Composite cross arm and transmission tower

Abstract

The present application discloses a composite cross arm and a transmission tower. The composite cross arm includes two post insulators and two stay insulators. One ends of the two post insulators and the two stay insulators are all used for connecting with the tower body of the transmission tower, and the other ends are connected together to form an end of the composite cross arm for hanging transmission lines. Wherein, the two stay insulators are located on the same side of the two post insulators and are respectively arranged adjacent to the two post insulators. At the same time, the included angle range between the two post insulators is 20° to 50°, and the included angle range between the post insulator and the adjacent stay insulator is 15° to 45°. The composite cross arm provided by the present application has strong stability and can provide favorable conditions for installing a first grading ring on the post insulator and a second grading ring on the stay insulator.

Description

Technical Field

[0001] This application relates to the technical field of power transmission, and particularly to a composite cross arm and a transmission tower. Background Art

[0002] Due to the advantages of light weight, high strength, corrosion resistance, easy processing, designability, and good insulation performance, composite materials are one of the ideal materials for building the structure of transmission towers. Moreover, the towers made of composite materials have the advantages of light tower weight, small tower head size, light structure, easy processing and forming, low transportation and assembly costs, corrosion resistance, resistance to high and low temperatures, high strength, low possibility of being stolen, and low line maintenance costs.

[0003] The inventors of this application found that the performance of the current towers made of composite materials needs to be improved. At present, the general composite cross arm is formed by combining post insulators and stay insulators, including single-column structure, single-column single-stay structure, double-column single-stay structure, etc. When the post insulator or stay insulator of the single-column or single-stay structure breaks, it will lead to the aging of the entire composite cross arm structure. Therefore, a more stable composite cross arm structure needs to be proposed. Summary of the Invention

[0004] The purpose of this application is to provide a composite cross arm and a transmission tower, which can ensure the stability of the composite cross arm and provide favorable conditions for installing the first grading ring on the post insulator and the second grading ring on the stay insulator.

[0005] To solve the above technical problems, a technical solution adopted in this application is: providing a composite cross arm, the composite cross arm includes two post insulators and two stay insulators. One ends of the two post insulators and the two stay insulators are all used for connecting with the tower body of the transmission tower, and the other ends are connected together to form the end of the composite cross arm for hanging the transmission line. Wherein, the two stay insulators are located on the same side of the two post insulators and are respectively adjacent to the two post insulators. At the same time, the included angle range between the two post insulators is 20° - 50°, and the included angle range between the post insulator and the adjacent stay insulator is 15° - 45°.

[0006] On the one hand, the above composite cross arm is provided with two post insulators and two stay insulators connected together to form the end for hanging the transmission line, so that a stable triangular structure is formed between the composite cross arm and the tower body, which can greatly improve the stability performance of the composite cross arm. On the other hand, the included angle range between the two post insulators is set to be 20° - 50° and the included angle range between the post insulator and the adjacent stay insulator is set to be 15° - 45°, which can not only meet the force requirements of the composite cross arm, but also provide favorable conditions for installing the first grading ring on the post insulator and the second grading ring on the stay insulator.

[0007] Among them, the post insulator includes an insulator and umbrella skirts wrapped around the periphery of the insulator. Among them, the insulator is a solid insulating core, or the insulator is a hollow insulating tube, and an insulating gas is sealed in the hollow insulating tube, and the absolute pressure value range of the insulating gas is 0.1 to 0.15 MPa.

[0008] Setting the insulator as a hollow insulating tube as described above, and an insulating gas with an absolute pressure value range of 0.1 to 0.15 MPa is sealed therein, which can avoid the daily maintenance and monitoring of the post insulator.

[0009] Among them, the umbrella skirt includes a plurality of spaced and identical umbrella bodies, and the umbrella bodies are radially symmetric with respect to the insulator.

[0010] The above setting that the umbrella body is radially symmetric with respect to the insulator is beneficial to the self-cleaning of the umbrella skirt and enables the post insulator to have characteristics such as pollution resistance, rain flash resistance, and ice flash resistance.

[0011] Among them, the post insulator further includes a first connecting fitting. The two ends of the post insulator are respectively connected with the first connecting fitting to realize the installation of the post insulator. The first connecting fitting includes: a flange cylinder, which is arranged as a hollow structure along the axial direction and sleeved on the end of the insulator; a flange plate, which seals the end of the flange cylinder away from the insulator; a first connecting plate, in the axial direction of the post insulator, the first connecting plate extends outward from the side of the flange plate away from the flange cylinder, and in the radial direction of the post insulator, the first connecting plate extends to the opposite sides of the flange cylinder and is connected with the flange cylinder; a second connecting plate, the side of the second connecting plate abuts against the plate surface of the first connecting plate and extends from the first connecting plate to the outer peripheral surface of the flange cylinder, so as to form an installable space between the first connecting plate and the second connecting plate; among them, the two first connecting plates at the two ends of the post insulator are not parallelly arranged.

[0012] The non-parallel arrangement of the two first connecting plates at the two ends of the above post insulator enables the post insulator to be installed and applied in different scenarios.

[0013] Among them, a plurality of cementing grooves arranged at intervals along the axial direction and a flow-through groove communicating with the plurality of cementing grooves are provided on the inner wall of the flange cylinder. Among them, the cementing grooves and the flow-through groove are filled with an adhesive to fixedly connect the flange cylinder and the insulator.

[0014] The above setting that the flow-through groove communicates with the cementing groove can improve the glue injection rate and can improve the anti-torsion performance of the composite cross arm without replacing the adhesive with better bonding performance.

[0015] Among them, the number of the flow grooves is multiple, and the multiple flow grooves are arranged at intervals along the circumferential direction of the flange cylinder; or, the bottom surface of the flow groove is a plane or a curved surface.

[0016] When the bottom surface of the above-mentioned flow groove is a plane, the torsional strength of the composite cross arm can be improved.

[0017] Among them, the widths of the multiple potting grooves are equal, and the width of the potting groove is smaller than the width of the interval between two adjacent potting grooves; or, the width of the potting groove does not exceed 12 mm; or, the ratio of the length of the contact part between the inner wall of the flange cylinder and the insulator to the outer diameter of the insulator ranges from 0.8 to 1.2.

[0018] The above setting that the width of the potting groove is smaller than the width of the interval between two adjacent potting grooves can improve the bending strength of the post insulator.

[0019] Among them, on the disk surface of the flange plate facing the insulator, there is a first sealing groove facing the end face of the insulator, and a first sealing member is arranged in the first sealing groove; and, on the inner wall of the flange cylinder, there is a second sealing groove adjacent to the flange plate, and the second sealing groove and the multiple potting grooves are arranged at intervals in sequence along the direction away from the flange plate, and a second sealing member is arranged in the second sealing groove; among them, the width of the first sealing groove and / or the second sealing groove remains unchanged or gradually becomes smaller in the direction close to the insulator.

[0020] The above setting of the second sealing groove and the second sealing member can prevent the adhesive in the potting process from entering the first sealing groove and corroding the first sealing member, resulting in the failure of the first sealing member. At the same time, the width of the second sealing groove gradually becomes smaller in the direction close to the insulator, which can prevent the second sealing member from falling off during the installation process.

[0021] Among them, the insulator is a hollow insulating tube, and a sunk groove is arranged on the disk surface of the flange plate far from the insulator, and a self-sealing valve is sunk in the sunk groove; and / or, a drying device is arranged in the insulator, and the drying device is installed on the disk surface of the flange plate close to the insulator.

[0022] The above setting of the self-sealing valve can, on the one hand, realize the extraction and filling of the gas in the insulator, and on the other hand, realize the sealing measurement and micro water value measurement before the product leaves the factory; the setting of the drying device can keep the inside of the insulator dry.

[0023] Among them, the composite cross arm further includes end fittings, and the end fittings include: a connecting column, which is cylindrical; a strut connecting plate, the side of which abuts against the outer peripheral surface of the connecting column. Among them, the other ends of the two strut insulators that are not connected to the tower body are installed on the strut connecting plate at intervals along the axial direction of the connecting column; there are two diagonal tension connecting plates, and both of the two diagonal tension connecting plates are arranged on the same side of the strut connecting plate and are used to respectively install the other ends of the two diagonal tension insulators that are not connected to the tower body; a hanging plate, which is located on the other side of the strut connecting plate away from the diagonal tension connecting plate and extends along the outer peripheral surface of the connecting column to form a semi-surrounding structure for hanging the transmission line.

[0024] The setting of the above-mentioned end fittings can ensure the connection strength between the strut insulator and the diagonal tension insulator.

[0025] Among them, the diagonal tension connecting plate is provided with a through hole, and a metal part is embedded in the through hole. The metal part is axially arranged as a hollow structure for a locking part to pass through to install the diagonal tension insulator on the diagonal tension connecting plate.

[0026] The setting of the above-mentioned metal part can increase the connection strength of the diagonal tension connecting plate and prevent the diagonal tension connecting plate from cracking under long-term stress.

[0027] Among them, the composite cross arm further includes a second connection fitting for connecting the tower body and the diagonal tension insulator. The second connection fitting includes: a first sub-connection fitting, which is connected to the diagonal tension insulator; a second sub-connection fitting, one end of which is connected to the first sub-connection fitting in an adjustable position, and the other end is used to connect to the tower body, so as to realize the connection between the diagonal tension insulator and the tower body.

[0028] The setting of the above-mentioned second connection fitting can make the structure of the composite cross arm variable and suitable for different application scenarios.

[0029] Among them, the first sub-connection fitting is provided with a plurality of installation parts arranged in an arc shape, and the second sub-connection fitting is alternatively connected to one of the installation parts.

[0030] The setting of the above-mentioned installation parts can make the distance between the diagonal tension insulator and the tower body adjustable.

[0031] To solve the above technical problems, another technical solution adopted by this application is: to provide a transmission tower, which includes a tower body and a composite cross arm as described above connected to the tower body.

[0032] The beneficial effects of the present application are as follows: On the one hand, for the composite cross arm of the present application, two post insulators and two stay insulators are arranged and connected together, so as to form a stable triangular structure between the composite cross arm and the tower body, which can greatly improve the stability performance of the composite cross arm. On the other hand, the included angle range between the two post insulators is set to be 20° to 50°, and the included angle range between the post insulator and the adjacent stay insulator is set to be 15° to 45°. While meeting the force requirements of the composite cross arm, it also optimizes the length of the composite cross arm and the width of the tower body, and provides favorable conditions for installing the first grading ring on the post insulator and the second grading ring on the stay insulator.

[0033] At the same time, the present application also arranges a flow groove on the inner wall of the flange cylinder to communicate adjacent two potting grooves, which can improve the potting rate, reduce the risk of air bubble retention, make the combination of the first connecting fitting and the insulator more firm, and thus can improve the anti-torsion performance of the composite cross arm without replacing the adhesive with better bonding performance.

[0034] In addition, the present application also arranges a second sealing groove and a second sealing member on the inner wall of the flange cylinder, which can prevent the adhesive during the potting process from entering the first sealing groove to corrode the first sealing member and cause the failure of the first sealing member. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. Among them:

[0036] Figure 1 is a schematic structural diagram of an embodiment of a transmission tower;

[0037] Figure 2 is Figure 1 a schematic structural diagram of the composite cross arm in

[0038] Figure 3 is Figure 2 a partial structural diagram of the composite cross arm;

[0039] Figure 4 is Figure 2 a schematic structural diagram when the post insulator and the first connecting fitting in

[0040] Figure 5 is Figure 4 a schematic cross-sectional view of the structure along the B-B section;

[0041] Figure 6 is Figure 5 an enlarged schematic diagram at C in

[0042] Figure 7 is Figure 4 A schematic structural diagram of the first connecting fitting in

[0043] Figure 8 is Figure 7 A schematic diagram of the first connecting fitting at another angle;

[0044] Figure 9 is Figure 7 A schematic diagram of the first connecting fitting at another angle;

[0045] Figure 10 is Figure 7 A schematic cross-sectional diagram of the first connecting fitting;

[0046] Figure 11 is Figure 10 An enlarged schematic diagram at position F in

[0047] Figure 12 is Figure 5 An enlarged schematic diagram at position D in

[0048] Figure 13 is Figure 12 An enlarged schematic diagram at position G in an application scenario;

[0049] Figure 14 is Figure 12 An enlarged schematic diagram at position G in another application scenario;

[0050] Figure 15 is Figure 5 An enlarged schematic diagram at position E in

[0051] Figure 16 is Figure 2 A schematic structural diagram of the end fitting in

[0052] Figure 17 is Figure 16 A schematic diagram of the end fitting at another angle;

[0053] Figure 18 is Figure 3 An enlarged schematic diagram at position A in

[0054] Figure 19 A schematic structural diagram of an embodiment of the composite cross arm of the present application. Specific embodiments

[0055] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0056] Referring to Figures 1 to 5 , the transmission tower 1000 includes a tower body 1100 and a composite cross arm 1200 connected to the tower body 1100. At the same time, the composite cross arm 1200 includes a post insulator 1210 and a stay insulator 1220.

[0057] The number of both the post insulator 1210 and the stay insulator 1220 is two. One ends of the two post insulators 1210 and the two stay insulators 1220 are all connected to the tower body 1100 of the transmission tower 1000, and the other ends are connected together to form the end of the composite cross arm 1200 for hanging the transmission line. Among them, the two stay insulators 1220 are located on the same side of the two post insulators 1210 and are respectively adjacent to the two post insulators 1210. At the same time, the included angle range between the two post insulators 1210 is 20° to 50°, for example, 20°, 30°, 40°, 45° or 50°. The included angle range between the post insulator 1210 and the adjacent stay insulator 1220 is 15° to 45°, for example, 15°, 30° or 45°.

[0058] Specifically, the tower body 1100 can be a transmission tower structure with common structures such as a lattice tower, a pole or a composite material tower. In this embodiment, the tower body 1100 is a lattice tower, and only a part of its structure is shown in the attached drawing.

[0059] At the same time, the setting of the two post insulators 1210 and the two stay insulators 1220 makes a stable triangular structure between the composite cross arm 1200 and the tower body 1100, which can greatly improve the stability performance of the composite cross arm 1200.

[0060] In addition, considering that the larger the angle between the two post insulators 1210, the greater the mechanical strength that the composite cross arm 1200 can bear, but the length of the composite cross arm 1200 and the width of the tower body 1100 also need to be increased accordingly. Therefore, the included angle range between the two post insulators 1210 is controlled within 20° to 50°, which not only meets the force requirements of the composite cross arm 1200, but also makes the length of the composite cross arm 1200 and the width of the tower body 1100 optimal. Similarly, controlling the included angle range between the post insulator 1210 and the adjacent stay insulator 1220 within 15° to 45° can also achieve the same purpose.

[0061] Specifically, as Figure 1 shown, three groups of composite cross arms are sequentially arranged on the tower body 1100 from bottom to top, specifically the composite cross arm 1200, the composite cross arm 1300, and the composite cross arm 1400. The lengths of the composite cross arm 1200, the composite cross arm 1300, and the composite cross arm 1400 extending outside the tower body 1100 are decreasing, increasing, or in other forms. That is to say, the lengths of the post insulators are decreasing, increasing, or in other forms from bottom to top. And the larger the length of the post insulator 1210, the smaller the included angle between the two post insulators 1210. Combining Figure 2 , assuming the included angle between the two post insulators 1210 is α, the lengths of the two post insulators 1210 are both L, and the width of the tower body 1100 perpendicular to the symmetry axis of the two post insulators 1210 in the horizontal direction is D. From the trigonometric formula, it can be obtained that:

[0062]

[0063] In an application scenario, taking the 500 kV transmission tower 1000 as an example, the range of L is 4000 mm to 8000 mm, and the range of D is 2500 mm to 3500 mm. From this, the minimum value of α can be calculated as 18°, and the maximum value of α is 51.8°. Therefore, the included angle range between the two post insulators 1210 can be controlled within 20° to 50°.

[0064] Similarly, combining Figure 3 , assuming the included angle between the post insulator 1210 and the adjacent stay insulator 1220 is β, and at the same time assuming the distance between the connection point of the post insulator 1210 on the tower body 1100 and the connection point of the adjacent stay insulator 1220 on the tower body 1100 is H. From the trigonometric formula, it can be obtained that:

[0065]

[0066] Taking the 500 kV transmission tower 1000 as an example, H is generally set to 2500 mm. From this, the minimum value of β can be calculated as 14.2°, and the maximum value of β is 43°. Since the size of H can be adjusted again, the included angle range between the post insulator 1210 and the adjacent stay insulator 1220 is controlled within 15° to 45°.

[0067] At the same time, setting the angular range between the two post insulators 1210 to be 20° to 50° can also provide favorable conditions for installing a first grading ring 12101 at the high-voltage end (the end far from the tower body 1100) of the post insulator 1210 and installing an end fitting 1240 (detailed introduction below) to connect the post insulator 1210 and the stay insulator 1220. Specifically, it can ensure that there is no interference between the first grading rings 12101 on the two post insulators 1210 and there is no interference between the first grading ring 12101 and the petticoat 1212 (detailed introduction below) of the post insulator 1210 and the end fitting 1240.

[0068] And setting the included angle range between the post insulator 1210 and the adjacent stay insulator 1220 to be 15° to 45° can provide favorable conditions for installing a first grading ring 12101 at the high-voltage end of the post insulator 1210 and installing a second grading ring 12201 at the high-voltage end (the end far from the tower body 1100) of the stay insulator 1220. Specifically, it can ensure that there is no interference between the first grading ring 12101 and the second grading ring 12201 when they are installed in a staggered manner.

[0069] Continue to refer to Figure 1 , in this embodiment, the installation heights of the two post insulators 1210 are the same, the installation heights of the two stay insulators 1220 are the same, and at the same time, the two stay insulators 1220 are both above or below the two post insulators 1210 (in the figure, it is shown that the two stay insulators 1220 are both above the two post insulators 1210).

[0070] Among them, the two post insulators 1210 can be horizontally arranged ( Figure 1 shown as horizontally arranged in

[0071] ), or can be inclined. At the same time, in this embodiment, the angles between the two post insulators 1210 and the adjacent stay insulators 1220 are equal, that is, the composite cross arm 1200 is a symmetric structure to ensure uniform force on the composite cross arm 1200. However, the present application is not limited thereto. For example, in other embodiments, the angle between one post insulator 1210 and the adjacent stay insulator 1220 is 20°, and the angle between the other post insulator 1210 and the adjacent stay insulator 1220 is 45°.

[0072] Refer to Figure 4 and Figure 5 , in this embodiment, the post insulator 1210 includes an insulator 1211 and a petticoat 1212 covering the periphery of the insulator 1211.

[0073] Specifically, the insulator 1211 can be a solid insulating core or a hollow insulating tube. When the insulator 1211 is a solid insulating core, it can be a solid core rod formed by winding or pultruding or pultrusion winding of glass fiber or aramid fiber impregnated with epoxy resin. When the insulator 1211 is a hollow insulating tube, it can be a hollow pultruded tube formed by pultrusion winding of glass fiber or aramid fiber impregnated with epoxy resin, or a glass steel tube formed by winding and curing or pultruding of glass fiber impregnated with epoxy resin, or an aramid fiber tube formed by winding and curing of aramid fiber impregnated with epoxy resin. There is no limitation here.

[0074] Among them, the insulator 1211 can be cylindrical (the attached drawing shows it in a cylindrical shape for illustration), conical or other shapes (such as drum-shaped), and there is no limitation here. Among them, when the insulator 1211 is conical, its tapered end (the end with a smaller diameter) is connected to the end fitting 1240, and the other end is connected to the tower body 1100.

[0075] In an application scenario, when the insulator 1211 is a hollow insulating tube, an insulating gas is sealed inside the insulator 1211, and the absolute pressure value range of the insulating gas is 0.1 - 0.15 Mpa. For example, 0.1 Mpa, 0.12 Mpa or 0.15 Mpa.

[0076] Specifically, the gas sealed inside the hollow insulating tube can be high-purity nitrogen, air, sulfur hexafluoride or other gases that have been dried, and there is no limitation here.

[0077] At the same time, setting the absolute pressure value range of the insulating gas to 0.1 - 0.15 Mpa can make the insulating gas not easily leak from the hollow insulating tube, exempting the post insulator 1210 from daily maintenance and monitoring, and also being able to meet the different pressure usage requirements existing between different regions and altitudes, so as to ensure that the gas inside the hollow insulating tube is in a non-negative pressure state when used in different regions, and at the same time, it can also make the hollow insulating tube have a larger margin for micro-water control, effectively reducing the difficulty of micro-water control.

[0078] In other application scenarios, when the insulator 1211 is a hollow insulating tube, an inert gas or solid materials such as polyurethane or liquid silicone rubber can also be sealed inside it, and there is no limitation here.

[0079] At the same time, the umbrella skirt 1212 can be made of materials such as high-temperature vulcanized silicone rubber, liquid silicone rubber or room-temperature vulcanized silicone rubber, and there is no limitation here.

[0080] Combined with Figure 5 and Figure 6, in this embodiment, the umbrella skirt 1212 includes a plurality of umbrella bodies 12121 that are spaced apart and identical, that is, all the umbrella bodies 12121 are the same. At the same time, the umbrella bodies 12121 are radially symmetric with respect to the insulator 1211, that is, the inclination directions of the two surfaces of the umbrella bodies 12121 facing away from each other are opposite and the inclination angles are the same. Specifically, the umbrella bodies 12121 are arranged to be radially symmetric with respect to the insulator 1211. On the one hand, compared with the prior art where the two surfaces of the umbrella bodies 12121 facing away from each other are inclined in the same direction, it can make the rainwater flow down along the umbrella skirt 1212 (if the two surfaces of the umbrella bodies 12121 facing away from each other are inclined in the same direction, the rainwater is likely to accumulate in the angle between the post insulator 1210 and the umbrella bodies 12121), so that a water film is not formed on the surface of the umbrella skirt 1212, and it is beneficial to the self-cleaning of the umbrella skirt 1212. On the other hand, it can make the two sides of the umbrella bodies 12121 facing away from each other have the same mechanical properties, making the post insulator 1210 have the characteristics of pollution resistance, rain flash resistance, ice flash resistance and being more economical.

[0081] In an application scenario, in order to avoid the formation of turbulence and pollution accumulation between adjacent umbrella bodies 12121, resulting in bridging, the distance between adjacent umbrella bodies 12121 is greater than 40 mm and does not exceed 60 mm. For example, 45 mm, 50 mm or 60 mm. Of course, the distance between adjacent umbrella bodies 12121 should be minimized as much as possible. In this way, the distribution density of the umbrella bodies 12121 can be increased, making it inconvenient for birds to stand on the sheath, thus preventing the occurrence of bird damage accidents. At the same time, under the requirement of ensuring the minimum creepage distance, the height of the umbrella bodies 12121 protruding from one side of the insulator 1211 is not greater than 80 mm, and is generally set to 50 mm - 80 mm, such as 50 mm, 60 mm or 70 mm, etc.

[0082] It should be noted that in other embodiments, the umbrella skirt 1212 can also be other structures. For example, the sizes of adjacent umbrella bodies 12121 are different, or the two surfaces of the umbrella bodies 12121 facing away from each other are inclined in the same direction. In short, the specific structure of the umbrella skirt 1212 in this application is not limited.

[0083] Continue to refer to Figure 4 , in this embodiment, the post insulator 1210 further includes a first connection fitting 1230. The two ends of the post insulator 1210 are respectively connected with the first connection fitting 1230 to realize the installation of the post insulator 1210. That is, the first connection fitting 1230 connected to one end of the post insulator 1210 is used to connect the post insulator 1210 with the tower body 1100, and the first connection fitting 1230 connected to the other end of the post insulator 1210 is used to connect the post insulator 1210 with the stay insulator 1220. At the same time, combined with Figure 7 , Figure 8 and Figure 9, the first connecting fitting 1230 includes: a flange cylinder 1231, a flange plate 1232, a first connecting plate 1233, and a second connecting plate 1234.

[0084] Among them, the flange cylinder 1231 is axially arranged as a hollow structure and sleeved on the end of the insulator 1211; the flange plate 1232 covers one end of the flange cylinder 1231 away from the insulator 1211, and the flange cylinder 1231 and the flange plate 1232 can be integrally formed or separately formed and then connected together by means such as welding; the first connecting plate 1233 extends from one side of the flange plate 1232 away from the flange cylinder 1231 to the opposite sides of the flange cylinder 1231 and is connected to the flange cylinder 1231. That is, in the axial direction of the post insulator 1210, the first connecting plate 1233 extends outward from one side of the flange plate 1232 away from the flange cylinder 1231, and in the radial direction of the post insulator 1210, the first connecting plate 1233 extends to the opposite sides of the flange cylinder 1231 and is connected to the flange cylinder 1231; the side of the second connecting plate 1234 abuts against the plate surface of the first connecting plate 1233 and extends from the first connecting plate 1233 to the outer peripheral surface of the flange cylinder 1231, so as to form an installable space between the first connecting plate 1233 and the second connecting plate 1234. This installable space can be used to place a locking member (such as a bolt, etc.) for locking the post insulator 1210 to the tower body 1100 or the stay insulator 1220. It can be understood that the setting of the second connecting plate 1234 can indirectly increase the contact area between the first connecting plate 1233 and the flange cylinder 1231, thereby improving the strength of the first connecting fitting 1230.

[0085] Specifically, setting the flange plate 1232 to cover one end of the flange cylinder 1231 away from the insulator 1211 can prevent the corrosion of the insulator 1211 by external water vapor, etc., play a protective role for the insulator 1211, extend the service life of the post insulator 1210, and at the same time, the settings of the first connecting plate 1233 and the second connecting plate 1234 can improve the strength of the first connecting fitting 1230, and further improve the strength of the post insulator 1210.

[0086] At the same time, in order to enable the post insulator 1210 to be installed and applied in different scenarios, the two first connecting plates 1233 at both ends of the post insulator 1210 are not parallel. Among them, the relative angle of the two non-parallel first connecting plates 1233 is determined by the actual situation of the connection structure on the tower body 1100, the connection structure on the stay insulator 1220, etc., and is not limited here. In one embodiment, the two first connecting plates 1233 are perpendicularly arranged, that is, the relative angle of the two first connecting plates 1233 is 90°.

[0087] Among them, in order to prevent the first connecting fitting 1230 from being corroded by water vapor or the like, the surface of the first connecting fitting 1230 is treated with hot-dip galvanization. At the same time, the internal material of the first connecting fitting 1230 can be materials such as cast aluminum, cast iron, or alloy steel, which is not limited here.

[0088] At the same time, various parts in the first connecting fitting 1230 can be connected together by means such as welding.

[0089] Refer to Figure 4 and Figure 10 In this embodiment, a plurality of cementing grooves 12311 arranged at intervals along the axial direction and a flow-through groove 12312 communicating with the plurality of cementing grooves 12311 are provided on the inner wall of the flange cylinder 1231. Among them, the cementing grooves 12311 and the flow-through groove 12312 are filled with an adhesive to fixedly connect the flange cylinder 1231 and the insulator 1211.

[0090] Specifically, in the production process, the first connecting fitting 1230 is connected to the post insulator 1210 by using a horizontal cementing process or a vertical cementing process: in the production process, the adhesive is first injected between the flange cylinder 1231 and the insulator 1211 through the injection hole, and then after a certain period of high-temperature curing, the first connecting fitting 1230 and the post insulator 1210 can be fixedly connected together.

[0091] The arrangement of the flow-through groove 12312 can enable the adhesive injected between the flange cylinder 1231 and the insulator 1211 to flow between adjacent cementing grooves 12311, thereby improving the injection rate, reducing the risk of air bubble retention, making the combination of the first connecting fitting 1230 and the insulator 1211 more firm, and thus improving the anti-torsion performance of the composite cross arm 1200 without replacing the adhesive with better bonding performance.

[0092] Among them, the number of the flow-through grooves 12312 can be one or multiple (for example, two, four, six or even more), and when the number of the flow-through grooves 12312 is multiple, the multiple flow-through grooves 12312 are arranged at intervals along the circumferential direction of the flange cylinder 1231. Among them, one flow-through groove 12312 can only communicate with two adjacent cementing grooves 12311, or can communicate with three, four or even all of the adjacent cementing grooves 12311, which is not limited here.

[0093] Among them, the bottom surface of the flow groove 12312 is a plane or a curved surface. Specifically, when the radial depth and width of the flow groove 12312 relative to the first connecting fitting 1230 are constant, the flow groove 12312 with a plane bottom surface is more complex to process and has a higher processing cost compared to the flow groove 12312 with a curved surface bottom surface. However, its torsional strength is higher because the contact area between the adhesive in the plane groove and the inner wall of the flange cylinder 1231 is larger. That is to say, the flow groove 12312 with a curved surface bottom surface is more convenient to process and has a lower processing cost compared to the flow groove 12312 with a plane bottom surface, but its torsional strength is slightly lower.

[0094] Among them, as Figure 11 shown, the widths of multiple potting grooves 12311 are equal, and the width of the potting groove 12311 is smaller than the width of the interval between two adjacent potting grooves 12311. Specifically, setting the width of the potting groove 12311 to be smaller than the width of the interval between two adjacent potting grooves 12311 can make the width of the potting matching groove 121101 on the insulator 1211 (as Figure 12 and Figure 13 shown, the potting matching groove 121101 on the insulator 1211 has the same specification as the potting groove 12311 on the flange cylinder 1231 and is arranged opposite to each other) also smaller than the width of the interval between two adjacent potting matching grooves 121101. Compared with the width of the potting matching groove 121101 being greater than or equal to the width of the interval between two adjacent potting matching grooves 121101, this setting can ensure the shear resistance of the post insulator 1210.

[0095] Among them, the width of the potting groove 12311 does not exceed 12 mm. Specifically, the axial shear strength of the insulator 1211 itself is relatively low. When it is damaged, the first part to be damaged is the part that is sleeved into the flange cylinder 1231 and not bonded by the adhesive, that is, the part of the insulator 1211 adjacent to the two potting matching grooves 121101. When the width of the flange cylinder 1231 is constant, if the width of the potting groove 12311 decreases, the distance between two adjacent potting grooves 12311 will increase, that is, the distance between two adjacent potting matching grooves 121101 on the insulator 1211 will increase, and its shear failure strength will increase, ultimately enhancing the shear resistance of the post insulator 1210 of the same specification. However, if the width of the potting groove 12311 is too small, it will lead to an increase in processing time and processing cost. Therefore, setting the width of the potting groove 12311 not to exceed 12 mm, for example, 12 mm, 10 mm, or 8 mm, etc., can not only ensure the strength of the composite cross arm 1200 but also ensure that the processing time and processing cost are within a reasonable range.

[0096] Among them, for the convenience of processing, the bottom surface of the potting groove 12311 is a curved surface.

[0097] Among them, the ratio of the length of the contact part between the inner wall of the flange cylinder 1231 and the insulator 1211 to the outer diameter of the insulator 1211 (i.e., the potting ratio) ranges from 0.8 to 1.2. For example, 0.8, 1.0 or 1.2. Specifically, as the potting ratio decreases, the strength of the composite cross arm 1200 will decrease significantly. For example, compared with a potting ratio of 0.8, when the potting ratio drops to 0.75, the strength of the composite cross arm 1200 will decrease by 20%. And compared with a potting ratio of 1.2, when the potting ratio rises to 1.4, although the strength of the composite cross arm 1200 will increase slightly, the cost will increase significantly. Therefore, setting the potting ratio range from 0.8 to 1.2 can enable the composite cross arm 1200 to have the advantages of low cost and high strength at the same time.

[0098] It should also be noted that in other embodiments, the potting grooves 12311 and the flow grooves 12312 can also have other dimensions, which are not limited here.

[0099] In an application scenario, in combination with Figure 12 and Figure 13 , on the disk surface of the flange 1232 facing the insulator 1211, there is a first sealing groove 12313 facing the end face of the insulator 1211, and a first sealing member 123131 is arranged in the first sealing groove 12313. Specifically, the first sealing member 123131 is arranged in the first sealing groove 12313 to prevent external water vapor or adhesive from entering the insulator 1211, thereby avoiding gas leakage in the insulator 1211, and preventing external water vapor or adhesive from entering the flange 1232, thus affecting the seal between the insulator 1211 and the first connecting fitting 1230.

[0100] Continuing to refer to Figure 12 and Figure 13 , on the inner wall of the flange cylinder 1231, there is also a second sealing groove 12314 adjacent to the flange 1232. The second sealing groove 12314 and the plurality of potting grooves 12311 are arranged at intervals in the direction away from the flange 1232 in sequence, and a second sealing member 123141 is arranged in the second sealing groove 12314. Specifically, the function of the second sealing member 123141 is different from that of the first sealing member 123131. The second sealing member 123141 is used to prevent the adhesive during the potting process from entering the first sealing groove 12313 and corroding the first sealing member 123131, resulting in the failure of the first sealing member 123131.

[0101] Among them, the width of the first sealing groove 12313 and / or the second sealing groove 12314 remains unchanged (as shown in Figure 13 ) or gradually becomes smaller (as shown in Figure 14As shown. Specifically, the first sealing groove 12313 with a width that remains unchanged in the direction close to the insulator 1211 is convenient to process, but the first sealing member 123131 inside it is prone to sliding or even falling off. At this time, in order to prevent the first sealing member 123131 from sliding relative to the first sealing groove 12313, the first sealing member 123131 is adhesively fixed in the first sealing groove 12313 by resin or silica gel; compared with the first sealing groove 12313 with a width that remains unchanged in the direction close to the insulator 1211, although the processing process of the first sealing groove 12313 with a width that gradually decreases in the direction close to the insulator 1211 is more complex, it can ensure that the first sealing member 123131 will not easily fall off. Among them, the width of the first sealing groove 12313 and / or the second sealing groove 12314 can decrease linearly (as shown in Figure 14 ), or it can decrease in a curve, which is not limited here.

[0102] In an application scenario, in combination with Figure 5 , Figure 12 and Figure 15 , when the insulator 1211 is a hollow insulating tube, a counterbore 12321 is provided on the disk surface of the flange 1232 away from the insulator 1211, and a self-sealing valve 12322 is sunk in the counterbore 12321. Specifically, the self-sealing valve 12322 is used for extracting and filling the gas inside the insulator 1211 on the one hand, and for sealing measurement and micro water value measurement before the product leaves the factory (after the product is detected to be qualified, the self-sealing valve 12322 needs to be sealed with materials such as liquid silicone rubber or epoxy resin).

[0103] At the same time, when the insulator 1211 is a hollow insulating tube, a drying device 12111 is provided inside the insulator 1211, and the drying device 12111 is installed on the disk surface of the flange 1232 close to the insulator 1211. Specifically, the drying device 12111 is used to keep the inside of the insulator 1211 dry. Among them, as shown in Figure 12 , the drying device 12111 is in a cage shape, inverted on the flange 1232, and the drying device 12111 is provided with through holes 121111 of the same size and evenly distributed to form a shielding cage, so as to ensure that the drying device 12111 will not affect the internal electric field of the insulator 1211 by using the shielding cage principle. At the same time, a desiccant is provided inside the drying device 12111, and the desiccant can be a molecular sieve desiccant, etc., which is not limited here.

[0104] It should be noted that the present application does not limit the specific structure and quantity of the drying device 12111, and the quantity of the drying device 12111 can be one, two or more.

[0105] It should be noted that the flange 1232 of the first connecting fitting 1230 can install the self-sealing valve 12322 and the drying device 12111 simultaneously, or only install one of the self-sealing valve 12322 and the drying device 12111 (for example, as shown in combination with Figure 5 , Figure 12 and Figure 15 , it can be seen that one of the two flanges 1232 at both ends of the post insulator 1210 only installs the drying device 12111, and the other only installs the self-sealing valve 12322).

[0106] In combination with Figure 2 , Figure 16 and Figure 17 , in this embodiment, the composite cross arm 1200 further includes an end fitting 1240 for realizing the connection between the post insulator 1210 and the stay insulator 1220. The end fitting 1240 includes a connecting column 1241, a post connecting plate 1242, a stay connecting plate 1243 and a hanging plate 1244.

[0107] The connecting column 1241 is in a cylindrical shape. The side of the post connecting plate 1242 abuts against the outer peripheral surface of the connecting column 1241. Among them, the other ends of the two post insulators 1210 that are not connected to the tower body 1100 are installed on the post connecting plate 1242 at intervals along the axial direction of the connecting column 1241 (the two post insulators 1210 are installed on the same side or different sides of the post connecting plate 1242). The number of stay connecting plates 1243 is two, and the two stay connecting plates 1243 are both arranged on the same side of the post connecting plate 1242. And the side of the stay connecting plate 1243 adjacent to the end connected to the post connecting plate 1242 abuts against the outer peripheral surface of the connecting column 1241 for installing the other ends of the two stay insulators 1220 that are not connected to the tower body 1100 respectively. The hanging plate 1244 is located on the other side of the post connecting plate 1242 away from the stay connecting plate 1243 and extends along the outer peripheral surface of the connecting column 1241 to form a semi-surrounding structure for hanging the transmission line. Among them, the hanging plate 1244 is provided with a hanging part 12441 for hanging the transmission line. The hanging part 12441 can specifically be a hanging hole, and its number can be one, two ( Figure 17 shown by two for illustration) or more, which is not limited here. It can be understood that at the same time, the hanging plate 1244 is also provided with a construction hole 12442 for construction hoisting. The construction hole 12442 can be set to one or multiple, which is not limited here.

[0108] Continue to refer to Figure 17, the number of the wire hanging plates 1244 is two, and the two wire hanging plates 1244 are arranged at intervals along the axial direction of the connecting column 1241. In this way, an intermediate connecting piece (not shown in the figure) can be arranged in the space between the two wire hanging plates 1244. The intermediate connecting piece can be connected to the wire hanging parts 12441 on the two wire hanging plates 1244 through a locking piece (such as a bolt), and then a wire hanging fitting is hung on the intermediate connecting piece to hang and connect the transmission wire. That is to say, at this time, the two wire hanging plates 1244 jointly bear the tension of the transmission wire, avoiding the easy damage when a single wire hanging plate 1244 bears the tension of the transmission wire, thereby improving the mechanical strength of the end fitting 1240 as a whole.

[0109] In an application scenario, the end fitting 1240 further includes a support plate 1246. The support plate 1246 covers the end face of the connecting column 1241 and extends outward from the connecting column 1241 to be connected to one side edge of the support column connecting plate 1242, that is, the support plate 1246 connects the end face of the connecting column 1241 and one side edge of the support column connecting plate 1242 at the same time, and the support plate 1246 is provided with two, respectively covering the two end faces of the connecting column 1241 and connecting to the two side edges of the support column connecting plate 1242. On the one hand, the support plate 1246 can be used to cover the end face of the connecting column 1241, and on the other hand, the support plate 1246 connects the connecting column 1241 and the support column connecting plate 1242 together, which can strengthen the overall stability of the end fitting 1240.

[0110] In another application scenario, the end fitting 1240 further includes a reinforcing member 1247. The reinforcing member 1247 is arranged on the outer peripheral surface of the connecting column 1241 along the axial direction of the connecting column 1241. Specifically, the reinforcing member 1247 is a plate member, and connects the stay cable connecting plate 1243 and the support plate 1246 at the same time, that is, the plate surface of the reinforcing member 1247 is connected to the stay cable connecting plate 1243, and both side edges of the reinforcing member 1247 are connected to the plate surface of the support plate 1246 close to the connecting column 1241, further strengthening the overall stability of the end fitting 1240 and improving the mechanical strength.

[0111] Similar to the first connecting fitting 1230, the surface of the end fitting 1240 is also treated with hot-dip galvanizing, and its internal material can also be materials such as cast aluminum, cast iron or alloy steel, and the various parts of the first connecting fitting 1230 can also be connected together by welding or other means.

[0112] In this embodiment, combined with Figure 2 and Figure 16 , third grading rings 1245 are further installed at both ends of the connecting column 1241. Specifically, connection holes (not shown in the figure) are provided on the support plate 126, and the third grading rings 1245 are fixedly connected to the end fitting 1240 through the connection holes. Among them, the third grading rings 1245 can be circular grading rings, racetrack-shaped grading rings or other special-shaped grading rings, which are not limited here.

[0113] Refer to Figure 16 In this embodiment, the stay connecting plate 1243 is provided with a through hole 12431, and a metal piece 12432 is embedded in the through hole 12431. The metal piece 12432 is axially arranged as a hollow structure for a locking member (such as a bolt) to pass through to install the stay insulator 1220 on the stay connecting plate 1243.

[0114] Specifically, the metal piece 12432 is used to increase the connection strength of the stay connecting plate 1243 and prevent the stay connecting plate 1243 from cracking under long-term stress. The material of the metal piece 12432 can be materials such as iron, aluminum, alloy steel, etc., which are not limited herein.

[0115] Combined with Figure 3 and Figure 18 In this embodiment, the composite cross arm 1200 further includes a second connecting fitting 1250 for connecting the tower body 1100 and the stay insulator 1220. The second connecting fitting 1250 includes a first sub-connecting fitting 1251 and a second sub-connecting fitting 1252.

[0116] The first sub-connecting fitting 1251 is connected to the stay insulator 1220; one end of the second sub-connecting fitting 1252 is connected to the first sub-connecting fitting 1251 in an adjustable position, and the other end is used to connect the tower body 1100, thereby realizing the connection between the stay insulator 1220 and the tower body 1100. Specifically, setting one end of the second sub-connecting fitting 1252 to be connected to the first sub-connecting fitting 1251 in an adjustable position can make the structure of the composite cross arm 1200 variable and suitable for different application scenarios.

[0117] In an application scenario, as Figure 18 shown, the first sub-connecting fitting 1251 is provided with a plurality of mounting portions 12511 arranged in an arc, and the second sub-connecting fitting 1252 is selectively connected to one of the mounting portions 12511. Specifically, the plurality of mounting portions 12511 are arranged in an arc, which can make the distance and relative angle between the tower body 1100 and the stay insulator 1220 adjustable.

[0118] In an application scenario, as Figure 18 shown, the first sub-connecting fitting 1251 is a fan-shaped flat-foot fitting, and the second sub-connecting fitting 1252 is a groove fitting.

[0119] In other embodiments, the plurality of mounting portions 12511 may also be arranged in a straight line along the extension direction of the stay insulator 1220, which is not limited herein.

[0120] In other embodiments, the second sub-connecting fitting 1252 may also be connected to the stay insulator 1220, and the first sub-connecting fitting 1251 may be connected to the tower body 1100, which is not limited herein.

[0121] Refer to Figure 19 , Figure 19 FIG. is a schematic structural diagram of an embodiment of the composite cross arm of the present application. The composite cross arm 2000 includes two post insulators 2100 and two stay insulators 2200. One ends of the two post insulators 2100 and the two stay insulators 2200 are all used for connecting to the tower body of the transmission tower, and the other ends are connected together to form the end of the composite cross arm 2000 for hanging the transmission line. Among them, the two stay insulators 2200 are located on the same side of the two post insulators 2100 and are respectively adjacent to the two post insulators 2100. At the same time, the included angle range between the two post insulators 2100 is 20° to 50°, and the included angle range between the post insulator 2100 and the adjacent stay insulator 2200 is 15° to 45°.

[0122] Among them, the composite cross arm 2000 in this embodiment has the same structure as the composite cross arm 1200 in any of the above embodiments. For details, please refer to the above embodiments and will not be repeated herein.

[0123] The above are only the embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A composite cross arm, characterized in that, the composite cross arm includes two post insulators and two stay insulators. One ends of the two post insulators and the two stay insulators are all used for connecting with the tower body of a transmission tower, and the other ends are connected together to form the end of the composite cross arm for hanging transmission lines. Wherein, the two stay insulators are located on the same side of the two post insulators and are respectively adjacent to the two post insulators. At the same time, the included angle range between the two post insulators is 20° to 50°, and the included angle range between the post insulator and the adjacent stay insulator is 15° to 45°; the post insulator includes an insulator and a skirt covering the periphery of the insulator. At the same time, the post insulator also includes a first connecting fitting. The two ends of the post insulator are respectively connected with the first connecting fitting to realize the installation of the post insulator. The first connecting fitting includes: a flange tube, which is axially arranged as a hollow structure and sleeved on the end of the insulator; a flange plate, covering the end of the flange tube away from the insulator; wherein, the inner wall of the flange tube is provided with a plurality of cementing grooves arranged at intervals along the axial direction. The cementing grooves are filled with an adhesive to fixedly connect the flange tube and the insulator, and the width of the cementing groove does not exceed 12 mm. The ratio range of the length of the part of the inner wall of the flange tube in contact with the insulator to the outer diameter of the insulator is 0.8 to 1.2; at the same time, the disk surface of the flange plate facing the insulator is provided with a first sealing groove facing the end surface of the insulator, and a first sealing member is arranged in the first sealing groove; and, the inner wall of the flange tube is provided with a second sealing groove adjacent to the flange plate. The second sealing groove and the plurality of cementing grooves are arranged at intervals in turn along the direction away from the flange plate, and a second sealing member is arranged in the second sealing groove.

2. The composite cross arm according to claim 1, characterized in that, the insulator is a solid insulating core body, or the insulator is a hollow insulating tube, and an insulating gas is sealed in the hollow insulating tube, and the absolute pressure value range of the insulating gas is 0.1 to 0.15 MPa.

3. The composite cross arm according to claim 2, characterized in that, the skirt includes a plurality of spaced and identical umbrella bodies, and the umbrella bodies are radially symmetric with respect to the insulator.

4. The composite cross arm according to claim 2, characterized in that, the first connecting fitting further includes: a first connecting plate, in the axial direction of the post insulator, the first connecting plate extends outward from the side of the flange plate away from the flange tube. In the radial direction of the post insulator, the first connecting plate extends to the opposite sides of the flange tube and is connected with the flange tube; a second connecting plate, the side edge of the second connecting plate abuts against the plate surface of the first connecting plate and extends from the first connecting plate to the outer peripheral surface of the flange tube, so that a mountable space is formed between the first connecting plate and the second connecting plate; wherein, the two first connecting plates at the two ends of the post insulator are not parallel.

5. The composite cross arm according to claim 1, characterized in that, a flow groove communicating with a plurality of the potting grooves is further provided on the inner wall of the flange cylinder, wherein the flow groove is also filled with an adhesive to fixedly connect the flange cylinder and the insulator.

6. The composite cross arm according to claim 5, characterized in that, the number of the flow grooves is multiple, and the multiple flow grooves are arranged at intervals along the circumferential direction of the flange cylinder; or, the bottom surface of the flow groove is a plane or a curved surface.

7. The composite cross arm according to claim 1, characterized in that, the widths of the plurality of potting grooves are equal, and the width of the potting groove is smaller than the width of the interval between two adjacent potting grooves.

8. The composite cross arm according to claim 1, characterized in that, the width of the first sealing groove and / or the second sealing groove remains unchanged or gradually decreases in the direction close to the insulator.

9. The composite cross arm according to claim 1, characterized in that, the insulator is a hollow insulating tube, a sunken groove is arranged on the surface of the flange plate far from the insulator, and a self-sealing valve is sunken in the sunken groove; and / or, a drying device is arranged inside the insulator, and the drying device is installed on the surface of the flange plate close to the insulator.

10. The composite cross arm according to claim 1, characterized in that, the composite cross arm further includes end fittings, and the end fittings include: a connecting column, and the connecting column is in a cylindrical shape; a support connecting plate, and the side of the support connecting plate abuts against the outer peripheral surface of the connecting column, wherein the other ends of the two support insulators not connected to the tower body are installed on the support connecting plate at intervals along the axial direction of the connecting column; two stay connecting plates, and the two stay connecting plates are both arranged on the same side of the support connecting plate and are used for respectively installing the other ends of the two stay insulators not connected to the tower body; a hanging plate, which is located on the other side of the support connecting plate far from the stay connecting plate and extends along the outer peripheral surface of the connecting column to form a semi-surrounding structure for hanging the transmission line.

11. The composite cross arm according to claim 10, characterized in that, the stay connecting plate is provided with a through hole, and a metal part is embedded in the through hole. The metal part is axially arranged in a hollow structure for a locking part to pass through to install the stay insulator on the stay connecting plate.

12. The composite cross arm according to claim 1, characterized in that, the composite cross arm further includes a second connecting fitting for connecting the tower body and the stay insulator, and the second connecting fitting includes: a first sub-connecting fitting, which is connected to the stay insulator; a second sub-connecting fitting, one end of which is connected to the first sub-connecting fitting in an adjustable position, and the other end of which is used for connecting the tower body, so as to realize the connection between the stay insulator and the tower body.

13. The composite cross arm according to claim 12, characterized in that, the first sub-connecting fitting is provided with a plurality of installation parts arranged in an arc shape, and the second sub-connecting fitting is alternatively connected to one of the installation parts.

14. A transmission tower, characterized in that, The transmission tower includes a tower body and a composite cross arm connected to the tower body as described in any one of claims 1 to 13.

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