A connection device for a surge arrester

Abstract

The application discloses a connecting device of a lightning arrester and relates to the technical field of lightning arresters. The connecting device comprises an upper end cap and a lower end cap, a plurality of limiting support strips are connected between the upper end cap and the lower end cap, a pusher is slidably connected to the lower end cap, the other end of each limiting support strip is in abutment with the corresponding pusher, a piston cavity is formed in the lower end cap, a sliding piston is slidably arranged in the piston cavity, the sliding piston divides the piston cavity into a first air cavity and a second air cavity, the first air cavity and the second air cavity are in communication, a plurality of release grooves corresponding to the limiting support strips are formed in the side wall of the second air cavity, and the pusher, the push block, the different air cavities and the release grooves are arranged. The problems that the lightning arrester cannot guarantee the connection tightness between resistance sheets under normal working conditions, cannot adaptively release pressure in the lightning arrester under high pressure, cannot unload the resistance sheets under extreme working conditions and cannot prevent the lightning arrester from exploding are solved.

Description

Technical Field

[0001] This invention relates to the field of surge arrester technology, and more particularly to a surge arrester connection device. Background Technology

[0002] In the field of power system safety protection, surge arresters are core equipment for resisting overvoltage surges. Their operational stability is directly related to the safe and reliable operation of the power grid. The core working unit of a surge arrester is a resistor element, which is composed of multiple resistor elements stacked together. Axial positioning is achieved through the upper and lower caps, while the limiting support bar is used to provide radial limiting and axial preload to ensure that the resistor elements fit tightly together, ensuring good conductivity and unobstructed pressure relief channels. Currently, the operating environment of the power system is becoming increasingly complex, and surge arresters often face extreme conditions such as short-circuit faults and direct lightning strikes, which can easily generate high temperature or high current surges.

[0003] In existing surge arrester connection structures, the limiting support bars mostly adopt a fixed connection method, which cannot adapt to component deformation caused by high temperature or high current. High temperature will cause thermal expansion of components such as resistors, upper caps, lower caps and limiting support bars. High current will cause resistors to heat up instantaneously and produce slight deformation. When these two factors are combined, the fixed limiting support bars are prone to loosening, resulting in loose resistor connections and poor contact. This will not only reduce the current carrying capacity of the surge arrester and weaken the overvoltage protection effect, but may also cause problems such as partial discharge and increased heating, resulting in damage to internal components. In severe cases, it may even cause the surge arrester to fail, threatening the safe and stable operation of the entire power system. In addition, some connection structures lack a reliable reset mechanism and cannot automatically return to the initial state after extreme operating conditions, requiring manual disassembly and maintenance, which increases operation and maintenance costs and downtime.

[0004] In the actual operation of surge arresters, in addition to high temperature and high current conditions, when subjected to overvoltage impulses, the resistors will conduct nonlinearly to quickly discharge the lightning current. During this process, a large amount of heat will be generated instantaneously, causing the internal air and insulating medium to expand and form high-pressure gas. If the high-pressure gas cannot be discharged in time and smoothly, the internal gas pressure of the surge arrester will continue to rise, which may damage the upper cap, lower cap, seals and other components, or even cause serious accidents such as shell rupture and explosion.

[0005] When the internal pressure of a surge arrester continues to rise, it will exert enormous axial and radial pressure on components such as the upper cap, lower cap, outer casing, and limiting support bars. This can easily cause deformation and breakage of the components. At the same time, the continuous high pressure will directly act on the resistor elements, causing them to be crushed, which will lead to an interruption of the internal circuit. In severe cases, it may even cause the outer casing to explode. This will not only damage the surge arrester itself, but may also endanger the safety of surrounding power equipment and personnel. Existing surge arresters lack emergency protection mechanisms for such extreme pressure relief failure scenarios, and cannot effectively avoid the above serious risks. Furthermore, some connection structures are prone to problems such as accidental breakage and detachment of the limiting support bars under extreme pressure, further aggravating the degree of equipment damage. Summary of the Invention

[0006] The purpose of this invention is to provide a connection device for a surge arrester, in order to solve the technical problems mentioned in the background art, namely, that existing surge arresters cannot guarantee the tightness of the connection between the resistor elements under normal operating conditions, cannot adaptively release pressure when there is high voltage inside the surge arrester, and cannot unload the resistor elements under extreme operating conditions to prevent the surge arrester from exploding.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a connection device for a surge arrester, comprising an upper cap and a lower cap, wherein multiple resistors are disposed between the upper cap and the lower cap, and multiple limiting supports are connected between the upper cap and the lower cap, and multiple pushing members corresponding one-to-one with the limiting supports are slidably connected to the lower cap, wherein the other end of each limiting support abuts against the corresponding pushing member, a piston cavity is formed on the lower cap, and a sliding piston is slidably disposed in the piston cavity, the sliding piston dividing the piston cavity into a first air cavity at the top and a second air cavity at the bottom, the first air cavity and the second air cavity being able to communicate, and multiple release grooves corresponding to the limiting supports are formed on the side wall of the second air cavity; When high temperature or high current occurs inside, the pusher pulls the limit support bar to extend, so that the resistor sheet is tightly connected; when high pressure gas is generated inside, the first gas chamber and the second gas chamber are connected, and the high pressure gas is released through the second gas chamber and the release groove. After the pressure is released, the sliding piston is reset in the reverse direction; when the pressure release requirement cannot be met, the limit support bar is disengaged from the pusher, releasing the axial pressure on the resistor sheet.

[0008] Preferably, the lower cap has several guide grooves along its circumference, and the pusher is slidably adapted to the guide grooves to achieve a sliding connection between the pusher and the lower cap; one end of the pusher is fixedly connected to the sliding piston and slides axially synchronously with the sliding piston; the lower cap is provided with multiple push blocks corresponding to the limiting support bar. When the release groove cannot meet the pressure relief requirement, the push block applies a radial thrust to the limiting support bar, pushing the limiting support bar away from the pusher and no longer applying pressure to the resistor sheet.

[0009] Preferably, the pusher has a connecting groove for introducing gas from inside the surge arrester into the first gas chamber, so that the gas pressure in the first gas chamber can respond to changes in the internal pressure of the surge arrester; the side wall of the sliding piston has a venting groove for selectively connecting the first gas chamber and the second gas chamber.

[0010] Preferably, the bottom sidewall of the second air chamber is provided with a reset elastic element, which abuts against the lower end face of the sliding piston and is used to provide a reverse reset force to the sliding piston and the pusher after the pressure is released, so as to drive them to reset to the initial position.

[0011] Preferably, the end of the pusher away from the sliding piston is provided with a bearing surface of a limiting support bar, and the lower end face of the limiting support bar is pressed against the bearing surface to form a stable abutment relationship for transmitting axial tensile force; the bearing surface is designed as an L-shaped stepped surface or an inwardly inclined support slope to prevent the limiting support bar from accidentally falling off in the non-unloaded state.

[0012] Preferably, the upper surface of the push block is designed as an outwardly inclined guide slope. When the pressure relief requirement cannot be met, causing the internal pressure to continue to rise, the pusher drives the limiting support bar to move down to contact the push block. The end of the push block that contacts the limiting support bar is an inclined surface. The inclined surface of the push block applies a radial thrust to the limiting support bar to overcome the friction or limiting force between the limiting support bar and the bearing surface of the pusher, so that the two separate.

[0013] Preferably, a sealing assembly is provided between the sliding piston and the piston chamber. The sealing assembly includes a dynamic sealing ring disposed on the side wall of the sliding piston. The vent groove is located axially below the dynamic sealing ring or between two dynamic sealing rings to prevent gas in the first air chamber from leaking to the second air chamber or the outside when the release groove is not opened. A sealing plug is fixedly provided in each release groove, and each sealing plug is fixedly connected to the sliding piston through a connector.

[0014] Preferably, the stiffness coefficient of the reset elastic element is preset and calibrated. When the internal pressure reaches the first threshold, which corresponds to a high temperature or high current scenario, the pusher pulls the limit support bar to extend. When the pressure reaches the second threshold, which corresponds to a high pressure gas scenario, the vent groove is used to connect the first and second air chambers. When the pressure reaches the third threshold, which corresponds to a scenario where the pressure relief requirement cannot be met, the pusher triggers the limit support bar to disengage from the pusher.

[0015] Preferably, the upper cap has multiple mounting slots evenly distributed along its circumference and corresponding one-to-one with the limiting support strips, and each mounting slot is connected to the other end of the limiting support strip; the limiting support strip is made of an insulating material with a certain elasticity, allowing radial deformation under the thrust of the pushing block, so as to smoothly detach from the bearing surface of the pushing member; the groove shape of the mounting slot is adapted to the upper structure of the limiting support strip to ensure the stability of the upper connection of the limiting support strip.

[0016] Preferably, the first threshold is set to the thermal expansion gas pressure generated in response to a large current impact, and the third threshold is set to the critical destructive gas pressure when the arrester thermally collapses and generates explosive gas; the release groove is evenly distributed along the circumferential sidewall of the piston cavity to ensure that the high-pressure gas can be discharged quickly and evenly.

[0017] The beneficial effects of this invention are: 1. Through the coordinated design of the venting groove, dynamic sealing ring, sealing plug, connector, and release groove, adaptive and precise pressure relief of high-pressure gas is achieved. The pressure relief channel is opened only when the gas pressure reaches the second threshold. Reliable sealing is maintained under non-high-pressure conditions, preventing gas leakage from affecting internal insulation performance. The release grooves are evenly distributed circumferentially to ensure rapid and uniform discharge of high-pressure gas, avoiding component damage caused by excessive local pressure. During pressure relief, the pusher continuously extends the limiting support bar to ensure the resistor element remains tightly fitted, balancing pressure relief performance and current flow stability. The tilting guide of the pusher block further enhances the performance. The elastic deformation of the inclined surface and the limiting support bar allows the limiting support bar to automatically detach from the pushing component when the air pressure reaches the critical failure threshold. This effectively relieves the axial pressure on the lower cap and the resistor sheet, preventing the resistor sheet from being crushed and the components from deforming or breaking. At the same time, it forms a multi-channel pressure relief structure, which, together with the original release groove, greatly improves the pressure relief efficiency, quickly reduces the internal air pressure, avoids the risk of the casing exploding, ensures the safety of surrounding equipment and personnel, and avoids internal structural disorder caused by the complete detachment of components. Overall, it improves the safety protection capability and failure resistance of the surge arrester under extreme and harsh conditions. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0019] Figure 2 This is a schematic diagram of the full cross-section structure of the present invention.

[0020] Figure 3 This is a schematic diagram of the structure of the present invention without the insulating outer shell.

[0021] Figure 4 This is a schematic diagram of the structure of the lower cap of the present invention.

[0022] Figure 5 This is a cross-sectional view of the lower cap of the present invention.

[0023] Figure 6 This is a schematic diagram of the piston, connecting member, and pushing member of the present invention.

[0024] The attached figures are labeled as follows: 1. Upper cap; 2. Lower cap; 3. Resistor piece; 5. Limiting support bar; 6. Pushing element; 7. Piston chamber; 8. Sliding piston; 9. First air chamber; 10. Second air chamber; 11. Release groove; 12. Guide groove; 13. Pushing block; 14. Connecting groove; 15. Ventilation groove; 16. Reset elastic element; 17. Sealing assembly; 18. Dynamic sealing ring; 19. Sealing plug; 20. Connecting element; 21. Mounting groove; 22. Insulating shell. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0026] In the field of power system safety protection, surge arresters are core equipment for resisting overvoltage surges. Their operational stability is directly related to the safe and reliable operation of the power grid. The core working unit of the surge arrester is the resistor element 3, which is composed of multiple resistor elements 3 stacked together. Axial positioning is achieved through the upper cap 1 and the lower cap 2. The limiting support bar 5 is used to provide radial limiting and axial preload to ensure that the resistor elements 3 are tightly fitted together, ensuring good conductivity and unobstructed pressure relief channels. Currently, the operating environment of the power system is becoming increasingly complex. Surge arresters often face extreme conditions such as short circuit faults and direct lightning strikes, which can easily generate high temperature or high current surges.

[0027] In existing surge arrester connection structures, the limiting support bar 5 is mostly fixed, which cannot adapt to component deformation caused by high temperature or high current. High temperature will cause thermal expansion of components such as resistor 3, upper cap 1, lower cap 2 and limiting support bar 5. High current will cause resistor 3 to heat up instantaneously and deform slightly. After the two are combined, the fixed limiting support bar 5 is prone to loosening, resulting in loose connection and poor contact of resistor 3. This will not only reduce the current carrying capacity of the surge arrester and weaken the overvoltage protection effect, but may also cause problems such as partial discharge and increased heating, causing damage to internal components. In severe cases, it may even cause the surge arrester to fail, threatening the safe and stable operation of the entire power system. In addition, some connection structures lack a reliable reset mechanism and cannot automatically return to the initial state after extreme working conditions, requiring manual disassembly and maintenance, which increases operation and maintenance costs and downtime.

[0028] To resolve the above technical issues, please refer to Figures 1 to 6As shown, a connection device for a surge arrester according to an embodiment of the present invention includes an insulating shell 22. An upper cap 1 and a lower cap 2 are fixedly connected to both ends of the insulating shell 22. Multiple resistor plates 3 are disposed between the upper cap 1 and the lower cap 2. Multiple limiting supports 5 are connected between the upper cap 1 and the lower cap 2. Multiple pushing members 6, corresponding one-to-one with the limiting supports 5, are slidably connected to the lower cap 2. The other end of each limiting support 5 abuts against the corresponding pushing member 6. A piston chamber 7 is opened on the lower cap 2. A sliding piston 8 is slidably disposed within the piston chamber 7, dividing the piston chamber 7 into a first air chamber 9 at the top and a second air chamber 10 at the bottom. The first air chamber 9 and the second air chamber 10 can communicate. When the internal temperature is high or the current is high... The pusher 6 pulls the limiting support 5 to extend, making the resistor 3 tightly connected. The lower cap 2 has several guide grooves 12 along its circumference. The pusher 6 slides and adapts to the guide grooves 12, achieving a sliding connection between the pusher 6 and the lower cap 2. One end of the pusher 6 is fixedly connected to the sliding piston 8 and slides axially synchronously with the sliding piston 8. The pusher 6 has a connecting groove 14, which is used to introduce gas from inside the surge arrester into the first gas chamber 9, allowing the gas pressure in the first gas chamber 9 to respond to changes in the internal pressure of the surge arrester. The side wall of the sliding piston 8 has a venting groove 15, which is used to selectively connect the first gas chamber 9 and the second gas chamber 10. A sealing assembly 17 is provided between the sliding piston 8 and the piston chamber 7. The sealing assembly 17 includes... A dynamic sealing ring 18 is provided on the side wall of the sliding piston 8. The vent groove 15 is located axially below the dynamic sealing ring 18 or between two dynamic sealing rings 18. The stiffness coefficient of the reset elastic element 16 is preset and calibrated. That is, according to the pressure threshold of different operating conditions of the surge arrester, the elastic stiffness parameter of the reset elastic element 16 is determined in advance through theoretical calculation and experimental verification. This ensures that the reset elastic element 16 only performs the preset compression or reset action when the internal air pressure reaches the corresponding preset threshold. When the internal pressure reaches the first threshold, which corresponds to a high temperature or high current scenario, the pusher 6 pulls the limit support bar 5 to extend. Multiple push blocks 13 corresponding to the limit support bar 5 are fixed on the lower end cap 2. Each limit support bar 5 corresponds to two push blocks 13. The pusher 6 is located between two corresponding push blocks 13 in the axial direction. The bottom side wall of the second air chamber 10 is provided with a reset elastic element 16, which abuts against the lower end face of the sliding piston 8. The upper cap 1 is provided with multiple mounting grooves 21 that are evenly distributed along its circumference and correspond one-to-one with the limiting support bar 5. Each mounting groove 21 is connected to the other end of the limiting support bar 5. The limiting support bar 5 is made of insulating material with a certain elasticity, which allows radial deformation under the thrust of the push block 13 to smoothly detach from the bearing surface of the pusher 6. The groove shape of the mounting groove 21 is adapted to the upper end structure of the limiting support bar 5 to ensure the stability of the upper end connection of the limiting support bar 5. The first threshold is set to the thermal expansion air pressure generated in response to the impact of a large current.

[0029] When lightning strikes or operational overvoltages occur, the large current flowing through multiple resistors 3 will generate violent electrodynamic vibrations and rapid thermal expansion. In a traditional rigid structure, such vibrations may cause minute gaps or loosening between multiple resistors 3. This invention uses the thermal pressure generated by the large current as a driving force to achieve the function of becoming tighter as it heats up.

[0030] Driven by air pressure, the piston actively pulls down the limiting support bar 5, applying additional axial clamping force to the resistor sheet 3. This effectively counteracts the loosening tendency caused by vibration and thermal expansion, ensuring that the resistor sheet 3 remains "zero gap" clamped even under extreme working conditions. If the zinc oxide type resistor sheet 3 is simply stacked, the contact resistance between the sheets will increase sharply if the clamping force is insufficient. Under high current, this will cause local high heat, and even arcing (sparking) between the sheets, directly burning the insulating edge of the resistor sheet 3.

[0031] The tightening action in the first state ensures a tight fit between the end faces of multiple resistor pieces 3, minimizing contact resistance and thus avoiding internal arcing and local overheating caused by poor contact due to heat or vibration. This significantly improves the current carrying capacity and electrical life of the surge arrester. The tightening action actually pulls the upper cap 1 and the lower cap 2 towards the middle to prevent airtightness leakage caused by shell deformation in the early stage of gas pressure rise, which can provide a basic guarantee for the precise constant pressure gas release in the subsequent second state.

[0032] During use, under normal operating conditions, the upper cap 1 and lower cap 2 apply axial preload to the resistor element 3. The limiting support bar 5 is in its initial extended state, with its upper end stably connected to the upper cap 1 through the mounting groove 21 and its lower end abutting against the support slope of the pusher 6, thus providing radial limiting for the upper cap 1 and lower cap 2 and ensuring that the multiple resistor elements 3 fit tightly together. The reset elastic element 16 is in its natural extension and contraction state, and both the sliding piston 8 and the pusher 6 are in their initial positions. The first air chamber 9 is connected to the inside of the surge arrester through the connecting groove 14, and the air pressure is kept balanced.

[0033] When the surge arrester encounters short circuits, lightning strikes, or other operating conditions, high temperatures or large currents are generated inside. These high temperatures or large currents cause the resistor 3 to thermally expand. The resistor 3 elongates in the axial vertical direction and expands slightly in the radial horizontal direction. The gap between the resistor 3 tends to increase. At the same time, the thermal expansion causes the temperature and pressure of the gas inside the surge arrester to rise. This high-pressure gas enters the first gas chamber 9 through the connecting groove 14 on the pusher 6, causing the gas pressure in the first gas chamber 9 to rise synchronously and reach a preset first threshold.

[0034] The high-pressure gas in the first air chamber 9 applies downward axial pressure to the upper end face of the sliding piston 8. This pressure overcomes the upward elastic support force of the reset elastic element 16, pushing the sliding piston 8 to slide axially downward along the inner wall of the piston chamber 7, causing relative movement between the sliding piston 8 and the lower end cap 2. The reset elastic element 16 is compressed, storing elastic potential energy. Since the pushing element 6 is fixedly connected to the sliding piston 8, and the pushing element 6 is slidably adapted to the lower end cap 2 through the guide groove 12, the guide groove 12 restricts the pushing element 6 to move only axially without radial offset. Therefore, when the sliding piston 8 slides downward, it drives the pushing element 6 to slide axially downward synchronously along the guide groove 12. The side walls of the sliding piston 8 and the piston chamber 7 that are in contact are all smooth surfaces. After special treatment, friction can be reduced and airtightness can be guaranteed. This technology is existing technology and will not be described in detail here.

[0035] The upper end of the limiting support bar 5 is embedded in the mounting groove 21 of the upper cap 1 and its position is fixed. The lower end abuts against the support slope of the pusher 6. The support slope of the pusher 6 is not shown in detail in the figure. When the pusher 6 slides down, it applies a downward axial force to the lower end of the limiting support bar 5. Because the limiting support bar 5 is made of insulating material with a certain elasticity, it extends axially under the action of axial force. During the extension process, it slightly contracts in the radial horizontal direction, which in turn generates a downward force on the lower cap 2.

[0036] Under the downward pulling force of the limiting support bar 5, the lower cap 2 makes a slight downward displacement in the axial direction, which cooperates with the upper cap 1 to offset the thermal expansion and elongation of the resistor sheet 3, so that the multiple resistor sheets 3 are kept in a tight fit. This prevents the multiple resistor sheets 3 from vibrating relative to each other when a large current or overvoltage is applied, which would cause the contact surfaces to not be able to make tight contact and avoid poor contact problems.

[0037] When the high temperature and high current conditions disappear, the internal temperature of the surge arrester gradually decreases, the resistor 3 contracts and resets, and when the internal gas cools down and the gas pressure drops below the first threshold, the reset elastic element 16 releases elastic potential energy, applies an upward elastic thrust to the lower end face of the sliding piston 8, pushes the sliding piston 8 to slide upward along the inner wall of the piston cavity 7 and resets, and the sliding piston 8 drives the pusher 6 to reset upward along the guide groove 12. The limiting support bar 5 returns to its initial extended state under its own elastic action, and the lower end cap 2 also resets upward to its initial position after the tension of the limiting support bar 5 disappears, and the entire device returns to normal operation.

[0038] By setting up a fixed connection structure between the guide groove 12, the pusher 6, and the sliding piston 8, the movement direction of the pusher 6 is ensured to be precise. Combined with the abutment relationship between the support slope and the limiting support bar 5, the axial tensile force can be stably transmitted, realizing the adaptive extension and reset of the limiting support bar 5. It can accurately offset the thermal expansion and elongation of the resistor 3 under high temperature and high current conditions, ensuring that the resistor 3 is always tightly attached, avoiding the decrease in current carrying capacity and weakening of protection effect caused by poor contact. The limiting support bar 5 uses elastic insulating material, taking into account both tensile force transmission and insulation safety, preventing leakage risk. The reset elastic element 16 realizes automatic reset of the device after extreme conditions, without the need for manual disassembly and maintenance, reducing operation and maintenance costs and downtime, and improving the overall operational stability and service life of the surge arrester under high temperature and high current conditions. Example 2

[0039] During the actual operation of a surge arrester, in addition to high temperature and high current conditions, when subjected to overvoltage impulses, the resistor 3 will undergo nonlinear conduction to rapidly discharge the lightning current. During this process, a large amount of heat will be generated instantaneously, causing the internal air and insulating medium to expand due to heat and form high-pressure gas. If the high-pressure gas cannot be discharged in time and smoothly, the internal gas pressure of the surge arrester will continue to rise, which may damage components such as the upper cap 1, the lower cap 2, and the seals, and may even cause serious accidents such as shell rupture and explosion.

[0040] Existing surge arresters often have fixed venting ports with fixed venting efficiency. They cannot adaptively adjust the timing and rate of venting according to changes in internal gas pressure. When high-pressure gas is generated instantaneously, problems such as untimely venting and uneven gas discharge often occur, which affect the structural integrity and operational reliability of the surge arrester and cannot meet the venting requirements under complex operating conditions. Some venting structures lack reliable sealing mechanisms, which can easily lead to gas leakage in non-high-pressure scenarios, affecting the internal insulation performance of the surge arrester. At the same time, the connection stability of the resistor element 3 cannot be guaranteed during the venting process, and poor contact of the resistor element 3 may occur due to component displacement, reducing the current carrying capacity.

[0041] To solve the above technical problems, based on the above embodiments, please refer to... Figures 1 to 6As shown, the technical solution includes a second air chamber 10. Multiple release grooves 11 corresponding to the limiting support strips 5 are provided on the side wall of the second air chamber 10. When high-pressure gas is generated inside, the first air chamber 9 communicates with the second air chamber 10. The high-pressure gas is depressurized through the second air chamber 10 and the release grooves 11. After depressurization, the sliding piston 8 resets in the reverse direction. A reset elastic element 16 is provided on the bottom side wall of the second air chamber 10. The reset elastic element 16 abuts against the lower end face of the sliding piston 8, providing a reverse reset force to the sliding piston 8 and the pushing member 6 after depressurization, driving them to reset to their initial positions. The end of the pushing member 6 away from the sliding piston 8 has a bearing surface for the limiting support strips 5. The lower end face of 5 is pressed against the bearing surface to form a stable contact relationship for transmitting axial tensile force. The bearing surface is designed as an L-shaped stepped surface or an inwardly inclined support slope to prevent the limiting support bar 5 from accidentally falling off in the non-unloaded state. The venting groove 15 is located axially between the two dynamic sealing rings 18 to prevent gas in the first air chamber 9 from leaking to the second air chamber 10 or the outside when the release groove 11 is not opened. Each release groove 11 is fixedly provided with a sealing plug 19, and each sealing plug 19 is fixedly connected to the sliding piston 8 through the connector 20. When the pressure reaches the second threshold, the second threshold corresponds to the high-pressure gas scenario, and the venting groove 15 is used to connect the first air chamber 9 and the second air chamber 10.

[0042] During use, the sealing assembly 17, sealing plug 19, and connector 20 function. Two dynamic sealing rings 18 seal the vent groove 15, keeping the first air chamber 9 isolated from the second air chamber 10. The connector 20 is in a tensioned state, tightly pulling the sealing plug 19 into the release groove 11, achieving a reliable seal of the release groove 11, avoiding unexpected gas leakage, ensuring internal insulation performance and air pressure balance, and ensuring that the resistor sheet 3 fits tightly.

[0043] When the surge arrester is subjected to an overvoltage surge, the resistor 3 nonlinearly conducts and discharges the lightning current, generating a large amount of heat inside. When the air and insulating medium are heated and expand to form high-pressure gas, the high-pressure gas quickly enters the first air chamber 9 through the connecting groove 14 on the pusher 6, so that the air pressure in the first air chamber 9 is consistent with the internal air pressure, and the air pressure rises rapidly and reaches the preset second threshold.

[0044] The high-pressure gas in the first gas chamber 9 applies downward axial pressure to the upper end face of the sliding piston 8. This pressure is greater than the upward elastic support force of the reset elastic element 16, pushing the sliding piston 8 to slide axially downward along the inner wall of the piston chamber 7. The sliding distance is greater than the sliding distance corresponding to the first threshold in Embodiment 1. The reset elastic element 16 is further compressed, storing more elastic potential energy. As the sliding piston 8 moves downward to a certain extent, the connecting piece 20 fixedly connected to the sliding piston 8 gradually loosens, no longer tightly pulling the sealing plug 19 into the corresponding release groove 11. A gap is formed between the sealing plug 19 and the release groove 11, preparing for subsequent gas discharge.

[0045] As the sliding piston 8 slides downward, the two dynamic sealing rings 18 on its side wall move downward synchronously. When the sliding piston 8 slides to the preset position, the venting groove 15 located between the two dynamic sealing rings 18 connects the first air chamber 9 and the second air chamber 10. At this time, selective communication between the two chambers is achieved, and the top of the venting groove 15 remains connected to the first air chamber 9.

[0046] Because the pusher 6 is fixedly connected to the sliding piston 8 and is limited by the guide groove 12, the pusher 6 slides axially downward synchronously with the sliding piston 8, causing the limiting support bar 5 to extend further. The upper end of the limiting support bar 5 is stably connected to the upper cap 1 through the mounting groove 21, applying a downward pulling force to the lower cap 2, causing the lower cap 2 to move downward in the axial direction accordingly, keeping the multiple resistor pieces 3 tightly connected, and avoiding poor contact due to component displacement during the pressure relief process.

[0047] High-pressure gas in the first gas chamber 9 flows into the second gas chamber 10 through the venting groove 15. The high-pressure gas entering the second gas chamber 10 is evenly distributed circumferentially and then applies an outward pushing force to the sealing plug 19, pushing the sealing plug 19 out of the release groove 11. The high-pressure gas is quickly discharged to the outside of the surge arrester through the release groove 11 to achieve pressure relief. The release groove 11 is evenly distributed circumferentially to ensure uniform gas discharge and avoid damage to components due to excessive local gas pressure.

[0048] When the high-pressure gas is continuously discharged through the release groove 11, and the internal gas pressure of the surge arrester and the gas pressure in the first gas chamber 9 and the second gas chamber 10 gradually decrease to below the second threshold, the reset elastic element 16 releases elastic potential energy, applies an upward elastic thrust to the lower end face of the sliding piston 8, pushes the sliding piston 8 to slide upward and reset along the inner wall of the piston chamber 7, and the sliding piston 8 drives the pusher 6 to reset upward along the guide groove 12. At the same time, the connecting element 20 is re-tensioned, and the sealing plug 19 is pulled back into the release groove 11 to achieve re-sealing of the release groove 11, so as to prevent moisture or impurities from corroding the lower end cap 2.

[0049] During the reset process of the sliding piston 8, the vent groove 15 moves upward with the sliding piston 8 and is resealed by the upper dynamic sealing ring 18. The first air chamber 9 and the second air chamber 10 are isolated again to prevent external gas from entering the surge arrester or internal gas from leaking, thus ensuring the internal insulation performance. The limit support bar 5 returns to its initial extended state under its own elasticity, and the lower cap 2 also resets upward to its initial position. The resistor sheet 3 remains tightly fitted, and the device returns to normal operation.

[0050] By setting up a venting groove 15 and two dynamic sealing rings 18, selective communication between the first air chamber 9 and the second air chamber 10 is achieved, enabling adaptive and precise pressure relief of high-pressure gas. The pressure relief channel is only opened when the gas pressure reaches the second threshold, ensuring reliable sealing under non-high-pressure conditions and preventing gas leakage from affecting the internal insulation performance. The release groove 11 is evenly distributed circumferentially to ensure rapid and uniform discharge of high-pressure gas, avoiding component damage caused by excessive local gas pressure. During the pressure relief process, the pusher 6 drives the limit support bar 5 to continuously extend, ensuring that the resistor 3 is always tightly fitted, balancing pressure relief performance and current flow stability. The entire pressure relief and reset process is completed automatically without manual intervention, improving the surge arrester's impact resistance and operational reliability under overvoltage impact conditions, and solving the technical problems of untimely, uneven, and unreliable pressure relief in existing fixed pressure relief structures. Example 3

[0051] Under extreme conditions, such as encountering a massive lightning strike or a prolonged short-circuit fault, the surge arrester may generate high-pressure gas that far exceeds the norm, or even experience thermal collapse, producing explosive gas. In such cases, even if the pressure is released through the pressure relief structure of Embodiment 2, the internal pressure may continue to rise because the gas generation rate far exceeds the exhaust rate of the release tank 11, making it impossible to meet the pressure relief requirements.

[0052] If the internal pressure continues to rise, it will exert enormous axial and radial pressure on components such as the upper cap 1, lower cap 2, outer casing, and limiting support bar 5 of the surge arrester, which can easily cause deformation and breakage of the components. At the same time, the continuous high pressure will directly act on the resistor 3, causing the resistor 3 to be crushed, which will lead to the interruption of the internal circuit. In severe cases, it may even cause the outer casing to explode, which will not only damage the surge arrester itself, but may also endanger the safety of surrounding power equipment and personnel. Existing surge arresters lack emergency protection mechanisms for such extreme pressure relief failure scenarios and cannot effectively avoid the above serious risks. In addition, some connection structures are prone to problems such as accidental breakage and detachment of the limiting support bar 5 under extreme pressure, which will further aggravate the damage to the equipment.

[0053] To solve the above technical problems, based on Embodiment 1 and Embodiment 2, please refer to... Figures 1 to 6As shown, the technical solution adopted includes a push block 13, the upper surface of which is designed as an outwardly inclined guide slope. The end of the push member 6 away from the sliding piston 8 is provided with a bearing surface of the limiting support bar 5. The lower end face of the limiting support bar 5 is pressed against the bearing surface to form a stable abutment relationship for transmitting axial tension. The bearing surface is designed as an inwardly inclined support slope to prevent the limiting support bar 5 from accidentally falling off in the non-unloaded state. The lower end cap 2 is provided with multiple push blocks 13 corresponding to the limiting support bar 5. When the release groove 11 cannot meet the pressure relief requirement, the push block 13 applies radial thrust to the limiting support bar 5, pushing the limiting support bar 5 away from the push member 6 and no longer applying pressure to the resistor sheet 3. When the pressure relief requirement cannot be met, the limiting support bar 5 disengages from the push member 6, releasing the axial pressure on the resistor sheet 3.

[0054] The upper surface of the push block 13 is designed as an outwardly inclined guide slope. When the pressure relief demand cannot be met and the internal pressure continues to rise, the pusher 6 drives the limiting support bar 5 to move down to contact the push block 13. The end of the push block 13 that contacts the limiting support bar 5 is an inclined surface. The inclined surface of the push block 13 applies a radial thrust to the limiting support bar 5 to overcome the friction or limiting force between the limiting support bar 5 and the bearing surface of the pusher 6, so that the two separate.

[0055] When the pressure reaches the third threshold, which corresponds to the scenario where the pressure relief requirement cannot be met, the push block 13 triggers the limit support bar 5 to separate from the pusher 6. The third threshold is set as the critical destructive gas pressure when the surge arrester generates explosive gas during thermal collapse. The release groove 11 is evenly distributed along the circumferential side wall of the piston chamber 7 to ensure that the high-pressure gas can be discharged quickly and evenly.

[0056] During use, under normal operation and conventional high-voltage pressure relief conditions, the operating status of each component is the same as in the two embodiments described above. The pusher 6, the limiting support 5, and the push block 13 are in their initial positions. The limiting support 5 is made of an insulating material with a certain degree of elasticity, which allows radial deformation under the thrust of the push block 13. This overcomes the friction and limiting force between the supporting inclined surface of the pusher 6 and the limiting support 5, allowing the limiting support 5 to detach from the bearing surface of the pusher 6, relieving the axial pressure on the resistor 3, and realizing emergency unloading and multi-channel pressure relief under extreme conditions.

[0057] When the surge arrester encounters extreme conditions such as extra-large or continuous lightning strikes or prolonged short-circuit faults, explosive high-pressure gas is generated inside. When the gas pressure rapidly exceeds the second threshold, the pressure relief through the release groove 11 is still insufficient to meet the demand. When the gas pressure continues to rise and reaches the preset third threshold, the explosive high-pressure gas inside the surge arrester quickly enters the first gas chamber 9 through the connecting groove 14, applying a huge downward axial pressure to the upper end face of the sliding piston 8. This pressure is much greater than the upward elastic support force of the reset elastic element 16, pushing the sliding piston 8 to slide axially downward along the inner wall of the piston chamber 7 to its maximum stroke. The reset elastic element 16 is compressed to its limit, the connecting piece 20 is completely relaxed, the sealing plug 19 has been completely pushed open by the high-pressure gas, and the release groove 11 is in the maximum open state.

[0058] The pusher 6 is fixedly connected to the sliding piston 8 and is limited by the guide groove 12. It slides axially downward synchronously with the sliding piston 8 and moves along the guide groove 12 to the lowest position. The pusher 6 drives the lower end of the limiting support bar 5 to move downward synchronously. The limiting support bar 5 is stretched to the maximum extension state. Its upper end is stably connected to the upper cap 1 through the mounting groove 21, and applies the maximum downward pulling force to the lower cap 2. At this time, the resistor sheet 3 still remains in a tight fit.

[0059] When the pusher 6 moves to the lowest position, the lower end of the limiting support bar 5 just contacts the inclined guide slope of the pusher block 13. Since the internal air pressure is still rising, the sliding piston 8 and the pusher 6 cannot continue to move downward. The inclined guide slope of the pusher block 13 applies an outward radial thrust to the lower end of the limiting support bar 5. The inclined surface converts the axial force transmitted by the pusher 6 into a radial thrust.

[0060] Because the limiting support bar 5 is made of insulating material with a certain elasticity, under the radial thrust of the pushing block 13, its lower end produces outward radial deformation. This deformation overcomes the friction and limiting force between the limiting support bar 5 and the supporting inclined surface of the pushing member 6, causing the lower end of the limiting support bar 5 to detach from the bearing surface of the pushing member 6. The upper end of the limiting support bar 5 is still embedded in the mounting groove 21 of the upper cap 1, and the lower end is in a free state after detachment.

[0061] After the limiting support bar 5 disengages from the pushing member 6, it no longer applies axial tension to the lower cap 2. The axial constraint of the lower cap 2 is released, and the lower cap 2 can move freely along the axial direction. This avoids the deformation and breakage of components such as the lower cap 2 and the resistor sheet 3 caused by continuous axial pressure, and prevents the resistor sheet 3 from being crushed by the strong pressure generated inside the surge arrester. At the same time, the high-pressure gas inside the surge arrester can form an additional pressure relief channel through the gap between the pushing member 6 and the guide groove 12, and the disengagement gap between the limiting support bar 5 and the pushing member 6. This, together with the original release groove 11, achieves multi-channel pressure relief, maximizes the pressure relief efficiency, and quickly reduces the internal gas pressure.

[0062] After the extreme working conditions end and the internal air pressure drops to a safe level, the limit support bar 5 and the pusher 6 can be replaced manually. The elastic element 16 is reset to release elastic potential energy and push the sliding piston 8 and the pusher 6 to return to their initial positions. After the sealing plug 19 and the connecting part 20 are reassembled, the device returns to normal operation.

[0063] By setting up a cooperative structure between the push block 13 and the limiting support bar 5, an emergency protection mechanism is provided for extreme pressure relief failure scenarios. When the internal air pressure reaches the critical damage threshold, the inclined guide slope of the push block 13 accurately converts the axial force into radial thrust, causing the limiting support bar 5 to automatically disengage from the pusher 6, relieving the axial pressure on multiple resistor plates 3, preventing the components from deforming or breaking due to excessive pressure, and preventing the resistor plates 3 from being crushed. The action is precise and stable.

[0064] The additional pressure relief channel formed after the limit support bar 5 detaches, together with the original release groove 11, realizes multi-channel pressure relief, quickly reduces the internal air pressure, effectively avoids serious risks such as shell explosion, and ensures the safety of surrounding equipment and personnel. The limit support bar 5 is made of elastic insulating material, which not only facilitates radial deformation detachment, but also ensures insulation performance. At the same time, the stable connection between the upper end and the mounting groove 21 avoids internal structural disorder caused by the complete detachment of the limit support bar 5, and improves the overall safety protection capability and failure resistance of the surge arrester under extreme and harsh conditions.

[0065] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A connection device for a surge arrester, comprising an upper cap and a lower cap, wherein a plurality of resistive elements are disposed between the upper cap and the lower cap, and a plurality of limiting support bars are connected together between the upper cap and the lower cap, characterized in that, The lower end cap is slidably connected with a plurality of pushers corresponding one-to-one with the limiting support bars. The other end of each limiting support bar abuts against the corresponding pusher. The lower end cap is provided with a piston chamber. A sliding piston is slidably provided in the piston chamber. The sliding piston divides the piston chamber into a first air chamber at the top and a second air chamber at the bottom. The first air chamber and the second air chamber can communicate with each other. The side wall of the second air chamber is provided with a plurality of release grooves corresponding to the limiting support bars. When the internal temperature is high or the current is large, the pusher pulls the limit support bar to extend, so that the resistor sheet is tightly connected. When high pressure gas is generated inside, the first gas chamber and the second gas chamber are connected. The high pressure gas is released through the second gas chamber and the release groove. After the pressure is released, the sliding piston is reset in the reverse direction. When the pressure release requirement cannot be met, the limit support bar is disengaged from the pusher, releasing the axial pressure on the resistor sheet.

2. The connection device for a surge arrester according to claim 1, characterized in that, The lower cap has several guide grooves along its circumference. The pusher is slidably adapted to the guide grooves to achieve a sliding connection between the pusher and the lower cap. One end of the pusher is fixedly connected to the sliding piston and slides axially synchronously with the sliding piston. The lower cap is provided with multiple push blocks corresponding to the limiting support bar. When the release groove cannot meet the pressure relief requirements, the push block applies a radial thrust to the limiting support bar, pushing the limiting support bar away from the pusher and no longer applying pressure to the resistor sheet.

3. The connection device for a surge arrester according to claim 2, characterized in that, The pusher is provided with a connecting groove, which is used to introduce the gas inside the surge arrester into the first gas chamber, so that the gas pressure in the first gas chamber can respond to the pressure change inside the surge arrester. The side wall of the sliding piston is provided with a venting groove, which is used to achieve selective communication between the first gas chamber and the second gas chamber.

4. The connection device for a surge arrester according to claim 3, characterized in that, The bottom sidewall of the second air chamber is provided with a reset elastic element, which abuts against the lower end face of the sliding piston. After the pressure is released, the reset elastic element provides a reverse reset force to the sliding piston and the pusher, driving them to reset to their initial positions.

5. The connection device for a surge arrester according to claim 4, characterized in that, The end of the pusher away from the sliding piston is provided with a bearing surface of a limiting support bar. The lower end of the limiting support bar is pressed against the bearing surface to form a stable abutment relationship for transmitting axial tensile force. The bearing surface is designed as an L-shaped stepped surface or an inwardly inclined support slope to prevent the limiting support bar from accidentally falling off in the non-unloaded state.

6. The connection device for a surge arrester according to claim 5, characterized in that, The upper surface of the push block is designed as an outwardly inclined guide slope. When the pressure relief requirement cannot be met and the internal pressure continues to rise, the pusher drives the limiting support bar to move down to contact the push block. The end of the push block that contacts the limiting support bar is an inclined surface. The inclined surface of the push block applies a radial thrust to the limiting support bar to overcome the friction or limiting force between the limiting support bar and the bearing surface of the pusher, so that the two separate.

7. The connection device for a surge arrester according to claim 6, characterized in that, A sealing assembly is provided between the sliding piston and the piston chamber. The sealing assembly includes a dynamic sealing ring disposed on the side wall of the sliding piston. The vent groove is located axially below the dynamic sealing ring or between two dynamic sealing rings to prevent gas in the first air chamber from leaking to the second air chamber or the outside when the release groove is not opened. A sealing plug is fixedly provided in each release groove, and each sealing plug is fixedly connected to the sliding piston through a connector.

8. The connection device for a surge arrester according to claim 7, characterized in that, The stiffness coefficient of the reset elastic element is preset and calibrated. When the internal pressure reaches the first threshold, which corresponds to a high temperature or high current scenario, the pusher pulls the limit support bar to extend. When the pressure reaches the second threshold, which corresponds to a high pressure gas scenario, the vent groove is used to connect the first and second air chambers. When the pressure reaches the third threshold, which corresponds to a scenario where the pressure relief requirement cannot be met, the pusher triggers the limit support bar to disengage from the pusher.

9. A connection device for a surge arrester according to claim 8, characterized in that, The upper cap has multiple mounting slots evenly distributed along its circumference and corresponding to the limiting support strips. Each mounting slot is connected to the other end of the limiting support strip. The limiting support strip is made of an insulating material with a certain elasticity, which allows it to undergo radial deformation under the thrust of the pushing block, so as to smoothly detach from the bearing surface of the pushing component. The groove shape of the mounting slot is adapted to the upper structure of the limiting support strip to ensure the stability of the upper connection of the limiting support strip.

10. A connection device for a surge arrester according to claim 9, characterized in that, The first threshold is set as the thermal expansion gas pressure generated in response to a large current impact, and the third threshold is set as the critical destructive gas pressure when the arrester thermally collapses and generates explosive gas. The release groove is evenly distributed circumferentially along the side wall of the piston cavity to ensure that the high-pressure gas can be discharged quickly and evenly.

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