Explosion-proof lightning arrester

Abstract

This invention provides an explosion-proof surge arrester, relating to the field of surge arrester technology. The surge arrester includes an insulating cylinder, a main resistor array, and a secondary resistor array. Internally, it also includes a thermally activated component, a circuit switch driven by the thermally activated component, and an expansion drive assembly that displaces upon contact with water. If the circuit switch is not displaced before the expansion drive assembly displaces, the secondary resistor array is short-circuited. If the circuit switch has already displaced before the expansion drive assembly displaces, the secondary resistor array and the main resistor array are connected in series. This invention, through the design of the thermally activated component and the expansion drive assembly, combined with the clearance groove on the pusher, ensures that the displacement of the expansion drive assembly can effectively drive the circuit switch and connect the secondary resistor array in series to the main circuit only under the condition that the surge arrester is aged and in rainy weather. This achieves intelligent diagnosis of the surge arrester's aging state and precise self-compensation of its operational capabilities, improving the surge arrester's anti-aging performance, operational reliability, and explosion-proof capability.

Description

Technical Field

[0001] This invention relates to the field of surge arrester technology, and more particularly to an explosion-proof surge arrester. Background Technology

[0002] Explosion-proof surge arresters serve as the first line of defense in power systems, protecting critical equipment from overvoltage damage. Their reliability directly impacts the stable operation of the power grid and the safety of power supply. Under extreme conditions such as lightning strikes or switching overvoltages, surge arresters must be able to rapidly dissipate enormous energy while ensuring their structural integrity to prevent secondary accidents caused by faults.

[0003] The metal oxide resistors at the core of surge arresters gradually age under long-term operating voltage, resulting in increased leakage current. Existing structures are typically single-column or simply connected in parallel. When some resistors experience a decrease in equivalent impedance due to aging, the system operating voltage will be applied more to the resistors that have not yet aged, accelerating their deterioration and creating a vicious cycle. Ultimately, this leads to a decrease in overall current carrying capacity, making the arrester prone to thermal breakdown during overvoltage surges. Current technology lacks online sensing of the aging state of internal resistors and an automatic compensation mechanism for performance degradation. Consequently, the protection level of surge arresters is irreversibly reduced, and this is difficult to detect in a timely manner.

[0004] Some designs that attempt to introduce compensation mechanisms may malfunction due to their singular triggering logic (such as responding only to temperature or only to external humidity). For example, if a surge arrester experiences a short-term temperature rise due to a momentary lightning strike, or if it is only in a rainy environment but the internal components have not aged, improperly connecting the backup resistor group to the main circuit may cause the backup resistor to age prematurely, potentially damaging the insulation of the system and even causing the protection to malfunction.

[0005] Given the aforementioned challenges, how to break through the passive protection mode and construct an explosion-proof surge arrester that can intelligently sense its internal aging state and accurately deploy backup protection capabilities when truly needed, thereby significantly improving its life-cycle safety, reliability, and explosion-proof capability, has become a key technical issue that the industry urgently needs to overcome.

[0006] Therefore, it is necessary to develop an explosion-proof surge arrester to solve the above problems. Summary of the Invention

[0007] The purpose of this invention is to provide an explosion-proof surge arrester, which aims to solve the problems of inaccurate internal aging state sensing, inability to intelligently activate backup protection capabilities as needed, and insufficient life-cycle safety reliability and limited explosion-proof capabilities caused by the passive rigidity of traditional explosion-proof mechanisms.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: an explosion-proof surge arrester, comprising an insulating cylinder and a main resistor assembly disposed within the insulating cylinder, wherein the insulating cylinder further comprises a secondary resistor assembly, and the surge arrester further comprises: A thermal actuator, one end of which is equipped with a circuit switch, is configured to cause the circuit switch to move when the internal temperature of the surge arrester rises. An expansion drive assembly includes a water-swellable component, which is capable of causing the expansion drive assembly to move after contact with water; If the thermal actuator does not cause the circuit switch to move before the expansion drive component moves, the secondary resistor group remains unchanged and is still in a short-circuited state; if the thermal actuator has already caused the circuit switch to move before the expansion drive component moves, the secondary resistor group is connected to the circuit and connected in series with the main resistor group.

[0009] Preferably, the thermal actuator is a bimetallic strip or a shape memory alloy actuator.

[0010] Preferably, the expansion drive assembly further includes a moving plate and a pushing member. The water-expanding member expands after absorbing water, driving the moving plate, and the moving plate causes the pushing member to move.

[0011] Preferably, the pusher is provided with a clearance groove, and when the thermal actuator does not drive the circuit switch to move but the expansion drive assembly moves, the clearance groove of the pusher corresponds to the movement path of the circuit switch.

[0012] Preferably, the circuit switch is a sliding electrical connector, including a first contact part and a second contact part that can slide relative to each other; When the first contacting element comes into contact with the second contacting element, the secondary resistor group is short-circuited; When the first and second electrical connectors are separated, the secondary resistor array is connected in series with the main circuit.

[0013] Preferably, the circuit switch further includes a mounting component connected to the thermal actuator, the first electrical contact component is slidably connected to the mounting component, and the second electrical contact component is located on the mounting component.

[0014] Preferably, the surge arrester further includes a pressure relief component, which is configured to release internal pressure by mechanically displacing a pressure relief channel when the internal air pressure of the surge arrester rises due to a fault.

[0015] Preferably, the end of the insulating cylinder is provided with a sealing cap, and the sealing cap is provided with a through terminal.

[0016] Preferably, a sealing ring is provided at the joint between the sealing cover and the insulating cylinder and the terminal block to ensure internal sealing.

[0017] Preferably, the outer surface of the insulating cylinder is provided with a skirt to increase the creepage distance and heat dissipation area.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention utilizes a thermal actuator to detect the continuous temperature rise inside the surge arrester in real time and drive the circuit switch to a ready position. The expansion actuator, upon contact with rainwater, generates a mechanical displacement, providing triggering force. A clearance groove on the pusher creates a sequential interlocking logic of "heat detection and preparation first, then water triggering," ensuring that the displacement of the expansion actuator effectively drives the circuit switch to connect the secondary resistor group in series to the main circuit only under the specific condition that the surge arrester is truly aged and in a rainy environment. The synergistic effect of these features enables intelligent diagnosis of the surge arrester's aging state and precise self-compensation for operational capabilities, significantly improving the surge arrester's anti-aging performance, operational reliability, and explosion-proof capability throughout its entire lifespan. Simultaneously, it fundamentally eliminates malfunctions caused by instantaneous lightning strikes or single environmental factors. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0020] Figure 2 This is a cross-sectional schematic diagram showing the location of the pressure relief component in this invention.

[0021] Figure 3 This is a cross-sectional schematic diagram showing the location of the expansion drive component in this invention.

[0022] Figure 4 This is the present invention. Figure 3 Enlarged view of a portion of point A in the middle.

[0023] Figure 5 This is a schematic diagram showing the location of the expansion drive component when the circuit switch is turned off in this invention.

[0024] Figure 6 This is a schematic diagram showing the location of the expansion drive component when the circuit switch is connected in this invention.

[0025] Figure 7 This is a schematic diagram showing the relative positions of the circuit switch and the expansion drive assembly when the surge arrester of the present invention is working normally.

[0026] Figure 8 This is a schematic diagram showing the relative positions of the circuit switch and the expansion drive component when the surge arrester of the present invention encounters rainy weather after aging and heating.

[0027] Figure 9 This is a top view of the location of the thermally activated component in this invention.

[0028] Figure 10This is a schematic diagram of the circuit connection relationship between the main resistor group and the auxiliary resistor group in this invention.

[0029] Figure label: 1. Insulating cylinder; 2. Main resistor assembly; 3. Secondary resistor assembly; 4. Thermal actuator; 5. Circuit switch; 51. First electrical connector; 52. Second electrical connector; 53. Mounting component; 6. Pressure expansion drive assembly; 61. Water-expanding component; 62. Moving plate; 63. Pushing component; 631. Clearance groove; 64. Second elastic component; 7. Pressure release assembly; 71. Pressure relief channel; 72. Fixing component; 73. First elastic component; 74. Movable component; 8. Sealing cap; 9. Terminal block. Detailed Implementation

[0030] 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

[0031] To improve the safety, reliability, and explosion-proof capability of surge arresters throughout their lifespan, such as... Figures 1 to 2 As shown, the present invention proposes an explosion-proof surge arrester, including an insulating cylinder 1 and a main resistor sheet group 2 disposed inside the insulating cylinder 1. The end of the insulating cylinder 1 is provided with a sealing cover 8, and the sealing cover 8 is provided with a through terminal 9. A sealing ring is provided at the joint between the sealing cover 8 and the insulating cylinder 1 and the terminal 9 to ensure internal sealing. The outer surface of the insulating cylinder 1 is provided with a skirt to increase the creepage distance and heat dissipation area.

[0032] The sealing cover 8 can be connected to the insulating cylinder 1 by adhesive or thread to achieve end sealing of the surge arrester; the insulating cylinder 1 can be an epoxy glass fiber cylinder or an epoxy resin sleeve, taking into account both insulation and mechanical strength; the main resistor plate group 2 is composed of multiple zinc oxide valve plates stacked into a column shape, and the end of the main resistor plate group 2 is subjected to axial compression force through elastic gaskets; there is a gap between the main resistor plate group 2 and the insulating cylinder 1, and the end of the main resistor plate group 2 can be provided with conductive plates, which are connected to the terminal 9.

[0033] The surge arrester also includes a pressure relief assembly 7, which is configured to release internal pressure by mechanically displacing the pressure relief channel 71 when the internal air pressure of the surge arrester rises due to a fault.

[0034] The pressure relief assembly 7 includes a pressure relief channel 71 disposed within the sealing cover 8. A fixing member 72 is disposed within the pressure relief channel 71. The fixing member 72 is detachably connected to the sealing cover 8. The fixing member 72 is located within the pressure relief channel 71 and at one end away from the main resistor group 2. A first elastic member 73 is disposed on the side of the fixing member 72 closest to the main resistor group 2. One end of the first elastic member 73 is connected to the fixing member 72, and the other end is connected to a movable member 74. The movable member 74 is slidably connected to the pressure relief channel 71.

[0035] When the internal air pressure of the surge arrester increases, the movable part 74 is squeezed to move closer to the fixed part 72, providing more space inside the surge arrester and slowing down the increase in air pressure. When thermal collapse occurs inside the surge arrester, the internal air pressure continues to rise until the internal air pressure of the surge arrester reaches its limit. At this point, the fixed part 72 breaks through the snap-fit ​​connection with the sealing cover 8 and is squeezed out of the sealing cover 8 by the air pressure, so that the pressure relief channel 71 is fully opened.

[0036] In this embodiment, the pressure relief assembly 7, composed of a fixed member 72, a first elastic member 73, and a movable member 74, achieves intelligent graded pressure relief control for internal fault gas pressure: when the gas pressure initially rises, the movable member 74 is pushed to compress the first elastic member 73, providing a buffer space and effectively delaying pressure accumulation; when a severe fault such as internal thermal collapse causes the gas pressure to reach its limit, the fixed member 72 breaks through its connection with the sealing cover 8 and is ejected as a whole, completely opening the pressure relief channel 71 and achieving directional and rapid overpressure relief. This mechanism, together with the reliable connection between the insulating cylinder 1 and the sealing cover 8 formed by adhesive or threads, and the sealing rings set at each joint, constitutes a multi-layered sealing defense, ensuring the extremely high sealing reliability and structural integrity of the surge arrester, significantly improving the safety and stability of the surge arrester when facing internal fault pressure impacts, and enhancing the explosion-proof capability of the surge arrester. Example

[0037] In actual use, surge arresters experience internal aging due to long-term operation, resulting in insufficient performance of the aged parts when struck by lightning again. This leads to the inability of the surge arrester's backup protection capability to be intelligently activated as needed, as well as the problem of insufficient life-cycle safety and reliability and limited explosion-proof capability caused by the passive and rigid nature of traditional explosion-proof mechanisms.

[0038] To solve the above-mentioned technical problems, in another embodiment of the present invention, such as Figures 1 to 10 As shown, the surge arrester's insulating cylinder 1 is also equipped with a secondary resistor group 3. The secondary resistor group 3 is spaced apart from the main resistor group 2. The secondary resistor group 3 can be coaxially arranged with the main resistor group 2. The secondary resistor group 3 can be arranged outside the main resistor group 2. The material of the secondary resistor group 3 can be the same as that of the main resistor group 2.

[0039] The surge arrester also includes a thermal actuator 4 and an expansion drive assembly 6. The thermal actuator 4 is located between the sealing cover 8 and the main resistor sheet group 2. The expansion drive assembly 6 is located inside the sealing cover 8. The sealing cover 8 has a receiving groove for accommodating the expansion drive assembly 6. One end of the thermal actuator 4 is equipped with a circuit switch 5. The thermal actuator 4 is configured to drive the circuit switch 5 to move when the internal temperature of the surge arrester rises. The expansion drive assembly 6 includes a water-expanding component 61. The water-expanding component 61 can drive the expansion drive assembly 6 to move after contacting water.

[0040] If the thermal actuator 4 does not cause the circuit switch 5 to move before the expansion drive assembly 6 moves, the secondary resistor group 3 will not change and will remain in a short-circuited state; if the thermal actuator 4 has already caused the circuit switch 5 to move before the expansion drive assembly 6 moves, the secondary resistor group 3 will be connected to the circuit and connected in series with the main resistor group 2.

[0041] The thermal actuator 4 is a bimetallic strip or shape memory alloy actuator. One end of the thermal actuator 4 is connected to the sealing cover 8, and the other end is connected to the circuit switch 5. When the internal temperature of the surge arrester rises, the thermal actuator 4 deforms, causing the circuit switch 5 at one end to move onto the moving path of the expansion drive assembly 6. When the surge arrester is in normal working condition, the thermal actuator 4 is in a neutral position. Figure 9 At the location of the solid line, when the internal temperature of the surge arrester rises, the thermal actuator 4 is in a state of... Figure 9 The location of the middle dashed line.

[0042] The thermal actuator 4 is located on the side of the main resistor group 2 inside the surge arrester near the sealing cover 8. The proximity of the thermal actuator 4 to the main resistor group allows for more accurate reflection of its temperature changes and reduces the influence of external temperature. Under normal temperature conditions, the thermal actuator 4 will not move the circuit switch 5 onto the moving path of the expansion drive assembly 6. Only after the thermal actuator 4's temperature rises will it move the circuit switch 5 onto the moving path of the expansion drive assembly 6. The deformation limit of the thermal actuator 4 after heating can be the state when the circuit switch 5 is moved onto the moving path of the expansion drive assembly 6.

[0043] Under normal operating conditions, the internal resistors of the surge arrester will also have a very weak leakage current flowing through them at the system operating voltage. However, the heat generated by the current is very limited, and the surge arrester's own heat dissipation design can dissipate the heat, resulting in a small temperature rise in the surge arrester, which is far lower than that caused by environmental changes.

[0044] Surge arresters naturally age over time, resulting in increased leakage current, which causes them to generate more heat under normal voltage. If, under the same environmental conditions, the surface temperature or internal temperature rise of a surge arrester is consistently and significantly higher than that of similar normal equipment, this may indicate that the internal resistors have begun to age, leakage current is increasing, and there is a risk of thermal runaway.

[0045] The water-swellable component 61 is an expandable body made of high molecular polymer material, which can expand upon contact with water and recover upon drying. The expansion drive assembly 6 also includes a moving plate 62 and a pusher 63. After the water-swellable component 61 absorbs water and expands, it drives the moving plate 62, and the moving plate 62 drives the pusher 63 to generate displacement. The sealing cover 8 is provided with a moving groove for the moving component and the pusher 63 to move. A water-permeable plate is provided at the end of the moving groove away from the main resistor sheet group 2. The surface of the water-permeable plate can be concave. The water-swellable component 61 is located on the side of the water-permeable plate closer to the main resistor sheet group 2. The side of the water-swellable component 61 away from the water-permeable plate is the moving plate 62, and the pusher 63 is located on the side of the moving plate 62 away from the water-swellable component 61.

[0046] The pusher 63 is provided with a clearance groove 631. When the thermal actuator 4 does not drive the circuit switch 5 to move and the expansion drive assembly 6 moves, the clearance groove 631 of the pusher 63 corresponds to the moving path of the circuit switch 5. The clearance groove 631 can ensure that when the expansion drive assembly 6 moves before the thermal actuator 4, it will not affect the operation of the thermal actuator. This ensures that the surge arrester will only connect the auxiliary resistor group 3 and the main resistor group 2 in series when the internal temperature rises first and then encounters a rainy environment.

[0047] When the surge arrester is not aging or only encounters rainy weather, thanks to the design of the relief groove 631 on the pusher 63, the operation of the expansion drive assembly 6 will not trigger the circuit switch 5 to change its state. The auxiliary resistor group 3 will always remain short-circuited, avoiding unnecessary connection, ensuring that the main circuit operation is not affected, and reducing potential fault points caused by the malfunction of the compensation circuit.

[0048] The material selection of the water-swellable component 61 and the precision structural design of the pusher component 63 and the relief groove 631 ensure the high environmental relevance of the compensation action; not only is the stimulation of "water" required, but the action sequence is also strictly limited, so that the surge arrester can intelligently distinguish different states such as normal working conditions, instantaneous overload, and real aging, showing excellent environmental adaptability and eliminating the possibility of malfunction from the structure.

[0049] The pusher 63 includes a push rod and a push part. The clearance groove 631 is located on the push part. The push part can contact the circuit switch 5. A second elastic member 64 can be sleeved on the push rod. One end of the second elastic member 64 is connected to the side of the moving plate 62 away from the water-swellable member 61, and the other end is connected to the clearance groove 631 of the sealing cover 8. The second elastic member 64 is used to help the expansion drive assembly 6 return to its initial state after the water-swellable member 61 dries.

[0050] When the water-swellable component 61 comes into contact with water, water molecules penetrate into the interior of the material, destroying these temporary connection points, allowing the polymer chains to become free, extend or slip relative to each other, which macroscopically manifests as expansion; when the water evaporates, the temporarily destroyed physical cross-linking points will reform, pulling the polymer chains back to their original state, thereby restoring the material to its original shape.

[0051] When the surge arrester ages due to long-term operation, resulting in increased leakage current and continuously rising operating temperature, the thermal action component 4 will pre-position the circuit switch 5 in the operating position. Once it rains, the auxiliary resistor group 3 will be automatically connected in series with the main circuit to compensate for the loss of equivalent resistance and current carrying capacity due to the aging of the main resistor group 2, so that the surge arrester can still maintain a qualified protection level within the remaining life cycle and delay the scrapping time of the entire equipment.

[0052] The circuit switch 5 is a sliding electrical connector, including a first contact 51 and a second contact 52 that can slide relative to each other; when the first contact 51 contacts the second contact 52, the secondary resistor group 3 is short-circuited; when the first contact 51 separates from the second contact 52, the secondary resistor group 3 is connected in series with the main circuit; the circuit switch 5 also includes a mounting part 53 connected to the thermal actuator 4, the first contact 51 is slidably connected to the mounting part 53, and the second contact 52 is located on the mounting part 53 and fixedly connected to the mounting part 53.

[0053] One end of the auxiliary resistor assembly 3 is electrically connected to the terminal block, and the other end is electrically connected to the end of the main resistor assembly 2 near the sealing cover 8. The first terminal block 51 is electrically connected to the main resistor assembly 2, and the second terminal block 52 is electrically connected to the terminal block 9. When the first terminal block 51 is located near the sealing cover 8, it is in contact with and electrically connected to the second terminal block 52. When the first terminal block 51 is located away from the sealing cover 8, the first terminal block 51 and the second terminal block 52 are separated.

[0054] When the first contact 51 contacts the second contact 52, the contact post is directly electrically connected to the main resistor group 2, short-circuiting the secondary resistor group 3. When the first contact 51 is pushed by the expansion drive assembly 6 and separated from the second contact 52, the circuit directly connected to the main resistor group 2 is cut off, the short circuit of the secondary resistor group 3 is released, and the secondary resistor group 3 is connected in series with the main resistor group 2.

[0055] When the internal temperature of the surge arrester rises, the thermal actuator moves the circuit switch 5 at its end to the corresponding position at the bottom of the expansion drive assembly 6. At this time, the circuit switch 5 is in the connected state, keeping the auxiliary resistor group 3 short-circuited. When the internal temperature of the surge arrester rises and then encounters rainy weather, the expansion drive assembly 6 activates, pushing the circuit switch 5, which is already at its bottom, to disconnect the circuit switch 5. At this time, the short-circuited circuit of the auxiliary resistor group 3 is broken, and the main resistor group 2 and the auxiliary resistor group 3 inside the surge arrester are connected in series, thus compensating for the resistance of the surge arrester.

[0056] It should be noted that when the surge arrester ages naturally due to operating time, the leakage current of the surge arrester increases and the internal temperature rises. The thermal actuator 4 is activated, which drives the circuit switch 5 to move and place it on the movement path of the expansion drive assembly 6. Since the operating temperature of the surge arrester remains high after aging, the thermal actuator 4 always places the circuit switch 5 on the movement path of the expansion drive assembly 6. At this time, the first contact 51 and the second contact 52 of the circuit switch 5 are still in contact, and the auxiliary resistor group 3 is in a short-circuited state and will not participate in the normal operation of the surge arrester until it is replaced manually or in rainy weather.

[0057] When the surge arrester ages and encounters rainy weather, the circuit switch 5 is already on the movement path of the expansion drive assembly 6. The water-expanding component 61 in the expansion drive assembly 6 begins to expand after contacting water, pushing the moving plate 62 and the pushing component 63 to move closer to the circuit switch 5. The pushing component 63 pushes the first contact component 51 of the circuit switch 5, separating it from the second contact component 52, thus releasing the short circuit state of the auxiliary resistor group 3. The auxiliary resistor group 3 is now in series with the main resistor group 2, compensating for the aged main resistor group 2 and preventing lightning strikes from damaging the aged surge arrester.

[0058] When the surge arrester is not aged and encounters rainy weather, the circuit switch 5 is in its initial position and is not on the movement path of the expansion drive assembly 6. The water-expanding component 61 in the expansion drive assembly 6 begins to expand after contacting water, pushing the moving plate 62 and the pusher 63 to move away from the water-expanding component 61. After the pusher 63 moves to its limit, the clearance groove 631 of the pusher 63 is located on the movement path of the circuit switch 5. If the surge arrester is struck by lightning, the internal temperature of the surge arrester rises, and the thermal action component 4 drives the circuit switch 5 to move. When the circuit switch 5 moves to its limit position, it is in the clearance groove 631 position of the pusher 63. The circuit where the circuit switch 5 is located is still in a connected state, and the auxiliary resistor group 3 is still in a short-circuited state and does not participate in the operation of the surge arrester.

[0059] The surge arrester does not activate immediately upon detecting overvoltage or high temperature. Instead, it is designed with a series triggering condition: "the thermal actuator 4 senses and prepares first, and then the expansion drive assembly 6 executes the operation when it encounters water." This design ensures that compensation only occurs when the surge arrester is truly aged and in a rainy environment. This effectively prevents false compensation caused by instantaneous lightning strikes or non-aging factors, and controls the connection of the secondary resistor group 3 at the most necessary and safest moment, greatly improving the accuracy of compensation and the reliability of the system.

[0060] This invention, through the setting of the thermal actuator 4, realizes the sensing and response to the continuous temperature rise inside the surge arrester caused by the aging of the valve plates, and drives the circuit switch 5 to move to the ready position; through the setting of the expansion pressure drive component 6 which expands upon contact with water, mechanical displacement is generated after sensing the rainy environment to execute the switching action; through the structural design of the clearance groove 631 on the pusher 63, it is ensured that the displacement of the expansion pressure drive component 6 can effectively trigger the state switching of the circuit switch 5 only in the specific sequence of "sensing the internal temperature rise first, and then contacting the rainwater"; the above synergistic effect enables the auxiliary resistor plate group 3 to be intelligently and accurately connected in series to the main circuit when the surge arrester is aging and in rainy weather, thereby effectively compensating for the performance degradation of the main resistor plate group 2, significantly improving the surge arrester's anti-aging ability, operational reliability and service life throughout its life cycle, and fundamentally preventing maloperation caused by instantaneous lightning strikes or individual environmental factors.

[0061] 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. An explosion-proof surge arrester, comprising an insulating cylinder and a main resistor array disposed within the insulating cylinder, characterized in that, The insulating cylinder also contains a secondary resistor assembly, and the surge arrester also includes: A thermal actuator, one end of which is equipped with a circuit switch, is configured to cause the circuit switch to move when the internal temperature of the surge arrester rises. An expansion drive assembly includes a water-swellable component, which is capable of causing the expansion drive assembly to move after contact with water; If the thermal actuator does not cause the circuit switch to move before the expansion drive component moves, the secondary resistor group remains unchanged and is still in a short-circuited state; if the thermal actuator has already caused the circuit switch to move before the expansion drive component moves, the secondary resistor group is connected to the circuit and connected in series with the main resistor group.

2. The surge arrester according to claim 1, characterized in that, The thermal actuator is a bimetallic strip or a shape memory alloy actuator.

3. The surge arrester according to claim 2, characterized in that, The expansion drive assembly also includes a moving plate and a pushing component. The water-expanding component expands after absorbing water, driving the moving plate, and the moving plate causes the pushing component to move.

4. The surge arrester according to claim 3, characterized in that, The pusher is provided with a clearance groove. When the thermal actuator does not drive the circuit switch to move but the expansion drive assembly moves, the clearance groove of the pusher corresponds to the movement path of the circuit switch.

5. The surge arrester according to claim 1, characterized in that, The circuit switch is a sliding electrical connector, including a first and a second electrical contact that can slide relative to each other. When the first contacting element comes into contact with the second contacting element, the secondary resistor group is short-circuited; When the first and second electrical connectors are separated, the secondary resistor array is connected in series with the main circuit.

6. The surge arrester according to claim 5, characterized in that, The circuit switch also includes a mounting component connected to a thermal actuator, wherein the first electrical connector is slidably connected to the mounting component, and the second electrical connector is located on the mounting component.

7. The surge arrester according to claim 1, characterized in that, It also includes a pressure relief component, which is configured to open a pressure relief channel by mechanical displacement to release internal pressure when the internal air pressure of the surge arrester rises due to a fault.

8. The surge arrester according to claim 1, characterized in that, The end of the insulating cylinder is provided with a sealing cap, and the sealing cap is provided with a through terminal.

9. The surge arrester according to claim 8, characterized in that, A sealing ring is provided at the joint between the sealing cover and the insulating cylinder and terminal to ensure internal sealing.

10. The surge arrester according to claim 1, characterized in that, The outer surface of the insulating cylinder is provided with a skirt to increase the creepage distance and heat dissipation area.

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