Three-phase combined overvoltage protector

Abstract

The invention belongs to the field of power system overvoltage protectors, and discloses a three-phase combined overvoltage protector which comprises a plurality of phase units and a plurality of ground units, each phase unit and each ground unit comprise a nonlinear resistor and a discharge gap which are connected in series, and a lead is arranged at one end, away from the nonlinear resistor, of each discharge gap; the discharge gap comprises a second metal sheet connected with the non-linear resistor, and a second electrode, an electrode support body and a gasket are sequentially arranged at one end, far away from the non-linear resistor, of the second metal sheet; an insulating cylinder is arranged in the electrode supporting body, a first electrode is arranged at one end, close to the gasket, of the insulating cylinder and located outside the electrode supporting body, a first metal sheet and a net-shaped metal sheet are sequentially arranged at one end, away from the gasket, of the first electrode, and a spring is arranged between the first metal sheet and the net-shaped metal sheet. According to the invention, accidents caused by overheat of the overvoltage protector due to overhigh continuous discharge temperature can be prevented.

Description

Technical Field

[0001] The present invention relates to the field of overvoltage protectors for power systems, and particularly to a three-phase combined overvoltage protector. Background Art

[0002] A three-phase combined overvoltage protector (hereinafter referred to as the overvoltage protector) is a new type of overvoltage protector, mainly used in the power grids of power generation, power supply, and power consumption enterprises to protect electrical equipment such as transformers, switches, busbars, and motors. It can limit atmospheric overvoltages and switching overvoltages caused by various switches, and can reliably limit overvoltages between phases and between phases and ground.

[0003] The overvoltage protector adopts a structure combining zinc oxide nonlinear resistors and discharge gaps, so that the two protect each other. The discharge gap makes the charge rate of the zinc oxide resistor zero, and the nonlinear characteristics of zinc oxide cause the discharge gap to extinguish the arc immediately after operation, without continuous current and chopped wave. The discharge gap no longer undertakes the arc extinguishing task, improving the service life of the product. However, due to the influence of various factors such as moisture, aging, and pollution, defects may occur inside the overvoltage protector during operation, resulting in frequent arc discharge of the discharge gap, causing serious heating of the internal zinc oxide resistor, thermal breakdown of the overvoltage protector, and accidents, and further causing serious accidents such as short circuits of high-voltage busbars. To avoid this problem, the current main technical means is to regularly inspect, test, and replace the overvoltage protector, and there are also solutions for online monitoring of the working state of the overvoltage protector in the prior art. However, when the overvoltage protector is severely heated due to internal defects and not discovered and processed in time, the prior art cannot solve the problem of accidental accidents caused by its overheating and burning.

[0004] Therefore, how to provide a three-phase combined overvoltage protector is an urgent problem to be solved at present. Summary of the Invention

[0005] Embodiments of the present invention provide a three-phase combined overvoltage protector to solve the problem in the prior art that when the overvoltage protector is severely heated due to internal defects, it cannot solve the problem of accidental accidents caused by its overheating and burning.

[0006] To provide a basic understanding of some aspects of the disclosed embodiments, a simple summary is given below. This summary part is not a general review, nor is it intended to identify key / important constituent elements or delineate the protection scope of these embodiments. Its sole purpose is to present some concepts in a simple form as a prelude to the subsequent detailed description.

[0007] According to an embodiment of the present invention, there is provided a three-phase combined overvoltage protector.

[0008] In one embodiment, a three-phase combined overvoltage protector includes a plurality of phase units and a plurality of ground units. Each phase unit and ground unit includes a non-linear resistor and a discharge gap connected in series. A lead is provided at one end of the discharge gap away from the non-linear resistor. The discharge gap includes a second metal sheet connected to the non-linear resistor. At one end of the second metal sheet away from the non-linear resistor, a second electrode, an electrode support body, and a washer are sequentially provided. An insulating cylinder is provided inside the electrode support body. A first electrode is provided at one end of the insulating cylinder close to the washer and outside the electrode support body. At one end of the first electrode away from the washer, a first metal sheet and a mesh metal sheet are sequentially provided. A spring is provided between the first metal sheet and the mesh metal sheet.

[0009] In one embodiment, the first electrode, the first metal sheet, and the mesh metal sheet together act as an electrode to provide a discharge path when overvoltage occurs. When the voltage exceeds the threshold value set by the three-phase combined overvoltage protector, the gap between the first electrode, the first metal sheet, and the mesh metal sheet discharges to guide the overvoltage to the ground.

[0010] In one embodiment, the mesh metal sheet is connected to the lead, and the second metal sheet is connected in series with the non-linear resistor.

[0011] In one embodiment, when the three-phase combined overvoltage protector is operating under the normal working voltage, the discharge gap is not conducting and isolates the power frequency voltage. When an overvoltage is generated in the power system and the voltage value of the overvoltage reaches the gap breakdown value of the three-phase combined overvoltage protector, the discharge gap breaks down and discharges, and the non-linear resistor conducts to limit the voltage.

[0012] In one embodiment, when the three-phase combined overvoltage protector is operating normally, the temperature is less than 70 degrees Celsius, and the first electrode and the washer are magnetic and in an attracted state. When the inside of the three-phase combined overvoltage protector is in a defective discharge state, the temperature reaches the Curie temperature point of the materials of the first electrode and the washer; the first electrode and the washer lose magnetism, the discharge gap becomes larger, and the electrode stops discharging.

[0013] In one embodiment, the first electrode and the washer losing magnetism and the discharge gap becoming larger includes: When the first electrode and the washer lose magnetism, the spring drives the first metal sheet and the first electrode to move away from the second electrode, so that the distance between the first electrode and the second electrode becomes larger.

[0014] In one embodiment, when the first metal sheet and the first electrode move away from the second electrode, the insulating cylinder connected to the first electrode and the electrode support body are in sliding fit to ensure the sealing of the gap cavity.

[0015] In one embodiment, a magnet steel layer is provided at a portion where the first electrode contacts the washer, and the magnet steel layer has the same material composition as the washer.

[0016] In one embodiment, the material compositions of the magnet steel layer and the washer both include iron oxide, magnesium oxide, and copper oxide, and the Curie temperature of the magnet steel layer and the washer is greater than or equal to 102 degrees Celsius.

[0017] In one embodiment, the insulating cylinder and the electrode support are made of the same electroceramic material, and the electrode support is in a cylindrical structure.

[0018] The technical solutions provided by the embodiments of the present invention may include the following beneficial effects: The present invention provides a three-phase combined overvoltage protector with temperature-controlled adjustable discharge gap. By improving the existing discharge gap electrodes, when internal defects in the overvoltage protector cause frequent discharges in the discharge gap, generating a large amount of heat, and the temperature reaches above the Curie temperature point of the electrode and the washer, the washer and the first electrode demagnetize, the electromagnetic force between the washer and the first electrode disappears, the spring returns to the normal state, driving the first metal sheet and the first electrode to move upward together, the distance between the first electrode and the second electrode (i.e., the discharge gap) becomes larger, and the electrode stops discharging, preventing accidents caused by overheating of the overvoltage protector due to excessive temperature during continuous discharge.

[0019] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present invention, and are used together with the specification to explain the principles of the present invention.

[0021] Figure 1 is a structural diagram of the phase unit / ground unit of the overvoltage protector shown according to an exemplary embodiment; Figure 2 is an internal component diagram of the phase unit / ground unit shown according to an exemplary embodiment; Figure 3 is a component position diagram when the electrode temperature is normal shown according to an exemplary embodiment; Figure 4 is a component position diagram when the electrode temperature is abnormal shown according to an exemplary embodiment; Figure 5 is one of the structural diagrams of the three-phase combined overvoltage protector shown according to an exemplary embodiment; Figure 6 is the second structural diagram of the three-phase combined overvoltage protector shown according to an exemplary embodiment.

[0022] Reference Signs: 1. Nonlinear resistor; 2. Discharge gap; 21. Second metal sheet; 22. Second electrode; 23. Electrode support; 24. Washer; 25. Insulating cylinder; 26. First electrode; 27. First metal sheet; 28. Spring; 29. Mesh metal sheet; 3. Lead wire. Detailed implementation mode

[0023] The following description and the drawings fully illustrate the specific implementation modes herein, enabling those skilled in the art to practice them. Parts and features of some implementation modes can be included in or replace parts and features of other implementation modes. The scope of the implementation modes herein includes the entire scope of the claims and all available equivalents of the claims. In this document, the terms "first", "second", etc. are only used to distinguish one element from another, without requiring or implying any actual relationship or order between these elements. In fact, the first element can also be called the second element, and vice versa. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a structure, device or equipment including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such structure, device or equipment. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the structure, device or equipment including the said element. The various embodiments herein are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other.

[0024] The terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. in this document indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing this document and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present invention. In the description of this document, unless otherwise specified and limited, the terms "installed", "connected", "coupled" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the internal communication of two elements. It can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0025] In this document, unless otherwise stated, the term "plurality" means two or more.

[0026] In this text, the character " / " indicates an "or" relationship between the preceding and following objects. For example, A / B means: A or B.

[0027] In this text, the term "and / or" is a description of the association relationship of an object, indicating that three relationships can exist. For example, A and / or B means: A or B, or, these three relationships of A and B.

[0028] It should be understood that although the various steps in the flowchart are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear description in this text, the execution of these steps has no strict order limit, and these steps can be executed in other orders. Moreover, at least a part of the steps in the figure may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same moment, but can be executed at different moments. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed alternately or in turn with at least a part of other steps or sub-steps or stages of other steps.

[0029] Each module in the device or system of this application can be implemented in whole or in part by software, hardware, and their combination. The above-mentioned modules can be embedded in the processor of the computer device in hardware form or independent of it, or stored in the memory of the computer device in software form, so that the processor can call and execute the operations corresponding to each of the above modules.

[0030] Without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0031] Figures 1-6 An embodiment of a three-phase combined overvoltage protector of the present invention is shown.

[0032] In this alternative embodiment, the three-phase combined overvoltage protector includes a plurality of phase units and a plurality of ground units, and each phase unit and ground unit includes a non-linear resistor 1 and a discharge gap 2 connected in series. A lead 3 is provided at one end of the discharge gap 2 away from the non-linear resistor 1; the discharge gap 2 includes a second metal sheet 21 connected to the non-linear resistor 1. A second electrode 22, an electrode support 23, and a washer 24 are sequentially provided at one end of the second metal sheet 21 away from the non-linear resistor 1; an insulating cylinder 25 is provided inside the electrode support 23. A first electrode 26 is provided at one end of the insulating cylinder 25 close to the washer 24 and outside the electrode support 23. A first metal sheet 27 and a mesh metal sheet 29 are sequentially provided at one end of the first electrode 26 away from the washer 24. A spring 28 is provided between the first metal sheet 27 and the mesh metal sheet 29.

[0033] In this alternative embodiment, the first electrode 26, the first metal sheet 27, and the mesh metal sheet 29 together function as an electrode to provide a discharge path during overvoltage occurrence. When the voltage exceeds the threshold value set by the three-phase combined overvoltage protector, the gaps between the first electrode 26, the first metal sheet 27, and the mesh metal sheet 29 discharge to guide the overvoltage to the ground.

[0034] In this alternative embodiment, the mesh metal sheet 29 is connected to the lead 3, and the second metal sheet 21 is connected in series with the non-linear resistor 1.

[0035] In this alternative embodiment, when the three-phase combined overvoltage protector is under the normal operating voltage, the discharge gap 2 is non-conductive and isolates the power frequency voltage; when an overvoltage occurs in the power system and the voltage value of the overvoltage reaches the gap breakdown value of the three-phase combined overvoltage protector, the discharge gap 2 breaks down and discharges, and the non-linear resistor 1 conducts to limit the voltage.

[0036] In this alternative embodiment, when the three-phase combined overvoltage protector is operating normally, the temperature is less than 70 degrees Celsius, and the first electrode 26 and the washer 24 are magnetic and in an attracted state; when the internal part of the three-phase combined overvoltage protector is in a defective discharge state, the temperature reaches the Curie temperature point of the materials of the first electrode 26 and the washer 24; the first electrode 26 and the washer 24 demagnetize, the discharge gap becomes larger, and the electrode stops discharging.

[0037] In this alternative embodiment, the demagnetization of the first electrode 26 and the washer 24 and the increase in the discharge gap include: When the first electrode 26 and the washer 24 demagnetize, the spring 28 drives the first metal sheet 27 and the first electrode 26 to move away from the second electrode 22, so that the distance between the first electrode 26 and the second electrode 22 becomes larger.

[0038] In this alternative embodiment, when the first metal sheet 27 and the first electrode 26 move away from the second electrode 22, the insulating cylinder 25 connected to the first electrode 26 and the electrode support 23 are in sliding fit to ensure the sealing of the gap cavity.

[0039] In this alternative embodiment, a magnetic steel layer is provided at the part where the first electrode 26 contacts the washer 24, and the material composition of the magnetic steel layer is the same as that of the washer 24.

[0040] In this alternative embodiment, the material compositions of the magnetic steel layer and the washer 24 both include iron oxide, magnesium oxide, and copper oxide, and the Curie temperature of the magnetic steel layer and the washer 24 is greater than or equal to 102 degrees Celsius.

[0041] In this alternative embodiment, the insulating cylinder 25 and the electrode support 23 are made of the same electro-ceramic material, and the electrode support 23 is a cylindrical structure.

[0042] To facilitate the understanding of the above technical solution of the present invention, the above technical solution of the present invention will be further described from the perspectives of architecture and principle as follows: The present invention provides a three-phase combined overvoltage protector with a temperature-controlled adjustable discharge gap, which can avoid the accidental burnout caused by internal defect faults of the overvoltage protector. It is an improvement on the discharge gap electrode of the existing overvoltage protector.

[0043] 1. Add a washer between the first electrode and the electrode support. The washer is fixed on the electrode support and is made of a magnet steel with main materials of iron oxide (Fe2O3), magnesium oxide (MgO), and copper oxide (CuO). Its Curie temperature is about 102 degrees Celsius.

[0044] 2. Add a layer of magnet steel with main materials of iron oxide (Fe2O3), magnesium oxide (MgO), and copper oxide (CuO) to the part of the first electrode in contact with the washer.

[0045] 3. Add an insulating cylinder. The insulating cylinder is fixedly connected to the first electrode and is made of the same material as the electrode support, generally a special porcelain material, which has good electrical insulation performance, dielectric strength, anti-electro-erosion, and anti-aging properties.

[0046] 4. Add a pair of springs between the first metal sheet and the mesh metal sheet. One end of the spring is fixedly connected to the first metal sheet, and the other end is fixedly connected to the mesh metal sheet.

[0047] As Figure 2 shown, the present invention provides a three-phase combined overvoltage protector with a temperature-controlled adjustable discharge gap. It is an improvement on the discharge electrode of the existing overvoltage protector, adding a washer 24, an insulating cylinder 25, and a spring 28; and the first electrode is improved by adding a layer of magnet steel with main materials of iron oxide (Fe2O3), magnesium oxide (MgO), and copper oxide (CuO) to the part of the first electrode 26 in contact with the washer 24; the insulating cylinder 25 is fixedly connected to the first electrode 26.

[0048] The magnet steel needs to reach a Curie temperature of 102 degrees Celsius. The magnet steel with main materials of iron oxide (Fe2O3), magnesium oxide (MgO), and copper oxide (CuO) can be achieved through the following ratio: Magnesium oxide (MgO): 5.5 - 7 mol%.

[0049] Copper oxide (CuO): 6 - 9 mol%.

[0050] Iron oxide (Fe2O3): 47 - 49.5 mol%.

[0051] The first electrode 26, the second electrode 22 and the electrode support 23 form the discharge gap of the overvoltage protector. Usually, the electrodes are made of metal materials with good electrical conductivity and adopt a spherical structure. In the present invention, a magnetic steel layer mainly composed of iron oxide (Fe2O3), magnesium oxide (MgO), and copper oxide (CuO) is added to the part where the first electrode 26 contacts the washer 24; the electrode support 23 is made of special porcelain material and adopts a cylindrical structure; under normal circumstances, the spacing of the discharge gap is usually between a few millimeters and a few centimeters. It can withstand a certain voltage and discharge under overvoltage conditions.

[0052] A washer 24 is added between the first electrode 26 and the electrode support 23. The washer 24 is fixed on the electrode support 23. The washer 24 is made of the above-mentioned magnetic steel material, and the washer is made of magnetic steel with the main materials of iron oxide (Fe2O3), magnesium oxide (MgO), and copper oxide (CuO), and its Curie temperature is about 102 degrees Celsius.

[0053] The first metal sheet 27 is fixedly connected to the first electrode 26. The elastic piece at the lower part of the mesh metal sheet 29 has a certain elasticity and can ensure that it always remains in contact with the first metal sheet 27. The first electrode 26, the first metal sheet 27, and the mesh metal sheet 29 together play the role of an electrode and are used to provide a discharge path when overvoltage occurs. When the voltage exceeds the threshold set by the protector, the gap between the electrodes will discharge, thereby guiding the overvoltage to the ground and protecting the circuit from damage.

[0054] The design of the mesh structure of the mesh metal sheet 29 helps to evenly distribute the electric field, reduce the local electric field intensity, avoid partial discharge, thereby protecting the electrodes from being electro-erosion and ensuring the uniformity and stability of the discharge.

[0055] A pair of springs 28 are provided between the first metal sheet 27 and the mesh metal sheet 29. One end of the spring 28 is fixedly connected to the first metal sheet 27, and the other end is fixedly connected to the mesh metal sheet 29.

[0056] The mesh metal sheet 29 is connected to the high-voltage lead and cast together with the outer shell; the second metal sheet 21 is connected in series with a zinc oxide non-linear resistor, and the zinc oxide non-linear resistor is directly hot-pressed together with the outer shell material, thus forming a phase unit of the overvoltage protector. The overvoltage protector selects silicone rubber as the outer shell material, and four silicone rubber high-voltage cables and zinc oxide varistors are integrally vulcanized and formed by one-time molding from the inside, mainly used to prevent moisture and explosion-proof problems.

[0057] As Figures 5-6 shown, the overvoltage protector consists of three phase units and one ground unit to form a four-star structure, and each unit is composed of a discharge gap 2 and a zinc oxide non-linear resistor connected in series. Figure 6In the figure, FR is a zinc oxide nonlinear resistor, and CG is a discharge gap. The three-phase high-voltage leads are respectively led out by three phase units. Due to the symmetric structure, any three of them can be respectively connected to the A, B, and C phases. The grounding lead is led out by the ground unit. Under the normal operating voltage, the gap is not conducting, isolating the power frequency voltage and protecting the zinc oxide nonlinear resistor. At this time, no current flows through the grounding lead. When an overvoltage occurs in the power system and the voltage value reaches the breakdown value of the overvoltage protector gap, the gap breaks down and discharges, and the zinc oxide nonlinear resistor of the overvoltage protector conducts to limit the voltage. After the overvoltage disappears, the discharge gap assembly immediately returns to normal automatically. Generally, overvoltages generated in the system are instantaneous. However, when there are defects inside the overvoltage protector, the gap may also break down and discharge frequently under normal operating voltage, resulting in a sharp increase in temperature, and ultimately the overvoltage protector overheats and causes accidents.

[0058] As Figure 3 shown, when the overvoltage protector is operating normally, the temperature is generally below 70 degrees Celsius. At this time, the first electrode 26 and the washer 24 are magnetic and will be attracted together, and the spring is stretched. As Figure 4 shown, when frequent discharges due to internal defects in the overvoltage protector cause the temperature to rise, when the temperature rises to about 102 degrees Celsius, reaching the Curie temperature point of the materials of the electrode and the washer 24, the first electrode 26 and the washer 24 lose their magnetism, and the electromagnetic force between the washer 24 and the first electrode 26 disappears. The spring 28 returns to its normal state, driving the first metal sheet 27 and the first electrode 26 to move upward together. The distance between the first electrode 26 and the second electrode 22 (i.e., the discharge gap) becomes larger, and the electrode stops discharging, preventing accidents caused by overheating of the overvoltage protector due to continuous discharge at too high a temperature.

[0059] When the first electrode 26 and the washer 24 lose their magnetism and the first metal sheet 27 and the first electrode 26 move upward together, the insulating cylinder 25 fixedly connected to the first electrode 26 can slide freely with respect to the electrode support 23, but can ensure the sealing of the gap cavity.

[0060] The present invention is not limited to the structure already described and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. A three-phase combined overvoltage protector, characterized in that, It includes several phase units and several ground units, and each phase unit and ground unit includes a non-linear resistor (1) and a discharge gap (2) connected in series. A lead wire (3) is provided at one end of the discharge gap (2) far from the non-linear resistor (1). The discharge gap (2) includes a second metal sheet (21) connected to the non-linear resistor (1). At one end of the second metal sheet (21) far from the non-linear resistor (1), a second electrode (22), an electrode support (23) and a washer (24) are sequentially arranged. An insulating cylinder (25) is arranged inside the electrode support (23). A first electrode (26) is arranged at one end of the insulating cylinder (25) close to the washer (24) and outside the electrode support (23). At one end of the first electrode (26) far from the washer (24), a first metal sheet (27) and a mesh metal sheet (29) are sequentially arranged. A spring (28) is arranged between the first metal sheet (27) and the mesh metal sheet (29).

2. The three-phase combined overvoltage protector according to claim 1, characterized in that, The first electrode (26), the first metal sheet (27) and the mesh metal sheet (29) together act as an electrode to provide a discharge path when overvoltage occurs. When the voltage exceeds the threshold value set by the three-phase combined overvoltage protector, the gap between the first electrode (26), the first metal sheet (27) and the mesh metal sheet (29) discharges to guide the overvoltage to the ground.

3. The three-phase combined overvoltage protector according to claim 1, characterized in that, The mesh metal sheet (29) is connected to the lead wire (3), and the second metal sheet (21) is connected in series with the non-linear resistor (1).

4. A three-phase combined overvoltage protector according to claim 1, characterized in that, When the three-phase combined overvoltage protector is under the normal operating voltage, the discharge gap (2) is not conducting and isolates the power frequency voltage. When an overvoltage is generated in the power system and the voltage value of the overvoltage reaches the gap breakdown value of the three-phase combined overvoltage protector, the discharge gap (2) breaks down and discharges, and the non-linear resistor (1) conducts to limit the voltage.

5. A three-phase combined overvoltage protector according to claim 4, characterized in that, When the three-phase combined overvoltage protector is working normally, the temperature is less than 70 degrees Celsius, and the first electrode (26) and the washer (24) are magnetic and in an attracted state. When the inside of the three-phase combined overvoltage protector is in a defective discharge state, the temperature reaches the Curie temperature point of the materials of the first electrode (26) and the washer (24); the first electrode (26) and the washer (24) lose magnetism, the discharge gap becomes larger, and the electrode stops discharging.

6. The three-phase combined overvoltage protector according to claim 5, characterized in that, The first electrode (26) and the washer (24) lose magnetism, and the discharge gap becomes larger, including: When the first electrode (26) and the washer (24) lose magnetism, the spring (28) drives the first metal sheet (27) and the first electrode (26) to move away from the second electrode (22), so that the distance between the first electrode (26) and the second electrode (22) becomes larger.

7. The three-phase combined overvoltage protector according to claim 6, characterized in that, When the first metal sheet (27) and the first electrode (26) move away from the second electrode (22), the insulating cylinder (25) connected to the first electrode (26) is in sliding fit with the electrode support (23) to ensure the sealing of the clearance cavity.

8. The three-phase combined overvoltage protector according to claim 1, characterized in that, A magnetic steel layer is provided at the portion of the first electrode (26) in contact with the washer (24), and the material composition of the magnetic steel layer is the same as that of the washer (24).

9. The three-phase combined overvoltage protector according to claim 8, characterized in that, The material compositions of the magnetic steel layer and the washer (24) both include iron oxide, magnesium oxide and copper oxide, and the Curie temperature of the magnetic steel layer and the washer (24) is greater than or equal to 102 degrees Celsius.

10. The three-phase combined overvoltage protector according to claim 1, characterized in that, The insulating cylinder (25) and the electrode support (23) are made of the same electroceramic material, and the electrode support (23) is in a cylindrical structure.

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