Low-voltage porcelain bushing for high current and its manufacturing process

Abstract

The application discloses a kind of low-voltage pure porcelain sleeve high-current insulating bushings and preparation process thereof, belong to electric power insulation fittings technical field, including integrated pure porcelain insulating sleeve, high-current conducting assembly, sealing buffer assembly, reinforcing flange assembly and heat dissipation flow guide assembly.The application breaks through the upper limit of traditional low-voltage pure porcelain sleeve 2000A current-carrying, solves the core technical problems such as existing product high current operating condition temperature rise is too high, porcelain sleeve stress cracking, sealing leakage, poor heat dissipation, poor vibration resistance, realizes 3000A-6000A super large current long-term stable operation, improves bushing insulation performance, mechanical performance and service life comprehensively, meets the use demand of harsh industrial scene.

Description

Technical Field

[0001] This invention belongs to the field of power insulation accessories technology, specifically relating to a low-voltage pure porcelain bushing high-current insulating bushing used in low-voltage distribution transformers, complete sets of distribution cabinets, and high-current switchgear, and its manufacturing process. It is particularly suitable for power scenarios with long-term continuous operation of ultra-high current of 3000A-6000A in metallurgy, chemical industry, rail transportation, and large industrial and mining enterprises. Background Technology

[0002] Low-voltage insulating bushings are core components of low-voltage power transmission and distribution systems. Their main functions are to achieve electrical isolation between high and low voltage chambers, fix conductive conductors through them, and provide insulation protection and sealing. They are widely used in various low-voltage power equipment. Pure porcelain insulating bushings have become the mainstream choice for low-voltage power distribution equipment due to their advantages such as stable insulation performance, resistance to high and low temperatures, corona resistance, aging resistance, high mechanical strength, and controllable overall cost.

[0003] Currently, most traditional low-voltage pure porcelain bushings on the market are designed with a current carrying capacity of 2000A or below, which can only meet the needs of small to medium current applications. In ultra-high current operating scenarios of 3000A and above, existing products have revealed several fundamental technical defects:

[0004] (1) Insufficient current carrying capacity and uncontrolled temperature rise: The cross-sectional size of the traditional conductive rod is too small and heat dissipation has not been optimized. Under high current, the skin effect is significant and the temperature rise of the conductor rises sharply. High temperature will accelerate the aging and failure of the seal, and at the same time cause thermal fatigue damage to the porcelain sleeve.

[0005] (2) Defects in porcelain bushing structure and easy stress cracking: Traditional porcelain bushings all adopt a straight pipe structure with equal wall thickness. After the large current heats up, a large temperature difference is formed inside and outside the porcelain bushing. Thermal expansion and contraction generate continuous stress concentration, which can easily cause the porcelain bushing to crack and the insulation to break down, thus causing short circuit failure of the equipment.

[0006] (3) Simple sealing structure and high risk of leakage: Traditional products only use a single layer of ordinary rubber seal, which has poor high temperature resistance and deformation resistance. It is easy to harden and crack under high current and high temperature environment, resulting in leakage of insulating oil and intrusion of external water vapor and dust, which damages the internal insulation environment of the equipment.

[0007] (4) No dedicated heat dissipation structure and serious heat accumulation: Traditional bushings are not designed with independent heat dissipation channels, and the operating heat cannot be dissipated quickly, forming a vicious cycle of "heating - aging - more prone to heat generation", which greatly shortens the service life of the equipment;

[0008] (5) Poor reliability of fixed structure and weak vibration resistance: Conventional flanges are ordinary flat clamping structures with simple limiting methods. Under continuous vibration conditions of industrial equipment, the bushing is prone to loosening and displacement, which directly reduces insulation stability and threatens the safety of power grid operation.

[0009] At the same time, some existing high-current operating conditions have switched to composite insulating bushings, which temporarily improves the current carrying capacity. However, these products have problems such as poor weather resistance, easy aging, weak anti-pollution flashover ability, and short service life, and cannot be adapted to the harsh industrial environment with high temperature, high dust and strong vibration.

[0010] In summary, both traditional pure porcelain bushings and composite insulating bushings have significant technical shortcomings. The industry has long lacked a low-voltage pure porcelain bushing that can meet the requirements of ultra-high current, long cycle, and high reliability operation of 3000A-6000A. This problem has become a technical bottleneck restricting the development of low-voltage high-current power equipment. Summary of the Invention

[0011] The purpose of this invention is to overcome the many shortcomings of the existing technology and provide a low-voltage pure porcelain bushing with high current insulation and its manufacturing process. It breaks through the 2000A current carrying capacity limit of traditional low-voltage pure porcelain bushings and solves the core technical problems of excessive temperature rise, porcelain bushing stress cracking, sealing leakage, poor heat dissipation, and poor vibration resistance under high current conditions. It enables long-term stable operation of ultra-high current of 3000A-6000A, comprehensively improves the bushing's insulation performance, mechanical properties and service life, and meets the needs of harsh industrial scenarios.

[0012] To address the aforementioned technical problems, this invention provides a low-voltage pure ceramic bushing with high-current insulation, comprising an integrated pure ceramic insulating bushing, a high-current conductive component, a sealing and buffering component, a reinforced flange component, and a heat dissipation and current guiding component.

[0013] The integrated pure porcelain insulating sleeve is made of high-purity alumina ceramic sintered in one piece, with a seamless structure and a gradient wall thickness structure with a drum shape in the middle and straight tubes at both ends.

[0014] The high-current conductive component is provided through the central through hole of the integrated pure porcelain insulating sleeve and is coaxially assembled with the integrated pure porcelain insulating sleeve.

[0015] The reinforced flange assembly is fixedly sleeved on the outer wall of the middle part of the integrated pure porcelain insulating sleeve for overall installation and positioning of the sleeve;

[0016] The sealing buffer assembly fills the assembly gap between the two ends of the high current conductive assembly and the inner wall of the integrated pure porcelain insulating sleeve, as well as the mating end face between the reinforcing flange assembly and the integrated pure porcelain insulating sleeve.

[0017] The heat dissipation and flow guiding component is embedded between the outer wall of the reinforced flange component and the high current conductive component, forming an annular convection heat dissipation channel.

[0018] Preferably, the integrated pure porcelain insulating sleeve uses 95% high-purity alumina ceramic raw material with a sintering density ≥3.9g / cm³; the wall thickness adopts a differentiated gradient distribution, with the straight tube sections at both ends having a wall thickness of 8-12mm and the drum-shaped section in the middle having a maximum wall thickness of 18-22mm; the central through hole of the integrated pure porcelain insulating sleeve is a stepped through hole with enlarged holes at both ends and a regular round hole in the middle, and the inner wall of the through hole is precision ground and polished, with a surface roughness ≤Ra0.8μm.

[0019] This invention utilizes 95% high-purity alumina ceramic, integrally sintered without seams, ensuring fundamental performance in terms of insulation, high-temperature resistance, and mechanical strength. Abandoning the traditional straight tube design with uniform wall thickness, it pioneers a gradient wall thickness configuration with a central drum shape and straight ends: thinner walls at both ends and thicker walls in the middle. This adapts to temperature changes caused by high-current operation, effectively offsetting stress concentration caused by thermal expansion and contraction, and fundamentally preventing ceramic bushing cracking. The central drum shape also provides precise flange positioning, improving assembly stability. The central through-hole is designed as a stepped structure with enlarged holes at both ends and a regular circular hole in the middle, with precision-polished inner walls, further optimizing assembly accuracy and insulation performance.

[0020] Preferably, the high-current conductive component includes an integrated oxygen-free copper conductive rod and a press-fit conductive terminal.

[0021] The integrated oxygen-free copper conductive rod has a solid circular cross-section structure, and the cross-sectional dimensions are matched and set according to the current carrying capacity of 3000A-6000A. The two ends of the integrated oxygen-free copper conductive rod are machined with threaded connection sections and positioning steps. Multiple axial flow guiding heat dissipation grooves are evenly opened on the outer wall of the middle part of the integrated oxygen-free copper conductive rod.

[0022] The press-fit conductive terminals are fixed to both ends of the integrated oxygen-free copper conductive rod, and the contact surfaces are silver-plated with a silver plating thickness of ≥10μm.

[0023] This invention utilizes a solid conductive rod forged from T2 oxygen-free copper. Its large cross-section design meets the requirements for ultra-high current conduction of 3000A-6000A, exhibiting low conductor resistance and strong current carrying capacity. Multiple axially oriented heat dissipation grooves are evenly distributed around the outer wall of the conductive rod, actively mitigating the skin effect under high current conditions, rapidly dissipating heat from the conductor's interior, and controlling operating temperature rise. The conductive terminals are assembled using a high-strength cold-pressing process, with silver plating on the contact surfaces, significantly reducing contact resistance and preventing localized overheating at the connection points.

[0024] Preferably, the reinforced flange assembly includes an aluminum alloy forged flange, an annular limiting clamp, and locking bolts;

[0025] The aluminum alloy forged flange has an arc-shaped groove in the middle that matches the drum-shaped section in the middle of the integrated pure porcelain insulating sleeve. A high-temperature resistant silicone buffer pad is pasted on the inner wall of the arc-shaped groove. Mounting ear plates are symmetrically arranged on both sides of the aluminum alloy forged flange, and the ear plates have fixing through holes.

[0026] The annular limiting clamp is set on one side of the aluminum alloy forged flange and is fastened by locking bolts to achieve radial limiting and fixing of the integrated pure ceramic insulating sleeve.

[0027] This invention uses a forged aluminum alloy flange with an arc-shaped groove in the center that matches the drum-shaped section of the porcelain sleeve. A high-temperature resistant silicone buffer pad is attached to the inside of the groove, and together with two sets of upper and lower limiting clamps, a flexible clamping and limiting structure is formed. Unlike traditional rigid clamping flanges, this structure ensures that the sleeve is firmly installed and resistant to equipment vibration, while avoiding damage to the porcelain components caused by rigid compression. Mechanical stability and protection are improved simultaneously.

[0028] Preferably, the sealing buffer assembly includes an end composite sealing sleeve, an end face sealing gasket, and a flange sealing layer;

[0029] The end composite sealing sleeve adopts a double-layer composite structure of silicone rubber and fluororubber, and is interference-fitted into the gap between the through holes at both ends of the integrated oxygen-free copper conductive rod and the integrated pure porcelain insulating sleeve.

[0030] The end face sealing gasket is sleeved inside the crimped conductive terminal and is fitted to the end face of the integrated pure ceramic insulating sleeve.

[0031] The flange sealing layer is a high-temperature resistant epoxy resin sealant, which is uniformly coated on the gap between the aluminum alloy forged flange and the integrated pure porcelain insulating sleeve, and forms an integral sealing structure after curing.

[0032] This invention breaks through the traditional single-layer rubber sealing mode, constructing a three-stage sealing structure consisting of a double-layer composite rubber, an end-face gasket, and an epoxy resin layer. The end uses a double-layer composite sleeve of silicone rubber and fluororubber, possessing high elasticity, high temperature resistance, and aging resistance, adapting to the thermal deformation of the ceramic sleeve and conductive rod to achieve dynamic sealing. The end-face gasket seals the end gaps. The flange mating surface is cured with high-temperature resistant epoxy resin sealant to form a rigid, permanent seal. The multi-stage sealing works together to completely prevent the intrusion of oil, moisture, and dust, solving the leakage problem.

[0033] Preferably, the heat dissipation and flow guiding component includes an annular heat dissipation groove, an axial ventilation flow guiding groove, and a thermally conductive filling layer;

[0034] The annular heat dissipation groove is formed on the outer wall of the drum-shaped section in the middle of the integrated pure ceramic insulating sleeve, and is located inside the arc-shaped groove of the aluminum alloy forged flange.

[0035] The axial ventilation guide groove is evenly opened along the outer wall of the integrated pure ceramic insulating sleeve and is connected to the annular heat dissipation groove.

[0036] The thermally conductive filling layer is a high thermal conductivity ceramic thermally conductive adhesive, which fills the gap between the aluminum alloy forged flange and the outer wall of the integrated pure ceramic insulating sleeve, so as to realize the rapid conduction of heat to the aluminum alloy forged flange for heat dissipation.

[0037] Furthermore, a heat conduction component is provided between the high-current conductive component and the inner wall of the integrated pure ceramic insulating sleeve.

[0038] This invention constructs an integrated three-dimensional active heat dissipation channel consisting of an annular heat dissipation groove, an axial ventilation guide groove, and a high thermal conductivity filling layer. The heat generated by the conductive rod is sequentially transferred to the flange through a ceramic sleeve and high thermal conductivity ceramic adhesive, and then dissipates rapidly to the external environment via air convection formed by the annular groove and the axial guide groove. This three-dimensional heat dissipation structure is an original design, with heat dissipation efficiency far exceeding that of traditional natural heat dissipation methods, and strictly controls the temperature rise under full load operation.

[0039] This invention optimizes the matching relationship of parameters of each component through the coordinated operation of five major modules, enabling the product to have multiple advantages such as high current carrying capacity, low temperature rise, crack resistance, leakage prevention, strong vibration resistance, and long service life, and fully adapt to the operation requirements of low-voltage ultra-high current power equipment.

[0040] The present invention also provides a manufacturing process for the above-mentioned low-voltage pure ceramic high-current insulating bushing, which specifically includes the following steps:

[0041] S1 Raw Material Pretreatment and Ceramic Sleeve Molding: 95% high-purity alumina ceramic powder is selected, ball-milled, spray-dried, and dry-pressed, and then sintered at a high temperature of 1620℃-1650℃ for 2-3 hours to obtain an integrated pure ceramic insulating sleeve; after molding, the through holes and outer walls are finely ground and polished, and pressure resistance non-destructive testing is completed.

[0042] S2 high-current conductive component processing and forming: T2 oxygen-free copper forging is used to prepare an integrated oxygen-free copper conductive rod, the surface is polished and then silver-plated, and axial heat dissipation grooves and end connection structures are processed; high-strength cold pressing process is used to fix the press-fit conductive terminals to both ends of the integrated oxygen-free copper conductive rod, and the conductivity performance is tested.

[0043] S3 Sealing and Buffer Assembly Prefabrication: Processing and preparing a double-layer composite sealing sleeve of silicone rubber and fluororubber, a high-temperature end face sealing gasket, and preparing a high-temperature epoxy resin sealant for later use;

[0044] S4 Overall Assembly: The double-layer composite sealing sleeve is interference-fitted to the through holes at both ends of the integrated pure ceramic insulating sleeve, the high-current conductive component is inserted and the end face sealing gasket is installed; high thermal conductivity ceramic thermally conductive adhesive is applied inside the arc-shaped groove of the aluminum alloy forged flange, the reinforced flange component is clamped in the middle of the integrated pure ceramic insulating sleeve and tightened with locking bolts, and finally epoxy resin sealant is filled in the gap between the aluminum alloy forged flange and the outer wall of the integrated pure ceramic insulating sleeve.

[0045] S5 Curing and Finished Product Inspection: The assembled bushing is left to cure at room temperature for 24 hours, and insulation withstand voltage test, current flow temperature rise test, sealing performance test, and mechanical strength test are carried out in sequence. The finished product is obtained after all items pass the test.

[0046] The low-voltage pure porcelain bushing high-current insulating bushing prepared by the above process has an overall rated power frequency withstand voltage of ≥10kV, which meets the national standard for low-voltage power equipment; the continuous rated current carrying range is 3000A-6000A, and the temperature rise during long-term full-load continuous operation is ≤45K.

[0047] In summary, this invention possesses several outstanding technological advancements and substantial innovations, with the following specific beneficial effects:

[0048] (1) A leapfrog breakthrough in current carrying capacity

[0049] This invention relies on the original structure of large-section T2 oxygen-free copper conductive rod and axial heat dissipation groove, which effectively weakens the skin effect of high current and increases the current carrying capacity of traditional low-voltage pure ceramic bushings from 2000A to 3000A-6000A, filling the market gap of low-voltage ultra-high current pure ceramic bushings. It can be directly applied to various high-current power distribution equipment.

[0050] (2) Excellent temperature rise control effect

[0051] The product features a unique three-dimensional heat dissipation system, which, combined with the built-in heat dissipation grooves on the conductive rod, forms a triple heat dissipation mode of "internal heat dissipation of the conductor + conduction heat dissipation of the ceramic sleeve + external convection heat dissipation". The temperature rise of the product during long-term full-load continuous operation is ≤45K, effectively avoiding problems such as aging of seals and insulation failure caused by high temperature.

[0052] (3) Completely solve the problem of stress cracking in porcelain bushings

[0053] The innovative gradient wall thickness drum-shaped porcelain bushing structure, combined with 95% high-purity alumina high-strength ceramic material, can effectively offset the thermal stress caused by the temperature difference between the inside and outside of the porcelain bushing under high current conditions, and prevent porcelain bushing cracking and insulation breakdown caused by thermal expansion and contraction, thus greatly improving mechanical strength and operational safety.

[0054] (4) Long-term reliable sealing performance

[0055] It adopts a three-level composite gradient sealing system, which combines the advantages of elastic dynamic sealing and rigid curing sealing. It is resistant to high temperature, aging, and deformation, and can isolate water vapor, oil, and dust intrusion for a long time. Its sealing life is far superior to that of traditional single-layer sealing structures, and the equipment maintenance cycle is significantly extended.

[0056] (5) Mechanical stability and vibration resistance are greatly improved.

[0057] The flexible limiting flange structure with arc-shaped groove and silicone buffer pad balances tightness and cushioning. Under the strong vibration environment of industrial equipment, the sleeve will not loosen or shift, making it suitable for harsh working conditions such as metallurgy and chemical industry.

[0058] (6) Long service life and wide compatibility

[0059] The integrated ceramic structure is resistant to high and low temperatures, corona, flashover, and aging. It has no vulnerable or weak parts and its service life is more than three times that of traditional composite insulating bushings. The product interface is compatible with existing low-voltage equipment installation standards and can directly replace traditional bushings, making it highly versatile.

[0060] (7) Easy to assemble and conducive to industrialization and promotion

[0061] The overall design adopts a modular approach, with a compact structure, precise positioning, and simple assembly process, requiring no complex debugging. The raw materials and processing technology are mature, and the production and manufacturing costs are controllable, making it suitable for large-scale mass production and market promotion. Attached Figure Description

[0062] Figure 1 This is a schematic diagram of the structure of the low-voltage pure porcelain bushing high-current insulating bushing of the present invention;

[0063] Figure 2 This is a process diagram for manufacturing the low-voltage pure ceramic high-current insulating bushing of the present invention. Detailed Implementation

[0064] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0065] like Figure 1 The low-voltage pure ceramic high-current insulating bushing shown includes an integrated pure ceramic insulating bushing 1, a high-current conductive component, a sealing buffer component, a reinforcing flange component, and a heat dissipation and current guiding component.

[0066] Specifically, the integrated pure porcelain insulating sleeve 1 is integrally sintered from 95% high-purity alumina ceramic raw material, with a seamless structure and a gradient wall thickness structure with a central drum shape and straight tubes at both ends, achieving a sintering density ≥3.9g / cm³. The wall thickness adopts a differentiated gradient distribution, with the straight tube sections at both ends having a wall thickness of 8-12mm and the central drum-shaped section having a maximum wall thickness of 18-22mm. The central through hole of the integrated pure porcelain insulating sleeve is a stepped through hole with enlarged holes at both ends and a regular round hole in the middle. The inner wall of the through hole is precision ground and polished, with a surface roughness ≤Ra0.8μm.

[0067] Specifically, the high-current conductive component is disposed through the central through-hole of the integrated pure ceramic insulating sleeve and is coaxially assembled with the integrated pure ceramic insulating sleeve 1. The high-current conductive component includes an integrated oxygen-free copper conductive rod 2 and a press-fit conductive terminal 3; the integrated oxygen-free copper conductive rod 2 has a solid circular cross-section structure, and the cross-sectional dimensions are matched according to the current carrying capacity of 3000A-6000A. The integrated oxygen-free copper conductive rod 2 has threaded connection sections and positioning steps processed at both ends. Multiple axial flow guiding and heat dissipation grooves are evenly opened on the circumferential outer wall of the middle part of the integrated oxygen-free copper conductive rod 2. The press-fit conductive terminal 3 is fixed to both ends of the integrated oxygen-free copper conductive rod 2 by a high-strength cold pressing process, and the contact surface is silver-plated with a silver plating thickness ≥10μm.

[0068] Specifically, the reinforced flange assembly is fixedly sleeved on the outer wall of the middle part of the integrated pure porcelain insulating sleeve 1 for overall installation and positioning of the sleeve. The reinforced flange assembly includes an aluminum alloy forged flange 4, an annular limiting clamp 5, and locking bolts 6; the aluminum alloy forged flange 4 has an arc-shaped groove in the middle that matches the drum-shaped section in the middle of the integrated pure porcelain insulating sleeve 1, and a high-temperature resistant silicone buffer pad is pasted on the inner wall of the arc-shaped groove; mounting ears are symmetrically arranged on both sides of the aluminum alloy forged flange 4, and the ear plates have fixing through holes; the annular limiting clamp 5 is set at the bottom end of the aluminum alloy forged flange 4 and is fastened by the locking bolts 6 to achieve radial limiting and fixing of the integrated pure porcelain insulating sleeve.

[0069] Specifically, the sealing and buffering assembly fills the assembly gap between the two ends of the high-current conductive component and the inner wall of the integrated pure ceramic insulating sleeve, as well as the mating end face of the reinforcing flange assembly and the integrated pure ceramic insulating sleeve. The sealing and buffering assembly includes an end composite sealing sleeve, an end face sealing gasket, and a flange sealing layer 7; the end composite sealing sleeve adopts a double-layer composite structure of silicone rubber and fluororubber, and is interference-fitted into the gap between the through holes at both ends of the integrated oxygen-free copper conductive rod 2 and the integrated pure ceramic insulating sleeve 1; the end face sealing gasket is sleeved inside the crimped conductive terminal 3 and is fitted to the end face of the integrated pure ceramic insulating sleeve 1; the flange sealing layer 7 is a high-temperature resistant epoxy resin sealant, which is uniformly coated on the mating gap between the aluminum alloy forged flange 4 and the integrated pure ceramic insulating sleeve 1, and forms an integral sealing structure after curing.

[0070] Specifically, the heat dissipation and flow guiding component is embedded between the reinforced flange assembly and the outer wall of the integrated oxygen-free copper conductive rod 2, forming an annular convection heat dissipation channel 10. Simultaneously, a heat conduction component 11 is disposed between the integrated oxygen-free copper conductive rod 2 and the inner wall of the integrated pure ceramic insulating sleeve 1. The heat dissipation and flow guiding component includes an annular heat dissipation groove, an axial ventilation guide groove 8, and a thermally conductive filling layer 9. The annular heat dissipation groove is located on the outer wall of the drum-shaped section in the middle of the integrated pure ceramic insulating sleeve 1, inside the arc-shaped slot of the aluminum alloy forged flange 4. The axial ventilation guide groove 8 is uniformly distributed along the circumference of the outer wall of the integrated pure ceramic insulating sleeve 1 and communicates with the annular heat dissipation groove. The thermally conductive filling layer 9 is a high thermal conductivity ceramic thermally conductive adhesive, filling the gap between the aluminum alloy forged flange 4 and the outer wall of the integrated pure ceramic insulating sleeve 1, enabling rapid heat conduction to the aluminum alloy forged flange for heat dissipation.

[0071] Combination Figure 2 As shown, the manufacturing process of the aforementioned low-voltage pure porcelain bushing high-current insulating bushing specifically includes the following steps:

[0072] S1 Raw Material Pretreatment and Ceramic Sleeve Molding: 95% high-purity alumina ceramic powder is selected, ball-milled, spray-dried, and dry-pressed, and then sintered at a high temperature of 1620℃-1650℃ for 2-3 hours to obtain an integrated pure ceramic insulating sleeve; after molding, the through holes and outer walls are finely ground and polished, and pressure resistance non-destructive testing is completed.

[0073] S2 high-current conductive component processing and forming: T2 oxygen-free copper forging is used to prepare an integrated oxygen-free copper conductive rod, the surface is polished and then silver-plated, and axial heat dissipation grooves and end connection structures are processed; high-strength cold pressing process is used to fix the press-fit conductive terminals to both ends of the integrated oxygen-free copper conductive rod, and the conductivity performance is tested.

[0074] S3 Sealing and Buffer Assembly Prefabrication: Processing and preparing a double-layer composite sealing sleeve of silicone rubber and fluororubber, a high-temperature end face sealing gasket, and preparing a high-temperature epoxy resin sealant for later use;

[0075] S4 Overall Assembly: The double-layer composite sealing sleeve is interference-fitted to the through holes at both ends of the integrated pure ceramic insulating sleeve, the high-current conductive component is inserted and the end face sealing gasket is installed; high thermal conductivity ceramic thermally conductive adhesive is applied inside the arc-shaped groove of the aluminum alloy forged flange, the reinforced flange component is clamped in the middle of the integrated pure ceramic insulating sleeve and tightened with locking bolts, and finally epoxy resin sealant is filled in the gap between the aluminum alloy forged flange and the outer wall of the integrated pure ceramic insulating sleeve.

[0076] S5 Curing and Finished Product Inspection: The assembled bushing is left to cure at room temperature for 24 hours, and insulation withstand voltage test, current flow temperature rise test, sealing performance test, and mechanical strength test are carried out in sequence. The finished product is obtained after all items pass the test.

[0077] The following section provides a detailed explanation of the manufacturing process of the aforementioned low-voltage pure porcelain bushing high-current insulating bushing, using a practical example.

[0078] Example 1 (3000A Class Low Voltage Pure Porcelain Bushing High Current Insulating Bushing)

[0079] The above-described manufacturing process yields an insulating bushing with a rated current carrying capacity of 3000A. Its specific structure and parameters are as follows:

[0080] The integrated pure porcelain insulating sleeve is made of 95% high-purity alumina ceramic sintered in one piece, with a sintering density ≥3.9g / cm³; the straight tube sections at both ends have a wall thickness of 10mm, and the drum-shaped section in the middle has a maximum wall thickness of 20mm; the central through hole is a stepped hole with a diameter of 22mm in the middle and an inner wall roughness of Ra0.8μm.

[0081] The high-current conductive component uses a solid T2 oxygen-free copper conductive rod with a diameter of 20mm. Six axial heat dissipation grooves are evenly opened around the circumference of the rod, with a depth of 2mm and a width of 3mm for each groove. The conductive terminals are assembled by cold pressing, and the silver plating layer on the contact surface is 10μm thick.

[0082] The reinforced flange assembly uses a forged aluminum alloy flange, with a 3mm thick high-temperature resistant silicone buffer pad pasted on the inner side of the arc-shaped groove, and a set of annular limit clamps at the top and bottom to complete the fastening.

[0083] The sealing and buffer assembly uses a double-layer composite sealing sleeve of silicone rubber and fluororubber, and the flange gap is filled with high-temperature resistant epoxy resin sealant.

[0084] The heat dissipation and airflow guiding component has an annular heat dissipation groove and an axial ventilation and airflow guiding groove. The groove is 4mm wide and 3mm deep. The gap between the flange and the ceramic sleeve is filled with high thermal conductivity ceramic thermally conductive adhesive.

[0085] The performance test results are as follows:

[0086] The bushing has a rated power frequency withstand voltage of 10kV; it can operate continuously at full load for 24 hours with a maximum temperature rise of 42K; the bushing has no abnormal heating, no leakage, and the porcelain bushing has no deformation or cracking; the insulation resistance is ≥1000MΩ, and all indicators meet national standards.

[0087] Example 2 (6000A Class Low Voltage Pure Porcelain Bushing High Current Insulating Bushing)

[0088] The above-described fabrication process yields an ultra-high current insulating bushing with a rated current carrying capacity of 6000A. Based on Example 1, the structural parameters are optimized to enhance the overall load-bearing capacity.

[0089] The wall thickness of the straight pipe sections at both ends of the integrated pure ceramic insulating sleeve has been adjusted to 12mm, and the maximum wall thickness of the drum-shaped section in the middle is 22mm, further enhancing the overall structural strength.

[0090] The high-current conductive component uses a 30mm diameter T2 oxygen-free copper solid conductive rod with 8 axial flow-guiding heat dissipation grooves to increase the heat dissipation area and conduction cross-section; the silver plating layer on the contact surface of the conductive terminal is 9μm thick.

[0091] The reinforced flange is thickened and strengthened to improve its mechanical compressive and vibration resistance.

[0092] The width of the heat dissipation channel was adjusted to 5mm and the depth to 4mm. The thickness of the high thermal conductivity ceramic thermal adhesive filling was increased to enhance the heat conduction efficiency.

[0093] The performance test results are as follows:

[0094] The bushing can operate continuously at full load for 24 hours with a maximum temperature rise of 44K. Its sealing performance, insulation performance and mechanical strength all meet the standards and it can operate stably under ultra-high current conditions for a long time.

[0095] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape, principle and application direction of this application should be covered within the scope of protection of this application.

Claims

1. A low-voltage pure porcelain bushing high-current insulating bushing, characterized in that: Includes an integrated pure ceramic insulating sleeve, a high-current conductive component, a sealed buffer component, a reinforced flange component, and a heat dissipation and flow guiding component. The integrated pure porcelain insulating sleeve is made of high-purity alumina ceramic sintered in one piece, with a seamless structure and a gradient wall thickness structure with a drum shape in the middle and straight tubes at both ends. The high-current conductive component is provided through the central through hole of the integrated pure porcelain insulating sleeve and is coaxially assembled with the integrated pure porcelain insulating sleeve. The reinforced flange assembly is fixedly sleeved on the outer wall of the middle part of the integrated pure porcelain insulating sleeve for overall installation and positioning of the sleeve; The sealing buffer assembly fills the assembly gap between the two ends of the high current conductive assembly and the inner wall of the integrated pure porcelain insulating sleeve, as well as the mating end face between the reinforcing flange assembly and the integrated pure porcelain insulating sleeve. The heat dissipation and flow guiding component is embedded between the outer wall of the reinforced flange component and the high current conductive component, forming an annular convection heat dissipation channel.

2. The low-voltage pure porcelain bushing high-current insulating bushing according to claim 1, characterized in that: The integrated pure porcelain insulating sleeve is made of 95% high-purity alumina ceramic raw material with a sintering density ≥3.9g / cm³. The wall thickness adopts a differentiated gradient distribution, with the straight tube sections at both ends having a wall thickness of 8-12mm and the drum-shaped section in the middle having a maximum wall thickness of 18-22mm. The central through hole of the integrated pure porcelain insulating sleeve is a stepped through hole with enlarged holes at both ends and a regular round hole in the middle. The inner wall of the through hole is precision ground and polished, with a surface roughness ≤Ra0.8μm.

3. The low-voltage pure porcelain bushing high-current insulating bushing according to claim 1, characterized in that: The high-current conductive component includes an integrated oxygen-free copper conductive rod and a press-fit conductive terminal. The integrated oxygen-free copper conductive rod has a solid circular cross-section structure, and the cross-sectional dimensions are matched and set according to the current carrying capacity of 3000A-6000A. The two ends of the integrated oxygen-free copper conductive rod are machined with threaded connection sections and positioning steps. Multiple axial flow guiding heat dissipation grooves are evenly opened on the outer wall of the middle part of the integrated oxygen-free copper conductive rod. The press-fit conductive terminals are fixed to both ends of the integrated oxygen-free copper conductive rod, and the contact surfaces are silver-plated with a silver plating thickness of ≥10μm.

4. The low-voltage pure porcelain bushing high-current insulating bushing according to claim 1, characterized in that: The reinforced flange assembly includes an aluminum alloy forged flange, an annular limiting clamp, and locking bolts; The aluminum alloy forged flange has an arc-shaped groove in the middle that matches the drum-shaped section in the middle of the integrated pure porcelain insulating sleeve. A high-temperature resistant silicone buffer pad is pasted on the inner wall of the arc-shaped groove. Mounting ear plates are symmetrically arranged on both sides of the aluminum alloy forged flange, and the ear plates have fixing through holes. The annular limiting clamp is set on one side of the aluminum alloy forged flange and is fastened by locking bolts to achieve radial limiting and fixing of the integrated pure ceramic insulating sleeve.

5. The low-voltage pure porcelain bushing high-current insulating bushing according to claim 4, characterized in that: The sealing and buffer assembly includes an end composite sealing sleeve, an end face sealing gasket, and a flange sealing layer. The end composite sealing sleeve adopts a double-layer composite structure of silicone rubber and fluororubber, and is interference-fitted into the gap between the through holes at both ends of the integrated oxygen-free copper conductive rod and the integrated pure porcelain insulating sleeve. The end face sealing gasket is sleeved inside the crimped conductive terminal and is fitted to the end face of the integrated pure ceramic insulating sleeve. The flange sealing layer is a high-temperature resistant epoxy resin sealant, which is uniformly coated on the gap between the aluminum alloy forged flange and the integrated pure porcelain insulating sleeve, and forms an integral sealing structure after curing.

6. The low-voltage pure porcelain bushing high-current insulating bushing according to claim 4, characterized in that: The heat dissipation and flow guiding component includes an annular heat dissipation groove, an axial ventilation flow guiding groove, and a thermally conductive filling layer; The annular heat dissipation groove is formed on the outer wall of the drum-shaped section in the middle of the integrated pure ceramic insulating sleeve, and is located inside the arc-shaped groove of the aluminum alloy forged flange. The axial ventilation guide groove is evenly opened along the outer wall of the integrated pure ceramic insulating sleeve and is connected to the annular heat dissipation groove. The thermally conductive filling layer is a high thermal conductivity ceramic thermally conductive adhesive, which fills the gap between the aluminum alloy forged flange and the outer wall of the integrated pure ceramic insulating sleeve, so as to realize the rapid conduction of heat to the aluminum alloy forged flange for heat dissipation.

7. The low-voltage pure porcelain bushing high-current insulating bushing according to claim 6, characterized in that: A heat conduction component is provided between the high-current conductive component and the inner wall of the integrated pure ceramic insulating sleeve.

8. A manufacturing process for a low-voltage pure porcelain bushing high-current insulating bushing as described in any one of claims 1-7, characterized in that, Includes the following steps: S1 Raw Material Pretreatment and Ceramic Sleeve Molding: 95% high-purity alumina ceramic powder is selected, ball-milled, spray-dried, and dry-pressed, and then sintered at a high temperature of 1620℃-1650℃ for 2-3 hours to obtain an integrated pure ceramic insulating sleeve; after molding, the through holes and outer walls are finely ground and polished, and pressure resistance non-destructive testing is completed. S2 high-current conductive component processing and forming: T2 oxygen-free copper forging is used to prepare an integrated oxygen-free copper conductive rod, the surface is polished and then silver-plated, and axial heat dissipation grooves and end connection structures are processed; high-strength cold pressing process is used to fix the press-fit conductive terminals to both ends of the integrated oxygen-free copper conductive rod, and the conductivity performance is tested. S3 Sealing and Buffer Assembly Prefabrication: Processing and preparing a double-layer composite sealing sleeve of silicone rubber and fluororubber, a high-temperature end face sealing gasket, and preparing a high-temperature epoxy resin sealant for later use; S4 Overall Assembly: The double-layer composite sealing sleeve is interference-fitted to the through holes at both ends of the integrated pure ceramic insulating sleeve, the high-current conductive component is inserted and the end face sealing gasket is installed; high thermal conductivity ceramic thermally conductive adhesive is applied inside the arc-shaped groove of the aluminum alloy forged flange, the reinforced flange component is clamped in the middle of the integrated pure ceramic insulating sleeve and tightened with locking bolts, and finally epoxy resin sealant is filled in the gap between the aluminum alloy forged flange and the outer wall of the integrated pure ceramic insulating sleeve. S5 Curing and Finished Product Inspection: The assembled bushing is left to cure at room temperature for 24 hours, and insulation withstand voltage test, current flow temperature rise test, sealing performance test, and mechanical strength test are carried out in sequence. The finished product is obtained after all items pass the test.

9. The manufacturing process of the low-voltage pure porcelain bushing high-current insulating bushing according to claim 8, characterized in that: The low-voltage pure porcelain bushing high-current insulating bushing has an overall rated power frequency withstand voltage of ≥10kV, which conforms to the national standard for low-voltage power equipment; the continuous rated current carrying range is 3000A-6000A, and the temperature rise during long-term full-load continuous operation is ≤45K.

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