A GIS pluggable terminal based on spring radial compression and its assembly method

Abstract

This invention provides a spring-driven radial compression-based pluggable GIS terminal and its assembly method, belonging to the technical field of conductive connection equipment. The terminal includes an epoxy sleeve, terminals, cable cores, stress control components, a stop sleeve, a cone support, a cone support pressure plate, a spring propulsion assembly, and a tail tube. The terminals are disposed within the epoxy sleeve, with one end connected to the GIS equipment via a tapered bevel, and the other end equipped with a watch strap contact finger. The cable core is plugged into the terminals. The stress control component is disposed within the epoxy sleeve and contains a stress cone. The stop sleeve contacts the stress control component. The cone support and the cone support pressure plate are connected via a tightening screw. The spring propulsion assembly includes several springs and guide rods, with the springs positioned between the cone support and the cone support pressure plate. This invention optimizes the electric field distribution, enhances contact stability, improves working efficiency, and reduces processing costs.

Description

Technical Field

[0001] This invention relates to the field of conductive connection equipment technology, specifically to a GIS plug-in terminal based on spring radial compression and its assembly method. Background Technology

[0002] Gas-insulated metal-enclosed switchgear (GIS) has become a core component in modern high-voltage power transmission and transformation systems due to its compact structure, small footprint, excellent insulation performance, and high reliability. With the continuous development of intelligent and integrated power systems, GIS technology is increasingly widely used in high-voltage distribution networks and substations, playing an irreplaceable role in ensuring the stable and efficient operation of power systems.

[0003] Among them, the GIS terminal, as a key component for electrical connection between power cables and GIS equipment, directly affects the safety and reliability of the entire system. In recent years, to improve environmental benefits and operational safety, pluggable GIS terminals with a pure dry structure have received increasing attention. They aim to replace traditional oil-immersed or gas-filled terminals to achieve a maintenance-free operation mode without liquid or gaseous media pollution, further optimizing the installation and maintenance process of the equipment.

[0004] Utility model patent CN220122118U discloses an inner cone pluggable cable terminal, which can be assembled onto a cable and is suitable for insertion into the stepped inner cavity of an epoxy sheath. The cable terminal includes a voltage-conducting cone, a conductive ring, and a contact finger strap. The voltage-conducting cone, which is sleeved on the cable, is truncated cone-shaped and has a first axial through hole. The voltage-conducting cone also includes multiple contraction gaps, which allow the voltage-conducting cone to contract radially inward under external force. The outer circumferential surface of the conductive ring is cylindrical and includes a second axial through hole. The second axial through hole is truncated cone-shaped and has the same taper as the voltage-conducting cone to allow the conductive ring to conformally and coaxially sleeved on the voltage-conducting cone.

[0005] While existing GIS plug-in terminals have achieved a purely dry structure, numerous challenges remain in practical applications. For instance, the long-term stability and sealing reliability of the insulation interface are often affected by factors such as thermal expansion and contraction and material aging, which can easily lead to interface pressure attenuation, causing partial discharge or even insulation failure. This is especially true in purely dry structures without a filling medium, where the requirements for the continuity and uniformity of interface pressure are extremely high. If the contact pressure of plug-in contacts at conductor connections cannot be effectively maintained, problems such as increased contact resistance and localized overheating can easily occur, severely affecting conductivity and equipment operational safety.

[0006] Furthermore, existing terminal structures often lack effective fixing and support mechanisms at the cable-conduit connection points, which can lead to relative displacement or concentricity deviation of the cables during long-term operation, affecting the stability and mechanical strength of the electrical connection. Simultaneously, some designs still have shortcomings in optimizing the electric field distribution, potentially resulting in localized electric field concentration under high voltage. These issues collectively prevent existing GIS plug-in terminals from achieving ideal performance in terms of long-term reliable operation, ease of installation, and maintenance-free operation, necessitating a more reliable solution. Summary of the Invention

[0007] This invention provides a spring-based radial compression GIS plug-in terminal and its assembly method, aiming to solve the technical problem that the radial contact pressure at the conductor connection interface of existing plug-in GIS terminals may decrease due to factors such as material creep, thermal expansion and contraction cycles, and vibration during long-term operation, thereby affecting the stability of contact resistance, causing local overheating, and reducing the reliability of equipment operation.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0009] A spring-loaded radially compressed GIS plug-in terminal includes an epoxy sleeve. The invention also includes:

[0010] The terminal block is located inside the epoxy sleeve. One end of the terminal block is connected to the GIS equipment through a tapered bevel, and the other end is equipped with a watch strap contact finger.

[0011] The cable core is connected to the terminal block via a plug-in connection;

[0012] A stress control component is disposed inside the epoxy sleeve, and a stress cone is provided inside the stress control component;

[0013] The stop sleeve contacts the stress control component;

[0014] The cone support and the cone support pressure plate are connected by a tightening screw;

[0015] A spring-driven assembly includes several springs and a guide rod. The springs are disposed between the cone support and the cone support pressure plate. The guide rod is fixed to the cone support, passes through the cone support pressure plate, and is then fixed by a nut.

[0016] The tail tube is bolted to the lower end of the epoxy sleeve, with an O-ring seal between them; the tail sealing structure, from the inside out, includes a waterproof strip, an epoxy mud layer, and a heat shrink tubing.

[0017] The spring propulsion assembly is used to continuously provide radial pressure to ensure tight contact between the stress cone and the epoxy sleeve interface; the spring is sleeved on the guide rod and the preload is adjusted by a nut.

[0018] Furthermore, the lower end of the stress control component is provided with a first inclined surface, and the cone support is provided with a second inclined surface. The first inclined surface and the second inclined surface cooperate to form a self-locking structure for transmitting and maintaining interface pressure.

[0019] The epoxy sleeve has a bimetallic shielding structure inside, including a high-voltage shielding layer and a grounding shielding layer. The electric field distribution is optimized by finite element method to control the electric field strength and avoid partial discharge.

[0020] The terminal block is plugged into the GIS device, and the watch strap contact is a spring contact.

[0021] Furthermore, the tail tube is provided with a detachable grounding lug and a cable fixing support device to keep the cable concentric with the terminal.

[0022] Furthermore, the tail sealing structure is a multi-stage dynamic sealing system, wherein: the waterproof tape is a polymer waterproof material; the epoxy mud layer is an epoxy resin-based sealing material; and the heat-shrinkable sleeve is a heat-shrinkable polymer material.

[0023] Furthermore, the stress cone is a prefabricated silicone rubber component, formed by injection molding; the epoxy sleeve is made of bisphenol epoxy resin by vacuum casting.

[0024] Furthermore, the epoxy sleeve or tailpipe is also equipped with an intelligent monitoring interface for connecting a temperature sensor or partial discharge sensor to achieve online monitoring of the operating status.

[0025] In addition, the present invention also discloses a method for assembling a GIS plug-in terminal based on spring radial compression, comprising the following steps:

[0026] Step 1: Insert the stress control component and the stop into the epoxy sleeve;

[0027] Step 2: Install the cone support, spring, guide rod, and cone support pressure plate, and pre-tighten them with nuts;

[0028] Step 3: Connect the terminal block to the cable core;

[0029] Step 4: Install the tailpipe and secure it with bolts, then apply an O-ring seal;

[0030] Step 5: Wrap waterproof tape around the end of the tailpipe, apply epoxy putty, fit the heat shrink tubing, and heat to cure.

[0031] Step 6: Perform electrical testing and interface pressure verification.

[0032] This invention systematically improves the reliability of GIS plug-in terminals through a spring radial clamping mechanism and multi-component collaborative design. It employs a spring-driven assembly and a beveled self-locking structure to dynamically compensate for interface pressure attenuation, ensuring an effective contact pressure of ≥0.2MPa between the stress cone and the epoxy sleeve. A bimetallic shielding structure and finite element-optimized electric field distribution significantly reduce the risk of partial discharge. The plug-in connection between the terminals and cable cores, coupled with spring contacts, maintains a stable contact resistance below 20μΩ, accommodating concentricity deviations of ±0.5mm. A multi-stage dynamic sealing system at the tail enhances waterproof and airtight performance. An optional intelligent monitoring interface enables real-time sensing of operating conditions such as temperature and partial discharge. The assembly method incorporates pre-tightening calibration and pressure verification processes to ensure controllable, measurable, and traceable terminal performance.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] This application systematically improves the reliability of GIS plug-in terminals through a spring radial compression and multi-component collaborative design. The spring propulsion assembly compensates for thermal expansion and contraction through elastic deformation, and, in conjunction with the stress control component and the inclined self-locking structure of the cone support, ensures that the stress cone and epoxy bushing maintain effective contact of ≥0.2MPa at all times, suppressing partial discharge and insulation failure. The plug-in connection between the terminal and the cable core uses spring-loaded contact fingers. The elastic contact can adapt to slight core eccentricity, and the contact resistance is stable below 20μΩ, resulting in low conductivity loss and convenient plugging and unplugging, which helps avoid local overheating. This invention, through the core mechanism of spring radial compression, solves the problems of interface pressure attenuation, poor conductivity, and sealing failure in the prior art, achieving breakthroughs in insulation reliability, conductivity, environmental adaptability, and ease of maintenance, meeting the long-term stable operation requirements of high-voltage power transmission and transformation systems. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0037] Figure 2 For the present invention Figure 1 A magnified view of a portion of point A in the middle.

[0038] Figure label:

[0039] 101 Epoxy sleeve, 102 Terminal block, 103 Watch strap contact finger, 104 Cable core, 105 Stress control component, 106 Stress cone, 107 Stop sleeve, 108 Cone support, 109 Cone support pressure plate, 110 Tightening screw, 111 Spring push assembly, 112 Spring, 113 Guide rod, 114 Tail tube, 115 First inclined surface, 116 Second inclined surface, 117 Waterproof tape, 118 Epoxy mud layer, 119 Heat shrink tubing. Detailed Implementation

[0040] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the embodiments of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0041] In the description of the embodiments of the present invention, it should be understood that the terms "length", "vertical", "horizontal", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention.

[0042] Furthermore, 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. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0043] In this embodiment of the invention, unless otherwise explicitly 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, an electrical connection, or a communication 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 embodiment of the invention according to the specific circumstances.

[0044] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0045] The following disclosure provides many different implementations or examples for carrying out different structures of the embodiments of the present invention. To simplify the disclosure of the embodiments of the present invention, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the embodiments of the present invention. Furthermore, reference numerals and / or reference letters may be repeated in different examples of the embodiments of the present invention; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various implementations and / or arrangements discussed.

[0046] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0047] Example 1:

[0048] See Figure 1 and Figure 2 This embodiment discloses a GIS pluggable terminal based on spring radial compression, including an epoxy sleeve 101. This embodiment also includes:

[0049] Terminal 102 is disposed inside the epoxy sleeve 101. One end of terminal 102 is connected to the GIS equipment through a tapered inclined surface, and the other end is provided with a watch strap contact finger 103.

[0050] The cable core 104 is connected to the terminal block 102 via a plug-in connection;

[0051] A stress control component 105 is disposed inside the epoxy sleeve 101, and a stress cone 106 is provided inside the stress control component 105.

[0052] The stop sleeve 107 is in contact with the stress control component 105;

[0053] The cone support 108 and the cone support pressure plate 109 are connected by a tightening screw 110;

[0054] The spring propulsion assembly 111 includes several springs 112 and guide rods 113. The springs 112 are disposed between the cone support 108 and the cone support pressure plate 109. The guide rods 113 are fixed to the cone support 108 and pass through the cone support pressure plate 109 and are then fixed by nuts.

[0055] Tail tube 114 is bolted to the lower end of epoxy sleeve 101, with an O-ring seal between them; the tail sealing structure, from the inside to the outside, includes waterproof tape 117, epoxy mud layer 118 and heat shrink tubing 119.

[0056] The spring propulsion assembly 111 is used to continuously provide radial pressure to ensure tight contact between the stress cone 106 and the epoxy sleeve 101; the spring 112 is sleeved on the guide rod 113 and the preload is adjusted by the nut.

[0057] Furthermore, the stress control component 105 has a first inclined surface 115 at its lower end, and the cone support 108 has a second inclined surface 116. The first inclined surface 115 and the second inclined surface 116 cooperate to form a self-locking structure for transmitting and maintaining interface pressure.

[0058] The epoxy sleeve 101 has a bimetallic shielding structure inside, including a high-voltage shielding layer and a grounding shielding layer. The electric field distribution is optimized by finite element method to control the electric field strength and avoid partial discharge.

[0059] The terminal block 102 is plugged into the GIS device, and the strap contact 103 is a spring contact.

[0060] Furthermore, the tail tube 114 is provided with a detachable grounding lug and a cable fixing support device to keep the cable concentric with the terminal.

[0061] Furthermore, the tail sealing structure is a multi-stage dynamic sealing system, wherein: the waterproof tape 117 is a polymer waterproof material; the epoxy mud layer 118 is an epoxy resin-based sealing material; and the heat-shrinkable sleeve 119 is a heat-shrinkable polymer material.

[0062] Furthermore, the stress cone 106 is a prefabricated silicone rubber component, formed by injection molding; the epoxy sleeve 101 is made of bisphenol epoxy resin by vacuum casting.

[0063] Furthermore, the epoxy sleeve 101 or tail pipe 114 is also equipped with an intelligent monitoring interface for connecting a temperature sensor or a partial discharge sensor to realize online monitoring of the operating status.

[0064] In addition, this embodiment also discloses a GIS pluggable terminal assembly method based on spring radial compression, including the following steps:

[0065] Step 1: Install the stress control component 105 and the stop sleeve 107 into the epoxy sleeve 101; Step 2: Install the cone support 108, spring 112, guide rod 113 and cone support pressure plate 109, and pre-tighten them with nuts;

[0066] Step 3: Connect the terminal block 102 to the cable core 104;

[0067] Step 4: Install tailpipe 114 and secure it with bolts, then apply an O-ring seal;

[0068] Step 5: Wrap waterproof tape 117 around the end of tail pipe 114, apply epoxy putty (corresponding to epoxy putty layer 118), fit heat shrink tubing sleeve 119 and heat to cure;

[0069] Step 6: Perform electrical testing and interface pressure verification.

[0070] To facilitate a better understanding of the present invention by those skilled in the art, the present invention will be further described below in conjunction with specific embodiments.

[0071] This embodiment addresses the shortcomings of existing GIS plug-in terminals in terms of insulation interface pressure maintenance, electric field distribution optimization, mechanical stability, and intelligent monitoring. It achieves dynamic compensation of insulation interface pressure by providing continuous radial pressure through the spring propulsion assembly 111 and combining the inclined self-locking structure of the stress control component 105 and the cone support 108. At the same time, the electric field distribution is optimized through the bimetallic shielding structure, the tail tube 114 support device ensures mechanical stability, and the intelligent monitoring interface enables real-time status perception, forming a three-in-one reliability improvement system integrating electrical, mechanical, and intelligent technologies.

[0072] In this embodiment, the specific structures of each component are as follows:

[0073] The spring propulsion assembly 111 includes four sets of cylindrical compression springs 112, made of 50CrVA spring 112 steel, with an elastic modulus k = 20 N / mm and a free length of 80 mm, evenly distributed between the cone support 108 and the cone support pressure plate 109. Four guide rods 113 are evenly distributed at the bottom of the cone support 108 and pass through four corresponding guide holes on the cone support pressure plate 109. Each guide rod 113 is fitted with one of the springs 112 and is locked with a nut to provide preload by compressing the spring. The guide rod 113 has a diameter of 10 mm, a galvanized surface, is fixed to the bottom surface of the cone support 108, passes through the guide holes of the cone support pressure plate 109, and is locked with an M10 nut. Rotating the nut compresses the spring 112 to a preload length of 60 mm, with an initial preload force F = k × ΔL = 20 N / mm × 20 mm = 400 N.

[0074] The stress control component 105 has a 30° first inclined surface 115 at its lower end, with a height of 15mm. The cone support 108 has a matching 30° second inclined surface 116 at its upper end. When the two inclined surfaces are in contact, they form a wedge-shaped self-locking structure. According to the principle of inclined plane mechanics, the radial pressure Fr = F × tanθ = 400N × tan30° ≈ 231N. This pressure is transmitted through the stress control component 105 to the internal silicone rubber stress cone 106, maintaining an interface pressure of 0.25MPa between it and the inner wall of the epoxy sleeve 101. The design safety threshold is ≥0.2MPa.

[0075] This embodiment differs from the existing static compression structure. This embodiment compensates for the thermal expansion and contraction of the material by using the elastic deformation of the spring 112. For example, when the temperature changes by ±50℃, the spring 112 can adapt to the length change of ±1.2mm. Combined with the inclined plane self-locking to prevent pressure relaxation, after 1000 hours of aging test, the interface pressure attenuation rate is <5%, which solves the problem of unstable interface pressure caused by the lack of filling medium in the pure dry structure and significantly improves the insulation life.

[0076] Furthermore, in this embodiment, the stress cone 106 is pre-injected from methyl vinyl silicone rubber (Shore hardness 65A) with a surface resistivity ≥1×10⁻⁶. 14 Ω・cm, volume resistivity ≥1×10 15 Ω・cm, by optimizing the radius of curvature of the cone surface, with the large end R=50mm and the small end R=30mm, the electric field gradient is made uniform.

[0077] The epoxy sleeve 101 is made of bisphenol A type epoxy resin (Tg=150℃) vacuum casting, with a copper high-voltage shielding layer (thickness 0.5mm, extending 100mm in a trumpet shape) and an aluminum grounding shielding layer (thickness 0.3mm) pre-embedded inside, distributed in a ring shape 50mm below the stress cone 106.

[0078] In practical applications, a three-dimensional electric field model was established using ANSYS Maxwell finite element simulation. A rated voltage of 126kV was applied, and the calculated electric field strength at the tip of stress cone 106 of the original structure reached 25kV / mm, exceeding the allowable value of 20kV / mm for silicone rubber. After optimization, the tip electric field was reduced to 18kV / mm using a double shielding layer with a spacing of 80mm, controlling the potential gradient within 15kV / mm to prevent partial discharge initiation (discharge threshold ≥20kV / mm).

[0079] The terminal block 102 is made of T2 oxygen-free copper (conductivity ≥58MS / m). Its connection to the GIS equipment uses a 1:10 tapered bevel with a cone length of 50mm, coupled with spring 112 contacts and 6 sets of beryllium bronze plates. The contact pressure is 5N / plate, achieving low contact resistance, with actual testing showing <20μΩ. The cable core 104 insertion end has an annular groove, and the contact fingers 103 are evenly distributed circumferentially. During insertion, the elastic deformation of the contact fingers generates a radial clamping force. After 100 insertion and extraction tests, the contact resistance change rate is <3%.

[0080] This embodiment utilizes the elastic compensation mechanism of the spring 112 contact finger to accommodate slight eccentricity of the wire core, allowing a concentricity deviation of ±0.5mm, thus avoiding poor contact due to mechanical tolerances and improving conductivity reliability.

[0081] Furthermore, in this embodiment, the tail tube 114 is an aluminum alloy casting with a tensile strength ≥200MPa. The inner wall is provided with 3 sets of annular positioning bosses, 2mm high and 30mm apart. It is used in conjunction with a detachable cable fixing bracket made of nylon. The clamping force can be adjusted by M6 bolts, which can control the cable concentricity error within ±0.3mm to prevent displacement caused by long-term vibration.

[0082] This embodiment adopts a multi-stage sealing structure, with the tail seal using a three-stage system consisting of waterproof tape 117, epoxy mud layer 118, and heat shrink tubing 119.

[0083] Inner layer: Butyl rubber waterproof tape, 1mm thick, elongation at break ≥400%, wrapped in 3 layers to form the first watertight barrier;

[0084] Middle layer: Epoxy resin-based sealant, with a tensile strength ≥30MPa after curing, a water absorption rate <0.1%, and a filling thickness of 5mm to fill irregular gaps;

[0085] Outer layer: EVA heat shrink tubing, shrinkage rate 30%, temperature resistance -40℃~120℃, after heating to 110℃ shrinks to form a tight wrapping layer, passed IP68 waterproof test, no water leakage after immersion in 1m water for 24 hours.

[0086] Furthermore, as the transmission capacity increases, the Joule heat of the conductor and the heat of dielectric loss accumulate, leading to excessive temperature rise inside the terminal and accelerating material aging. Therefore, a microchannel cooling system is integrated into the tailpipe 114 structure to actively and efficiently remove heat through liquid cooling.

[0087] The tailpipe 114 has a double-layer hollow structure, with microchannel cooling channels machined in the interlayer. These channels are connected to an external circulating coolant system through inlet and outlet connectors.

[0088] Furthermore, the equivalent hydraulic diameter of the microchannel is between 0.5 mm and 2 mm, the channel wall is hydrophilic, and the coolant is a propylene glycol aqueous solution with a mixing ratio of 1:1.

[0089] The inlet and outlet connectors of the tailpipe 114 are connected to an external circulating cooling system via oil-resistant hoses. The circulating cooling system includes a micro gear pump, a plate-type air-cooled radiator, and an expansion tank. The speed of the gear pump can be PID closed-loop regulated according to the terminal operating temperature.

[0090] In practical use, the tailpipe 114 is made of precision-cast aluminum alloy with a biomimetic serpentine microchannel inside. The hydraulic diameter is 1.2mm and the total length is about 4m, covering the hot spot area connected to the cable. Externally, it is equipped with a small circulation pump, a liquid storage tank and an air-cooled radiator to form a closed circulation system.

[0091] The coolant is a 50% propylene glycol aqueous solution, and the flow rate can be adjusted by the pump speed, ranging from 0.5 to 2 L / min. Under the operating condition of a rated current of 2000A, the temperature at the root of the stress cone 106 using the micro-cooling terminal is reduced by up to 25°C compared to the traditional natural cooling terminal, and the temperature dropped from 105°C to 80°C in tests.

[0092] Low-temperature operation ensures the stability of the preload of spring 112 and significantly reduces the risk of increased contact resistance due to temperature rise. Experiments show that at a current of 2000A, the contact resistance is stable at 15μΩ, rising to 22μΩ without cooling.

[0093] Example 2:

[0094] This embodiment is basically the same as Embodiment 1, except that in this embodiment, an intelligent monitoring interface with an M12×1 thread is provided in the middle of the epoxy sleeve 101, which can be connected to:

[0095] Temperature sensor, PT100 platinum resistance, accuracy ±0.5℃, installed in the groove on the bottom of stress cone 106, monitors the interface temperature rise in real time, and issues an alarm when the temperature at the monitoring point exceeds 50°C;

[0096] The partial discharge sensor, specifically a high-frequency current transformer, has a detection sensitivity of ≤10pC. It is connected in series in the grounding shielding circuit and transmits data to the backend system via a USB-C interface to achieve early warning of partial discharge. An alarm is triggered when the discharge amount is ≥50pC.

[0097] The terminal assembly method is as follows:

[0098] 1. Spring 112 preload calibration: Adjust the nut using a torque wrench. Preload control procedure:

[0099] ①Initial state: Spring 112 has a free length of 80mm, and the distance between the cone support 108 and the cone support pressure plate 109 is 70mm;

[0100] ② First pre-tightening: Rotate the nuts to a spacing of 65mm, pre-tightening force F=20N / mm×15mm=300N, corresponding to a torque of 3.5N・m;

[0101] ③ Secondary calibration: After installing stress control component 105, measure the interface pressure using a pressure sensor and adjust it to 0.25MPa, corresponding to a spacing of 60mm, a preload of 400N, and a torque of 5N·m.

[0102] 2. Positioning of the electric field shielding layer:

[0103] The high-voltage shielding layer is 10mm away from the tapered bevel end of terminal 102, and is bonded with conductive adhesive. The resistivity is ≤1×10⁻⁶. -3 Ω・cm, ensuring equipotential bonding; the grounding shield layer is welded to the 114 grounding lug of the tail pipe through a φ2mm copper wire, and the grounding resistance is <0.1Ω.

[0104] 3. Interface pressure verification: A thin-film pressure sensor was inserted into the gap between the stress cone 106 and the sleeve. The pressure measured at room temperature was 0.26 MPa and at 85℃ was 0.24 MPa, which meets the design requirement of ≥0.2 MPa.

[0105] 4. Contact resistance test: Using the four-terminal method, a test current of 100A is applied. The contact resistance between terminal 102 and the wire core is 18μΩ, which is lower than the industry standard of ≤50μΩ.

[0106] 5. Partial discharge test: When 1.1 times the rated voltage (138.6kV) is applied, the partial discharge quantity is <5pC, which is far below the national standard limit of ≤10pC.

[0107] By using the elastic compensation of spring 112 and the inclined self-locking structure, the problem of pressure attenuation at the interface of the pure dry terminal is solved. After life test verification, the interface pressure retention rate is ≥90% within 10 years, which is 50% higher than the existing technology.

[0108] Meanwhile, the bimetallic shielding layer, combined with finite element optimization, reduces the maximum electric field strength from 25kV / mm to 18kV / mm, which is lower than the discharge threshold of silicone rubber, and increases the partial discharge initiation voltage by 30%, effectively preventing insulation failure.

[0109] The core physical challenge faced by existing dry GIS terminals is that, without liquid / gas medium compensation, the interface between the silicone rubber stress cone 106 and the epoxy sleeve 101 experiences pressure attenuation due to material creep and thermal expansion and contraction. This invention, based on Hooke's Law F=k·Δx and the principle of inclined plane mechanics Fr=F·tanθ, constructs a dynamic pressure system capable of automatically compensating for volume changes.

[0110] Spring 112 in spring propulsion assembly 111 provides a constant and recoverable axial preload force F. This force is converted into radial pressure Fr through the mating angle θ = 30° ± 5° between the first inclined surface 115 at the lower end of stress control member 105 and the second inclined surface 116 at the upper end of cone support 108. Spring 112 is sleeved on guide rod 113, and the preload force is adjusted by nut. When the temperature changes by ΔT = ± 50℃, spring 112 can completely compensate for the interface gap change through deformation of ΔL = ± 1.2mm, so that the interface pressure is always maintained above the safety threshold of ≥ 0.2MPa, fundamentally solving the interface stability problem of pure dry structure.

[0111] This invention employs a watchband-style contact finger 103 structure at the connection end between the terminal 102 and the cable core 104, utilizing its elastic deformation capability to adaptively compensate for assembly tolerances. Each contact finger acts independently, providing approximately 5N of radial contact pressure. When there is a concentricity deviation of ±0.5mm, the elastic deformation of the contact finger array redistributes the contact pressure, but the total contact area and pressure remain stable, thereby maintaining the contact resistance below 20μΩ and ensuring the long-term reliability of the current-carrying connection.

[0112] This invention features a pre-installed intelligent monitoring interface, such as an M12×1 thread, at the epoxy sleeve 101 or tail pipe 114. This interface can be directly connected to a temperature sensor or a partial discharge sensor to achieve in-situ acquisition of temperature rise at the stress cone 106 interface or partial discharge signals from the grounding shield layer, realizing an integrated design of state perception and the terminal body.

[0113] Example 3:

[0114] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the stress cone 106 is made of a silicone rubber-based functional gradient material, whose dielectric constant decreases gradually from the outer side in contact with the epoxy sleeve 101 to the inner side in contact with the cable core 104, with a gradient range of 4.5 to 3.2, and the Shore hardness of the material increases gradually from 50A on the inner side to 70A on the outer side.

[0115] Furthermore, the functional gradient material is prepared by gradient co-injection molding and lamination composite molding process, with no less than 5 layers and the interlayer dielectric constant change rate is no greater than 0.3 / mm.

[0116] Furthermore, in practical use, the stress cone 106 is prepared using functional gradient materials. It uses methyl vinyl silicone rubber as the matrix, with the outer side (contacting the epoxy sleeve) filled with barium strontium titanate (BST) nanoparticles with high dielectric constant (ε≈18), accounting for 25% by weight; and the inner side (contacting the wire core) filled with boron nitride (BN) nanosheets with high thermal conductivity and low dielectric constant (ε≈4.5), accounting for 20% by weight. From the outer side to the inner side, the BST content decreases linearly, while the BN content increases linearly.

[0117] Furthermore, a 5-layer gradient co-injection molding process is adopted, with the material formula of each layer varying according to the design gradient. The layers are injected into the mold one by one, and finally hot-pressed and vulcanized at 170°C and 15MPa pressure for 30 minutes.

[0118] In specific implementation, the stress cone 106 is prepared using a gradient co-injection molding and lamination composite molding process:

[0119] Step A: Place the 5-layer silicone rubber compound with different filler ratios into the injection molding machine barrel in sequence;

[0120] Step B: By controlling the injection sequence and flow rate through the program, the five layers of material are injected into the mold cavity from the outside to the inside in order of dielectric constant from high to low, forming a preform with a composition gradient;

[0121] Step C: Hold the vulcanizing solution at 170°C and 15MPa for 30 minutes to allow the interlayer interfaces to diffuse and fuse together, forming an integral component with a continuous gradient change in dielectric constant and hardness.

[0122] Actual testing showed that the gradient change in dielectric constant resulted in a more uniform electric field distribution. Simulations demonstrated that the electric field strength at the stress cone tip further decreased from 18 kV / mm to 15 kV / mm. The outer side exhibited higher hardness (70 A), effectively transferring and maintaining interfacial pressure; the inner side was softer (50 A), better encasing the conductor and preventing micro-slippage. After 2000 thermal cycles (-40°C to +105°C), the interfacial pressure retention rate increased from 95% to 98%. The high thermal conductivity BN filler on the inner side dissipated heat from the conductor more quickly, reducing the temperature inside the stress cone by approximately 8°C under the same load.

[0123] The design of the stress cone 106 in this invention breaks the limitation of uniform performance of a single material. By gradient composite of silicone rubber matrix and different functional fillers, such as boron nitride filling the inner side and barium strontium titanate filling the outer side, the dielectric constant, hardness and thermal conductivity change continuously in the radial direction (from epoxy sheath to cable core). The performance of each segment matches the functional requirements of the corresponding position. The specific principle is as follows: the dielectric constant gradient is 4.5 on the outer side and 3.2 on the inner side, which adapts to the smooth transition of the interface electric field. The distribution of the electric field in different dielectric media follows that the electric field strength E is inversely proportional to the dielectric constant ε (E∝1 / ε). When the dielectric constants of the two media change abruptly, the electric field lines will bend sharply at the interface, resulting in a sudden increase in local field strength.

[0124] The outer side of the stress cone contacts the epoxy bushing. By adding a high dielectric constant filler (such as barium strontium titanate, ε≈18), the dielectric constant is increased to 4.5, which is close to the dielectric constant of the epoxy bushing (3.8-4.5), eliminating the dielectric abrupt change at the interface between the two. The inner side of the stress cone 106 contacts the cable core 104. By adding a low dielectric constant, high thermal conductivity filler (such as boron nitride, ε≈4.5), the dielectric constant is reduced to 3.2, which matches the dielectric constant of the insulation layer of the cable core 104 (2.8-3.2), avoiding electric field concentration at the core interface.

[0125] The interlayer transition is achieved through at least five layers of gradient co-injection molding, ensuring that the dielectric constant change rate of each layer is ≤0.3 / mm, thus achieving a smooth and continuous transition from 4.5 to 3.2. This guides the uniform distribution of electric field lines and avoids local field strength peaks. In this embodiment, the hardness gradient ranges from 50A on the inner side to 70A on the outer side, balancing interface adhesion and structural support. The inner side of the stress cone wraps around the cable core, with a hardness of 50A (soft). This allows it to adapt to minor unevenness on the surface of the cable core (such as minor protrusions after the core is twisted) through elastic deformation, ensuring a tight fit with the core and preventing local electric field increases caused by gaps. The outer side of the stress cone contacts the epoxy sleeve and transmits spring pressure, with a hardness of 70A (hard). This ensures stable bearing of the radial pressure transmitted by the spring propulsion assembly, preventing excessive deformation of the stress cone under pressure, ensuring long-term stability of the interface pressure, and resisting mechanical friction from the inner wall of the epoxy sleeve.

[0126] This invention also achieves a thermal conductivity gradient, aiding in heat dissipation and delaying aging. Boron nitride (BN) is a highly thermally conductive insulating filler with a thermal conductivity of approximately 30-60 W / (m·K), while barium strontium titanate (BST) has a lower thermal conductivity of approximately 0.1-0.3 W / (m·K). The gradient distribution of the fillers naturally creates a gradient in thermal conductivity. The inner side has a high BN content and is filled with 20% boron nitride, which can quickly dissipate the heat generated by the cable core. The outer side has a high BST content; although its thermal conductivity is low, its proximity to the epoxy bushing shortens the heat dissipation path, thus not affecting overall heat dissipation, achieving on-demand heat distribution.

[0127] This invention employs a gradient co-injection molding and lamination composite molding process. By controlling the injection sequence and filler ratio through a program, a gradient structure of no less than 5 layers can be formed in one step, with no obvious interfaces between layers (due to the continuous transition of components). This avoids the risk of interlayer delamination in traditional multi-layer adhesive structures and does not require additional special equipment, thus meeting the needs of industrial production.

[0128] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0129] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A spring-driven radial compression-based GIS plug-in terminal, comprising an epoxy sleeve, characterized in that, Also includes: The terminal block is disposed inside the epoxy sleeve. One end of the terminal block is connected to the GIS equipment through a tapered bevel, and the other end is provided with a watch strap contact finger. The cable core is connected to the terminal block via a plug-in connection. A stress control component is disposed inside the epoxy sleeve, and a stress cone is provided inside the stress control component. A stop sleeve, which contacts the stress control component; The cone support and the cone support pressure plate are connected by a tightening screw; A spring-driven assembly includes several springs and a guide rod. The springs are disposed between the cone support and the cone support pressure plate. The guide rod is fixed to the cone support, passes through the cone support pressure plate, and is then fixed by a nut. The tail tube is bolted to the lower end of the epoxy sleeve, with an O-ring seal between them. The tail sealing structure, from the inside out, includes a waterproof strip, an epoxy mud layer, and a heat-shrinkable sleeve. The spring propulsion assembly continuously provides radial pressure to ensure tight contact between the stress cone and the epoxy sleeve. The spring is sleeved on the guide rod, and the preload is adjusted by a nut. The lower end of the stress control component has a first inclined surface, and the cone support has a second inclined surface. The first and second inclined surfaces cooperate to transmit and maintain the interface pressure.

2. The GIS pluggable terminal based on spring radial compression according to claim 1, characterized in that: The epoxy sleeve has a bimetallic shielding structure inside, including a high-voltage shielding layer and a grounding shielding layer. The electric field distribution is optimized by finite element method to control the electric field strength and avoid partial discharge.

3. A GIS pluggable terminal based on spring radial compression according to claim 1, characterized in that: The terminal block is plugged into the GIS device, and the watch strap contact is a spring contact.

4. A GIS pluggable terminal based on spring radial compression according to claim 1, characterized in that: The tail tube is equipped with a detachable grounding lug and a cable fixing support device to keep the cable concentric with the terminal.

5. A GIS pluggable terminal based on spring radial compression according to claim 1, characterized in that: The tail sealing structure is a multi-stage dynamic sealing system. Among them: the waterproof tape is a polymer waterproof material; the epoxy mud layer is an epoxy resin-based sealing material; and the heat shrink tubing is a heat shrinkable polymer material.

6. A GIS pluggable terminal based on spring radial compression according to claim 1, characterized in that: The epoxy sleeve or tailpipe is also equipped with an intelligent monitoring interface for connecting a temperature sensor or partial discharge sensor to achieve online monitoring of the operating status.

7. A GIS pluggable terminal based on spring radial compression according to claim 1, characterized in that: The tailpipe has a double-layer hollow structure, and microchannel cooling channels are machined in the interlayer of the tailpipe. The channels are connected to the external circulating coolant system through inlet and outlet connectors.

8. A method for assembling a GIS pluggable terminal based on spring radial compression as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Insert the stress control component and the stop into the epoxy sleeve; Step 2: Install the cone support, spring, guide rod, and cone support pressure plate, and pre-tighten them with nuts; Step 3: Connect the terminal block to the cable core; Step 4: Install the tailpipe and secure it with bolts, then apply an O-ring seal; Step 5: Wrap waterproof tape around the end of the tailpipe, apply epoxy putty, fit the heat shrink tubing, and heat to cure. Step 6: Perform electrical testing and interface pressure verification.

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