A transformer

Abstract

The application discloses a transformer and relates to the technical field of power transformers, which comprises a transformer oil tank, an oil storage cabinet and an expansion joint. The oil storage cabinet is arranged on the tank cover of the transformer oil tank and is directly communicated with the transformer oil tank through an open bottom. The upper part of the expansion joint is fixed to the inner top of the oil storage cabinet, extends downward and passes through the tank cover opening. A counterweight is arranged in the expansion joint and moves up and down with the expansion and contraction of the expansion joint, so that a downward force is applied when the expansion joint is stretched, and thus the top of the bushing lifting structure of the transformer oil tank keeps a slight positive pressure. The application omits the independent cabinet feet and separate pipelines of the traditional oil storage cabinet, simplifies the top structure and reduces the cost. The lower part of the expansion joint extends into the oil tank, fully utilizes the redundant space of the oil tank and reduces the transformer oil consumption. The counterweight keeps the top of the bushing lifting structure in slight positive pressure all the time, prevents air leakage and insulation failure caused by negative pressure and significantly improves the operation reliability of the transformer.

Description

Technical Field

[0001] This application relates to the field of power transformer technology, and in particular to a transformer. Background Technology

[0002] When a large-capacity power transformer is in operation, the transformer oil expands and contracts with changes in load, resulting in a significant change in oil volume. To compensate for this volume change, an oil conservator is usually installed on top of the transformer. The conservator has a retractable space (such as a bellows, bladder, or contraction joint) inside to hold the excess transformer oil after expansion and to push the oil back into the tank when the oil temperature drops.

[0003] In existing technologies, oil conservators are typically mounted on the highest point of the transformer tank using independent support legs. This ensures that the air end of the expansion space is higher than the top of all bushing risers, thus using the weight of the oil column to maintain positive pressure at the top of the risers and prevent air infiltration. However, this arrangement has significant drawbacks: firstly, the oil conservator occupies space at the top of the transformer, limiting the angle and height of the high-voltage bushings and forcing them to be arranged at an angle, increasing the overall footprint and structural complexity; secondly, it requires additional support legs and independent oil filling and draining pipelines, increasing manufacturing and installation difficulty and cost.

[0004] To address the aforementioned issues, those skilled in the art have proposed a solution that integrates the oil conservator and its expansion / contraction space entirely within the transformer tank. This solution eliminates the need for an external oil conservator and its legs, placing the compensation chamber directly within the redundant space of the tank. This completely eliminates the interference of the oil conservator on bushing arrangement and significantly reduces transformer oil consumption and manufacturing costs. However, in practical applications, a key technical flaw has been identified: when the expansion / contraction space is entirely within the tank, its air end position is significantly lowered, creating a substantial height difference with structures such as the high-voltage riser and low-voltage riser located at the top of the tank. During periods of low temperature or reduced load causing oil volume contraction, this height difference makes it highly susceptible to negative pressure at the top of the riser, damaging the sealing structure and allowing air and moisture to seep into the transformer, seriously threatening insulation safety and operational reliability.

[0005] Therefore, how to simplify the structure of the oil conservator while ensuring the reliability of transformer operation has become an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0006] This application proposes a transformer that simplifies the structure of the oil conservator while ensuring the reliability of transformer operation.

[0007] To achieve the above objectives, this application discloses the following technical solutions:

[0008] This application provides a transformer, including a transformer tank, an oil conservator, and an expansion joint; the oil conservator is installed on the tank cover of the transformer tank, and the bottom opening of the oil conservator is directly connected to the transformer tank; the upper part of the expansion joint is fixed to the inner top of the oil conservator, and the expansion joint extends downward and passes through the opening of the tank cover; a counterweight is provided inside the expansion joint, and the counterweight moves up and down with the expansion joint to apply a downward force when the expansion joint extends, thereby maintaining a slight positive pressure at the top of the bushing lifting structure at the top of the transformer tank.

[0009] In some embodiments, the expansion joint has an internal air cavity, and its outer surface is in contact with transformer oil.

[0010] In some embodiments, a breather is provided on the top or upper side of the oil tank. One side of the breather is connected to the air chamber of the expansion joint through a connecting pipe passing through the oil tank, and the other side is connected to the atmosphere.

[0011] In some embodiments, the counterweight is fixed to the bottom inner side of the telescopic joint.

[0012] In some embodiments, the mass of the counterweight satisfies the following relationship: M×g = S×ρ×g×h;

[0013] Where M is the mass of the counterweight, S is the bottom cross-sectional area of ​​the expansion joint, ρ is the density of the transformer oil, g is the gravitational acceleration, and h is the height difference between the highest level of the transformer oil and the bottom of the expansion joint when it is extended to its maximum position.

[0014] In some embodiments, the expansion joint is provided with a guide structure, which is fixed to the inner wall of the oil tank or the opening of the tank cover and extends in a vertical direction. The expansion joint and the guide structure are slidably engaged.

[0015] In some embodiments, a guide tube is provided inside the expansion joint, with the upper end of the guide tube fixed to the top inner side of the expansion joint and the lower end of the guide tube fixed to the bottom inner side of the expansion joint or a counterweight block.

[0016] In some embodiments, the bushing riser structure includes at least one of a high-pressure riser, a low-pressure riser, and a high-pressure neutral point riser.

[0017] In some embodiments, a gas relay is also included, which is connected via a main pipeline to the top of the oil conservator and the top of the transformer tank.

[0018] In some embodiments, the main pipeline is also connected to multiple branch pipes, which are respectively connected to the top of the high-pressure riser, the low-pressure riser and the high-pressure neutral point riser.

[0019] As can be seen from the above technical solution, the transformer provided in this application has its oil conservator directly installed on the cover of the transformer tank, with its bottom opening directly connected to the tank. This eliminates the need for the independent support structure and separate oil injection / discharge pipelines of traditional oil conservators, significantly simplifying the transformer's top structure and reducing manufacturing and installation costs. The upper part of the expansion joint is fixed to the top of the inner side of the oil conservator and passes downward through the cover opening, while its lower part is located inside the transformer tank. This fully utilizes the redundant space inside the tank to accommodate the expansion and contraction stroke of the expansion joint, meeting the oil volume compensation requirements without increasing the volume of the oil conservator, reducing the amount of transformer oil used, and further reducing material costs. A counterweight is installed inside the expansion joint, which moves up and down with the expansion and contraction of the expansion joint. When the transformer oil temperature decreases and its volume shrinks, the gravity of the counterweight causes the expansion joint to extend downward, pressing the oil in the oil conservator back into the transformer tank. This keeps the top of the bushing riser structure at the top of the tank under a slight positive pressure, effectively preventing air and moisture from seeping into the transformer through the seals due to negative pressure. This avoids a decrease in insulation performance and the risk of failure, significantly improving the long-term operational reliability of the transformer. In summary, this application simplifies the structure of the oil conservator while ensuring the reliability of transformer operation, overcoming the technical difficulty of balancing these two aspects in the prior art. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort, and this application can be applied to other similar scenarios based on the provided drawings, all of which fall within the scope of protection of this application. Unless obvious from the linguistic context or otherwise specified, the same reference numerals in the drawings represent the same structure or operation.

[0021] Figure 1 A front view of a single-phase on-load tap-changing transformer provided in an embodiment of this application;

[0022] Figure 2 A top view of a single-phase on-load tap-changing transformer provided in an embodiment of this application;

[0023] Figure 3 A front view of a three-phase on-load tap-changing transformer provided in an embodiment of this application;

[0024] Figure 4 A top view of a three-phase on-load tap-changing transformer provided in an embodiment of this application;

[0025] Figure 5 A schematic diagram of the expansion joint in an extended state provided in an embodiment of this application;

[0026] Figure 6 A schematic diagram of the expansion joint in a compressed state provided in an embodiment of this application;

[0027] The annotations in the attached figures are explained as follows:

[0028] 10 Transformers;

[0029] 100 transformer oil tank;

[0030] 200 oil storage tanks;

[0031] 300 expansion joint; 310 counterweight;

[0032] 400 bushing riser structure; 410 high-voltage riser seat; 420 low-voltage riser seat; 430 high-voltage neutral point riser seat;

[0033] 500 respirators;

[0034] 600 gas relay; 610 main pipe; 620 branch pipe. Detailed Implementation

[0035] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are merely illustrative of the application and not intended to limit it. The described embodiments are only a part of the embodiments of the present application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without inventive effort are within the scope of protection of the present application.

[0036] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0037] The applicant's research revealed that some related technologies involve embedding the oil conservator 200 entirely inside the transformer oil tank 100. When the oil temperature drops, negative pressure can easily occur in the riser area at the top of the transformer oil tank 100, causing air and moisture to seep into the transformer 100 through the seals, affecting insulation performance and safe operation.

[0038] Based on this, this application provides a transformer 10, which simplifies the top structure while maintaining a slight positive pressure at the top of the riser by directly setting the oil conservator 200 on the tank cover and partially embedding the expansion joint 300 in the transformer oil tank 100, and with the setting of the counterweight 310. This achieves both structural simplification and operational reliability.

[0039] To simplify the top structure of the transformer 10 and ensure operational reliability, this application provides a transformer 10, which includes a transformer oil tank 100, an oil conservator 200, an expansion joint 300, and a bushing lifting structure 400.

[0040] like Figure 1 and Figure 2 As shown, in one embodiment of this application, the transformer 10 is a single-phase on-load tap-changing transformer 10, including a transformer oil tank 100, an oil conservator 200, an expansion joint 300, and a set of bushing lifting structures 400. The oil conservator 200 is installed on the tank cover of the transformer oil tank 100, and the bottom opening of the oil conservator 200 is directly connected to the transformer oil tank 100. The upper part of the expansion joint 300 is fixed to the inner top of the oil conservator 200, and the expansion joint 300 extends downward and passes through the opening of the tank cover. A counterweight 310 is installed inside the expansion joint 300, and the counterweight 310 moves up and down with the expansion and contraction of the expansion joint 300. The set of bushing lifting structures 400 is installed on the top of the oil tank, and its top is the highest point of the oil system.

[0041] like Figure 3 and Figure 4 As shown, in another embodiment of this application, the transformer 10 is a three-phase on-load tap-changing transformer 10, including a transformer tank 100 (covering the three-phase transformer body), a shared oil conservator 200, an expansion joint 300, and three sets of bushing lifting structures 400. The oil conservator 200 is installed on the tank cover of the transformer tank 100, with its bottom opening communicating with the tank. The upper part of the expansion joint 300 is fixed to the top of the inner side of the oil conservator 200, extends downward through the tank cover opening, and has a counterweight 310 installed inside. The three sets of bushing lifting structures 400 are arranged side by side on the top of the tank, and the oil conservator 200 and the expansion joint 300 together provide oil volume compensation and micro-positive pressure maintenance for the three sets of lifting structures.

[0042] The following detailed description uses a single-phase on-load tap-changing transformer 10 as an example. In the three-phase on-load tap-changing transformer 10, only the number of lifting structures is three. The structure and working principle of the oil tank, oil conservator 200 and single expansion joint 300 are similar to those of the single-phase on-load tap-changing transformer 10, and will not be repeated here.

[0043] The transformer tank 100 houses the transformer body and insulating oil of the transformer 10, and its top is equipped with a cover. The cover is typically a flat plate with openings for mounting a riser and connecting to the oil conservator 200. The oil conservator 200 is mounted on the cover of the transformer tank 100, and its bottom has an opening that directly connects to the opening of the transformer tank 100's cover. The two can be connected by flanges, welding, or other sealing methods to ensure a reliable seal at the connection. This design eliminates the need for separate legs supporting the oil conservator 200 above the tank and also eliminates the need for separate oil filling / draining pipelines, significantly simplifying the structural layout of the transformer 10's top and reducing manufacturing and installation costs. Furthermore, because the oil conservator 200 sits directly on the cover, the overall height of the transformer is reduced, facilitating installation and minimizing the space required for high-voltage bushings and the transformer's footprint.

[0044] The expansion joint 300 is located inside the oil conservator 200, with its upper part fixed to the inner top of the oil conservator 200. The expansion joint 300 extends downwards and passes through the tank cover opening, so that its lower part is located inside the transformer oil tank 100. The expansion joint 300 can employ a bellows or bladder-type expansion structure, providing good elasticity and oil resistance. Because the lower part of the expansion joint 300 extends into the oil tank, it fully utilizes the redundant space within the tank to accommodate the expansion stroke of the expansion joint 300. This eliminates the need to increase the volume of the oil conservator 200 to meet oil volume compensation requirements, thereby reducing the total amount of transformer oil used and further lowering material costs. Furthermore, this layout allows for a more compact design of the oil conservator 200's volume, resulting in a cleaner and more aesthetically pleasing appearance.

[0045] A counterweight 310 is installed inside the telescopic joint 300, and the counterweight 310 moves up and down as the telescopic joint 300 extends and retracts. The counterweight 310 can be made of metal, such as stainless steel, cast iron, or lead, or other high-density materials. The counterweight 310 can be fixed to the bottom inner side of the telescopic joint 300, or it can be suspended in other positions inside the telescopic joint 300, as long as it can move up and down synchronously with the telescopic joint 300. See also Figure 5 When the transformer oil temperature decreases and its volume shrinks, the weight of the counterweight 310 causes the expansion joint 300 to extend downward, pushing the oil in the oil conservator 200 back into the transformer oil tank 100, thereby keeping the top of the bushing lifting structure 400 at the top of the transformer oil tank 100 under a slight positive pressure.

[0046] Because the top of the bushing riser structure 400 maintains a slight positive pressure, it effectively prevents air and moisture from seeping into the transformer 10 through the seals due to negative pressure, avoiding a decrease in insulation performance and the risk of failure, and significantly improving the long-term operational reliability of the transformer 10. Compared with traditional solutions that rely on springs or air pressure to maintain pressure, the counterweight 310 solution has a simple structure, high reliability, and convenient maintenance, and does not have problems such as spring fatigue failure or air pressure leakage.

[0047] See Figure 6 When the transformer oil temperature rises and its volume expands, the expanded oil flows from the transformer oil tank 100 through the tank cover opening into the oil conservator 200. The oil pressure inside the oil conservator 200 increases, applying pressure to the outer surface of the expansion joint 300, causing the expansion joint 300 to compress upwards. The compression of the expansion joint 300 absorbs the oil volume expansion, preventing excessive pressure inside the oil tank. The counterweight 310 rises synchronously with the expansion joint 300; under compression, its gravity is overcome by the oil pressure, thus not affecting the normal compression action of the expansion joint 300.

[0048] To further optimize the working environment of the expansion joint 300, in some embodiments, the interior of the expansion joint 300 is an air cavity, and the outer surface of the expansion joint 300 is in contact with the transformer oil. The air cavity inside the expansion joint 300 is isolated from the external oil cavity, and the two are physically isolated by the wall of the expansion joint 300. When the transformer oil volume changes, the oil pressure acts directly on the outer surface of the expansion joint 300, causing the expansion joint 300 to undergo corresponding expansion and contraction deformation, thereby achieving oil volume compensation.

[0049] Because the expansion joint 300 has an internal air cavity, its own weight is relatively light. The gravity of the counterweight 310 can more effectively drive the expansion joint 300 to extend downwards, avoiding the problem of the expansion joint 300's own excessive weight negating part of the counterweight effect. The gas in the air cavity can be air, nitrogen, or other inert gases; for example, dry air is the most economical and convenient. In other embodiments, the air cavity can also be filled with an inert gas at a certain pressure to provide a certain pre-tension to the expansion joint 300 in the initial state, further improving the system's response sensitivity.

[0050] To maintain pressure balance between the air chamber of the expansion joint 300 and the outside atmosphere, in some embodiments, a breather 500 is provided on the top or upper side of the oil tank 200. One side of the breather 500 is connected to the air chamber of the expansion joint 300 via a connecting pipe passing through the oil tank 200, while the other side is connected to the atmosphere. The breather 500 may contain a desiccant, such as silica gel or molecular sieve, to filter moisture and impurities from the air entering the air chamber. The desiccant can be replaced or regenerated periodically to maintain its moisture-absorbing properties.

[0051] When the expansion joint 300 is compressed, the gas in the air chamber is discharged to the atmosphere through the connecting pipe and the breather 500; when the expansion joint 300 is extended, the atmosphere is drawn into the air chamber through the breather 500 and the connecting pipe. The breather 500 ensures that the expansion joint 300 can freely expand and contract while preventing external humid air from directly entering the air chamber, further improving the system's moisture-proof performance. In other embodiments, the breather 500 may also integrate a dust filter function to prevent airborne particles from entering the air chamber and avoid wear on the inner wall of the expansion joint 300.

[0052] To ensure the effective functioning of the counterweight 310, in some embodiments, the counterweight 310 is fixed to the inner bottom of the telescopic joint 300. Fixed to the bottom of the telescopic joint 300, the counterweight 310 maximizes the effect of gravity when the telescopic joint 300 extends, returning oil pressure to the oil tank system, thereby improving the reliability of maintaining a slight positive pressure. The counterweight 310 can be fixed to the bottom of the telescopic joint 300 by welding, bolting, or bonding. For example, when using bolting, threaded holes can be pre-drilled in the counterweight 310 and through holes can be pre-drilled in the bottom of the telescopic joint 300, and the two can be fastened together with bolts for easy disassembly and maintenance.

[0053] The shape of the counterweight 310 can match the inner cavity shape of the expansion joint 300, such as being circular, annular, or polygonal, to facilitate installation and fixation. For example, when the expansion joint 300 is a cylindrical bellows, the counterweight 310 can be shaped like a disc or annulus to ensure good contact with the inner wall of the expansion joint 300, preventing swaying or displacement during expansion and contraction. In other embodiments, the counterweight 310 can also be configured as multiple small blocks, evenly distributed in the circumferential direction at the bottom of the expansion joint 300, to reduce the weight of a single counterweight 310, facilitating handling and installation.

[0054] To make the design of the counterweight 310 more scientific and reasonable, in some embodiments, the mass of the counterweight 310 satisfies the following relationship: M×g =S×ρ×g×h. Where M is the mass of the counterweight 310 in kilograms; S is the bottom cross-sectional area of ​​the expansion joint 300 in square meters; ρ is the density of the transformer oil in kilograms per cubic meter; g is the acceleration due to gravity in meters per square second; and h is the height difference between the highest level of the transformer oil and the bottom of the expansion joint 300 when it is fully extended in meters. The mass of the counterweight 310 calculated using this formula can maintain a suitable micro-positive pressure at the top of the bushing lifting structure 400 under various operating conditions, preventing excessive pressure due to excessive weight or insufficient micro-positive pressure due to insufficient weight.

[0055] For example, for a 110kV transformer 10, S is approximately 0.03 square meters, ρ is approximately 895 kg per cubic meter, g is taken as 9.8 m per square second, and h is approximately 0.5 m, then M is approximately 13.4 kg. In actual design, adjustments can be made according to specific parameters. In other embodiments, considering the weight of the expansion joint 300 itself and the force exerted on the expansion joint 300 by the gas pressure inside the air chamber, a correction coefficient can be added to the above formula to make the calculation results more accurate.

[0056] To ensure stable expansion and contraction of the telescopic joint 300 in a predetermined direction, in some embodiments, the telescopic joint 300 is provided with a guide structure. The guide structure is fixed to the inner wall of the oil tank 200 or at the opening of the tank cover and extends vertically, with the telescopic joint 300 slidingly engaging with the guide structure. The guide structure can take the form of a guide sleeve, guide rib, or guide ring, etc., with a smooth inner surface and a low coefficient of friction. For example, the guide sleeve can be a cylindrical structure, fitted around the outer circumference of the telescopic joint 300, with the inner diameter of the guide sleeve slightly larger than the outer diameter of the telescopic joint 300, leaving an appropriate gap between them to ensure smooth sliding.

[0057] The guide structure constrains the expansion joint 300, preventing radial offset or swaying during expansion and contraction, thus ensuring the smoothness and reliability of its movement and extending its service life. The guide structure can be made of metal or wear-resistant plastic. For example, a guide sleeve made of polytetrafluoroethylene (PTFE) has excellent self-lubricating and oil-resistant properties, maintaining good sliding performance even under long-term oil immersion. In other embodiments, the guide structure may also be provided with lubrication grooves or holes to store lubricating oil or grease, further reducing frictional resistance.

[0058] As another implementation of the guiding structure, in some embodiments, a guide tube is provided inside the expansion joint 300. The upper end of the guide tube is fixed to the top inner side of the expansion joint 300, and the lower end of the guide tube is fixed to the bottom inner side of the expansion joint 300 or the counterweight 310. The guide tube expands and contracts synchronously with the expansion joint 300, guiding the expansion joint 300 to expand and contract axially on the one hand, and restricting the radial deformation of the expansion joint 300 on the other hand, preventing the expansion joint 300 from undergoing non-uniform deformation or bulging when the oil pressure fluctuates, thereby further improving the working stability and durability of the expansion joint 300.

[0059] The guide tube can be made of stainless steel, aluminum alloy, or high-strength plastic tubing, and its wall thickness is designed according to the stress conditions; for example, the wall thickness can be 2 mm to 5 mm. Compared to external guide structures, internal guide tubes do not occupy the space between the oil tank 200 and the tank cover, resulting in a more compact structure, especially suitable for installations with limited space. In other embodiments, the guide tube can also be configured as a multi-segment telescopic structure to accommodate a larger telescopic stroke.

[0060] To clarify the specific type of the bushing riser structure 400, in some embodiments, the bushing riser structure 400 includes at least one of a high-voltage riser seat 410, a low-voltage riser seat 420, and a high-voltage neutral point riser seat 430. These riser seats are all bushing lead-out structures at the top of the transformer tank 100, and their tops are the highest points of the oil system, making them most prone to negative pressure when the oil temperature drops. This application maintains a slight positive pressure using a counterweight 310, effectively protecting the tops of all these riser seats and preventing air leakage. The structural form of the riser seat is well-known in the art and will not be described in detail here. In other embodiments, the bushing riser structure 400 may also include a voltage regulating riser seat or other special-purpose riser seats, and the technical solutions of this application are also applicable.

[0061] To further improve the safety protection function of transformer 10, in some embodiments, transformer 10 also includes a gas relay 600. The gas relay 600 is connected to the top of the oil conservator 200 and the top of the transformer oil tank 100 via the main pipeline 610. The gas relay 600 is used to monitor abnormal gas or oil flow caused by internal faults in transformer 10. When an abnormality is detected, it issues an alarm or triggers a trip to protect the safe operation of transformer 10. The gas relay 600 can be a float-type or baffle-type gas relay commonly used in the art, and its working principle is well known to those skilled in the art. For example, the float-type gas relay 600 has two floats inside; the upper float is used for light gas alarm, and the lower float is used for heavy gas trip, enabling graded responses to faults of different degrees.

[0062] Furthermore, based on the above embodiments, multiple branch pipes 620 are connected to the main pipeline 610, and the branch pipes 620 are respectively connected to the top of the high-voltage riser 410, the low-voltage riser 420, and the high-voltage neutral point riser 430. Through the branch pipes 620, the gas at the top of each riser can be effectively monitored by the gas relay 600, ensuring comprehensive monitoring of internal faults in the transformer 10. The diameter of the branch pipe 620 can be smaller than the diameter of the main pipeline 610; for example, the diameter of the main pipeline 610 is 50 mm, and the diameter of the branch pipe 620 is 10 mm to 20 mm. The connection between the branch pipe 620 and the top of the riser should maintain a good seal to prevent oil and gas leakage. In other embodiments, valves may also be provided on the branch pipes 620 for disconnecting the connection between a specific riser and the gas relay 600 during maintenance or repair, facilitating individual handling without affecting the normal operation of other components. In addition, the connection between branch pipe 620 and main pipe 610 can be in the form of a tee or a manifold, so that the gas from each branch pipe 620 is collected in the main pipe 610 and enters the gas relay 600 in a unified manner, simplifying the pipeline layout.

[0063] The following describes a complete working process of the transformer 10 provided in the embodiments of this application, in conjunction with the above-described implementation methods.

[0064] Under normal operating conditions, the oil conservator 200 and the transformer oil tank 100 are filled with transformer oil, the expansion joint 300 is in a certain equilibrium position, and the counterweight 310 remains at the corresponding height along with the expansion joint 300. At this time, the top of the bushing lifting structure 400 is under a slight positive pressure, and the gas relay 600 is in standby mode.

[0065] When the load on transformer 10 increases or the ambient temperature rises, the transformer oil temperature rises, and the oil volume expands. The expanded oil enters the oil conservator 200 from the transformer oil tank 100 through the tank cover opening, increasing the oil pressure inside the oil conservator 200 and applying pressure to the outer surface of the expansion joint 300. Under this oil pressure, the expansion joint 300 compresses upward, and the gas in the gas chamber is discharged to the atmosphere through the connecting pipe and the breather 500. The counterweight 310 rises synchronously with the expansion joint 300. During this process, the compression of the expansion joint 300 absorbs the oil volume expansion, preventing excessive pressure inside the oil tank. At the same time, the guide structure or guide pipe ensures that the expansion joint 300 compresses smoothly in the vertical direction without swaying or jamming.

[0066] When the load on transformer 10 decreases or the ambient temperature drops, the transformer oil temperature decreases, and the oil volume shrinks. The oil pressure inside the oil conservator 200 decreases, reducing the pressure on the outer surface of the expansion joint 300. At this time, the gravity of the counterweight 310 causes the expansion joint 300 to extend downwards, pushing the oil in the oil conservator 200 back into the transformer tank 100. The air chamber draws in atmospheric air through the breather 500, replenishing the volume required for the expansion joint 300 to extend. During this process, because the counterweight 310 continuously applies a downward force, the top of the bushing lifting structure 400 at the top of the transformer tank 100 always maintains a slightly positive pressure, effectively preventing air and moisture from seeping into the transformer 10 due to negative pressure. The guide structure or guide tube also plays a guiding and protective role during the extension process.

[0067] Throughout the operation, the gas relay 600 monitors the gas status of the oil conservator 200, oil tank, and the tops of each riser in real time via the main pipe 610 and branch pipe 620. If a local overheating or discharge fault occurs inside the transformer 10, the generated gas will rise along the oil circuit, pass through the branch pipe 620 and the main pipe 610, and enter the gas relay 600. The float or baffle inside the gas relay 600 detects the gas accumulation or sudden change in oil flow, immediately issuing an alarm signal or triggering a trip to ensure the safe operation of the transformer 10.

[0068] In summary, the transformer 10 provided in this application simplifies the top structure of the transformer 10 and maintains a slight positive pressure in the raised seat area by directly mounting the oil conservator 200 on the tank cover and directly communicating with the oil tank, and cooperating with the expansion joint 300 structure with counterweight 310. This effectively solves the problems of complex structure and negative pressure leakage in related technologies, and has the outstanding advantages of simple structure, low cost and reliable operation.

[0069] In the above context, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0070] In the description of the embodiments of this application, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. "And / or" in this article is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone.

[0071] It should be noted that, for ease of description, only the parts relevant to the application are shown in the accompanying drawings. Unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0072] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed, and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. The scope of this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described application concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A transformer, characterized in that, Includes transformer oil tank (100), oil conservator (200) and expansion joint (300); The oil storage tank (200) is installed on the cover of the transformer oil tank (100), and the bottom opening of the oil storage tank (200) is directly connected to the transformer oil tank (100); The upper part of the telescopic joint (300) is fixed to the top of the inner side of the oil tank (200), and the telescopic joint (300) extends downward and passes through the opening of the tank cover; The expansion joint (300) is provided with a counterweight (310), which moves up and down with the expansion joint (300) to apply a downward force when the expansion joint (300) extends, thereby maintaining a slight positive pressure on the top of the bushing lifting structure (400) at the top of the transformer tank (100).

2. The transformer as described in claim 1, characterized in that, The expansion joint (300) has an air cavity inside, and the outer surface of the expansion joint (300) is in contact with transformer oil.

3. The transformer as described in claim 2, characterized in that, A breather (500) is provided on the top or upper side of the oil tank (200). One side of the breather (500) is connected to the air chamber of the expansion joint (300) through the oil tank (200) via a connecting pipe, and the other side is connected to the atmosphere.

4. The transformer as described in claim 1, characterized in that, The counterweight (310) is fixed to the inner bottom of the telescopic joint (300).

5. The transformer as described in claim 1, characterized in that, The mass of the counterweight (310) satisfies the following relationship: M×g=S×ρ×g×h; Where M is the mass of the counterweight (310), S is the bottom cross-sectional area of ​​the expansion joint (300), ρ is the density of the transformer oil, g is the gravitational acceleration, and h is the height difference between the highest liquid level of the transformer oil and the bottom of the expansion joint (300) when it is extended to its maximum position.

6. The transformer as described in claim 1, characterized in that, The expansion joint (300) is provided with a guide structure, which is fixed to the inner wall of the oil tank (200) or the opening of the tank cover and extends in the vertical direction. The expansion joint (300) and the guide structure are slidably engaged.

7. The transformer as described in claim 1, characterized in that, The telescopic joint (300) is provided with a guide tube inside. The upper end of the guide tube is fixed to the top inner side of the telescopic joint (300), and the lower end of the guide tube is fixed to the bottom inner side of the telescopic joint (300) or the counterweight (310).

8. The transformer as described in claim 1, characterized in that, The bushing riser structure (400) includes at least one of a high-pressure riser seat (410), a low-pressure riser seat (420), and a high-pressure neutral point riser seat (430).

9. The transformer as described in claim 1, characterized in that, It also includes a gas relay (600), which is connected to the top of the oil tank (200) and the top of the transformer tank (100) via a main pipeline (610).

10. The transformer as described in claim 9, characterized in that, The main pipeline (610) is also connected to multiple branch pipes (620), which are respectively connected to the top of the high-pressure riser (410), the low-pressure riser (420) and the high-pressure neutral point riser (430).

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