Detection device for oil inlet pipe and oil return pipe in oil chromatography online monitoring system

Abstract

The invention discloses a detection device for an oil inlet pipe and an oil return pipe in an oil chromatography on-line monitoring system, and relates to the technical field of transformers, a device body is arranged in the oil chromatography on-line monitoring system, and the oil inlet pipe and the oil return pipe for connecting the oil chromatography on-line monitoring system and a transformer body are respectively provided with a tee joint; an oil inlet joint and an oil return joint on the back surface of the device body are respectively connected with one port of each of the two tee joints; an electromagnetic valve I and an electromagnetic valve II are respectively mounted on the oil inlet pipe and the oil return pipe and positioned at an oil valve flange opening of the transformer body; the first electromagnetic valve and the second electromagnetic valve are in electric control connection with an oil inlet and return valve terminal on the back face of the device body through electromagnetic valve lines. The transformer oil chromatography on-line monitoring device is connected in an existing transformer oil chromatography on-line monitoring oil way pipeline to detect an oil inlet pipe and an oil return pipe, so that related potential safety hazards are reduced, and heavy loss is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of transformers, and particularly relates to a detection device for the inlet and return oil pipes in an on-line oil chromatogram monitoring system. Background Art

[0002] The inlet and return oil pipes in an on-line oil chromatogram monitoring system for transformers are generally passed through galvanized pipes or other protective sleeves and buried under the pebbles in the accident oil drainage pool of the transformer. During normal inspections, it is impossible to see potential hazards or leaks in the oil pipes from the outside. However, during the operation process of several years or even longer, it is very difficult to ensure that the oil pipes are always intact. If the oil pipes are severely damaged, it may cause a transformer oil leakage accident, thus affecting the safe operation of the power grid. Summary of the Invention

[0003] The purpose of the present invention is to provide a detection device for the inlet and return oil pipes in an on-line oil chromatogram monitoring system in view of the defects and deficiencies of the prior art. The device is connected to the oil pipeline of the existing on-line oil chromatogram monitoring system for transformers to detect the inlet and return oil pipes, thereby reducing related potential safety hazards and avoiding major losses.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions: It includes a device body, a solenoid valve 1, a solenoid valve 2, and a tee. The device body is arranged in the on-line oil chromatogram monitoring system, and tees are installed on both the inlet pipe and the return pipe where the on-line oil chromatogram monitoring system is connected to the transformer body. The inlet oil connector and the return oil connector on the back of the device body are respectively connected to one end port of the two tees. Solenoid valve 1 and solenoid valve 2 are respectively installed at the positions of the oil valve flange ports of the transformer body on the inlet pipe and the return pipe. Solenoid valve 1 and solenoid valve 2 are respectively electrically controlled and connected to the inlet and return oil valve terminals on the back of the device body by solenoid valve wires. Inside the device body, there is an oil cylinder and a driving device for driving the movement of the oil cylinder. The driving device can be a stepping motor. A photoelectric switch 1 and a photoelectric switch 2 are respectively arranged above the oil cylinder. A solenoid valve 3 is installed on the oil pipe connecting the oil cylinder to the inlet oil connector, and a solenoid valve 4 is installed on the oil pipe connecting the oil cylinder to the return oil connector. A vent tank is also arranged inside the device body, and a solenoid valve 5 is installed on the pipeline connecting the oil cylinder to the vent tank. A pressure sensor 1 is installed on the inlet oil connector, a pressure sensor 2 is installed on the return oil connector, and a pressure sensor 3 is installed on the oil cylinder. Pressure sensor 1, pressure sensor 2, pressure sensor 3, solenoid valve 1, solenoid valve 2, solenoid valve 3, solenoid valve 4, and solenoid valve 5 are all electrically controlled and connected to the control board arranged at the top inside the device body.

[0005] With the above design, during the intermittent period of the oil chromatogram work, the device body is started regularly (the start time can be set by oneself), the solenoid valve 5 is opened, the driving device is started, and it runs to the photoelectric switch 1, that is, the smaller end of the internal volume of the oil cylinder, and the driving device stops;

[0006] Detect the inlet pipe: Solenoid valve 1 is normally open. Open solenoid valve 3, and the driving device starts to drive the oil cylinder to run to photoelectric switch 2. The oil of the transformer body will enter the oil cylinder through the inlet pipe. After a certain period of time or when the pressure sensor 3 detects that the oil pressure exceeds the atmospheric pressure, the inside of the oil cylinder is basically filled with transformer oil. At this time, solenoid valve 5 can be opened and the driving device can be used to drive the cylinder to run a little in the direction of photoelectric switch 1 to empty the possible gas in the oil cylinder. Then, first close solenoid valve 5, and then energize and close solenoid valve 1. In this way, a closed loop is formed between the inlet pipe and the oil cylinder. At this time, the driving device drives the cylinder to continue running in the direction of photoelectric switch 1, so that the oil sample in the oil cylinder will be compressed into the inlet pipe. Because the compressibility of the liquid is very small, the pressures detected by pressure sensor 1 and pressure sensor 3 will increase rapidly. When it reaches 200 - 300 Kpa or other set pressures, close solenoid valve 3. Pressure sensor 1 detects the pressure of the inlet pipe between solenoid valve 1 and solenoid valve 3. If the pressure change is not significant within a certain period of time, it means that the inlet pipe has no leakage, otherwise there is a problem with the inlet pipe. After detecting that the inlet pipe is intact, de-energize and open solenoid valve 1, energize and open solenoid valve 3, the oil cylinder runs to photoelectric switch 1, close solenoid valve 3, and prepare for the next detection.

[0007] Similarly, detect whether the return pipe is intact.

[0008] Oil pressure detection of the transformer body: Pressure sensor 1 and pressure sensor 2 are respectively connected to the inlet pipe and the return pipe, and can detect the pressures in the inlet pipe and the return pipe in real time. Generally, the inlet pipe is connected to the lower part of the transformer body, and the return pipe is connected to the middle part of the transformer body; According to the formula: P = ρgh, calculate the pressure. According to the rise and fall of the oil temperature of the transformer body, the vertical distance from the oil surface to the oil pressure test point will change, which will also cause a certain change in the pressure detection value. If the pressure change exceeds a certain value (excluding the pressure change caused by the operation of other equipment), it is necessary to check equipment such as the transformer breather. In the formula, P represents the pressure unit (Pa), ρ represents the density of the transformer oil, generally 895 kg / m 3 , g represents the acceleration of gravity, generally 9.8 m / s 2， h represents the height of the transformer oil, that is, the vertical distance from the liquid surface to the measurement point, and the unit is (m).

[0009] Preferably, a liquid level sensor is installed on the emptying tank to monitor in real time the amount of oil flowing into the emptying tank when emptying the gas in the oil cylinder to avoid overflow.

[0010] Preferably, a driving device driver for controlling the driving device is provided inside the device body, and the driving device driver is electrically connected to the control board.

[0011] Preferably, the control board is electrically connected to a display screen and a power switch disposed outside the device body.

[0012] Preferably, a switching power supply electrically connected to the control board is provided inside the device body.

[0013] Preferably, the bottom of the oil cylinder is mounted on the slider of a linear guide pair at the bottom inside the device body by means of a bracket.

[0014] Preferably, at the position where the solenoid valve wire is located outside the on-line oil chromatogram monitoring system, a power line protection tube is sleeved.

[0015] Preferably, several pressure sensors are installed on the oil inlet pipe and the oil return pipe to alternately detect the internal oil pressure of the transformer. According to the pressure changes of these pressure sensors, it is judged whether the internal pressure of the transformer is within the normal range. Alternately detecting the pressure by several pressure sensors can reduce or even avoid misjudgment.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a detection device for the oil inlet and return pipes in an on-line oil chromatogram monitoring system. A remotely controllable valve is installed at the oil valve flange of the transformer body, so that the oil pipe can form a closed-loop system, which is convenient for detecting whether the oil pipe and each connection point are in good condition, timely discovering faults such as breakage, leakage, and blockage of the oil inlet and return pipes of the on-line oil chromatogram monitoring system, timely closing the oil circuit, and prompting to check or replace the oil pipe to avoid the occurrence of oil leakage from the oil pipe; Multiple pressure sensors can be installed in the oil inlet and return pipes at the same time to measure the internal oil pressure of the transformer. According to the pressure changes of these pressure sensors, it is judged whether the internal pressure of the transformer is within the normal range. Alternately detecting the pressure by multiple pressure sensors can reduce or even avoid misjudgment. If multiple pressures exceed the normal value, it will affect the normal operation of the transformer, and it can prompt to check the breather of the transformer or the actual oil level of the transformer, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the front view of the device body in the present invention.

[0018] Figure 2 is Figure 1 the left view of

[0019] Figure 3 is Figure 1 the top view of

[0020] Figure 4 is the internal structure schematic diagram of the device body in the present invention.

[0021] Figure 5 is the installation schematic diagram of the present invention.

[0022] Figure 6It is a position diagram of the device body in the on-line oil chromatographic monitoring system in the present invention.

[0023] Figure 7 It is a schematic diagram of the present invention.

[0024] Explanation of reference numerals:

[0025] Device body 1, power switch 2, oil inlet joint 3, oil return joint 4, solenoid valve 1 5, solenoid valve 2 6, solenoid valve 3 7, solenoid valve 4 8, solenoid valve 5 9, vent tank 10, drive device 11, switching power supply 12, photoelectric switch 1 13, photoelectric switch 2 14, drive device driver 15, control board 16, oil cylinder 17, pressure sensor 1 18, pressure sensor 2 19, pressure sensor 3 20, liquid level sensor 21, linear guide pair 22, display screen 23, solenoid valve wire 24, tee 25, transformer body 26, on-line oil chromatographic monitoring system 27, oil inlet pipe 28, oil return pipe 29. Specific embodiments

[0026] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the accompanying drawings. Only the preferred embodiments in the description are taken as examples. All other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the present invention.

[0027] As Figures 1-7 shown, the following technical solutions are adopted in this specific embodiment: It includes a device body 1, a solenoid valve 1 5, a solenoid valve 2 6 and a tee 25; the device body 1 is arranged in the on-line oil chromatographic monitoring system 27, and tees 25 are connected in series on both the oil inlet pipe 28 and the oil return pipe 29 where the on-line oil chromatographic monitoring system 27 is connected to the transformer body 26. At the same time, several pressure sensors are installed on the oil inlet pipe 28 and the oil return pipe 29 to alternately detect the oil pressure inside the transformer, and judge whether the internal pressure of the transformer is within the normal range according to the pressure changes of these pressure sensors. Alternately detecting the pressure by several pressure sensors can reduce or even avoid misjudgment;

[0028] The oil inlet joint 3 and the oil return joint 4 on the back of the device body 1 are respectively connected to one end of the two tees 25; solenoid valve 1 5 and solenoid valve 2 6 are respectively installed at the oil valve flange positions of the transformer body 26 on the oil inlet pipe 28 and the oil return pipe 29; solenoid valve 1 5 and solenoid valve 2 6 are respectively electrically controlled and connected to the inlet and outlet oil valve terminals on the back of the device body 1 by the solenoid valve wire 24. The solenoid valve wire 24 is sleeved with a power line protection tube at the position outside the on-line oil chromatographic monitoring system 27.

[0029] Inside the device body 1, there is an oil cylinder 17 and a driving device 11 for driving the movement of the oil cylinder. The driving device 11 can be a stepping motor. The bottom of the oil cylinder 17 is installed on the slider of the linear guide pair 22 at the inner bottom of the device body 1 by means of a bracket, which can play a role in supporting and guiding during the operation of the oil cylinder 17. Inside the device body 1, there is a driving device driver 15 for controlling the driving device 11. The driving device driver 15 is electrically connected to the control board 16 arranged at the inner top of the device body 1. The control board 16 issues a control command to the driving device driver 15 to control the operation of the driving device 11. The control board 16 is electrically connected to the display screen 23 and the power switch 2 arranged outside the device body 1. The display screen 23 is used for controlling and feedbacking the data of the control board 16. Inside the device body 1, there is also a switching power supply 12 electrically connected to the control board 16. The power switch 2 controls the power supply and cut-off of the switching power supply 12 through the control board 16.

[0030] On the inner top wall of the device body 1, an optical switch one 13 and an optical switch two 14 are respectively installed above the oil cylinder 17. An electromagnetic valve three 7 is installed on the oil pipe connecting the oil cylinder 17 and the oil inlet joint 3. An electromagnetic valve four 8 is installed on the oil pipe connecting the oil cylinder 17 and the oil return joint 4. Inside the device body 1, there is also an emptying tank 10. A liquid level sensor 21 is installed on the emptying tank 10 to monitor in real time the amount of oil flowing into the emptying tank 10 when emptying the gas in the oil cylinder 17 to avoid overflow. An electromagnetic valve five 9 is installed on the pipeline connecting the oil cylinder 17 and the emptying tank 10. A pressure sensor one 18 is installed on the oil inlet joint 3, a pressure sensor two 19 is installed on the oil return joint 4, and a pressure sensor three 20 is installed on the oil cylinder 17. The pressure sensor one 18, the pressure sensor two 19, the pressure sensor three 20, the electromagnetic valve one 5, the electromagnetic valve two 6, the electromagnetic valve three 7, the electromagnetic valve four 8, and the electromagnetic valve five 9 are all electrically connected to the control board 16.

[0031] When using the present invention, during the intermittent period of the oil chromatography work, the device body 1 is started regularly (the start time can be set by oneself), the electromagnetic valve five 9 is opened, the driving device 11 is started, and when it runs to the optical switch one 13, that is, the smaller end of the internal volume of the oil cylinder 17, the driving device 11 stops.

[0032] Detect the inlet pipe: The solenoid valve 1 5 is normally open. Open the solenoid valve 3 7, and the driving device 11 starts to drive the oil cylinder 17 to run to the photoelectric switch 2 14. The oil in the transformer body 26 will enter the oil cylinder 17 through the inlet pipe 28. After a certain period of time or when the pressure sensor 3 20 detects that the oil pressure exceeds the atmospheric pressure, the inside of the oil cylinder 17 is basically filled with transformer oil. At this time, the solenoid valve 5 9 can be opened and the driving device 11 can be used to drive the cylinder 17 to run a little in the direction of the photoelectric switch 1 13 to evacuate the possible gas in the oil cylinder 17. Then, first close the solenoid valve 5 9, and then energize and close the solenoid valve 1 5. In this way, a closed loop is formed between the inlet pipe 28 and the oil cylinder 17. At this time, the driving device 11 drives the cylinder 17 to continue running in the direction of the photoelectric switch 1 13, so that the oil sample in the oil cylinder 17 will be compressed into the inlet pipe 28. Because the compressibility of the liquid is very small, the pressures detected by the pressure sensor 1 18 and the pressure sensor 3 20 will increase rapidly. When the pressure reaches 200 - 300 Kpa or other set pressures, close the solenoid valve 3 7. The pressure sensor 1 18 detects the pressure of the inlet pipe 28 between the solenoid valve 1 5 and the solenoid valve 3 7. If the pressure does not change much within a certain period of time, it means that the inlet pipe 28 has no leakage. Otherwise, there is a problem with the inlet pipe 28. After detecting that the inlet pipe 28 is intact, the solenoid valve 1 5 is de-energized and opened, the solenoid valve 3 7 is energized and opened, the oil cylinder 17 runs to the photoelectric switch 1 13, the solenoid valve 3 7 is closed, and the next detection is prepared.

[0033] Similarly, detect whether the return pipe 29 is intact.

[0034] Oil pressure detection of the transformer body 26: The pressure sensor 1 18 and the pressure sensor 2 19 are respectively connected to the inlet pipe 28 and the return pipe 29, and can detect the pressures in the inlet pipe 28 and the return pipe 29 in real time. Generally, the inlet pipe 28 is connected to the lower part of the transformer body 26, and the return pipe 29 is connected to the middle part of the transformer body 26; According to the formula: P = ρgh, calculate the pressure. According to the rise and fall of the oil temperature of the transformer body 26, the vertical distance from the oil surface to the oil pressure test point will change, which will cause a certain change in the pressure detection value. If the pressure change exceeds a certain value (excluding the pressure change caused by the operation of other equipment), it is necessary to check equipment such as the transformer breather. In the formula, P represents the pressure unit (Pa), ρ represents the density of the transformer oil, generally 895 kg / m 3 , g represents the acceleration of gravity, generally 9.8 m / s 2， h represents the height of the transformer oil, that is, the vertical distance from the liquid surface to the measurement point, and the unit is (m).

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] 1. Install a remotely controllable valve at the flange opening of the oil valve on the transformer body to form a closed-loop system for the oil pipe, facilitating the detection of the integrity of the oil pipe and each connection point, promptly discovering faults such as breakage, leakage, and blockage in the inlet and return oil pipelines of the on-line oil chromatogram monitoring system, promptly closing the oil circuit, and prompting an inspection or replacement of the oil pipe to avoid oil leakage from the oil pipe;

[0037] 2. At the same time, install multiple pressure sensors in the inlet and return oil pipelines to measure the internal oil pressure of the transformer. Based on the pressure changes of these pressure sensors, determine whether the internal pressure of the transformer is within the normal range. The multiple pressure sensors alternately detect the pressure, which can reduce or even avoid misjudgment. If multiple pressures exceed the normal value, it will affect the normal operation of the transformer, and it can prompt an inspection of the breather of the transformer or the actual oil level of the transformer, etc.

[0038] For those skilled in the art, they can modify the technical solutions recorded in the foregoing embodiments and make equivalent replacements for some technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A detection device for oil inlet and return oil pipes in an oil chromatography online monitoring system, characterized in that: It comprises a device body (1), a solenoid valve 1 (5), a solenoid valve 2 (6) and a tee (25); the device body (1) is arranged in an oil chromatogram online monitoring system (27), and the tee (25) is installed on an oil inlet pipe (28) and an oil return pipe (29) connecting the oil chromatogram online monitoring system (27) and a transformer body (26); an oil inlet connector (3) and an oil return connector (4) on the back of the device body (1) are respectively connected to one of the ports of the two tees (25); A solenoid valve 1 (5) and a solenoid valve 2 (6) are installed respectively on the oil inlet pipe (28) and the oil return pipe (29) at the oil valve flange opening of the transformer body (26); the solenoid valve 1 (5) and the solenoid valve 2 (6) are electrically connected to the oil inlet and return valve terminals on the back of the device body (1) by means of a solenoid valve line (24); an oil cylinder (17) and a driving device (11) for driving the oil cylinder to move are arranged inside the device body (1); the driving device (11) can be a stepper The motor is provided with a photoelectric switch 1 (13) and a photoelectric switch 2 (14) respectively located above the oil cylinder (17); a solenoid valve 3 (7) is installed on the oil pipe connecting the oil cylinder (17) and the oil inlet joint (3); a solenoid valve 4 (8) is installed on the oil pipe connecting the oil cylinder (17) and the oil return joint (4); a drain tank (10) is also provided inside the device body (1); a solenoid valve 5 (9) is installed on the pipeline connecting the oil cylinder (17) and the drain tank (10); the oil inlet joint ( 3), a pressure sensor 1 (18) is installed on the oil return joint (4), a pressure sensor 2 (19) is installed on the oil cylinder (17), and a pressure sensor 3 (20) is installed on the oil cylinder (17); the pressure sensor 1 (18), the pressure sensor 2 (19), the pressure sensor 3 (20), the solenoid valve 1 (5), the solenoid valve 2 (6), the solenoid valve 3 (7), the solenoid valve 4 (8) and the solenoid valve 5 (9) are all electrically connected to a control panel (16) arranged at the top of the device body (1).

2. The detection device for oil inlet and return oil pipes in an oil chromatography online monitoring system according to claim 1, characterized in that: During the interval of the oil chromatography operation, the device body (1) is started at a fixed time, the electromagnetic valve five (9) is opened, the driving device (11) is started, and the driving device (11) is stopped when the photoelectric switch one (13) is turned on, i.e., the internal volume of the oil cylinder (17) is at a smaller end; The oil inlet pipe is tested: the electromagnetic valve 1 (5) is normally open, the electromagnetic valve 3 (7) is opened, the driving device (11) is started to drive the oil cylinder (17) to move to the photoelectric switch 2 (14), and the oil in the transformer body (26) enters the oil cylinder (17) through the oil inlet pipe (28). After a certain period of time, the inside of the oil cylinder (17) is basically filled with transformer oil. At this time, the electromagnetic valve 5 (9) is opened and the driving device (11) drives the cylinder (17) to move slightly in the direction of the photoelectric switch 1 (13) to exhaust the gas that may exist in the oil cylinder (17). Then, the electromagnetic valve 5 (9) is closed first, and then the electromagnetic valve 1 (5) is powered on and closed. In this way, a closed loop is formed between the oil inlet pipe (28) and the oil cylinder (17). At this time, the driving device (11) drives the cylinder (17) to move to the photoelectric switch 1 If the oil in the oil cylinder (17) continues to run in the direction (13), the oil sample in the oil cylinder (17) will be compressed into the oil inlet pipe (28). Since the compressibility of the liquid is very small, the pressure detected by the pressure sensor 1 (18) and the pressure sensor 3 (20) will increase rapidly. When the set pressure is reached, the solenoid valve 3 (7) is closed. The pressure sensor 1 (18) detects the pressure of the oil inlet pipe (28) between the solenoid valve 1 (5) and the solenoid valve 3 (7). If the pressure does not change much within a certain period of time, it means that the oil inlet pipe (28) has no leakage. Otherwise, there is a problem with the oil inlet pipe (28). After the oil inlet pipe (28) is found to be intact, the solenoid valve 1 (5) is powered off and opened, and the solenoid valve 3 (7) is powered on and opened. The oil cylinder (17) runs to the photoelectric switch 1 (13), and the solenoid valve 3 (7) is closed to prepare for the next test. Similarly, check whether the oil return pipe (29) is intact; Oil pressure detection of transformer body (26): pressure sensor 1 (18) and pressure sensor 2 (19) are connected to the oil inlet pipe (28) and the oil return pipe (29) respectively, and can detect the pressure in the oil inlet pipe (28) and the oil return pipe (29) in real time. Generally, the oil inlet pipe (28) is connected to the lower part of the transformer body (26), and the oil return pipe (29) is connected to the middle part of the transformer body (26); according to the formula: P = ρgh, the pressure is calculated. According to the rise and fall of the oil temperature of the transformer body (26), the vertical distance from the oil surface to the oil pressure test point will change, which will cause a certain change in the pressure detection value. If the pressure change exceeds a certain value, it is necessary to check the transformer respirator and other equipment.

3. The detection device for oil inlet and return oil pipes in an oil chromatography online monitoring system according to claim 1, characterized in that: The drain tank (10) is provided with a liquid level sensor (21) for real-time monitoring of the amount of oil flowing into the drain tank (10) when the gas in the oil cylinder (17) is drained, so as to avoid overflow.

4. The detection device for oil inlet and return oil pipes in an oil chromatography online monitoring system according to claim 1, characterized in that: A drive device driver (15) for controlling the drive device (11) is arranged inside the device body (1), and the drive device driver (15) is electrically connected to a control panel (16).

5. The detection device for oil inlet and return oil pipes in an oil chromatography online monitoring system according to claim 1, characterized in that: The control panel (16) is electrically connected to a display screen (23) and a power switch (2) arranged outside the device body (1).

6. The detection device for oil inlet and return oil pipes in an oil chromatography online monitoring system according to claim 1, characterized in that: The device body (1) is provided with a switch power supply (12) electrically connected to the control panel (16).

7. The detection device for oil inlet and return oil pipes in an oil chromatography online monitoring system according to claim 1, characterized in that: The bottom of the oil cylinder (17) is mounted on a slider of a linear guide pair (22) at the bottom of the device body (1) by means of a bracket.

8. The detection device for oil inlet and return oil pipes in an oil chromatography online monitoring system according to claim 1, characterized in that: The solenoid valve line (24) is located outside the oil chromatogram online monitoring system (27) and is sheathed with a power line protection tube.

9. The detection device for oil inlet and return oil pipes in an oil chromatography online monitoring system according to claim 1, characterized in that: A plurality of pressure sensors are installed on the oil inlet pipe (28) and the oil return pipe (29) to detect the oil pressure inside the transformer alternately. According to the pressure changes of these pressure sensors, it is judged whether the pressure inside the transformer is within a normal range. The plurality of pressure sensors detect the pressure alternately to reduce or even avoid misjudgment.

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