An explosion-proof oil-immersed current transformer

Abstract

This utility model provides an explosion-proof oil-immersed current transformer, belonging to the field of current transformers. It includes a transformer body, with an oil conservator at the top and an expander above the conservator, equipped with a top pressure relief component. Below the conservator is a porcelain bushing, and below the bushing, from top to bottom, are a riser and an oil tank. A bottom pressure relief component is located on the side of the oil tank. The beneficial effect of this utility model is that, based on existing oil-immersed current transformers, it not only retains the top pressure relief component at the expander but also adds an additional bottom pressure relief component at the oil tank. This allows for rapid pressure relief and explosion-proof protection when the internal pressure of the transformer body increases sharply, through the coordinated operation of the two pressure relief components.

Description

Technical Field

[0001] This utility model belongs to the field of current transformers, specifically relating to an explosion-proof oil-immersed current transformer. Background Technology

[0002] In modern power systems, oil-immersed current transformers are critical equipment, widely used in power grids of different voltage levels such as 35kV, 110kV, and 220kV. They undertake important tasks such as current and energy measurement, metering, and relay protection, playing an indispensable role in the safe and stable operation of the power system. However, because they are filled with a large amount of insulating oil, when a short circuit occurs in the power system or an abnormal arc fault such as breakdown of the main insulation of the equipment occurs, the insulating oil will decompose at high temperatures, producing a large amount of gas. This will cause the internal pressure of the transformer to rise sharply, potentially leading to an explosion and threatening the safety of equipment and personnel.

[0003] Currently, most existing oil-immersed current transformers only have an explosion-proof structure at the expansion joint. For example, Chinese patent CN115020072A discloses a highly reliable explosion-proof oil-immersed current transformer with an explosion-proof structure at the expansion joint. In this case, when the internal pressure of the transformer increases, the expansion joint will first extend to reduce the pressure inside the transformer. If the pressure continues to increase, the explosion-proof structure at the expansion joint will rupture, thereby achieving rapid pressure relief and preventing explosions in pressure-concentrated parts such as the lower oil tank and porcelain bushing.

[0004] However, relying solely on the explosion-proof structure at the expansion joint has significant limitations. Specifically, due to the small internal flow channels of the expander, the internal pressure cannot be quickly transmitted to the top when abnormal discharge occurs. Therefore, relying solely on the explosion-proof design at the expansion joint is insufficient to quickly and effectively release excessive internal pressure, resulting in poor explosion-proof performance and potentially causing the product's fuel tank, porcelain insulator, and other components to rupture, posing a significant safety hazard during power grid operation. Utility Model Content

[0005] The purpose of this invention is to address the problem that existing oil-immersed current transformers cannot quickly release pressure when abnormal discharge occurs in the equipment. This invention proposes and designs an explosion-proof oil-immersed current transformer, which can quickly release pressure and prevent explosion when abnormal arc faults such as short circuits in the power system or breakdown of the main insulation of the equipment occur, causing a sharp increase in internal pressure. This fully protects the safety of the equipment and surrounding facilities.

[0006] To achieve the above objectives, the technical solution provided by this utility model is as follows: an explosion-proof oil-immersed current transformer, comprising a body, an oil tank at the upper part of the body, an expander above the oil tank, and a top pressure relief component on the expander; a porcelain bushing below the oil tank, and a riser and an oil tank arranged sequentially from top to bottom below the porcelain bushing, with a bottom pressure relief component on the side of the oil tank. Based on this, this utility model, based on existing oil-immersed current transformers, not only retains the top pressure relief component at the expander of existing oil-immersed current transformers, but also adds an additional bottom pressure relief component at the oil tank. This allows for rapid pressure relief and explosion-proof performance when the internal pressure of the transformer body increases sharply, through the coordinated operation of the two pressure relief components.

[0007] Furthermore, the bottom pressure relief assembly includes a pressure relief hole on the tank body, a mounting base on the outside of the pressure relief hole, and an explosion-proof disc sealed inside the mounting base. A pressure plate and an explosion-proof baffle are sequentially installed from the inside out on the outside of the explosion-proof disc via fasteners. A gap is provided between the explosion-proof baffle and the pressure plate, allowing insulating oil to be ejected through the gap. Under normal operating conditions, the pressure inside the device will not exceed the limit of the explosion-proof disc, and the sealing structure between the explosion-proof disc and the mounting base prevents insulating oil leakage at the explosion-proof disc. When an arc fault occurs inside the device, a large amount of gas is instantly generated, causing a sharp increase in internal pressure. When this pressure exceeds the rated burst pressure limit of the explosion-proof disc, the explosion-proof disc will burst, thus achieving rapid pressure relief. During the pressure relief process, the explosion-proof baffle on the outside of the explosion-proof disc changes the direction of the insulating oil's ejection, causing the insulating oil to flow out through the gap between the explosion-proof baffle and the pressure plate, preventing direct ejection of the insulating oil.

[0008] Furthermore, a filter section is provided in the middle of the compressed sheet, and filter holes are uniformly distributed throughout the surface of the filter section. In the event of an explosion-proof sheet bursting, the filter section can filter the insulating oil during its outflow, preventing fragments generated inside the sheet or after the explosion from being ejected with the insulating oil, thus avoiding damage to surrounding equipment or personnel.

[0009] Furthermore, the filter section uses permanent magnet material, which enables it to directly adsorb metal fragments to a certain extent, preventing some smaller metal fragments from being sprayed out with the insulating oil.

[0010] Furthermore, the explosion-proof disc is equipped with pre-crack lines, which serve as weak points to prevent it from tearing when the internal pressure of the transformer reaches a preset threshold. This ensures stable and efficient pressure relief. Compared to traditional explosion-proof discs, this type of disc with pre-crack lines provides more uniform and controllable pressure release, effectively reducing the risk of injury to surrounding equipment and personnel caused by fragments flying due to irregular breakage.

[0011] Furthermore, the expander includes an expansion joint, the bottom of which is connected to the oil tank, and a top pressure relief assembly is provided on the top of the expansion joint. The top pressure relief assembly can adopt the same structure as the bottom pressure relief assembly, that is, it can directly open a corresponding pressure relief hole on the top of the expansion joint, and install a mounting base, explosion-proof plate, pressure plate and other structures in sequence on the outside of the pressure relief hole.

[0012] Furthermore, the expander also includes an expander cover, which comprises a cylindrical protective column with openings at both ends. The cylindrical protective column covers the outside of the expansion joint, with its lower end fixedly connected to the oil tank and its upper end covered by an expander top cover. The expander top cover and the cylindrical protective column are connected by a breakable connection structure. In this case, because the expander cover in this invention adopts a split structure consisting of the cylindrical protective column and the expander top cover, when the expansion joint expands and stretches to the top position of the expander cover, the expander top cover at the expander cover will be subjected to an upward thrust. The breakable connection structure between the cylindrical protective column and the expander top cover will separate under force, causing the expander top cover to fly up. This ensures that the expansion joint can continue to stretch vertically. Moreover, when the expansion joint continues to stretch to a certain extent, if it reaches the rated burst pressure of the explosion-proof disc at the top pressure relief assembly, the explosion-proof disc at that location will burst, thereby rapidly releasing the pressure.

[0013] Furthermore, the expansion joint is configured from bottom to top as a connecting flange part and a bellows part. The connecting flange part is connected to the oil tank by fasteners. The inner diameter of the connecting flange part is equal to the inner diameter of the bellows part. In this way, by increasing the opening size at the connection between the oil tank and the expansion joint, the pressure matching relationship of each component is optimized.

[0014] As can be seen from the above technical solution, this utility model has the following advantages: First, this utility model achieves all-round, multi-layer explosion-proof protection; at this time, when the internal pressure of the vessel rises abnormally, the expansion joint can use its own extension and the explosion-proof plate at the top pressure relief component to relieve pressure at the top of the vessel, alleviating the pressure rise trend; at the same time, the bottom pressure relief component at the oil tank can serve as another line of defense, releasing the high pressure at the bottom of the vessel, playing a role in rapid pressure relief and explosion prevention; at the same time, it avoids pressure concentration at weak points in the oil tank, greatly reducing the risk of oil tank explosion and ensuring equipment safety in all aspects; second, this utility model improves pressure relief efficiency and reliability; it can flexibly relieve pressure according to different fault levels and pressure changes through the coordinated work of the dual pressure relief components; that is, when the pressure is low... Effective pressure relief can be achieved solely through the top pressure relief component at the expansion joint; however, when a severe fault causes a sharp rise in pressure, the pressure relief component at the oil tank can quickly intervene. The two components work together to greatly improve the overall pressure relief efficiency, ensuring reliable operation under various complex working conditions and preventing explosion-proof failure due to the failure of a single structure. Furthermore, this invention also helps to extend the service life of the equipment. By setting explosion-proof pressure relief structures at two key locations, this invention effectively disperses and controls internal pressure, reduces damage to internal components and the outer casing caused by pressure shocks, and lowers the probability of aging and damage to the equipment due to long-term pressure. This extends the overall service life of the oil-immersed current transformer, reduces equipment replacement and maintenance costs, and improves the stability and economy of power system operation. Attached Figure Description

[0015] To more clearly illustrate the technical solution of this utility model, the drawings used in the description will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a structural schematic diagram of a specific embodiment of the present utility model;

[0017] Figure 2 This is a schematic diagram of the structure of the oil tank in this utility model when the first type of bottom pressure relief component is used;

[0018] Figure 3 This is a schematic diagram of the structure of the oil tank in this utility model when the second type of bottom pressure relief component is used;

[0019] Figure 4 A schematic diagram of the structure of the expander outer cover in this utility model;

[0020] Figure 5 This is a schematic diagram of the expansion joint in this utility model.

[0021] In the diagram: 1. Expander; 2. Oil conservator; 3. Porcelain sleeve; 4. Elevator seat; 5. Oil tank; 6. Secondary coil; 7. Secondary terminal block; 8. Expander top cover; 9. Easily breakable connection structure; 10. Cylindrical protective column; 11. Bellows section; 12. Connecting flange section; 13. Expansion joint; 14. Housing; 15. Mounting base; 16. Sealing ring; 17. Explosion-proof baffle; 18. Pre-splitting line; 19. Explosion-proof disc; 20. Pressure plate; 21. Bottom pressure relief assembly; 22. Filter section; 23. Filter hole. Detailed Implementation

[0022] To make the objectives, features, and advantages of this utility model more apparent and understandable, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this patent, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this patent.

[0023] like Figures 1 to 5 As shown, this utility model provides an explosion-proof oil-immersed current transformer, which includes a body composed of an expander 1, an oil conservator 2, a primary terminal block, a porcelain bushing 3, a primary winding, transformer oil, a riser 4, an oil tank 5, a secondary coil 6, and a secondary terminal block 7. Furthermore, this utility model includes a top pressure relief assembly at the expander 1 and a bottom pressure relief assembly 21 at the oil tank 5.

[0024] Specifically, in this embodiment, such as Figure 4 , Figure 5As shown, the expander 1 includes an expansion joint 13 and an expansion cover covering the outside of the expansion joint 13. The expansion joint 13 is configured from bottom to top as a connecting flange portion 12, a bellows portion 11, and a top mounting portion. The connecting flange portion 12 is connected to the top of the oil conservator 2 by bolts or other fasteners. Preferably, the inner diameter of the connecting flange portion 12 is equal to or slightly smaller than the inner diameter of the bellows portion 11. This increases the opening size at the connection between the oil conservator 2 and the expansion joint 13, thereby increasing the connection channel between the expansion joint 13 and the oil conservator 2, optimizing the pressure fit between the components, and ensuring that insulating oil can quickly enter the interior of the expansion joint 13. The top mounting part is installed with the top pressure relief assembly by fasteners such as bolts. The top pressure relief assembly can be constructed by directly opening a corresponding pressure relief hole on the top of the expansion joint 13, and sequentially installing components such as mounting base, explosion-proof plate, and pressure plate on the outside of the pressure relief hole. The explosion-proof plate at this location is used to achieve the corresponding explosion action. For example, the explosion-proof pressure relief structure provided at the expansion joint 13 in Chinese Patent No. CN115020072A, and the structure of the bottom pressure relief assembly described below.

[0025] The expander cover includes a cylindrical protective column 10 with openings at both ends. The cylindrical protective column 10 covers the outside of the expansion joint 13. The lower end of the cylindrical protective column 10 is connected to the oil tank 2 by means of threaded connection, welding, etc. The upper end of the cylindrical protective column 10 is covered with an expander top cover 8. The expander top cover 8 and the cylindrical protective column 10 are connected by a breakable connection structure 9. For example: 1. The expander top cover 8 and the cylindrical protective column 10 are connected by a ring of small-thickness, easily broken, and the material of the breakable connection column can be some common brittle materials; 2. The expander top cover 8 and the cylindrical protective column 10 are connected by a ring of easily separated buckle structure. In this case, the breakable connection structure 9 includes a groove at the lower edge of the expander top cover 8 and a buckle at the upper edge of the cylindrical protective column 10, and the buckle is engaged in the groove.

[0026] Since the expander cover in this utility model adopts a split structure consisting of a cylindrical protective column 10 and an expander top cover 8, when the expander joint 13 expands and stretches to the top position of the expander cover, the expander top cover 8 at the expander cover will be subjected to an upward thrust. The easily breakable connection structure 9 between the cylindrical protective column 10 and the expander top cover 8 will be separated by force. At this time, the expander top cover 8 will be lifted by force, thereby ensuring that the expander joint 13 can continue to stretch in the vertical direction. Moreover, when the expander joint 13 continues to stretch to a certain extent, if it reaches the rated burst pressure of the explosion-proof disc at the top pressure relief component, the explosion-proof disc at that location will burst, thereby quickly releasing the pressure.

[0027] like Figure 2 As shown, the bottom pressure relief assembly 21 includes a pressure relief hole on the housing 14 of the oil tank 5. A mounting base 15 is installed on the outside of the pressure relief hole by welding or other methods. An explosion-proof disc 19 is sealed inside the mounting base 15 by a sealing ring 16, preferably made of high-performance fluorosilicone rubber. A cross-shaped pre-crack line 18 is provided in the center of the explosion-proof disc 19. The presence of this pre-crack line 18 establishes a weak point for the explosion-proof disc 19, allowing it to precisely rupture along the pre-crack line 18 when the internal pressure of the transformer reaches a preset threshold, avoiding irregular tearing and achieving stable and efficient pressure relief. Furthermore, compared to traditional explosion-proof discs 19, the pressure release of this type of explosion-proof disc 19 with the pre-crack line 18 is more uniform and controllable, effectively reducing the risk of injury to surrounding equipment and personnel caused by fragments flying due to irregular rupture of the explosion-proof disc 19. A pressure plate 20 and an explosion-proof baffle 17 are sequentially installed from the inside out on the outside of the explosion-proof disc 19 using bolts or other fasteners. The pressure plate 20 has a ring-shaped structure and is used to press the explosion-proof sheet 19. A gap is provided between the explosion-proof baffle 17 and the pressure plate 20 to allow insulating oil to spray out. This gap can be created by providing a notch on the inner surface of the explosion-proof baffle 17, a notch on the outer surface of the pressure plate 20, or by providing multiple washers between the explosion-proof baffle 17 and the pressure plate 20. When using multiple washers, washers of appropriate thickness are selected first, and then the bolts used to install the explosion-proof baffle are sequentially passed through the explosion-proof baffle 17, the corresponding washers, the pressure plate 20, and the explosion-proof sheet 19. The explosion-proof baffle 17 is threaded onto the mounting base 15, thus securing all components while ensuring a gap between the explosion-proof baffle 17 and the pressure plate 20 via washers. When a notch is provided on the inner surface of the explosion-proof baffle 17 and / or on the outer surface of the pressure plate 20, the bolts used to install the explosion-proof baffle 17 can be directly threaded through the explosion-proof baffle 17, pressure plate 20, and explosion-proof sheet 19 before being threaded onto the mounting base 15, securing all components while creating the required gap through the corresponding notches. Furthermore, during equipment transportation, pearl cotton can be added between the explosion-proof baffle 17 and the explosion-proof sheet 19 to protect the explosion-proof sheet 19.

[0028] Under normal operating conditions, the pressure inside the device will not exceed the limit of the explosion-proof disc 19, and the sealing structure between the explosion-proof disc 19 and the mounting base 15 can prevent insulating oil leakage at the explosion-proof disc 19. When an arc fault occurs inside the device, a large amount of gas will be generated instantly, causing a sharp increase in the internal pressure. When the pressure exceeds the rated burst pressure limit of the explosion-proof disc 19, the explosion-proof disc 19 will burst, thereby achieving rapid pressure relief. Moreover, during the pressure relief process, since the device has an explosion-proof baffle 17 on the outside of the explosion-proof disc 19, it can change the direction of the insulating oil, allowing the insulating oil to flow out from the gap between the explosion-proof baffle and the pressure plate 20, preventing the insulating oil from spraying out directly.

[0029] In addition, as a preferred embodiment, this utility model also provides a second bottom pressure relief assembly 21, such as... Figure 3 As shown, this bottom pressure relief assembly 21 and Figure 2 The difference between the bottom pressure relief assembly 21 described above and the one described below is that the bottom pressure relief assembly 21 has a filter section 22 in the middle of the pressure plate 20, and multiple filter holes 23 are evenly distributed through the surface of the filter section 22. In the event of a burst explosion of the explosion-proof plate 19, the insulating oil can be filtered by the filter section 22 during its outflow, preventing fragments generated inside the device or after the explosion-proof plate 19 bursts from being ejected with the insulating oil, thus avoiding damage to surrounding equipment or personnel. Furthermore, the filter section 22 is preferably made of permanent magnet material, which allows it to directly adsorb metal fragments to a certain extent, preventing smaller metal fragments from passing through the filter holes 23 and being ejected with the insulating oil.

[0030] Based on this, when this invention is applied in a power system, it can achieve comprehensive and multi-layered explosion-proof protection. Specifically, when the internal pressure of the transformer body rises abnormally, on the one hand, this invention can utilize the extension of the expansion joint 13 itself and the rupture of the explosion-proof plate 19 at the top pressure relief assembly to relieve pressure at the top of the transformer body, mitigating the upward pressure trend. On the other hand, this invention can utilize the bottom pressure relief assembly 21 at the oil tank 5 as another line of defense to release the high pressure at the bottom of the transformer body, achieving rapid pressure relief and explosion prevention. Simultaneously, it avoids pressure concentration at weak points in the oil tank 5, greatly reducing the risk of explosion of the oil tank 5 and comprehensively ensuring equipment safety.

[0031] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An explosion-proof oil-immersed current transformer, comprising a body, an oil tank (2) disposed on the upper part of the body, an expander (1) disposed above the oil tank (2), and a top pressure relief assembly disposed on the expander (1); a porcelain sleeve (3) disposed below the oil tank (2), and a riser (4) and an oil tank (5) disposed sequentially from top to bottom below the porcelain sleeve (3); characterized in that, The side of the fuel tank (5) is provided with a bottom pressure relief assembly (21).

2. The explosion-proof oil-immersed current transformer according to claim 1, characterized in that, The bottom pressure relief assembly (21) includes a pressure relief hole opened on the side wall of the oil tank (5). A mounting base (15) is provided on the outside of the pressure relief hole. An explosion-proof plate (19) is sealed and installed inside the mounting base (15). A pressure plate (20) and an explosion-proof baffle (17) are installed on the outside of the explosion-proof plate (19) from the inside to the outside by fasteners. A gap is provided between the explosion-proof baffle (17) and the pressure plate (20).

3. The explosion-proof oil-immersed current transformer according to claim 2, characterized in that, A filter section (22) is provided in the middle of the tablet (20), and filter holes (23) are uniformly penetrated on the surface of the filter section (22).

4. The explosion-proof oil-immersed current transformer according to claim 3, characterized in that, The filter section (22) is made of permanent magnet material.

5. The explosion-proof oil-immersed current transformer according to claim 2, characterized in that, The explosion-proof sheet (19) is provided with a pre-crack line (18).

6. The explosion-proof oil-immersed current transformer according to claim 1, characterized in that, The expander (1) includes an expansion joint (13), the bottom of which is connected to the oil tank (2), and a top pressure relief assembly is provided on the top of the expansion joint (13).

7. The explosion-proof oil-immersed current transformer according to claim 6, characterized in that, The expander (1) also includes an expander cover, which includes a cylindrical protective column (10) with openings at both ends. The cylindrical protective column (10) is covered on the outside of the expansion joint (13). The lower end of the cylindrical protective column (10) is fixedly connected to the oil tank (2). The upper end of the cylindrical protective column (10) is covered with an expander top cover (8). The expander top cover (8) and the cylindrical protective column (10) are connected by a breakable connection structure (9).

8. The explosion-proof oil-immersed current transformer according to claim 6, characterized in that, The expansion joint (13) is configured from bottom to top as a connecting flange part (12) and a bellows part (11). The connecting flange part (12) is connected to the oil tank (2) by fasteners. The inner diameter of the connecting flange part (12) is equal to the inner diameter of the bellows part (11).

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