Oil sampling and injecting device for bushing and transformer without power-off

Abstract

The present application belongs to the technical field of power transmission and distribution equipment detection and maintenance device, and particularly relates to a bushing and transformer oil sampling and oil injection device without power interruption, comprising a downward transition unit, a vacuum oil sampling unit and an oil-gas separation protection unit. The downward transition unit leads the oil path of the oil outlet of the bushing or transformer to a low operating height. The vacuum oil sampling unit comprises a cylinder and a rodless piston arranged in the cylinder. The rodless piston separates the cylinder into an oil sample cavity and a driving cavity. The driving cavity is connected to a vacuum pressure dual-purpose pump through a gas path, and the oil sample cavity is connected to the output end of the downward transition unit through an oil inlet pipeline. A bidirectional lip seal ring is arranged on the outer periphery of the rodless piston, which is suitable for bidirectional sealing under positive and negative pressure. A spiral flushing connector is arranged on the oil inlet path to enable the oil to spiral and flush the inner wall of the oil sample cavity. The oil-gas separation tank is internally provided with a staggered baffle and a wire mesh demister to prevent the oil from being sucked into the vacuum pump. The present application can take sealed oil samples and supplement oil without power interruption, avoid moisture and impurity pollution, and ensure the authenticity and reliability of the oil sample data.

Description

Technical Field

[0001] This invention belongs to the technical field of power transmission and distribution equipment testing and maintenance devices, and particularly relates to a device for taking oil samples and injecting oil into bushings and instrument transformers without power interruption. Background Technology

[0002] Oil-immersed bushings and instrument transformers are critical equipment in power systems, and the condition of their internal insulating oil directly affects the safe operation of the equipment. Dissolved gas chromatography analysis and micro-moisture detection of the insulating oil can effectively diagnose insulation defects such as discharge, overheating, and moisture absorption, making it an important means of condition-based maintenance for power equipment. Currently, many operating 110kV and 220kV older bushings have internal oil conservators under negative pressure, lacking independent oil expansion space. Furthermore, the bushings only have a vent plug at the top and a drain plug at the bottom, without a dedicated oil sampling valve. Oil sampling requires first opening the top vent plug to break the negative pressure before sampling from the bottom drain plug. Disassembling the top vent plug while energized poses serious safety risks such as oil spraying, grounding short circuits, and high-voltage electric shock to personnel; operating procedures explicitly prohibit live-line operations. Therefore, bushing oil sampling must be combined with transformer outage pre-testing, resulting in untimely defect tracking and necessitating waiting for annual outage maintenance windows. Frequent outages also cause grid load shedding and economic losses, fundamentally contradicting the condition-based maintenance strategy.

[0003] In existing technologies, solutions that convert internal negative pressure to a slightly positive pressure by adding an expander oil tank to the top of the bushing and then drawing oil from it still rely on the bushing's own positive pressure for oil extraction. This approach is unsuitable when the oil level in the bushing is insufficient or the expander fails. While using a vacuum pump to evacuate the sampling bottle allows for fully sealed sampling, the sampling chamber and pipeline cannot be effectively cleaned, leading to cross-contamination between the first and subsequent oil samples. Furthermore, the sampling volume is difficult to control precisely and lacks an anomaly protection mechanism. Some solutions separate oil extraction and replenishment into independent operation paths, resulting in complex structures and altering the working pressure of the insulating oil inside the bushing, posing safety hazards. The dual-syringe series sampling method relies on the equipment having positive pressure oil output capabilities, making it unsuitable for negative pressure bushings and limiting the sampling volume. None of these solutions simultaneously address the integrated requirements of uninterrupted oil extraction from negative pressure bushings, oil system circulation cleaning, fully sealed and contamination-free sampling, and anomaly protection.

[0004] Meanwhile, during the process of removing the top vent bolt to break the negative pressure, humid air and dust were directly drawn into the bushing. Repeated disassembly and reassembly of the vent plug and drain plug accelerated the aging of the PTFE gasket. After the sealing performance deteriorated, rainwater and moisture seeped in, leading to excessive dielectric loss and frequent partial discharges. The drain plug was exposed for a long time, accumulating dust and rust. The unstable oil flow rate under negative pressure and the open oil receiving port caused characteristic gases to escape and moisture to mix in, resulting in severely distorted test data. The bushing is installed on top of the main transformer, with narrow operating space and close to the end screen grounding terminal. The risks of working at height are high, waste oil collection is difficult, and oil extraction operations can easily damage the end screen grounding, causing floating discharge or even bushing explosion. Summary of the Invention

[0005] The purpose of this invention is to provide a device for taking oil samples and injecting oil without power supply to bushings and current transformers, so as to solve the technical problems of existing low-oil equipment being unable to safely take oil without power supply due to internal negative pressure, and the easy introduction of moisture and impurities during the sampling process, which leads to oil sample distortion and equipment moisture.

[0006] To achieve the above objectives, the specific technical solution of the bushing and transformer oil sampling and injection device of the present invention is as follows: The bushing and transformer oil sampling and injection device without power interruption includes a lower lead-in conversion unit, a vacuum oil sampling unit, and an oil-gas separation protection unit. The lower lead-out adapter unit includes an oil take-out tee, an oil take-out fixture, a first manual ball valve, a copper pipe, a compression fitting, a lower lead-out connector body, a fixed permanent magnet, a plug, a plug fixing fixture, a second manual ball valve, and a quick-connect fitting. The oil take-out tee is used to connect to the oil take-out port of the bushing or the current transformer, and the copper pipe leads the oil circuit down to a low operating height. The vacuum oil sampling unit includes a cylinder and a rodless piston slidably disposed within the cylinder. The rodless piston divides the interior of the cylinder into an oil sample chamber and a drive chamber that are not interconnected. The drive chamber is connected to a vacuum pressure pump via a third solenoid valve, a fourth solenoid valve, a fourth manual ball valve, and a three-way valve. The solenoid valves switch the positive and negative pressure states of the drive chamber, driving the rodless piston to reciprocate. The cylinder is equipped with a first magnetic signal switch and a second magnetic signal switch for detecting the stroke position of the rodless piston. The oil sample chamber is connected to the output end of a lower lead-in adapter unit via a first solenoid valve. The oil sample chamber is also equipped with a second solenoid valve and a third manual ball valve, and a liquid level switch is installed inside the oil sample chamber. The oil-gas separation protection unit is connected in series in the gas path between the drive chamber and the vacuum pressure dual-purpose pump, and includes an oil-gas separation tank, a float level switch, a fifth manual ball valve and a vacuum gauge. The rodless piston is provided with at least one sealing ring on its outer periphery. The sealing ring has a bidirectional lip structure, with sealing lips extending from the middle to both sides. One sealing lip faces the oil sample chamber, and the other sealing lip faces the drive chamber, which is suitable for bidirectional sealing conditions of negative pressure oil suction and positive pressure oil discharge. A swirling flushing connector is provided on the oil inlet path between the first solenoid valve and the oil sample chamber. The swirling flushing connector includes a tubular shell, a guide column coaxially disposed in the center of the inner cavity of the shell, and multiple spiral guide blades fixedly connected between the outer wall of the guide column and the inner wall of the shell. The end of the guide column facing the oil inlet direction is a smoothly transitioned pointed conical arc shape, and the diameter of the end of the guide column facing the oil sample chamber gradually increases. The end of the tubular shell corresponding to the oil sample chamber is a funnel-shaped expansion adapted to the guide column. The oil-gas separator has an air inlet connected to an air inlet pipe that extends downward to the bottom of the tank's inner cavity. Multiple stainless steel baffles are arranged alternately between the air inlet and the top air outlet in the tank's inner cavity. A wire mesh demister is installed at the top air outlet.

[0007] Furthermore, the two ends of the copper pipe are respectively connected to the first manual ball valve and the lower connector body via compression fittings; the lower connector body is provided with a fixed permanent magnet for adsorption and fixation to the steel shell of the equipment; the operating end of the lower connector body is provided with a plug and a plug fixing fixture to block the operating port in the non-operating state; the second manual ball valve is located in the oil circuit of the lower connector body; and the quick-connect fitting is located at the interface of the operating end.

[0008] Furthermore, the quick-connect connector of the lower lead adapter unit is adapted to connect with the provided quick-connect socket, and the quick-connect socket is connected to the first solenoid valve via a connecting pipe; the second solenoid valve is connected to the oil discharge passage of the oil sample chamber, and the third and fourth solenoid valves form a gas path reversing valve group, which respectively control the vacuum passage and positive pressure passage of the drive chamber.

[0009] Furthermore, the oil outlet direction of the swirling flushing connector is tangent to the inner wall of the oil sample chamber, so that the oil entering the oil sample chamber forms a spiral swirling flow along the inner wall of the chamber and flushes the inner wall.

[0010] Furthermore, the air inlet of the oil-gas separator is connected to the air passage via a fourth manual ball valve, and the lower end of the air inlet pipe inside the tank extends to 10mm from the bottom of the tank; the float level switch is set at the upper warning level inside the tank; the air passage connected to the air outlet of the oil-gas separator is connected to a vacuum pressure dual-purpose pump via a three-way valve, and a fifth solenoid valve is set in the other passage of the three-way valve, which is a vacuum breaking solenoid valve.

[0011] Furthermore, the rodless piston is a magnetically coupled piston with a built-in permanent magnet ring. The first magnetic signal switch and the second magnetic signal switch are respectively set on the outer sides of both ends of the cylinder body, and the left and right limit stroke positions of the rodless piston are detected by magnetic field induction.

[0012] Furthermore, the device has a cyclic cleaning mode, which alternately switches the positive and negative pressure of the drive chamber by a vacuum pressure dual-purpose pump, driving the rodless piston to reciprocate. In conjunction with the opening and closing of the first solenoid valve and the second solenoid valve, multiple cyclic flushing of the oil sample chamber is achieved.

[0013] Furthermore, the operating end of the lower lead-in adapter unit can be reused as an oil replenishment interface. After removing the blockage and the blockage fixing fixture, it can be connected to the vacuum oil replenishment equipment to achieve uninterrupted, sealed oil replenishment.

[0014] A method for using a bushing, current transformer, and oil sampling device that does not require power interruption for oil sampling and oil injection includes the following steps: S1 docking preparation: Connect the quick-connect socket of the vacuum oil sampling unit to the quick-connect connector of the lower lead adapter unit to connect the oil circuit; S2 chamber exhaust: Start the vacuum and pressure dual-purpose pump to enter positive pressure mode, switch the gas path through the third and fourth solenoid valves, drive the rodless piston to move towards the oil sample chamber side, and expel the residual air in the oil sample chamber; S3 Circulation Cleaning: Switch the vacuum and pressure dual-purpose pump to vacuum mode, drive the rodless piston to move towards the drive chamber side, creating negative pressure in the oil sample chamber; open the first solenoid valve, and the oil in the sleeve or transformer enters the oil sample chamber through the swirling flushing joint to create a swirling flow, flushing the inner wall of the chamber; after the level switch senses that the oil sample is full, close the first solenoid valve, switch back to positive pressure mode, and open the second solenoid valve to discharge the oil in the chamber; repeat the above steps to complete multiple circulation cleanings of the oil sample chamber; S4 Formal Sampling: Vacuum the oil again until the oil sample chamber is full, switch to positive pressure mode, open the third manual ball valve, and smoothly inject the oil sample into the sampling container to complete the sampling.

[0015] A method for using a bushing, current transformer, and oil injection device for non-power-off oil sampling and injection includes the following steps: S1 Interface Connection: Remove the plug and plug fixing fixture from the operating end of the lower lead adapter unit, and connect it to the vacuum oil replenishment equipment via a quick-connect connector; S2 pipeline venting: Vacuum the oil supply line and the lower oil inlet line to remove air from the pipeline; S3 Sealed Oil Injection: Qualified insulating oil is slowly injected into the bushing or transformer through the lower oil lead using the pressure difference, keeping the oil circuit sealed throughout the process. S4 oil filling complete: After filling the target oil volume, close the second manual ball valve, remove the oil replenishment equipment, reinstall the plug and plug fixing fixture, and restore the sealing of the operating end.

[0016] The oil sampling and injection device for bushings and current transformers without power interruption has the following advantages: The oil sampling port is led from the top of the equipment to a low operating height of 1-1.5 meters above the ground via a downward transfer unit. Combined with the controllable negative pressure generated by the reciprocating motion of a rodless piston driven by a vacuum / pressure dual-purpose pump, oil sampling can be completed without disassembling the vent plug at the top of the bushing. This solves the industry problem of requiring a power outage for oil sampling with older negative pressure bushings. Simultaneously, the operating end can be reused as an oil replenishment interface, eliminating the need for an additional oil replenishment path. This allows for sealed oil replenishment of the bushing or transformer without power interruption, resulting in a compact structure and convenient operation.

[0017] A bidirectional lip seal ring is set on the outer circumference of the rodless piston, with sealing lips extending from the center to both sides. The two lips are positioned facing the oil sample chamber and the drive chamber, respectively. During negative pressure oil suction, the sealing lip facing the oil sample chamber further tightens against the pipe wall under negative pressure to achieve a self-tight seal; during positive pressure oil discharge, the sealing lip facing the drive chamber tightens against the pipe wall under positive pressure to achieve a self-tight seal. This single sealing ring structure adapts to both opposite operating conditions, reliably preventing media cross-flow between the oil sample chamber and the drive chamber without the need for multiple seals. The structure is simple and offers high sealing reliability.

[0018] The vortex flushing connector features a guide column and spiral guide vanes. The inlet end of the guide column is rounded and pointed to reduce flow resistance, while the outlet end gradually widens in diameter and has a funnel-shaped wall to facilitate outward diffusion of the liquid flow. After passing through the spiral guide vanes, the oil forms a high-speed vortex, entering the oil sample chamber tangentially and spiraling along the inner wall of the chamber, effectively removing residual oil film and impurities adhering to the inner wall. Combined with a dual-purpose vacuum and pressure pump that alternately switches between positive and negative pressure to drive the rodless piston in reciprocating motion, multiple cycles of cleaning the oil sample chamber are achieved, improving the cleaning effect and ensuring no cross-contamination of the oil sample chamber and pipeline before sampling, thus ensuring that the first oil sample is truly representative.

[0019] The inlet pipe of the oil-gas separator extends to the bottom of the tank, and the airflow is discharged from the bottom to the top. Multiple layers of stainless steel baffles arranged in a staggered pattern inside the tank force the airflow along an S-shaped path. Oil droplets lose kinetic energy during collisions and settle to the bottom of the tank. A wire mesh demister at the top outlet further intercepts tiny oil mists, forming a three-stage separation mechanism of "gravity settling + baffle collision + wire mesh interception". A float level switch is located at the warning level at the top of the tank. If the oil level in the tank rises abnormally, it triggers the fifth solenoid valve to open, breaking the vacuum and stopping the vacuum pump, providing a final safety protection for the vacuum pump and completely eliminating the risk of oil being sucked into the vacuum pump and damaging the equipment.

[0020] The entire oil circuit from the oil inlet to the sampling outlet is a fully enclosed system. During the sampling process, the insulating oil never comes into contact with the outside atmosphere, eliminating the possibility of moisture and impurities in the air mixing into the oil sample. At the same time, it avoids the escape of dissolved gases, ensuring the authenticity and reliability of data such as chromatographic analysis and trace moisture detection, and providing an accurate basis for equipment condition assessment.

[0021] Operators can complete all oil extraction and replenishment operations on the ground without having to work at heights, eliminating the risks of falls from heights and electric shocks from high voltage. Waste oil is discharged in a closed pipeline, avoiding equipment pollution and environmental problems. The dual-valve isolation structure reliably seals the oil circuit when not in operation, with a static leakage rate approaching zero, significantly reducing the failure rate of moisture and breakdown caused by casing seal damage, resulting in good economic and social benefits. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the lower lead-out adapter unit structure of the present invention; Figure 3 This is a top view of the lower lead-out adapter unit of the present invention; Figure 4 This is a schematic diagram of the installation structure of the plugging and fixing tooling of the present invention; Figure 5 This is a schematic diagram of the quick-connect fitting installation structure of the present invention; Figure 6 For the present invention Figure 5 Enlarged view of region A in the middle; Figure 7 This is a schematic diagram of the vacuum oil sampling unit structure of the present invention; Figure 8 This is a top view schematic diagram of the vacuum oil sampling unit of the present invention; Figure 9 This is a schematic diagram of the cylinder block structure of the present invention; Figure 10 This is a schematic cross-sectional view of the cylinder block structure of the present invention; Figure 11 This is a schematic cross-sectional view of the rodless piston and sealing ring of the present invention; Figure 12 This is a schematic cross-sectional view of the vortex flushing connector of the present invention; Figure 13 This is a schematic diagram of the oil-gas separator structure of the present invention; Figure 14 This is a schematic cross-sectional view of the oil-gas separator of the present invention. Explanation of markings in the diagram: 1. Oil sampling tee; 2. Oil sampling fixture; 3. First manual ball valve; 4. Copper pipe; 5. Compression fitting; 6. Lower lead-in connector body; 7. Fixed permanent magnet; 8. Plug; 9. Plug fixing fixture; 10. Second manual ball valve; 11. Quick-connect fitting; 12. Quick-connect socket; 13. Connecting pipe; 14. First solenoid valve; 15. Second solenoid valve; 16. Third manual ball valve; 17. Liquid level switch; 18. Cylinder body; 1801. Oil sample chamber; 1802. Drive chamber; 19. Third solenoid valve. 20. Fourth solenoid valve; 21. Fourth manual ball valve; 22. Fifth manual ball valve; 23. Vacuum gauge; 24. Oil-gas separator; 25. Float level switch; 26. Fifth solenoid valve; 27. Three-way valve; 28. Vacuum and pressure dual-purpose pump; 29. ​​Rodless piston; 30. First magnetic signal switch; 31. Second magnetic signal switch; 32. Sealing ring; 33. Swirl flushing connector; 34. Housing; 35. Guide column; 36. Spiral guide vane; 37. Stainless steel baffle; 38. Wire mesh demister. Detailed Implementation

[0023] To better understand the purpose, structure, and function of this invention, the following detailed description of the bushing, transformer-based oil sampling and injection device is provided in conjunction with the accompanying drawings.

[0024] like Figure 1-14 As shown, the bushing and transformer oil sampling and injection device of the present invention includes a lower lead-in conversion unit, a vacuum oil sampling unit, and an oil-gas separation protection unit. The lower lead-out adapter unit includes an oil tee 1, an oil tee 2, a first manual ball valve 3, a copper pipe, a compression fitting 5, a lower lead-out connector body 6, a fixed permanent magnet 7, a plug 8, a plug fixing fitting 9, a second manual ball valve 10, and a quick-connect fitting 11. The oil tee 1 is used to connect to the oil port of the bushing or the current transformer, and the copper pipe leads the oil circuit down to a low operating height. The vacuum oil sampling unit includes a cylinder 18 and a rodless piston 29 slidably disposed within the cylinder 18. The rodless piston 29 divides the interior of the cylinder 18 into an oil sample chamber 1801 and a drive chamber 1802 that are not interconnected. The drive chamber 1802 is connected to a vacuum pressure dual-purpose pump 28 via a third solenoid valve 19, a fourth solenoid valve 20, a fourth manual ball valve 21, and a three-way valve 27. The solenoid valves switch the positive and negative pressure states of the drive chamber 1802, driving the rodless piston 29 to reciprocate. The cylinder 18 is equipped with a first magnetic signal switch 30 and a second magnetic signal switch 31 for detecting the stroke position of the rodless piston 29. The oil sample chamber 1801 is connected to the output end of a lower lead-in adapter unit via a first solenoid valve 14. The oil sample chamber 1801 is also equipped with a second solenoid valve 15 and a third manual ball valve 16. A liquid level switch 17 is installed inside the oil sample chamber 1801. The oil-gas separation protection unit is connected in series in the air path between the drive chamber 1802 and the vacuum pressure dual-purpose pump 28, and includes an oil-gas separation tank 24, a float level switch 25, a fifth manual ball valve 22 and a vacuum gauge 23. The rodless piston 29 is provided with at least one sealing ring 32 on its outer periphery. The sealing ring 32 has a bidirectional lip structure, with sealing lips extending from the middle to both sides. One sealing lip faces the oil sample chamber 1801, and the other sealing lip faces the drive chamber 1802, which is suitable for bidirectional sealing conditions of negative pressure oil suction and positive pressure oil discharge. A swirling flushing connector 33 is provided on the oil inlet path between the first solenoid valve 14 and the oil sample chamber 1801. The swirling flushing connector 33 includes a tubular housing 34, a guide column 35 coaxially disposed in the center of the inner cavity of the housing 34, and a plurality of spiral guide blades 36 fixedly connected between the outer wall of the guide column 35 and the inner wall of the housing 34. The end of the guide column 35 facing the oil inlet direction is a smoothly transitioned pointed conical arc shape, and the diameter of the end of the guide column 35 facing the oil sample chamber 1801 gradually increases. The end of the tubular housing 34 corresponding to the oil sample chamber 1801 is a funnel-shaped expansion adapted to the guide column 35. The oil-gas separator 24 has an air inlet connected to an air inlet pipe that extends downward to the bottom of the tank's inner cavity. Multiple stainless steel baffles 37 are arranged alternately between the air inlet and the top air outlet in the tank's inner cavity. A wire mesh demister 38 is installed at the top air outlet.

[0025] Combination Figure 1-14 As shown, the lower lead-in adapter unit includes an oil tap tee 1, an oil tap fixture 2, a first manual ball valve 3, a copper pipe, a compression fitting 5, a lower lead-in connector body 6, a fixed permanent magnet 7, a plug 8, a plug fixing fixture 9, a second manual ball valve 10, and a quick-connect fitting 11. The oil tap tee 1 is used to connect to the oil tap of the bushing or transformer. One end is connected to the existing oil tap of the bushing or transformer, serving as the oil input end of the entire device. The other two ports are connected to the oil tap fixture 2 and the first manual ball valve 3, respectively. The oil tap fixture 2 and the first manual ball valve 3 are connected to the oil tap tee 1 via sealing rings 32, ensuring reliable sealing at the connection. The oil tap fixture 2 has a built-in sealed valve opening mechanism. During installation, the oil tap of the bushing or transformer can be opened in a sealed state without disassembling any parts of the original oil tap of the bushing, avoiding the risk of seal damage and oil leakage caused by disassembly.

[0026] like Figure 1-6As shown, the first manual ball valve 3 is connected in sequence to the compression fitting 5, the lower guide body 6, the second manual ball valve 10, and the quick-connect fitting 11 via a copper pipe 4 with a protective sleeve. The copper pipe serves as the lower oil line pipeline, with one end connected to the first manual ball valve 3 via the compression fitting 5 and the other end connected to the lower guide body 6 via the compression fitting 5. This lowers the oil line from the oil inlet at the top of the equipment to a low operating height of 1 to 1.5 meters above the ground, allowing operators to complete oil intake and replenishment operations from the ground without having to climb to a height.

[0027] A fixed permanent magnet 7 is installed on the lower lead connector body 6. During installation, the lower lead connector body 6 is fixed to the steel shell of the transformer or instrument transformer by the fixed permanent magnet 7, ensuring that the lower lead pipeline will not loosen or swing due to vibration during long-term operation. The second manual ball valve 10 is set in the oil circuit of the lower lead connector body 6 as an isolation valve at the operating end. The quick-connect connector 11 is set at the operating end interface of the lower lead connector body 6 for quick connection to oil intake or oil replenishment equipment.

[0028] The operating end of the lower connector body 6 is equipped with a plug 8 and a plug fixing fixture 9 in the non-operating state. The plug 8 is connected to the lower connector body 6 by threads, and the plug fixing fixture 9 is used to lock and fix the plug 8, sealing the operating end interface. The first manual ball valve 3 and the second manual ball valve 10 form a double valve isolation structure. In the non-operating state, the second manual ball valve 10 is normally closed, working with the plug 8 to seal the operating end interface and maintain the internal sealing of the oil circuit. The outer layer of the copper pipe is equipped with a protective sleeve, which can effectively prevent the copper pipe from being damaged by collision or friction during installation and use. The copper pipe has good flexibility and can be bent arbitrarily according to the on-site installation needs, but dead angles should be avoided during installation to ensure unobstructed oil circuit.

[0029] The vacuum oil sampling unit includes a quick-connect socket 12, a connecting pipe 13, a first solenoid valve 14, a second solenoid valve 15, a third manual ball valve 16, a level switch 17, a cylinder 18, a third solenoid valve 19, a fourth solenoid valve 20, a rodless piston 29, a first magnetic signal switch 30, and a second magnetic signal switch 31. A quick-connect connector 11 with a check valve is fitted to the quick-connect socket 12. When oil sampling or replenishment is required, the quick-connect socket 12 is inserted into the quick-connect connector 11 to quickly open the oil circuit. The quick-connect connector 11 has a check valve inside; when the quick-connect socket 12 is not inserted, the check valve automatically closes to prevent oil leakage; when the quick-connect socket 12 is inserted, the check valve is opened, and the oil circuit is open. The quick-connect socket 12 is connected to the first solenoid valve 14 via the connecting pipe 13.

[0030] The cylinder body 18 is a cylindrical sealed container, inside which a rodless piston 29 is slidably disposed. The rodless piston 29 divides the interior of the cylinder body 18 into two non-communicating chambers: an oil sample chamber 1801 and a drive chamber 1802. The oil sample chamber 1801 is used to temporarily store insulating oil samples extracted from bushings or transformers, while the drive chamber 1802 is used to receive positive or negative pressure from a vacuum-pressure pump 28 to drive the rodless piston 29 in reciprocating motion.

[0031] like Figure 10 , 11 As shown, at least one sealing ring 32 is provided on the outer periphery of the rodless piston 29. The sealing ring 32 has a bidirectional lip structure, with sealing lips extending from the middle to both sides. One sealing lip faces the oil sample chamber 1801, and the other sealing lip faces the drive chamber 1802. This sealing ring 32 is suitable for bidirectional sealing conditions of negative pressure oil suction and positive pressure oil discharge: when the oil sample chamber 1801 is under negative pressure for oil suction, the sealing lip facing the oil sample chamber 1801 further opens and adheres tightly to the pipe wall under the action of negative pressure, achieving a self-tight seal and reliably preventing gas from the drive chamber 1802 side from entering the oil sample chamber 1801; when the drive chamber 1802 is under positive pressure for oil discharge, the sealing lip facing the drive chamber 1802 further opens and adheres tightly to the pipe wall under the action of positive pressure, achieving a self-tight seal and reliably preventing oil from the oil sample chamber 1801 side from entering the drive chamber 1802. A sealing ring 32 structure can simultaneously adapt to the sealing requirements of two opposite working conditions. The structure is simple and the sealing reliability is high.

[0032] The oil sample chamber 1801 is connected to the output terminal of the lower lead-in transfer unit via the first solenoid valve 14. The first solenoid valve 14 is an oil inlet control valve, used to control whether the insulating oil in the bushing or transformer enters the oil sample chamber 1801. The oil sample chamber 1801 is also equipped with a second solenoid valve 15 and a third manual ball valve 16 as sampling outlets. The second solenoid valve 15 is used to control the discharge of oil samples in the oil sample chamber 1801, and the third manual ball valve 16 is a manual shut-off valve for the sampling outlet, used to control the flow rate of oil sample injected into the sampling container during sampling operations.

[0033] A level switch 17 is installed inside the oil sample chamber 1801. The probe of the level switch 17 extends into the oil sample chamber 1801 to a predetermined depth to detect the oil level inside the oil sample chamber 1801. When the oil level in the oil sample chamber 1801 rises to the point where it touches the probe of the level switch 17, the level switch 17 is activated, sending a signal to close the first solenoid valve 14, stopping the oil intake, and preventing the oil sample chamber 1801 from overflowing.

[0034] The drive chamber 1802 is connected to the vacuum-pressure dual-purpose pump 28 via the third solenoid valve 19, the fourth solenoid valve 20, the fourth manual ball valve 21, and the three-way valve 27. The third solenoid valve 19 and the fourth solenoid valve 20 form a gas path reversing valve group, which respectively controls the vacuum passage and the positive pressure passage of the drive chamber 1802. Specifically, the third solenoid valve 19 is located in the gas path between the drive chamber 1802 and the oil-gas separator 24, and is used to control the opening and closing of the vacuum circuit; the fourth solenoid valve 20 is located in the gas path between the positive pressure output end of the vacuum-pressure dual-purpose pump 28 and the drive chamber 1802, and is used to control the opening and closing of the positive pressure circuit. By controlling the third solenoid valve 19 and the fourth solenoid valve 20, the drive chamber 1802 can switch between vacuum and positive pressure states, thereby driving the rodless piston 29 to reciprocate.

[0035] The fourth manual ball valve 21 is installed in the air circuit between the drive chamber 1802 and the oil-gas separator 24. It serves as a manual shut-off valve for the air circuit and can be manually shut off during system maintenance or when the system is not in operation.

[0036] A first magnetic signal switch 30 and a second magnetic signal switch 31 are respectively installed on the outer sides of both ends of the cylinder body 18. The rodless piston 29 is a magnetically coupled piston with a built-in permanent magnet ring. The first magnetic signal switch 30 and the second magnetic signal switch 31 detect the left and right limit stroke positions of the rodless piston 29 through magnetic field induction. When the rodless piston 29 moves to the maximum limit position of the oil sample chamber 1801, the first magnetic signal switch 30 is activated; when the rodless piston 29 moves to the minimum limit position of the oil sample chamber 1801, the second magnetic signal switch 31 is activated. The signals from the first magnetic signal switch 30 and the second magnetic signal switch 31 are used by the control system to determine whether the rodless piston 29 has reached the predetermined position, thereby realizing the automatic control of the oil sampling, oil discharge, and cleaning process.

[0037] like Figure 13 , 14 As shown, the oil-gas separation protection unit is connected in series in the air path between the drive chamber 1802 and the vacuum / pressure dual-purpose pump 28, and includes an oil-gas separator 24, a float level switch 25, a fifth manual ball valve 22, a vacuum gauge 23, and a fifth solenoid valve 26. The air inlet of the oil-gas separator 24 is connected to the air path of the drive chamber 1802 via the fourth manual ball valve 21. The air inlet of the oil-gas separator 24 is connected to an air inlet pipe extending downward to the bottom of the tank's internal cavity, with the lower end of the air inlet pipe extending 10 mm from the bottom of the tank. When the air path carries oil mist or liquid oil, the oil-containing gas enters the bottom of the tank through the air inlet pipe and is then discharged. The oil settles to the bottom of the tank under gravity, while the gas flows upward.

[0038] The inner cavity of the oil-gas separator 24 is provided with multiple stainless steel baffles 37 arranged alternately between the air inlet and the top air outlet. Three to six stainless steel baffles 37 are provided, staggered and fixed to the inner wall of the tank along the height direction of the oil-gas separator 24. Adjacent baffles are arranged in opposite directions, and their projections on the horizontal plane overlap. When the airflow flows upward from the bottom of the tank, it is forced to flow along an S-shaped path under the guidance of the stainless steel baffles 37. Oil droplets lose kinetic energy during repeated collisions with the baffles, agglomerate into larger droplets, and then settle to the bottom of the tank, achieving gas-liquid separation.

[0039] A wire mesh demister 38 is installed at the top outlet of the oil-gas separator 24. The wire mesh demister 38 is made of woven stainless steel wire. Even after separation by the baffles, the gas may still carry tiny oil mists. These tiny oil mists are intercepted by the wire mesh as they pass through the demister 38, accumulating into oil droplets and flowing back to the bottom of the tank, further ensuring the cleanliness of the discharged gas. The oil-gas separator 24 forms a three-stage oil-gas separation mechanism of "gravity settling + baffle collision + wire mesh interception," effectively preventing oil from entering the vacuum / pressure pump 28.

[0040] A float level switch 25 is located at the upper warning level inside the oil-gas separator 24. When oil accumulates in the oil-gas separator 24 due to an abnormal situation and reaches the warning level, the float of the float level switch 25 rises with the liquid level to the activated position, triggering a linkage signal. This signal controls the fifth solenoid valve 26 to open, allowing outside air to enter the system to break the vacuum, and simultaneously controls the vacuum-pressure pump 28 to stop operating, preventing oil from being sucked into the vacuum-pressure pump 28. For the oil collected in the oil-gas separator 24, before its level reaches the air inlet of the air inlet pipe inside the oil-gas separator 24, it is discharged by manually opening the fifth manual ball valve 22 to prevent oil backflow.

[0041] The gas path connected to the outlet of the oil-gas separator 24 is connected to the vacuum-pressure pump 28 via a three-way valve 27. The three ports of the three-way valve 27 are respectively connected to the outlet of the oil-gas separator 24, the inlet of the vacuum-pressure pump 28, and the fifth solenoid valve 26. The fifth solenoid valve 26 is a vacuum-breaking solenoid valve; one end is connected to the three-way valve 27, and the other end is connected to the outside atmosphere. Under normal operation, the fifth solenoid valve 26 is closed; when the float level switch 25 is triggered or manual vacuum breaking is required, the fifth solenoid valve 26 opens, allowing outside air to enter the gas path and breaking the system vacuum.

[0042] A fifth manual ball valve 22 is also installed on the gas line between the three-way valve 27 and the gas outlet of the oil-gas separator 24. The fifth manual ball valve 22 serves as a manual shut-off valve for the gas line, used to cut off the gas line during system maintenance or when not in operation. The vacuum gauge 23 is used to monitor the vacuum level of the oil-gas separator 24 in real time. The operator can use the reading of the vacuum gauge 23 to determine whether the system vacuum level meets the requirements for oil extraction.

[0043] Combination Figure 1-14 As shown, the method for using the bushing, current transformer, and oil injection device for uninterrupted oil sampling and sampling provided by the present invention includes the following steps: S1 Connection Preparation: Connect the quick-connect socket 12 of the vacuum oil sampling unit to the quick-connect connector 11 of the lower lead adapter unit to open the oil circuit. Specifically, first confirm that the first manual ball valve 3 is in the open state and the second manual ball valve 10 is in the closed state. At this time, the insulating oil in the bushing or transformer has filled the copper pipe and the oil circuit in the lower lead connector body 6. Then remove the plug 8 and the plug fixing fixture 9, insert the quick-connect socket 12 into the quick-connect connector 11, and the check valve in the quick-connect connector 11 is opened, opening the oil circuit. The quick-connect socket 12 is connected to the first solenoid valve 14 through the connecting pipe 13, and then connected to the oil sample chamber 1801.

[0044] S2 Chamber Exhaust: The vacuum-pressure dual-purpose pump 28 is activated to enter positive pressure mode. The gas path is switched via the third solenoid valve 19 and the fourth solenoid valve 20, driving the rodless piston 29 towards the oil sample chamber 1801 to expel residual air. The first solenoid valve 14 and the second solenoid valve 15 are closed, while the third solenoid valve 19, the fourth solenoid valve 20, and the fourth manual ball valve 21 are opened. The vacuum-pressure dual-purpose pump 28 is activated and switched to positive pressure mode, injecting positive pressure gas into the drive chamber 1802. Under pressure, the rodless piston 29 moves towards the oil sample chamber 1801, expelling residual air through the second solenoid valve 15 and the third manual ball valve 16. When the rodless piston 29 moves to trigger the second magnetic signal switch 31, it indicates that the gas in the oil sample chamber 1801 has been emptied, and the third solenoid valve 19 is closed.

[0045] S3 Circulation Cleaning: Switch the dual-purpose vacuum and pressure pump 28 to vacuum mode, driving the rodless piston 29 to move towards the drive chamber 1802, creating negative pressure in the oil sample chamber 1801. Close the fourth solenoid valve 20, open the third solenoid valve 19 and the fourth manual ball valve 21, switch the dual-purpose vacuum and pressure pump 28 to vacuum mode, evacuating the drive chamber 1802. Under negative pressure, the rodless piston 29 moves towards the drive chamber 1802, increasing the volume of the oil sample chamber 1801 and creating negative pressure. When the rodless piston 29 moves to trigger the first magnetic signal switch 30, it indicates that the oil sample chamber 1801 has achieved sufficient vacuum.

[0046] When the first solenoid valve 14 is opened, the oil in the bushing or transformer, under negative pressure, flows through the copper pipe, lower lead-in body 6, quick-connect connector 11, quick-connect socket 12, connecting pipe 13, and the first solenoid valve 14 into the vortex flushing connector 33. As the oil flows through the vortex flushing connector 33, it forms a high-speed vortex under the guidance of the spiral guide vanes 36, entering the oil sample chamber 1801 tangentially and forming a spiral flush along the inner wall of the chamber, effectively stripping away residual oil film and impurities adhering to the inner wall of the oil sample chamber 1801. Once the level switch 17 senses that the oil sample chamber is full, it sends a signal to close the first solenoid valve 14.

[0047] Switch the vacuum-pressure dual-purpose pump 28 back to positive pressure mode, open the second solenoid valve 15, and drive the rodless piston 29 to move towards the oil sample chamber 1801, discharging the cleaning oil in the oil sample chamber 1801 through the second solenoid valve 15 and the third manual ball valve 16. Repeat the above "vacuum oil suction - positive pressure oil discharge" steps 2 to 3 times to complete multiple cycles of cleaning the oil sample chamber 1801, ensuring that there is no residual old oil and impurities in the oil sample chamber 1801 and the oil inlet pipeline.

[0048] S4 Formal Sampling: Following the vacuuming method in step S3, a fresh oil sample is drawn into the oil sample chamber 1801 until the level switch 17 is activated. The vacuum-pressure dual-purpose pump 28 is switched to positive pressure mode, and the third manual ball valve 16 is opened. The oil sample is then smoothly injected into the sampling container through the second solenoid valve 15 and the third manual ball valve 16, completing the sampling. During the sampling process, the entire oil circuit remains completely sealed, ensuring that the insulating oil never comes into contact with the outside atmosphere, thus preventing moisture and impurities from the air from mixing into the oil sample and preventing the escape of dissolved gases.

[0049] During the oil sampling process described above, the air path of the drive chamber 1802 is connected to the vacuum-pressure dual-purpose pump 28 via the oil-gas separator 24. When the oil level in the oil-gas separator 24 rises abnormally, triggering the float level switch 25, the float level switch 25 controls the fifth solenoid valve 26 to open, introducing outside air into the system to break the vacuum. At the same time, the vacuum-pressure dual-purpose pump 28 stops operating to prevent oil from entering the vacuum-pressure dual-purpose pump 28.

[0050] Combination Figure 1-14 As shown, the oil injection method of the bushing, current transformer oil sampling without power interruption, and oil injection device provided by the present invention includes the following steps: S1 Interface Connection: Remove the plug 8 and plug fixing fixture 9 from the operating end of the lower lead adapter unit, and connect to the vacuum oil replenishment equipment via quick-connect connector 11. The check valve inside quick-connect connector 11 is opened during connection, opening the oil replenishment circuit.

[0051] S2 pipeline venting: Start the vacuum and pressure dual-purpose pump 28, switch the gas path through the third solenoid valve 19 and the fourth solenoid valve 20, evacuate the oil replenishment pipeline and the lower oil lead pipeline, and vent the air in the pipeline to ensure that no gas enters the bushing or transformer during the oil replenishment process.

[0052] S3 Oil Injection: Qualified insulating oil is slowly injected into the bushing or transformer through the lower oil lead using pressure differential. Specifically, the oil replenishment tank of the vacuum oil replenishment device is connected to the quick-connect connector 11. Positive pressure is used to push the qualified insulating oil in the oil replenishment tank back into the bushing or transformer through the copper pipe, the first manual ball valve 3, and the oil tee 1, keeping the oil circuit sealed throughout the process.

[0053] S4 Oil filling complete: After filling to the target oil volume, close the second manual ball valve 10, remove the oil replenishment equipment, reinstall the plug 8 and plug fixing fixture 9, and restore the sealing of the operating end. The first manual ball valve 3 and the second manual ball valve 10 form a dual-valve isolation structure to ensure that the oil circuit is reliably sealed after oil filling is completed.

[0054] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A device for uninterrupted oil sampling and injection from bushings and current transformers, characterized in that: It includes a down-feeding transfer unit, a vacuum oil sampling unit, and an oil-gas separation and protection unit; The lower lead-out conversion unit includes an oil take-out tee (1), an oil take-out fixture (2), a first manual ball valve (3), a copper pipe (4), a compression fitting (5), a lower lead-out connector body (6), a fixed permanent magnet (7), a plug (8), a plug fixing fixture (9), a second manual ball valve (10), and a quick-connect fitting (11). The quick-connect fitting (11) is equipped with a check valve. The oil take-out tee (1) is used to connect to the oil take-out port of the bushing or the current transformer. The copper pipe (4) leads the oil circuit down to the low operating height. The vacuum oil sampling unit includes a cylinder (18) and a rodless piston (29) slidably disposed within the cylinder (18). The rodless piston (29) divides the interior of the cylinder (18) into two non-communicating oil sample chambers (1801) and a drive chamber (1802). The drive chamber (1802) is connected to a vacuum pressure dual-purpose pump (28) via a third solenoid valve (19), a fourth solenoid valve (20), a fourth manual ball valve (21), and a three-way valve (27). The drive chamber (1801) is switched via the solenoid valve. 2) The positive and negative pressure states drive the rodless piston (29) to reciprocate; the cylinder (18) is equipped with a first magnetic signal switch (30) and a second magnetic signal switch (31) to detect the stroke position of the rodless piston (29); the oil sample chamber (1801) is connected to the output end of the lower lead-in transfer unit through the first solenoid valve (14), the oil sample chamber (1801) is also equipped with a second solenoid valve (15) and a third manual ball valve (16), and a liquid level switch (17) is installed in the oil sample chamber (1801). The oil-gas separation protection unit is connected in series in the gas path between the drive chamber (1802) and the vacuum pressure pump (28), and includes an oil-gas separator (24), a float level switch (25), a fifth manual ball valve (22) and a vacuum gauge (23). The rodless piston (29) is provided with at least one sealing ring (32) on its outer periphery. The sealing ring (32) is a bidirectional lip structure, with sealing lips extending from the middle to both sides. One sealing lip is set towards the oil sample chamber (1801), and the other sealing lip is set towards the drive chamber (1802), which is suitable for bidirectional sealing conditions of negative pressure oil suction and positive pressure oil discharge. A swirling flushing connector (33) is provided on the oil inlet path between the first solenoid valve (14) and the oil sample chamber (1801). The swirling flushing connector (33) includes a tubular shell (34), a guide column (35) coaxially disposed in the center of the inner cavity of the shell (34), and multiple spiral guide blades (36) fixedly connected between the outer wall of the guide column (35) and the inner wall of the shell (34). The end of the guide column (35) facing the oil inlet direction is a rounded conical arc shape, and the diameter of the end of the guide column (35) facing the oil sample chamber (1801) gradually increases. The end of the tubular shell (34) corresponding to the oil sample chamber (1801) is a funnel-shaped expansion that matches the guide column (35). The oil-gas separator (24) has an air inlet connected to an air inlet pipe that extends downward to the bottom of the tank's inner cavity. Multiple stainless steel baffles (37) are arranged alternately between the air inlet and the top air outlet in the tank's inner cavity. A wire mesh demister (38) is installed at the top air outlet.

2. The bushing and transformer oil sampling and injection device according to claim 1, characterized in that, The two ends of the copper pipe (4) are connected to the first manual ball valve (3) and the lower lead-in body (6) respectively through the compression fitting (5); the lower lead-in body (6) is provided with a fixed permanent magnet (7) for adsorption and fixation to the steel shell of the equipment; the operating end of the lower lead-in body (6) is provided with a plug (8) and a plug fixing fixture (9) to block the operating port in the non-operating state; the second manual ball valve (10) is set in the oil circuit of the lower lead-in body (6); and the quick-connect fitting (11) is set at the operating end interface.

3. The bushing and transformer oil sampling and injection device according to claim 1, characterized in that, The quick-connect connector (11) of the lower lead adapter unit is adapted to be connected to the quick-connect socket (12). The quick-connect socket (12) is connected to the first solenoid valve (14) via the connecting pipe (13). The second solenoid valve (15) is connected to the oil discharge passage of the oil sample chamber (1801). The third solenoid valve (19) and the fourth solenoid valve (20) constitute a gas path reversing valve group, which respectively control the vacuum passage and the positive pressure passage of the drive chamber (1802).

4. The bushing and transformer oil sampling and injection device according to claim 1, characterized in that, The oil outlet direction of the swirling flushing connector (33) is tangent to the inner wall of the oil sample chamber (1801), so that the oil entering the oil sample chamber (1801) forms a spiral swirling flow along the inner wall of the chamber and flushes the inner wall.

5. The bushing and transformer oil sampling and injection device according to claim 1, characterized in that, The air inlet of the oil-gas separator (24) is connected to the air passage via the fourth manual ball valve (21), and the lower end of the air inlet pipe inside the tank extends to 10mm from the bottom of the tank; the float level switch (25) is set at the upper warning level inside the tank; the air passage connected to the air outlet of the oil-gas separator (24) is connected to the vacuum pressure dual-purpose pump (28) via a three-way valve (27), and the other passage of the three-way valve is equipped with a fifth solenoid valve (26), which is a vacuum breaking solenoid valve.

6. The bushing and transformer oil sampling and injection device according to claim 1, characterized in that, The rodless piston (29) is a magnetically coupled piston with a built-in permanent magnet ring. The first magnetic signal switch (30) and the second magnetic signal switch (31) are respectively set on the outer sides of both ends of the cylinder (18) to detect the left and right limit stroke positions of the rodless piston (29) through magnetic field induction.

7. The bushing and transformer oil sampling and injection device according to claim 1, characterized in that, The device has a circulating cleaning mode. By alternately switching the positive and negative pressure of the drive chamber (1802) through the vacuum pressure dual-purpose pump (28), the rodless piston (29) is driven to reciprocate. In conjunction with the opening and closing of the first solenoid valve (14) and the second solenoid valve (15), the oil sample chamber (1801) is flushed multiple times.

8. The bushing and transformer oil sampling and injection device according to claim 1, characterized in that, The operating end of the lower lead-in adapter unit can be reused as an oil replenishment interface. After removing the blockage (8) and the blockage fixing fixture (9), it can be connected to the vacuum oil replenishment equipment to achieve uninterrupted and sealed oil replenishment.

9. A method for using the bushing, transformer, and oil sampling / injection device described in any one of claims 1 to 8 for sampling oil without power interruption, characterized in that... Includes the following steps: S1 docking preparation: Connect the quick-connect socket (12) of the vacuum oil sampling unit to the quick-connect connector (11) of the lower lead adapter unit to open the oil circuit; S2 chamber exhaust: Start the vacuum and pressure dual-purpose pump (28) to enter the positive pressure mode, switch the gas path through the third solenoid valve (19) and the fourth solenoid valve (20), drive the rodless piston (29) to move towards the oil sample chamber (1801) side, and discharge the residual air in the oil sample chamber (1801); S3 Circulation Cleaning: Switch the vacuum and pressure dual-purpose pump (28) to vacuum mode, drive the rodless piston (29) to move towards the drive chamber (1802) side, so that the oil sample chamber (1801) forms a negative pressure; open the first solenoid valve (14), and the oil in the bushing or transformer enters the oil sample chamber (1801) after forming a vortex through the vortex flushing joint (33), flushing the inner wall of the chamber; after the liquid level switch (17) senses that the oil sample is full, close the first solenoid valve (14), switch back to positive pressure mode, open the second solenoid valve (15) to discharge the oil in the chamber; repeat the above steps to complete the multiple circulation cleaning of the oil sample chamber (1801); S4 Formal Sampling: Vacuum the oil again until the oil sample chamber (1801) is full, switch to positive pressure mode, open the third manual ball valve (16), and smoothly inject the oil sample into the sampling container to complete the sampling.

10. A method for using the bushing, transformer, and oil sampling and injection device according to any one of claims 1 to 8 without power interruption, characterized in that... Includes the following steps: S1 interface docking: Remove the plug (8) and plug fixing fixture (9) from the operating end of the lower lead adapter unit, and dock the vacuum oil replenishment equipment through the quick connector (11); S2 pipeline venting: Vacuum the oil supply line and the lower oil inlet line to remove air from the pipeline; S3 Sealed Oil Injection: Qualified insulating oil is slowly injected into the bushing or transformer through the lower oil lead using the pressure difference, keeping the oil circuit sealed throughout the process. S4 Oil filling completed: After filling the target oil volume, close the second manual ball valve (10), remove the oil replenishment equipment, reinstall the plug (8) and the plug fixing fixture (9), and restore the sealing of the operating end.

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