A lightning arrester

Abstract

The present invention discloses a lightning arrester, comprising an insulating tube, both ends of which are sealed with conductive seals, the insulating tube is filled with quartz sand, the quartz sand wraps an arc-starting wire and electrically connects the conductive seals at both ends, one end of the lightning arrester is fixedly connected to a grounding end or a live end via a connector, and the other end forms a discharge gap with the live end or the grounding end, the discharge gap is smaller than the air gap of the insulator, when a lightning overvoltage breaks through the discharge gap, the arc-starting wire fuses to induce an arc to discharge lightning, the arc is suppressed and extinguished by the quartz sand, and line tripping is avoided; compared with the prior art, the lightning arrester has the advantages of small cross-section, light weight, and the length can be manufactured and assembled according to the needs of the installation site, and the overall cost is greatly reduced, so that the lightning arrester can be installed on overhead transmission lines with a large area or even full coverage, thereby greatly reducing the lightning tripping rate and having technical and economic feasibility and practicality.

Description

Technical Field

[0001] The present invention relates to the technical field of lightning protection for transmission towers, and particularly to a lightning arrester. Background Art

[0002] Most of the transmission lines in the power system are overhead lines and are prone to lightning trip. According to statistics, lightning-induced trips account for about 80% of all trip times, bringing great difficulties to the power supply protection work during peak summer power consumption and causing serious losses to the national economy.

[0003] At present, transmission lines generally adopt lightning conductors and grounding for lightning protection, which are difficult to defend against side flashes. To defend against lightning with a relatively large lightning amplitude, a relatively small grounding resistance is required, and the construction and maintenance costs of the grounding grid are relatively high. A lightning arrester can discharge the lightning current into the ground to avoid tripping caused by continuous short-circuit of power frequency current. The length of transmission lines is usually dozens of kilometers or even hundreds of kilometers. However, since the protection range of a lightning arrester is only about 300 meters, to avoid lightning trips of transmission lines, lightning arresters need to be installed on all towers along the line. Zinc oxide lightning arresters have relatively high requirements for manufacturing processes, high costs, are overall heavy, difficult to transport and install, are prone to damage or even explosion, and require periodic tests during use, with too high operation and maintenance costs, resulting in the failure of zinc oxide lightning arresters to be widely promoted on transmission lines.

[0004] By installing a lightning protection device that uses gas generation to extinguish arcs on the tower, low-cost lightning protection can be achieved. However, since the high-pressure gas ejected explosively will generate a huge impact force, the requirements for the structural strength of the lightning arrester body and the installation bracket are relatively high, and it is more difficult to extinguish arcs for lines with higher voltage levels. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a lightning arrester with low manufacturing, installation and maintenance costs, safe and reliable, which can be widely used on transmission lines to significantly reduce the lightning trip rate of transmission lines.

[0006] The technical solution of the present invention is as follows: It includes an insulating tube, the two ends of which are sealed with conductive end caps. The insulating tube is filled with quartz sand, and the quartz sand wraps an arc-drawing wire that is electrically connected to the two conductive end caps at both ends. One end of the lightning arrester is fixedly connected to the grounding end or the live end of the tower through a connector, and the other end forms a discharge gap with the live end or the grounding end. The discharge gap is smaller than the air gap of the insulator. When the lightning overvoltage breaks down the discharge gap, the arc-drawing wire fuses to trigger an arc to discharge the lightning, and the arc is suppressed and extinguished by the quartz sand to avoid line tripping.

[0007] Compared with the prior art, the beneficial effects of the present invention are as follows: By installing the lightning arrester of the present invention on the grounding end or live end structure of the line, when the line at this place is struck by lightning, since the discharge gap is smaller than the insulator air gap, the lightning overvoltage preferentially breaks down the discharge gap, so that the insulator string is prevented from being damaged by the breakdown arc erosion. The arc-drawing wire fuses to generate an arc to discharge the lightning. The arc is suppressed by quartz sand to control the arc current and increase the arc voltage. After the lightning current is discharged, the power-frequency arc is extinguished within 10 milliseconds, avoiding line tripping. After the arc-drawing wire fuses, the lightning arrester becomes an insulator, and the discharge gap is greater than the insulator air gap after connecting the insulation length of the lightning arrester in series. After the lightning arrester completes one lightning protection, it automatically detaches. Although lightning tripping generally accounts for about 80% of the transmission line tripping, due to the huge number of hanging points, specifically for each hanging point of each tower, the probability of lightning-induced tripping per year is between one-thousandth and one-hundredth. The repeated lightning strike of a single lightning arrester is a very low-probability event. The lightning arrester of the present invention is for one-time use, and the manufacturing and installation costs are much lower than those of zinc oxide lightning arresters. Economically, it can achieve full coverage installation of transmission lines, thereby significantly reducing the lightning tripping rate and even achieving zero lightning tripping. Compared with gas-producing lightning arresters, the lightning arrester of the present invention has a stronger arc extinguishing ability and is an arc extinguishing technology with a high breaking capacity, which can extinguish the power-frequency short-circuit current of 50 - 100 kA, fully meeting the coordination requirements of the existing power grid. When the lightning arrester of the present invention extinguishes the arc, it will not generate impact force, avoiding the risk of excessive gas production and explosion and impact of gas-producing lightning arresters under a large short-circuit current. For voltage levels above 110 kV, the length of the gas production pipe reaches more than one meter, and the impact force generated by the supersonic jet airflow poses higher requirements for the installation structure and poses a risk of harm to nearby equipment and personnel.

[0008] Preferably, the arc-drawing wire is composed of one of copper, silver, gold, iron, aluminum or an alloy thereof, or graphene.

[0009] Preferably, the insulating tube is an epoxy resin fiberglass tube or a ceramic tube.

[0010] Preferably, the conductive end cap forming one end of the discharge gap is also connected to an electrode through a fuse. When the discharge gap is broken down by lightning overvoltage, the fuse melts and the electrode detaches from the lightning arrester.

[0011] Preferably, a cavity is included on the periphery of the fuse to connect with the end of the insulating tube. The inner wall of the cavity includes gas-producing material. When the fuse melts and generates arc heat to cause the gas-producing material to produce gas, the electrode is impacted by the high-pressure gas and detaches from the lightning arrester.

[0012] Preferably, the electrode extends a preset length circumferentially along the swing of the wire at the live end, and keeps the length of the discharge gap within a preset range when the wire at the live end swings.

[0013] Preferably, the connecting member includes a first clamping block and a second clamping block, which are fastened by bolts to form a clamping space matching the cross-section of the structural steel of the grounding end or the live end. The first clamping block is connected to a movable clamping block. The movable clamping block includes a first connecting block and a second connecting block perpendicular to each other. The first connecting block and the first clamping block are adjustably connected by a long screw hole and a bolt. A plurality of groups of screw holes are formed on the second connecting block. One end of the arrester is connected to the second connecting block by a U-shaped bolt and selects a group of screw holes, so as to meet the requirements of the discharge gap for the installation of the arrester.

[0014] Preferably, the discharge gap is equal to 70-90% of the lightning protection voltage gap of the line live conductor.

[0015] Preferably, a plurality of the arresters are axially connected by the conductive end caps or form the discharge gap to be combined into a series arrester.

[0016] Preferably, the middle part of the insulating pipe is traction-connected to the grounding end structure through an insulating guy wire. Description of the Drawings

[0017] Figure 1 It is a cross-sectional view of one implementation structure of an arrester of the present invention;

[0018] Figure 2 It is a schematic installation structure diagram of the first embodiment of the present invention;

[0019] Figure 3 It is a schematic assembly diagram of the connecting member in the first embodiment of the present invention;

[0020] Figure 4 It is a schematic sectional connection diagram of the second embodiment of the present invention;

[0021] Figure 5 It is a schematic installation structure diagram of the third embodiment of the present invention. Detailed Embodiments

[0022] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Embodiment 1

[0024] Please refer to Figures 1 to 3, this embodiment provides a lightning arrester 1, which includes an insulating tube 31 sealed at both ends with conductive end caps 34. The insulating tube 31 is filled with quartz sand 32, and the quartz sand 32 wraps an arc-drawing wire 33 which is electrically connected to the conductive end caps 34 at both ends. One end of the lightning arrester 1 is fixedly connected to the grounding end structure 8 of the pole tower through a connector 7, and the other end forms a discharge gap 3 with the live line body 4. The live line body 4 can be a wire or an additional electrode (not shown) on the wire. The discharge gap 3 is smaller than the air gap 5 of the insulator 6. When the lightning overvoltage breaks down the discharge gap 3, the arc-drawing wire 33 fuses to trigger an arc to discharge the lightning, and the arc is suppressed and extinguished by the quartz sand 32 to avoid line tripping. The arc-drawing wire 33 is made of copper wire or copper wire with an anti-corrosion surface layer added, and its diameter is between 0.1 and 0.3 mm. Under the condition that the manufacturing process is satisfied, using a thinner wire diameter can reduce the number of metal ions, which is beneficial to extinguishing the arc. The arc-drawing wire 33 can also be made of graphene wire, which generates insulating carbon dioxide gas under the action of the arc to improve the insulation performance. The insulating tube 31 is an epoxy resin fiberglass tube with an inner diameter of 20 - 30 mm and a wall thickness of 2 - 10 mm selected according to the application scenario. The size of the inner diameter considers the arc extinguishing effect of the filled quartz sand, and the wall thickness considers factors such as the pressure inside the tube when the arc is generated and the wind resistance and stress strength of the insulating tube. The diameter of the quartz sand 32 is between 0.1 and 0.5 mm, and preferably, quartz sand 32 with a uniform diameter of 0.2 - 0.3 mm is densely filled. The conductive end cap 34 forming one end of the discharge gap 3 is also connected to an electrode 2 through a fuse 37. When the discharge gap 3 is broken down by the lightning overvoltage, the fuse 37 fuses and the electrode 2 is separated from the lightning arrester 1. The electrode 2 includes a fuse 37, and a tube cavity 38 on the periphery of the fuse 37 is connected to the end of the insulating tube 31. The inner wall of the tube cavity 38 includes polymer gas-generating materials such as nylon. When the fuse 37 fuses to generate an arc and high temperature, the gas-generating material generates gas, and the electrode 2 is impacted by the high-pressure gas and separated from the lightning arrester 1. The electrode 2 also includes a transverse electrode body 39, which extends circumferentially along the swing of the live line body 4, with a length of 200 - 300 mm, and keeps the length of the discharge gap 3 within a preset range when the live line body 4 swings. The discharge gap 3 is 70 - 90% of the lightning protection voltage gap of the live line body 4, preferably 80%. For a 110 kV line, the discharge gap 3 is 850 mm long.

[0025] The connecting member 7 includes a first clamping block 11 and a second clamping block 10, which are fastened by bolts 16 to form a clamping space matching the steel section of the grounding end or the live end structure 8. The first clamping block 11 is connected to a movable clamping block. The movable clamping block includes a first connecting block 12 and a second connecting block 13 that are perpendicular to each other. The first connecting block 12 and the first clamping block 11 are adjustably connected by a long screw hole and a bolt. A plurality of groups of screw holes 14 are provided on the second connecting block 13. One end of the arrester 1 is connected to the second connecting block 13 by a U-shaped bolt 15 by selecting one group of screw holes 14, so as to meet the requirements of the discharge gap 3 for the installation of the arrester 1. For voltage levels above 220 kV, the length of the arrester 1 is relatively long, usually greater than 2 meters. Preferably, the middle part of the insulating tube 31 is traction-connected to the grounding end structure 8 by an insulating stay wire 9, which can improve the installation stability of the arrester.

[0026] Embodiment 2

[0027] As Figure 4 shown, the difference between this embodiment and Embodiment 1 is that in this embodiment, the length of the arrester 3 is relatively long. For the convenience of transportation and installation, the arrester 3 can be manufactured and transported in sections. During installation, the arrester 21 and the arrester 22 are axially connected by a conductive end cap 23 and a conductive end cap 24 to form a series arrester. The arrester 21 and the arrester 22 are in series connection. The principle of the series arrester in this embodiment is the same as that of the above embodiment, so it will not be repeated.

[0028] Embodiment 3

[0029] As Figure 5 shown, the similarity between this embodiment and Embodiment 2 is that in this embodiment, the length of the arrester 3 is relatively long. For the convenience of transportation and installation, the arrester 3 can be manufactured and transported in sections. The difference is that during installation, the arrester 21 and the arrester 22 are respectively installed on the grounding end 8 and the live end 4 by the connecting member 7. One end of each of the arrester 21 and the arrester 22 forms a discharge gap 3. The arrester 21 and the arrester 22 are connected by the discharge gap 3 to form a series arrester. The discharge gap 3 is smaller than the air gap 5 of the insulator 6. When the lightning overvoltage breaks down the discharge gap 3, the arc-drawing wires 33 in the arrester 21 and the arrester 22 are melted to trigger an arc to discharge the lightning. The arc is suppressed and extinguished by the quartz sand 32, avoiding line tripping. This embodiment can facilitate the integrated installation with the insulator, save the cost of the connection structure, and keep the length of the discharge gap 3 stable and unchanged when the conductor sways in the wind.

[0030] It can be seen from the above embodiments that the arrester of the present invention has a small cross-section and light weight compared with the prior art, and the length can be manufactured and assembled according to the needs of the installation site. No high-speed gas impact force will be generated when lightning strikes. The arrester of the present invention is connected in series with the discharge gap. In the operating state, no current passes through the arc-starting line. The cross-section of the arc-starting line can ignore the load current factor. The cross-section is small and the arc extinguishing ability is stronger. The overall cost of manufacturing, transportation, installation, operation and other links is greatly reduced, so that the arrester can be installed on a large area or even fully covered on the overhead transmission line, so as to achieve a significant reduction in the lightning tripping rate, so as to ultimately achieve "zero tripping" of lightning strikes on power transmission equipment while having technical and economic feasibility and practicality.

[0031] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A lightning arrester, characterized in that: Applied to overhead lines, it includes an insulating tube sealed at both ends with conductive end caps. The insulating tube is filled with quartz sand, and the quartz sand wraps the arc wire which is electrically connected to the conductive end caps at both ends. One end of the lightning arrester is fixedly connected to the grounding end or the live end of the pole tower through a connecting piece, and the other end forms a discharge gap with the live end or the grounding end. The discharge gap is smaller than the air gap of the insulator. When the lightning overvoltage breaks down the discharge gap, the arc wire melts to trigger an arc to discharge the lightning. The arc is suppressed and extinguished by the quartz sand to avoid line tripping.

2. The lightning arrester according to claim 1, wherein: The arc wire includes one of copper, silver, gold, iron, aluminum or an alloy thereof, or graphene.

3. An arrester according to claim 1, characterized in that: The insulating tube is an epoxy resin fiberglass tube or a ceramic tube.

4. The lightning arrester according to claim 1, characterized in that: The conductive end cap forming one end of the discharge gap is also connected to an electrode through a fuse. When the discharge gap is broken down by the lightning overvoltage, the fuse melts and the electrode is separated from the lightning arrester.

5. An arrester according to claim 4, characterized in that: A cavity is included on the periphery of the fuse to connect to the end of the insulating tube. The inner wall of the cavity includes a gas-producing material. When the fuse melts and generates an arc with high temperature to make the gas-producing material produce gas, the electrode is impacted by the high-pressure gas and separated from the lightning arrester.

6. The lightning arrester according to claim 5, characterized in that: The electrode extends a preset length circumferentially along the swing of the wire at the live end, and keeps the length of the discharge gap within a preset range when the wire at the live end swings.

7. The lightning arrester according to claim 1, characterized in that: The connecting piece includes a first clamp block and a second clamp block, which are fastened by bolts to form a clamping space matching the cross-section of the structural steel of the grounding end or the live end. The first clamp block is connected to a movable clamp block. The movable clamp block includes a first connecting block and a second connecting block that are perpendicular to each other. The first connecting block and the first clamp block are adjustably connected through a long screw hole and a bolt. A number of groups of screw holes are provided on the second connecting block. One end of the lightning arrester is connected to the second connecting block through a U-bolt by selecting one group of screw holes, so as to ensure that the installation of the lightning arrester meets the requirements of the discharge gap.

8. An arrester according to claim 1, characterized in that: The discharge gap is 70% - 90% of the air gap of the insulator.

9. The lightning arrester according to claim 1, wherein: A number of the lightning arresters are axially connected through the conductive end caps to form a series lightning arrester.

10. An arrester according to claim 1, characterized in that: The middle of the insulating tube is traction-connected to the grounding end structure through an insulating guy wire.

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