4 gas are mixed evenly

[0039] The mixed gas ratio is set to SF6:CF4=a:b, wherein a is the proportion of SF6 gas in each charging cycle T, b is the proportion of CF4 gas in each charging cycle T, and a+b=1; the first pressure reducing valve (11) and the second pressure reducing valve (21) are adjusted to 0.6MPa, the output flow of SF6 and CF4 is adjusted to 100L / min, the single charging cycle of the mass flow controller (30) is set to T, and the mass flow controller (30) is controlled to alternately output SF6 and CF4 in each charging cycle to make the mixing more uniform, specifically: first open the first solenoid valve (13) to charge the buffer tank (31) with SF6 gas for aT time, then close the first solenoid valve (13), open the second solenoid valve (23) and switch the mass flow controller (30), charge the buffer tank (31) with CF4 gas for bT time, and then close the second solenoid valve (23).

[0040] (3) Inflation ratio correction

[0041] Before the air chamber is inflated, the pressure value in the air chamber is measured by the second pressure sensor (38) as P0, the third solenoid valve (33) is opened to inflate the air chamber, and after the second inflation cycle is completed, the third solenoid valve (33) is closed, and the pressure value of the air chamber after the second inflation cycle is measured by the second pressure sensor (38) as P2. The average value of the pressure increase of the air chamber in a single inflation cycle is calculated as:

[0042]

[0043] Among them, △P T The average value of the pressure increase in the air chamber for a single inflation cycle;

[0044] Starting from the third inflation cycle, after each inflation cycle, the third solenoid valve (33) is closed, and the pressure value in the air chamber is measured by the second pressure sensor (38) to obtain a value P C , and determine whether the following formula is satisfied:

[0045] △P T <P M -P C <2△P T

[0046] Among them, P M Indicates the rated pressure of the gas chamber;

[0047] If not, continue to inflate. If satisfied, correct the inflation ratio by the following formula:

[0048]

[0049]

[0050] Wherein, a′ represents the corrected SF6 gas charging ratio in the last charging cycle T, and b′ represents the corrected CF4 gas charging ratio in the last charging cycle T.

[0051] (4) Obtaining the optimal inflation cycle T

[0052] Due to the frequent switching of the mass flow controller and the influence of the residual gas volume in the front-end pipeline of the mass flow controller, there is a large difference between the actual proportion of the prepared gas and the set proportion. The inflation cycle T is changed, and the SF6:CF4 ratio is set to 50%:50%. By changing the SF6 output time in a single inflation cycle, the CF4 output time changes accordingly. The output flow rate is set to 100L / min, and the CF4 output time is the same as the SF6 output time. The SF6 output time in a single inflation cycle is set to 5s, 10s, 20s, 30s, 40s, and 80s, respectively. Table 1 is obtained through experiments.

[0053] Table 1 SF6 / CF4 mixed gas inflation repeatability test results at different inflation cycles T

[0054]

[0055] The proportion of SF6 at 0h represents the immediate mixing degree, and the proportion of SF6 after 24h represents the inflation proportion after stabilization. The difference between the two (the proportion of SF6 at 24h - the proportion of SF6 at 0h) represents the proportion increment of SF6 at 24h. After many experimental results, the average value of the proportion increment of SF6 at 24h is shown in Table 1 above. The value is less than 1% in 5-20s, and the value is greater than 1 in 30-80s. Under normal circumstances, the smaller the average value of the proportion increment of SF6 at 24h, the better the mixing effect. It can be seen that the mixing effect is negatively correlated with the periodic inflation time, that is, the shorter the single inflation time, the better the mixing effect, so the period T is selected as 5-20s. The repeatability of SF6 proportion after 24 hours reflects the stability of the gas inflation proportion value under the time allocation. The larger the value, the greater the difference in inflation proportion values ​​after multiple configurations, which is not conducive to the later coefficient correction. From the repeatability data of SF6 proportion after 24 hours in the table, it can be seen that the repeatability is lower than 1% at 10s and 20s, and higher than 1% at 5s. Therefore, when the output time of the two component gases is 10s to 20s, the mixing effect and repeatability are better.

[0056] According to the test results, the actual mixed ratio of the prepared gas is inconsistent with the pre-set mixed ratio (i.e., the inflation time allocated according to the mixed ratio), so a coefficient correction is required. It is known that when SF6 and CF4 are output at the same flow rate for 10s each, the actual mixed ratio is 45.75%:54.25%, and when they are output at the same flow rate for 20s each, the actual mixed ratio is 46.42%:53.58%. According to the test results, the two gases are corrected between a single output of 10s and 20s to ensure that the actual configured mixing ratio meets the target requirements.

[0057] Since the difference in SF6 proportion between 10s and 20s is 0.67%, the difference is small, and the mixing ratio is equal to the flow ratio, the average SF6 proportion of 46.17% (corresponding to CF4 proportion of 53.83%) is used as the flow ratio of the two gases in a single output between 10s and 20s. During this time period, the output flow can be considered stable. Set the target mixing ratio to a%:b%, where a%+b%=1, and set the output flow rate to 100L / min; under the target mixing ratio and output flow conditions, the output time of the two gases in each cycle is xs and ys respectively, where x and y are both between 10s and 20s. The method for taking the values ​​of x and y is:

[0058] When the output time is 10s to 20s, the actual output flow rate of SF6 is Q SF6 , the actual output flow of CF4 is Q CF4 ,but

[0059] Q SF6 :Q CF4 =46.17%:53.83%

[0060] Convert to: Q CF4 =53.83×Q SF6 / 46.17

[0061] The actual mixed gas ratio a%:b% is:

[0062]

[0063] Convert to:

[0064] a%=x / (53.83y / 46.17+x)

[0065] The above x and y are based on the fact that the output time of the two gases is between 10s and 20s. Therefore, the output time of the two gases in each cycle should be between 10s and 20s and the smaller the better. Therefore, further calculation is required to obtain the minimum x and y. Within the above range of values, the output flow is considered stable. From the proportional relationship, it can be seen that when one parameter reaches the minimum value, the other parameter is also the minimum value. Therefore, let x=10s, y can take any value in [10, 20] to obtain different mixing ratios. From the above formula, it can be seen that the output mixing ratio range is (expressed in terms of SF6 percentage) a∈[30.01%, 46.17%]; similarly, let y=10s, x can take any value in [10, 20] to obtain different mixing ratios. From the above formula, it can be seen that the output mixing ratio range is (expressed in terms of SF6 percentage) a∈[46.17%, 63.17%]. This mixing ratio range of the prepared mixed gas meets the current needs of the State Grid (SF6 percentage is 40% to 60%).

[0066] Therefore, when obtaining a SF6 / CF4 mixed gas with a target mixing ratio of a%:b%, when 30.01%≤a%≤46.17%, let x=10, then y=(10-10a%) / 1.1659a%;

[0067] If 46.17%≤a%≤63.17%, let y=10, then x=11.659a% / (1-a%).

[0068] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for correcting the gas filling ratio of an alternating output SF6 / CF4 mixed gas filling device, characterized in that: The inflation device comprises: an SF6 gas circuit, a CF4 gas circuit, a mass flow controller (30), a buffer tank (31), an inflation pipeline, and a second pressure sensor (38); the output end of the SF6 gas circuit, the output end of the CF4 gas circuit, and the input end of the mass flow controller (30) are connected via a three-way pipe, the output end of the mass flow controller (30) is connected to the input end of the buffer tank (31) via a pipe, the output end of the buffer tank (31) is connected to the input end of the inflation pipeline via a pipe, the output end of the inflation pipeline is connected to the air chamber, and the second pressure sensor (38) is installed between the output end of the inflation pipeline and the air chamber; The inflation ratio correction method is as follows: (1) Setting the mixed gas ratio to SF6:CF4=a:b, wherein a is the proportion of SF6 gas in each charging cycle T, b is the proportion of CF4 gas in each charging cycle T, and a+b=1; setting the single charging cycle of the mass flow controller (30) to T, adjusting the output flow of SF6 and CF4 to 100 L / min, opening the SF6 gas line to charge the buffer tank (31) with SF6 gas for aT time, then closing the SF6 gas line, opening the CF4 gas line and switching the mass flow controller (30), charging the buffer tank (31) with CF4 gas for bT time, and then closing the CF4 gas line, and controlling the mass flow controller (30) to alternately output SF6 and CF4 in each charging cycle; (2) Before inflating the air chamber, the pressure value in the air chamber is measured by the second pressure sensor (38) as P0, the inflation pipeline is opened to inflate the air chamber, and after the second inflation cycle is completed, the inflation pipeline is closed, and the pressure value of the air chamber after the second inflation cycle is measured by the second pressure sensor (38) as P2. The average value of the pressure increase of the air chamber in a single inflation cycle is calculated as: Among them, △P T The average value of the pressure increase in the air chamber for a single inflation cycle; Starting from the third inflation cycle, after each inflation cycle, the inflation pipeline is closed, and the pressure value in the air chamber is measured by the second pressure sensor (38) to obtain a value P C , and determine whether the following formula is satisfied: △P T <P M -P C <2△P T Among them, P M Indicates the rated pressure of the gas chamber; If not, continue to inflate. If satisfied, correct the inflation ratio by the following formula: Wherein, a′ represents the corrected SF6 gas charging ratio in the last charging cycle T, and b′ represents the corrected CF4 gas charging ratio in the last charging cycle T.

2. A method for correcting the gas filling ratio of an alternating output SF6 / CF4 mixed gas filling device according to claim 1, characterized in that: The SF6 gas circuit comprises: an SF6 steel cylinder (10), a first pressure reducing valve (11), a first heat exchanger (12), and a first solenoid valve (13); the output end of the SF6 steel cylinder (10) is connected to the input end of the first pressure reducing valve (11) via a pipeline; the output end of the first pressure reducing valve (11) is connected to the input end of the first heat exchanger (12) via a pipeline; the output end of the first heat exchanger (12) is connected to the input end of the first solenoid valve (13) via a pipeline; and the output end of the first solenoid valve (13) serves as the output end of the SF6 gas circuit.

3. A method for correcting the gas filling ratio of an alternating output SF6 / CF4 mixed gas filling device according to claim 2, characterized in that: The CF4 gas circuit comprises: a CF4 cylinder (20), a second pressure reducing valve (21), a second heat exchanger (22), and a second solenoid valve (23); the output end of the CF4 cylinder (20) is connected to the input end of the second pressure reducing valve (21) via a pipeline; the output end of the second pressure reducing valve (21) is connected to the input end of the second heat exchanger (22) via a pipeline; the output end of the second heat exchanger (22) is connected to the input end of the second solenoid valve (23) via a pipeline; and the output end of the second solenoid valve (23) serves as the output end of the CF4 gas circuit.

4. A method for correcting the gas filling ratio of an alternating output SF6 / CF4 mixed gas filling device according to claim 3, characterized in that: The inflation pipeline comprises: a compressor (32) and a third solenoid valve (33); the input end of the compressor (32) is connected to the output end of the buffer tank (31) via a pipeline; the output end of the compressor (32) is connected to the input end of the third solenoid valve (33) via a pipeline; the output end of the third solenoid valve (33) serves as an inflation port for connecting to the air chamber.

5. A method for correcting the gas filling ratio of an alternating output SF6 / CF4 mixed gas filling device according to claim 4, characterized in that: The inflation device further comprises: a first pressure sensor (36) and a temperature sensor (37), wherein the first pressure sensor (36) and the temperature sensor (37) are respectively installed in a sealed manner on the buffer tank (31).

6. A method for correcting the gas filling ratio of an alternating output SF6 / CF4 mixed gas filling device according to claim 5, characterized in that: The inflation device also includes a vacuum pumping pipeline, which includes: a fourth solenoid valve (34), a vacuum pump (35), and a vacuum gauge (39); the input end of the fourth solenoid valve (34) is connected between the output end of the buffer tank (31) and the input end of the compressor (32), the output end of the fourth solenoid valve (34) is connected to the input end of the vacuum pump (35) through a pipeline, the output end of the vacuum pump (35) serves as the exhaust port of the device, and the vacuum gauge (39) is sealed and installed between the fourth solenoid valve (34) and the vacuum pump (35).

7. A method for correcting the charging ratio of an alternating output SF6 / CF4 mixed gas charging device according to claim 6, characterized in that: The working process of the vacuum pumping pipeline is as follows: open the fourth solenoid valve (34), the first solenoid valve (13) and the second solenoid valve (23), start the vacuum pump (35) to vacuum the device, and after the vacuum pumping is completed, close the fourth solenoid valve (34), the first solenoid valve (13) and the second solenoid valve (23).

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