A composite insulator device with a built-in piezoresistive unit

Abstract

The application discloses a composite insulator device with built-in pressure sensitive resistance unit, comprising: a pressure sensitive resistance unit, an insulating support, a reinforced arc extinguishing gap unit, and a mounting hardware; the pressure sensitive resistance unit comprises a pressure sensitive resistance subunit core, an insulating core rod, and an insulating outer sleeve; the reinforced arc extinguishing gap unit comprises an arc extinguishing cavity, an insulating support piece, and a gap electrode; the reinforced arc extinguishing gap unit is fixedly installed at both ends of the insulating support or uniformly arranged along the axial direction of the insulating support. The lightning arrester and the insulator are integrated and designed as a whole, meanwhile, the strong arc extinguishing capacity of the reinforced arc extinguishing gap unit is utilized to reduce the rated voltage of the pressure sensitive resistance unit, so that the device is miniaturized, lightened and low in cost; the device is completed with assembly when leaving the factory, and does not need to be adjusted and assembled on site; when being connected with an insulating wire, the insulating layer of the wire does not need to be stripped, and the installation and construction are simple and convenient.

Description

Technical Field

[0001] The present invention relates to the technical field of lightning protection and grounding technology, and in particular to a composite insulator device with a built-in varistor unit. Background Art

[0002] The existing external series gap arrester adopts a structure in which the arrester body is connected in series with a pure air gap or a gap with a support member. Due to the inherent lack of stability of this type of open external series gap in interrupting power frequency continuous current and the limitation of current test conditions that cannot support the development of long gap power frequency continuous current interruption test research, it is impossible to deeply and finely utilize the arc extinguishing ability of the external series gap. As a result, the rated voltage value of the current external series gap arrester body is too high, the device is large in size and weight, the overall cost is high, and the on-site installation and construction consumes a lot of manpower and material resources. Under the traditional method, the external series gap arrester and the line insulator are designed and produced independently of each other, and assembled on-site. The production process is consuming a lot, the on-site installation operation is complicated, the arrester occupies less tower head space, and has an adverse effect on the later live work. The above-mentioned shortcomings result in a high comprehensive cost of lightning protection when the external series gap arrester is used in current projects. Summary of the Invention

[0003] The present invention aims to solve one of the technical problems in the related art to at least some extent.

[0004] To this end, the present invention proposes a composite insulator device that integrates an external series gap arrester and a line suspension composite insulator into an integrated design, simplifies the production process, reduces material loss, and reduces the size of the device. At the same time, an enhanced arc-extinguishing gap is used to replace a pure air gap or a gap with a support member, thereby reducing the rated voltage of the varistor unit.

[0005] To achieve the above-mentioned object, an embodiment of the present invention provides a composite insulator device, which includes: a varistor unit, an insulating support, an enhanced arc-extinguishing gap unit, and a mounting hardware.

[0006] The varistor unit includes a varistor sub-unit core, an insulating core rod, and an insulating outer sleeve. The varistor sub-unit core includes a resistor sheet, a potential extraction electrode, and a curing sleeve.

[0007] The resistor sheets are arranged evenly in the axial direction, the potential extraction electrodes are located at the axial outer end of the resistor sheets, the resistor sheets and the potential extraction electrodes are stacked and pressed tightly in the axial direction, and the curing sleeve covers the partial outer surfaces of the resistor sheets and the potential extraction electrodes.

[0008] The insulating support comprises an insulating core rod and an insulating outer sleeve.

[0009] The insulating core rod axially penetrates the varistor sub-unit core and the insulating pillar; the outer surface and end surface of the varistor sub-unit core, the gap between the inner surface of the varistor sub-unit core and the outer surface of the insulating core rod, and the outer surface of the insulating core rod corresponding to the insulating pillar are entirely covered and filled with an insulating jacket, the insulating jacket material is a silicone rubber composite material, molded in one step, and the insulating jacket has an umbrella skirt.

[0010] The enhanced arc-extinguishing gap unit includes an arc-extinguishing cavity, an insulating support, and a gap electrode; the enhanced arc-extinguishing gap unit is fixed at both ends of the insulating support or is evenly arranged along the axial direction of the insulating support.

[0011] The varistor subunit core is fixed to the mounting fixture via the second connecting portion of the potential extraction electrode.

[0012] According to one embodiment of the present invention, the arc-extinguishing cavity is annular and includes at least two arc-extinguishing cavity unit sections.

[0013] According to one embodiment of the present invention, the insulating support is located at the hub position of the arc extinguishing cavity, the gap electrode is located at the hub position and spoke side of the arc extinguishing cavity, and the gap electrodes on the spoke side of the two arc extinguishing cavity unit sections are arranged in a straight line correspondingly.

[0014] The gap electrodes are located on the spoke side of the arc extinguishing cavity, and the gap electrodes are symmetrically placed in pairs within the curved surface formed by the two arc extinguishing cavity unit sections and the insulating pillars.

[0015] According to one embodiment of the present invention, the first connection portion of the potential extraction electrode is electrically connected to the adjacent gap electrode.

[0016] According to one embodiment of the present invention, the arc-extinguishing cavity unit segments are evenly distributed along the axial direction of the insulating support to form a series discharge channel.

[0017] According to one embodiment of the present invention, the arc extinguishing cavity unit segment includes at least one air gap cavity, and the air gap cavity includes: an arc extinguishing cavity insulating jacket, an arc extinguishing electrode, an isolation gas chamber, an air jet, and an arc extinguishing cavity insulating core rod.

[0018] According to one embodiment of the present invention, the arc-extinguishing electrodes are placed in pairs in the air gap chamber. The arc-extinguishing electrodes are solid spheres made of steel or copper. The diameter of the arc-extinguishing electrode spheres ranges from 8 mm to 18 mm, and the shortest distance between adjacent arc-extinguishing electrodes ranges from 2 mm to 20 mm.

[0019] According to one embodiment of the present invention, the arc extinguishing cavity insulating core rod is made of epoxy resin glass fiber drawing rod, the cross section of the arc extinguishing cavity insulating core rod is square, and the side length of the arc extinguishing cavity insulating core rod ranges from 5 mm to 30 mm.

[0020] According to one embodiment of the present invention, the air jet is located on the outer side of the insulating jacket of the arc extinguishing cavity, the air jet is cylindrical, and the diameter of the circular cross section of the air jet is in the range of 2 mm to 6 mm.

[0021] According to one embodiment of the present invention, the arc extinguishing cavity insulating core rod is provided along the arc extinguishing cavity insulating jacket and is adjacent to the air gap cavity.

[0022] The composite insulator device provided by the present invention has the electrical insulation performance and mechanical strength of conventional line insulators and can play the role of supporting and fixing conductors; it also has a lightning protection function, can limit the flashover path to the ground of the conductor when it is struck by lightning, maintain the stability of the discharge action voltage, and can reliably block the power frequency continuous current after the lightning strike, protecting the conductor and insulator from damage caused by lightning strikes; the lightning arrester and the insulator are integrated into an integrated design, and at the same time, the strong arc extinguishing ability of the enhanced arc-extinguishing gap unit is utilized to reduce the rated voltage of the varistor unit, thereby achieving miniaturization, lightweight and low cost of the device; the device is assembled when it leaves the factory, and there is no need to adjust the assembly parts on site. When connecting to the insulated conductor, there is no need to strip the insulation layer of the conductor, and the installation and construction are simple and convenient; the varistor unit of the device is designed to be divided into two sections, which has more balanced force and better rigidity and sealing performance; due to the air gap isolation, the power frequency operating voltage is mainly applied to the insulating support part, and the power frequency voltage that the varistor unit can withstand for a long time is very low, effectively solving the problem of resistor chip aging; the device has a sleek and compact appearance, reducing the risk of foreign objects being blown away by strong winds.

[0023] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0025] Figure 1 A structural diagram of a conventional out-of-band series gap arrester disclosed in an embodiment of the present invention;

[0026] Figure 2 Another structural diagram of a conventional external-band series gap arrester disclosed in an embodiment of the present invention;

[0027] Figure 3 This is a structural diagram of a composite insulator device disclosed in an embodiment of the present invention;

[0028] Figure 4 This is a schematic cross-sectional structural diagram of a composite insulator device along the central axis disclosed in an embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram of a typical structure of an enhanced arc-extinguishing gap unit of a composite insulator device disclosed in an embodiment of the present invention;

[0030] Figure 6 This is a schematic structural diagram of an enhanced arc-extinguishing gap unit of a composite insulator device using a plurality of arc-extinguishing cavity units connected in series according to an embodiment of the present invention;

[0031] Figure 7 This is a schematic diagram of the internal structure of the arc extinguishing cavity of the enhanced arc extinguishing gap unit of the composite insulator device disclosed in an embodiment of the present invention.

[0032] Figure numerals: 1—varistor unit; 2—insulating support; 3—enhanced arc-extinguishing gap unit; 4—mounting hardware; 101—resistor sheet; 102—potential extraction electrode; 103—curing sleeve; 104—insulating jacket of varistor unit; 201—insulating core rod; 202—insulating jacket of insulating support; 301—arc-extinguishing cavity; 302—insulating support; 303—gap electrode; 3011—arc-extinguishing cavity unit section; 30100—air gap chamber; 30101—arc-extinguishing cavity insulating jacket; 30102—arc-extinguishing electrode; 30103—isolating gas chamber; 30104—air jet; 30105—insulating core rod of arc-extinguishing cavity. DETAILED DESCRIPTION

[0033] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to provide a thorough and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments shown in the accompanying drawings is not intended to limit the present invention. In the accompanying drawings, identical elements are denoted by the same reference numerals.

[0034] Unless otherwise specified, the terms used herein (including technical terms) have the meanings commonly understood by those skilled in the art. In addition, it is understood that terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clear, the implementation process of the present invention is described in detail below with reference to the flowchart.

[0036] Metal oxide surge arresters with external series gaps (hereinafter referred to as external series gap arresters) are used for lightning overvoltage protection of overhead power lines. The main structure consists of two parts: the surge arrester body consisting of metal oxide resistors and insulating jackets, and the external series gap. It is usually installed in parallel next to the line insulator (string). There are two types of external series gaps currently used: one is a pure air gap, such as Figure 1 As shown, it consists of two electrodes, one electrode is fixed on the high voltage end of the arrester body, and the other electrode is fixed on the line conductor or the lower end of the insulator string; the other is with a support gap, such as Figure 2 As shown, it consists of two electrodes fixed at both ends of a composite insulating support. The lightning discharge path of both types of external series gaps is the air gap between the electrodes.

[0037] The purpose of the external series gap is to reduce the long-term power frequency voltage borne by the arrester during normal line operation, slowing the aging of the resistors and reducing maintenance workload. Only after the lightning overvoltage breaks through the external series gap can the arrester withstand the system's maximum power frequency overvoltage (the most severe operating conditions) for a short period of time. Therefore, the rated voltage parameters of the arrester body should be selected based on the principle of being able to reliably interrupt the power frequency freewheeling arc after a lightning strike under the most severe operating conditions. In the current technical standards for external series gap arresters GB / T 32520-2016 "External series gap metal oxide arresters (EGLA) for overhead transmission and distribution lines above AC 1kV" and DL / T 815-2012 "Composite sheathed metal oxide arresters for AC transmission lines", the selection of the rated voltage of the arrester body follows the above principles, with the rated voltage not less than (the corresponding power frequency follow current is in the mA level) or slightly less than (the arc extinguishing capability of the external series gap itself is appropriately considered, and the corresponding power frequency follow current is about several amperes) the maximum allowable power frequency overvoltage value of the system specified in the standard or acceptable for engineering operation as the specific selection condition. The typical recommended values ​​of the rated voltage standards of the external series gap arrester body selected for AC lines of different voltage levels are shown in Table 1.

[0038] Table 1 Typical recommended values ​​for rated voltage standards of external series gap arresters

[0039]

[0040]

[0041] Although the arc-extinguishing capability of the external series gap itself has been appropriately considered in the selection of the rated voltage of the arrester body, it can be seen from Table 1 that for a rated voltage less than the maximum power-frequency overvoltage of the system, the maximum deviation does not exceed 5% of the maximum power-frequency overvoltage, and the corresponding interruption of the power-frequency aftercurrent is at best a few amperes. Obviously, the arc-extinguishing capability of the external series gap is not deeply utilized. The main reason is that due to the limitations of the current test conditions, the long-gap power-frequency aftercurrent interruption test cannot be carried out. The lack of sufficient arc-extinguishing test data support naturally makes it impossible to achieve a refined design. Secondly, for open external series gaps such as pure air gaps and gaps with support members, the arc-extinguishing capability is greatly affected by the operating environment (wind, temperature, humidity, air density, etc.). The unstable arc-extinguishing performance determines the poor reliability of the device. The above reasons determine that under the existing structure of the arrester with an external series gap, the technical route of attempting to reduce the rated voltage of the arrester body by deeply utilizing the arc-extinguishing capability margin of the external series gap cannot be realized, resulting in the current value of the rated voltage of the arrester body being too high.

[0042] On the other hand, under traditional methods, the external series gap arrester and the line insulator are designed and produced independently of each other and assembled on site. Although there have been attempts in recent years to integrate the external series gap arrester with the line insulator, the external series gap of the integrated varistor unit (equivalent to the arrester body) still uses the conventional support member gap. Therefore, the rated voltage of the selected varistor unit does not change compared with Table 1.

[0043] The main problems or disadvantages of external series gap lightning arresters, which are designed to be separated from line insulators, in current engineering applications are high cost and difficulty in installation, which limits their wider promotion and application in overhead transmission and distribution lines. The high rated voltage of the lightning arrester body means that more resistors are needed during manufacturing, and technical problems such as potential distribution, mechanical strength, and explosion-proof performance caused by the high height need to be solved. The design and production of the device are difficult. The separate design of the lightning arrester and insulator means that more insulation and metal materials are needed, and there are many production processes, which ultimately leads to a high cost of the device. The high rated voltage of the lightning arrester body means that the device is large in size and weight, especially for high-voltage transmission lines. The line sections with a high incidence of lightning faults are often located in complex terrain such as mountains and hills. Sufficient mechanical strength of the pole tower and tower window space are required, and more manpower and material resources are needed for transportation and lifting. In addition, the lightning arrester is installed in combination with the insulator on site. In order to meet the insulation coordination requirements, the pure air gap needs to be manually adjusted during installation so that the gap distance does not exceed the allowable deviation, making on-site installation and construction difficult. The lightning arrester's position further compresses the remaining space on the tower head, causing trouble for subsequent live operations. Corresponding to the total operating mileage of my country's overhead transmission lines of nearly 2 million kilometers and the total operating mileage of overhead distribution lines of more than 4 million kilometers, the huge volume of external series gap lightning arresters used in transmission lines, the economic cost of lightning protection increased by the above-mentioned application shortcomings is significant.

[0044] Obviously, for external series gap lightning arresters, if the rated voltage of the lightning arrester body can be significantly reduced and the production and installation efficiency can be improved, the size and weight of the device can be reduced and the cost can be reduced. This is of great significance for reducing the cost of engineering lightning protection, improving the ability of transmission and distribution lines to resist lightning damage risks, and improving line operation reliability and operational efficiency.

[0045] The existing external series gap arrester adopts a structure in which the arrester body is connected in series with a pure air gap or a gap with a support member. Due to the inherent lack of stability of this type of open external series gap in interrupting power frequency continuous current and the limitation of current test conditions that cannot support the development of long gap power frequency continuous current interruption test research, it is impossible to deeply and finely utilize the arc extinguishing ability of the external series gap. As a result, the rated voltage value of the current external series gap arrester body is too high, the device is large in size and weight, the overall cost is high, and the on-site installation and construction consumes a lot of manpower and material resources. Under the traditional method, the external series gap arrester and the line insulator are designed and produced independently of each other, and assembled on-site. The production process is consuming a lot, the on-site installation operation is complicated, the arrester occupies less tower head space, and has an adverse effect on the later live work. The above-mentioned shortcomings result in a high comprehensive cost of lightning protection when the external series gap arrester is used in current projects. In response to the above-mentioned technical deficiencies, the present invention proposes an enhanced arc-extinguishing type built-in varistor suspension composite insulator, which integrates an external series gap arrester and a line suspension composite insulator into an integrated design, simplifying the production process, reducing material loss, and reducing the size of the device. At the same time, an enhanced arc-extinguishing gap is used to replace a pure air gap or a gap with a support member. The enhanced arc-extinguishing gap has a larger power frequency continuous current interruption capability (kA level) and stable and reliable arc-extinguishing performance to reduce the rated voltage of the varistor unit. Compared with the conventional external series gap arrester and line insulator split combination mode, the present invention has the advantages of small device size, light weight, simple on-site installation and construction, and low overall cost.

[0046] In order to solve the above-mentioned deficiencies in the prior art, the present invention provides a composite insulator device. Figure 3 and Figure 4As shown, the composite insulator device includes four parts, namely a varistor unit, an insulating support, an enhanced arc-extinguishing gap unit, and a mounting hardware. The varistor unit includes a varistor sub-unit core, an insulating core rod, and an insulating outer sleeve. The varistor sub-unit core includes a resistor sheet, a potential extraction electrode, and a curing sleeve. The resistor sheets are evenly arranged axially, and the potential extraction electrode is located at the axially outer end of the resistor sheet. The resistor sheet and the potential extraction electrode are stacked and pressed together axially, and the curing sleeve covers the partial outer surface of the resistor sheet and the potential extraction electrode. The varistor unit is designed to be two sub-units with equal rated voltages, which are placed on the high-voltage side and the low-voltage side of the device respectively. The middle part of the two sub-units is an insulating support. In order to meet the tensile strength requirements, the varistor unit and the insulating support share an insulating core rod, and the insulating core rod material is an epoxy resin glass fiber drawing rod. The interior of the varistor unit is a ring-shaped metal oxide resistor. Several resistors and two potential extraction electrodes with the same outer diameter as the resistor are stacked and pressed axially. The potential extraction electrodes are placed on the outside of the resistor. All resistors and partial outer surfaces of the potential extraction electrodes are covered with a curing sleeve to form a rigid body. The curing sleeve material is glass fiber reinforced plastic. The combination of the resistor, potential extraction electrode and curing sleeve is called the varistor sub-unit core. An insulating core rod is inserted between the two varistor sub-unit cores. The two ends of the insulating core rod are crimped with mounting hardware. The varistor sub-unit core is screwed to the high and low voltage end mounting hardware through the thread on the inner diameter of the potential extraction electrode at one end. The outer surface of the varistor subunit core, the gap between the inner surface of the varistor subunit core and the outer surface of the insulating core rod, and the outer surface of the insulating core rod corresponding to the insulating support are entirely covered and filled with a silicone rubber composite material, forming an external insulating jacket. The insulating jacket has a shed and is molded in one go. This not only provides overall external insulation for the device, but also further strengthens the stability of the varistor subunit core and achieves a complete external sealing of the insulating core rod. An enhanced arc-extinguishing gap unit is provided in parallel with the insulating support to form the external series gap of the varistor unit.

[0047] Enhanced arc-extinguishing gap unit structure Figure 5 As shown, it is composed of an arc extinguishing cavity, an insulating support and a gap electrode. Considering that the space occupied should not be too large, the arc extinguishing cavity is designed to be annular and segmented into arc extinguishing cavity unit sections. Gap electrodes are provided at both ends of each arc extinguishing cavity unit section, and are supported and fixed to the surfaces of the two ends of the insulating support through insulating supports. The potential lead-out electrode of the varistor sub-unit core should be electrically connected to the gap electrode of the adjacent arc extinguishing cavity unit section. The gap electrode material is steel with a galvanized surface, and the structural shape is designed according to specific needs. The number of arc extinguishing cavity unit sections is not limited to 2, and is positively correlated with the line voltage level. It is designed according to needs, and the arc extinguishing cavity unit sections are evenly arranged along the axial direction of the insulating support to form a series discharge channel, such as Figure 6 gesture.

[0048] The internal structure diagram of the arc extinguishing chamber is shown in Figure 7 , consisting of multiple air gap chambers connected in series. The number of air gap chambers connected in series is related to the line voltage level. The higher the voltage level, the more air gap chambers are connected in series. Each air gap chamber consists of a pair of metal arc-quenching electrodes wrapped in an arc-quenching cavity insulating jacket and an isolation air chamber between the electrodes. Each isolation air chamber is equipped with an external air jet. In order to increase the overall mechanical strength of the arc-quenching cavity, an arc-quenching cavity insulation core rod is provided through the interior of the arc-quenching cavity insulation jacket. Specifically, the arc-quenching electrodes are solid spheres made of steel or copper, with a diameter ranging from 8mm to 18mm. The arc-quenching electrodes are spaced evenly, with the shortest distance between two adjacent arc-quenching electrodes ranging from 2mm to 20mm. The arc-quenching cavity insulation jacket is made of silicone rubber composite material. The arc-quenching cavity insulation core rod is made of epoxy resin glass fiber drawing rod, which can be a rectangular cross-section with a side length ranging from 5mm to 30mm. The radial cross-section of the air jet is circular, with a diameter ranging from 2mm to 6mm.

[0049] The enhanced arc-extinguishing type built-in varistor suspension composite insulator provided by the present invention has the electrical insulation performance and mechanical strength of conventional line insulators and can play the role of supporting and fixing conductors; it also has a lightning protection function, can limit the flashover path to the ground of the conductor when it is struck by lightning, maintain the stability of the discharge action voltage, and can reliably block the power frequency continuous current after the lightning strike, protecting the conductor and insulator from lightning damage; the lightning arrester and insulator are integrated into an integrated design, and at the same time, the strong arc extinguishing ability of the enhanced arc-extinguishing gap unit is utilized to reduce the rated voltage of the varistor unit, thereby achieving miniaturization, lightweight and low cost of the device; the device is assembled when leaving the factory, and there is no need to adjust the assembly components on site. When connecting to the insulated conductor, there is no need to strip the insulation layer of the conductor, and the installation and construction are simple and convenient; the varistor unit of the device is designed to be divided into two sections, which has more balanced force and better rigidity and sealing performance; due to the spatial gap isolation, the power frequency operating voltage is mainly applied to the insulating support part, and the power frequency voltage that the varistor unit can withstand for a long time is very low, effectively solving the problem of resistor chip aging; the device has a sleek and compact appearance, reducing the risk of foreign objects being blown away by strong winds.

[0050] The lightning protection action process of the enhanced arc-extinguishing type built-in varistor suspension composite insulator is as follows: when the overhead line group is struck by lightning, when the lightning overvoltage amplitude exceeds the discharge action voltage of the enhanced arc-extinguishing type built-in varistor suspension composite insulator (the discharge action voltage is less than the minimum gap discharge voltage of the line insulator or tower window, generally the former is at least 15% lower than the latter), the air between the arc-extinguishing electrodes inside the enhanced arc-extinguishing gap unit breaks down, the varistor unit is subjected to the lightning overvoltage, and instantly presents a low-impedance characteristic. The lightning energy is released to the ground along the enhanced arc-extinguishing type built-in varistor suspension composite insulator channel, and at the same time, a power-frequency follow-current arc is formed along the lightning impulse discharge channel. At this time, the independent air gap chambers divide the power-frequency arc into multiple short arcs. The high temperature generated by the arc rapidly heats the air within the air gap chamber. The gas expands, creating a pressure differential with the outside world and being ejected through the air jet. Because the arc root remains on the surface of the quenching electrode, the hot air flow carries the arc column out of the air gap chamber, stretching the arc axially. Simultaneously, the arc column is subject to electromagnetic thrust in the magnetic field generated by the line current. This pushes the arc column out of the air gap chamber and into direct contact with the outside air, enhancing the diffusion of the arc plasma and heat dissipation, accelerating the arc deionization process. At the beginning of the power-frequency continuous arc, the arc channel has a large arc resistance because the particles are not yet fully ionized. As the arc develops, the arc resistance gradually decreases. When the arc resistance decreases to its minimum value, the arc current rises to its maximum value. Thereafter, the arc resistance is dominated by the deionization process of the arc pushed out of the air gap chamber. The arc current decreases as the arc resistance increases again. This process continues irreversibly until the arc resistance increases sufficiently to reduce the arc current to zero. Usually, the power-frequency continuous current crosses the zero point of the voltage before the continuous current crosses the zero point. Research shows that, depending on the design parameters, the maximum continuous current peak that can be interrupted by the enhanced arc-extinguishing gap unit can reach 1kA to 3kA. Moreover, due to the non-open air gap, the stability of the continuous current interruption is almost unaffected by the operating environment. Even when the surface of the arc-extinguishing cavity insulation jacket and the isolation gas chamber are frozen, the continuous current can still be stably interrupted. In addition, the effective operation number of the enhanced arc-extinguishing gap unit can reach dozens of times, which is fully capable of meeting the requirements of the use of the varistor unit.

[0051] After a lightning strike, the most demanding working condition of the varistor unit is to withstand the maximum power frequency overvoltage of the system. At this time, the varistor unit instantly returns to a high impedance state. Under the rated voltage value recommended by the current technical standards, the varistor unit itself can suppress the power frequency continuous current to a maximum level of several amperes, directly blocking the continuous current. The present invention can reduce the rated voltage value of the varistor unit, and use the arc extinguishing ability of the enhanced arc extinguishing gap unit to block the power frequency continuous current in the circuit that increases due to the reduction in the rated voltage of the varistor unit. Therefore, it is only necessary to reasonably select the rated voltage of the varistor unit so that the peak power frequency continuous current in the circuit does not exceed the arc extinguishing ability of the enhanced arc extinguishing gap unit, and the power frequency continuous current can be effectively blocked. For the value range of the rated voltage of the varistor unit, based on the volt-ampere characteristic curve of the metal oxide resistor under the current typical process, the cross-sectional area of ​​the resistor is from 615mm 2 to 7850mm 2 , covering 10kV ~ 1000kV line levels, the switching impulse residual pressure test results are shown in Table 2. The pressure ratio range corresponding to the impulse current of 1kA ~ 3kA is about 1.3 ~ 1.5. The rated voltage of the varistor unit is reduced according to this ratio. Compared with the current standard recommended value (Table 1), it can be reduced by about 23% ~ 33%. The reduction is significant, which supports the realization of good miniaturization, lightweight and low-cost design goals.

[0052] Table 2 Typical metal oxide resistor switching impact residual voltage test results

[0053]

[0054] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0055] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0056] The invention has been described above with reference to a few embodiments. However, it is readily apparent to a person skilled in the art that other embodiments than the ones disclosed above are equally within the scope of the invention, as defined by the appended patent claims.

[0057] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / the [means, component, etc.]" are to be interpreted openly as referring to at least one instance of the means, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not necessarily need to be performed in the exact order disclosed, unless explicitly stated otherwise.

Claims

1. A composite insulator device with a built-in varistor unit, characterized in that: The composite insulator device comprises: A varistor unit (1), an insulating support (2), an enhanced arc-extinguishing gap unit (3), and a mounting hardware (4); the varistor unit (1) is designed to be two subunits with equal rated voltages, which are respectively placed on the high-voltage side and the low-voltage side of the composite insulator device; the middle part of the two subunits is the insulating support (2); and the varistor unit (1) and the insulating support (2) share an insulating core rod; The varistor unit (1) comprises a varistor subunit core, an insulating core rod (201), and a first insulating outer sleeve (104); the varistor subunit core comprises a resistor sheet (101), a potential extraction electrode (102), and a curing sleeve (103); the resistor sheet (101) is evenly arranged in the axial direction; the potential extraction electrode (102) is located at the axial outer end of the resistor sheet (101); the resistor sheet (101) and the potential extraction electrode (102) are stacked and pressed in the axial direction; and the curing sleeve (103) covers the partial outer surfaces of the resistor sheet (101) and the potential extraction electrode (102); The insulating support (2) comprises an insulating core rod (201) and a second insulating outer sleeve (202); The insulating core rod (201) axially penetrates the varistor subunit core and the insulating pillar (2); the outer surface and end surface of the varistor subunit core and the gap between the inner surface of the varistor subunit core and the outer surface of the insulating core rod (201) are entirely covered and filled with the first insulating jacket (104); the outer surface of the insulating core rod (201) corresponding to the insulating pillar (2) is entirely covered with the second insulating jacket (202); the first insulating jacket (104) and the second insulating jacket (202) are made of a silicone rubber composite material and are molded in one step, and the first insulating jacket (104) and the second insulating jacket (202) are in the shape of an umbrella skirt; The enhanced arc-extinguishing gap unit (3) comprises an arc-extinguishing cavity (301), an insulating support (302), and a gap electrode (303); the enhanced arc-extinguishing gap unit (3) is fixed to both ends of the insulating support (2) or is evenly arranged along the axial direction of the insulating support (2); the insulating support (302) is located at the hub position of the arc-extinguishing cavity (301), the gap electrode (303) is located at the hub position and the spoke side of the arc-extinguishing cavity (301), and the gap electrodes (303) on the spoke side of two arc-extinguishing cavity unit sections (3011) are arranged in a straight line corresponding to each other; the arc-extinguishing cavity (301) is annular and is segmented to form arc-extinguishing cavity unit sections, and gap electrodes are provided at both ends of each arc-extinguishing cavity unit section, and are fixed to the surfaces of both ends of the insulating support (2) through the insulating support; the number of the arc-extinguishing cavity unit sections is not limited to 2, and the arc-extinguishing cavity unit sections are evenly arranged along the axial direction of the insulating support (2) to form a series channel; The varistor subunit core is fixed to the mounting hardware (4) via the second connection portion of the potential extraction electrode (102).

2. The composite insulator device according to claim 1, characterized in that: The first connection portion of the potential extraction electrode (102) is electrically connected to the adjacent gap electrode (303).

3. The composite insulator device according to claim 1, characterized in that: The arc extinguishing cavity unit section (3011) comprises at least one air gap chamber (30100), and the air gap chamber (30100) comprises: an arc extinguishing cavity insulating jacket (30101), an arc extinguishing electrode (30102), an isolation gas chamber (30103), an air jet (30104), and an arc extinguishing cavity insulating core rod (30105).

4. The composite insulator device according to claim 3, characterized in that: The arc-extinguishing electrodes (30102) are placed in pairs in the air gap chamber (30100); the arc-extinguishing electrodes (30102) are solid spheres made of steel or copper; the diameter of the arc-extinguishing electrodes (30102) ranges from 8 mm to 18 mm, and the shortest distance between adjacent arc-extinguishing electrodes (30102) ranges from 2 mm to 20 mm.

5. The composite insulator device according to claim 4, characterized in that: The arc extinguishing cavity insulating core rod (30105) is made of an epoxy resin glass fiber drawing rod, the arc extinguishing cavity insulating core rod (30105) has a square cross-section, and the side length of the arc extinguishing cavity insulating core rod (30105) ranges from 5 mm to 30 mm.

6. The composite insulator device according to claim 3, characterized in that: The air jet (30104) is located on the outer side of the arc extinguishing cavity insulating jacket (30101), the air jet (30104) is cylindrical, and the diameter of the circular cross section of the air jet (30104) ranges from 2 mm to 6 mm.

7. The composite insulator device according to claim 1 or 3, characterized in that: The arc extinguishing cavity insulating core rod (30105) is arranged along the arc extinguishing cavity insulating jacket (30101) and is adjacent to the cavity position of the air gap chamber (30100).

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