CN117461096A - Center tension line for overhead transmission line with breakage detection function and overhead transmission line comprising same - Google Patents
Center tension line for overhead transmission line with breakage detection function and overhead transmission line comprising same Download PDFInfo
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Abstract
The present invention relates to a center tension wire for an overhead transmission line having a breakage detection function and an overhead transmission line including the same. More particularly, the present invention relates to a center tension line for an overhead power line and an overhead power line including the same, which can easily and accurately detect whether the center tension line is broken not only before the overhead power line is installed to an iron tower or before a clamping work for installing the overhead power line, but also after the overhead power line is installed to the iron tower, and further, not only is excellent in a sag characteristic of the overhead power line for preventing sagging of the overhead power line due to an excellent tensile strength of the center tension line, but also improves an overhead workability due to a sufficient flexibility of the center tension line, and simultaneously can suppress corrosion and damage of a wire disposed around the center tension line, thereby enabling to prevent or minimize an increase in resistance of the overhead power line and a reduction in power transmission amount caused thereby, and can realize a light weight of the overhead power line and a reduction in manufacturing cost.
Description
Technical Field
The present invention relates to a center tension wire for an overhead transmission line having a breakage detection function and an overhead transmission line including the same. More particularly, the present invention relates to a center tension line for an overhead power line and an overhead power line including the same, which can easily and accurately detect whether the center tension line is broken not only before the overhead power line is installed to an iron tower or before a clamping work for installing the overhead power line, but also after the overhead power line is installed to the iron tower, and further, not only is excellent in a sag characteristic of the overhead power line for preventing sagging of the overhead power line due to an excellent tensile strength of the center tension line, but also improves an overhead workability due to a sufficient flexibility of the center tension line, and simultaneously can suppress corrosion and damage of a wire disposed around the center tension line, thereby enabling to prevent or minimize an increase in resistance of the overhead power line and a reduction in power transmission amount caused thereby, and can realize a light weight of the overhead power line and a reduction in manufacturing cost.
Background
Among the methods of supplying power from a power station to a city, a factory, or the like through a substation, there are an overhead transmission system using an overhead transmission line connected to an iron tower and an underground transmission system using an underground transmission line buried underground, and the overhead transmission system accounts for about 90% of the korean domestic transmission systems.
Existing overhead transmission lines typically use steel-cored aluminum stranded wires (Aluminum Conductor Steel Reinforced; ACSR) overhead transmission lines of Zhou Jiaoge strands of aluminum alloy conductor outside the center tension line for achieving high tension characteristics.
However, in the steel-cored aluminum strand (ACSR) overhead transmission line, since the load of the steel core itself used as the center tension line is large, the sag is large, and it is also limited to increase the weight of the aluminum conductor in order to increase the power transmission amount of the overhead transmission line, and in order to reduce the sag of the overhead transmission line or increase the power transmission amount with respect to the same sag, an attempt has been made to lighten the overhead transmission line by using a fiber-reinforced composite material in the center tension line.
Fig. 1 is a diagram schematically showing a cross-sectional structure of an existing overhead transmission line provided with a central tension line including a fiber reinforced composite material.
As shown in fig. 1, an existing overhead transmission line may include a central tension line 10 and a conductive wire 20 disposed therearound, and the central tension line 10 may include: a core layer 11 composed of a carbon fiber reinforced composite material; and a cover layer 12 composed of a glass fiber reinforced composite material for suppressing corrosion of the wire 20 caused by dissimilar metal contact corrosion, i.e., galvanic corrosion (galvanic corrosion), between the core layer 11 and the wire 20.
However, in such an existing overhead transmission line, due to the higher specific gravity of the glass fiber reinforced composite material constituting the cover layer 12 of the center tension line 10, for example, about 2.0g/cm 3 Is limited in weight and thus the sag characteristics may be lowered, and the conductive wire 20 disposed around the center tension wire and contacting and rubbing with the cover layer 12 may be damaged due to the high hardness of the glass fiber reinforced composite material, with the result that an increase in resistance due to a decrease in the sectional area of the conductive wire 20 may be generatedAnd the reduction of the power transmission. In addition, there is also a problem in that the manufacturing cost of the overhead transmission line increases due to the use of the relatively high glass fiber reinforced composite material.
In addition, in the conventional overhead transmission line, since the wire 20 is disposed around the center tension line 10, there is a problem that it is impossible to confirm whether the center tension line 10 disposed inside the overhead transmission line is broken before the overhead transmission line is installed, on the other hand, a technique of inserting an optical fiber inside the center tension line 10 and transmitting light of a specific wavelength by transmitting a light transmission device at one end portion of the center tension line 10, and confirming whether the transmitted light is detected by installing a light detection device at the other end portion of the center tension line 10, thereby confirming whether the optical fiber is broken, thereby confirming whether the center tension line 10 is broken has been used.
However, when an optical fiber is inserted into the center tension wire 10, there is a problem that the optical fiber is not broken even if the center tension wire 10 is broken, or conversely, it is difficult to accurately detect whether the center tension wire is broken only by breaking the optical fiber or the like, although the center tension wire 10 is not broken.
Further, since the optical transmission device and the optical detection device are installed at both ends of the center tension line 10 to confirm whether the overhead transmission line is broken, the overhead transmission line can be confirmed to be broken only before the clamping work of the overhead transmission line, and thus, the overhead transmission line cannot be detected after the installation of the overhead transmission line.
Further, in the case of visually observing the optical signal transmitted from one end to the other end of the optical fiber inserted into the center tension line 10, it is only possible to detect whether the optical fiber is completely broken or not and it is impossible to detect the specific position of the broken portion of the optical fiber and the center tension line.
Accordingly, there is an urgent need for a center tension line for an overhead power line and an overhead power line including the same, which can easily and accurately detect whether the center tension line is broken and a broken position not only before the overhead power line is installed to an iron tower or before a clamping work for installing the overhead power line but also after the overhead power line is installed, and which is excellent in not only a sag property for preventing the overhead power line of the overhead power line from sagging due to an excellent tensile strength of the center tension line, but also an improvement in an overhead workability due to a sufficient flexibility of the center tension line, and which can suppress corrosion and damage of a wire disposed around the center tension line, thereby enabling to avoid or minimize an increase in resistance of the overhead power line and a reduction in power transmission caused thereby, and which can realize a reduction in weight and a manufacturing cost of the overhead power line.
Disclosure of Invention
Problems to be solved by the invention
The present invention provides a center tension line for an overhead transmission line and an overhead transmission line including the same, which can easily and accurately detect whether the center tension line is broken and the position of the broken, not only before the overhead transmission line is mounted on an iron tower or before a clamping work for mounting the overhead transmission line, but also after the overhead transmission line is mounted.
Further, an object of the present invention is to provide a center tension line for an overhead transmission line, which is excellent in sag characteristics for preventing an overhead transmission line from sagging due to excellent tensile strength, and which improves overhead workability due to sufficient flexibility of the center tension line, and an overhead transmission line including the same.
Further, an object of the present invention is to provide a center tension line for an overhead transmission line and an overhead transmission line including the same capable of suppressing corrosion and damage of a wire disposed around the center tension line, thereby being capable of avoiding or minimizing an increase in resistance of the overhead transmission line and a reduction in power transmission amount caused thereby.
Further, an object of the present invention is to provide a center tension line for an overhead power line, which can achieve weight reduction and manufacturing cost reduction of the overhead power line, and an overhead power line including the same.
Technical proposal for solving the problems
In order to solve the problem of the shell, the invention provides a central tension wire for an overhead transmission line, which is characterized in that,
the center tension line for overhead transmission line includes: a core layer comprising a fiber reinforced plastic comprising reinforcing fibers in a thermoset resin matrix; and a detection unit which is inserted into the core layer and includes one or more optical fibers and a protection tube surrounding the optical fibers, wherein the protection tube includes: an interfacial layer comprising reinforcing fiber penetration in the core layer; and an inner layer that is impermeable to the reinforcing fibers.
The center tension line for an overhead transmission line is characterized in that the interface layer is a layer formed by mixing the reinforcing fibers with a polymer resin constituting the protective layer.
Further, there is provided a center tension line for an overhead transmission line, wherein the length occupied by the interface layer is 60% or more based on the outer circumference of the protective tube in any cross section of the protective tube.
Further, there is provided a center tension line for an overhead transmission line, wherein the interface layer includes a region having a thickness of 5 μm or more in an arbitrary cross section of the protective tube.
Further, there is provided a center tension line for an overhead transmission line, wherein the average thickness of the interface layer is 5 μm or more in any cross section of the protective tube.
In another aspect, there is provided a center tension line for an overhead transmission line, wherein a ratio of cross-sectional areas of the detection portions, i.e., a cross-sectional area ratio, is 1 to 12% based on a cross-sectional area of the core layer in an arbitrary cross-section of the center tension line.
The central tension line for overhead transmission lines is characterized in that the tensile strength of the central tension line including the detection unit is 2,800MPa or more.
Here, there is provided a center tension line for an overhead transmission line, characterized in that the following equation 1 is satisfied.
[ mathematics 1]
0.ltoreq.b-a.ltoreq.50% of the outer diameter of the core layer
In the above-mentioned formula 1, a reference numeral,
b refers to the longest distance, i.e. the largest distance,
a refers to the shortest distance, i.e., the smallest distance, among the distances between the surface of the detection portion and the surface of the core layer.
In another aspect, there is provided a center tension line for an overhead transmission line, wherein the protective tube is an insulating tube composed of a polymer resin having a tensile strength of 60MPa or more, an elongation of 5% or more, a tensile elastic modulus of 2000MPa or more, a bending strength of 90MPa or more, a bending modulus of 2500MPa or more, a melting point of 100 to 260 ℃ and a glass transition temperature of 80 to 82 ℃.
The central tension line for overhead transmission lines is characterized in that the polymer resin is polyvinyl chloride (PVC) or polybutylene terephthalate (PBT).
In another aspect, there is provided a center tension line for an overhead transmission line, characterized in that the reinforcing fiber comprises a carbon fiber comprising a high-strength continuous fiber having a diameter of 3 to 35 μm, the carbon fiber having a tensile strength of 3.5 to 5.0Gpa, an elastic modulus of 140 to 600Gpa, and a thermal expansion coefficient of 0 μm/m ℃ or less.
The central tension line for overhead transmission lines is characterized in that the total volume ratio of the carbon fibers is 50 to 85% based on the volume of the core layer excluding the detection portion.
Here, the total volume ratio of the carbon fiber is defined as follows.
Total volume ratio (%) = (total volume of carbon fiber/volume of core layer except for detection portion) ×100
Further, there is provided a center tension wire for an overhead transmission line, wherein the thermosetting resin matrix comprises a base resin having a glass transition temperature (Tg) of 205 ℃ or higher.
And, there is provided a center tension wire for an overhead transmission line, wherein the base resin comprises an epoxy resin.
In another aspect, there is provided a center tension line for an overhead transmission line, wherein the detecting portion includes a gap formed between the protection tube and the optical fiber.
Further, there is provided a center tension wire for an overhead transmission line, characterized by further comprising a cover layer which is made of a metallic material having an electrical conductivity of 55 to 64% iacs and which surrounds the core layer.
Here, there is provided a center tension wire for an overhead transmission line, characterized in that the metal material includes an aluminum material, and the thickness of the cover layer is 0.3 to 2.5mm.
Further, there is provided a center tension line for an overhead transmission line, wherein a gap is formed between the core layer and the cover layer.
In another aspect, there is provided an overhead transmission line, comprising: the center tension wire for the overhead transmission line; and a conductor formed by twisting a plurality of aluminum alloys or aluminum wires arranged around the center tension wire for the overhead transmission line.
Effects of the invention
The center tension line for overhead transmission line of the present invention includes the inner detecting portion including the optical fiber protected with the protecting tube, and has an excellent effect of being able to easily and accurately detect whether the center tension line is broken and the broken position since whether the center tension line is broken is detected in OTDR (Optical Time Domain Deflectometers) by such detecting portion.
The center tension wire for overhead transmission line of the present invention is composed of a fiber-reinforced plastic material in which reinforcing fibers such as carbon fibers are included in a polymer resin, and the cross-sectional area ratio of the detection portion included in the center tension wire is precisely adjusted, so that the center tension wire has excellent sag characteristics capable of preventing sagging of the overhead transmission line by securing sufficient tensile strength and excellent effects of improving the overhead line workability by sufficient flexibility of the center tension wire.
Also, the center tension wire for an overhead transmission line of the present invention can suppress corrosion and damage of a wire by the aluminum pipe of the cover layer, thereby having an excellent effect of avoiding or minimizing an increase in resistance of the overhead transmission line and a reduction in power transmission amount caused thereby.
The center tension wire for an overhead transmission line according to the present invention has an excellent effect of being capable of reducing weight of the overhead transmission line and reducing manufacturing costs by using a material having a low specific gravity and manufacturing costs.
Drawings
Fig. 1 is a view schematically showing a sectional structure of a conventional overhead transmission line.
Fig. 2 is a diagram schematically showing a cross-sectional structure related to one embodiment of a center tension line for an overhead transmission line of the present invention.
Fig. 3 is an electron micrograph of the interface layer in fig. 2 in which the protective tube is formed and in which the protective tube is not formed.
Fig. 4 is a reference diagram schematically showing a method of measuring the thickness of the interface layer of the protection pipe in fig. 2.
Fig. 5 is a view schematically showing a state in which the detection portion is exposed at the end of the core layer in the center tension line for an overhead transmission line shown in fig. 2.
Fig. 6 is a view schematically showing a state in which one end of the center tension wire for the overhead transmission line shown in fig. 5 is fastened to a clamp.
Fig. 7 is a schematic diagram showing an example of detecting whether or not the center tension line is damaged by an OTDR (optical time domain reflectometer; optical Time Domain Deflectometers) method.
Fig. 8 is a diagram schematically showing an embodiment related to the position of a detection portion in a core layer in the center tension line for an overhead transmission line shown in fig. 2.
Fig. 9 is a view schematically showing a cross-sectional structure related to another embodiment of the center tension line for an overhead transmission line of the present invention.
Fig. 10 is a diagram schematically illustrating a cross-sectional structure related to one embodiment of the overhead transmission line of the present invention including the center tension line illustrated in fig. 2.
Fig. 11 is a graph showing a bending test (bonding test) method of a center tension line and OTDR test data in the case where an interface layer is formed on a protection tube in the embodiment.
Fig. 12 is a photograph showing the results of a breaking test in the case where an interface layer is not formed in the protective tube in the example.
Detailed Description
Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments described herein, and may be embodied in other forms. Rather, the embodiments described herein are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. Throughout the specification, like reference numerals denote like constituent elements.
Fig. 2 is a view schematically showing a cross-sectional structure related to one embodiment of the center tension line for overhead transmission lines of the present invention, fig. 3 is an electron micrograph of the case where the interface layer of the protective tube is formed and the case where the interface layer is not formed in fig. 2, fig. 4 is a view schematically showing a state where the detection portion is exposed at the end of the core layer in the center tension line for overhead transmission lines shown in fig. 2, and fig. 5 is a view schematically showing a state where one end of the center tension line for overhead transmission lines shown in fig. 4 is fastened to a clamp.
As shown in fig. 2 and 3, the center tension wire 100 for overhead transmission lines of the present invention may include a core layer 110 composed of fiber reinforced plastic; and a detecting part 120 provided inside the core layer 110 and including a hollow optical fiber 122 inserted inside a protection tube 121, and further including a cover layer 130 selectively wrapping the core layer 110, and the like.
Since the center tension line 100 is formed to extend continuously in the longitudinal direction of the overhead power line, in a case where the overhead power line including the conductor disposed around the center tension line is installed between the towers, tension acts in the longitudinal direction of the center tension line 100, so that a sufficient tensile strength can be ensured.
The core layer 110 may be formed of a fiber reinforced plastic including reinforcing fibers in a thermosetting resin matrix. The thermosetting resin matrix may be formed of a base resin such as an epoxy resin, an unsaturated polyester resin, a bismaleimide resin, and a polyimide resin having a glass transition temperature (Tg) of 205 ℃ or higher, and preferably may be formed by adding an additive such as a curing agent, a curing accelerator, and a mold release agent to the epoxy resin. In the case where the glass transition temperature (Tg) of the base resin is less than 200 ℃, the heat resistance of the center tension line 100 is insufficient, and thus it is not suitable for an overhead transmission line having an operating temperature of about 180 ℃.
On the other hand, the glass transition temperature (Tg) of the base resin may be evaluated using DMA (dynamic mechanical analysis; dynamic Maechanical Analyzer), and the evaluation device may use DMA device of TA Instrument company, but is not limited thereto.
In particular, the epoxy resin may include diglycidyl ether bisphenol a type epoxy resin, multifunctional epoxy resin, diglycidyl ether bisphenol F type resin, and the like, and preferably, may include a mixture of these three epoxy resins. The case of mixing the three epoxy resins for use can relatively improve heat resistance and bending characteristics and flexibility as compared with the case of using diglycidyl ether bisphenol a type epoxy resin alone.
The curing agent may include an anhydride curing agent of methyltetrahydrophthalic anhydride (MTHPA), tetrahydrophthalic anhydride (THPA), hexahydrophthalic anhydride (HHPA), methylnadic anhydride (NMA), preferably, methyltetrahydrophthalic anhydride or methylnadic anhydride, or, as an alicyclic polyamine compound such as Menthanediamine (MDA), isophoronediamine (IPDA); amine curing agents such as aliphatic amine compounds, e.g., diaminodiphenyl sulfone (DDS) and diaminodiphenyl methane (DDM), may include liquid curing agents.
The content of the acid anhydride-based curing agent may be 70 to 150 parts by weight and the content of the amine-based curing agent may be 20 to 50 parts by weight based on 100 parts by weight of the base resin, and in the case where the content of the acid anhydride-based curing agent is less than 70 parts by weight or the content of the amine-based curing agent is less than 20 parts by weight, heat resistance may be reduced due to insufficient curing upon curing of the thermosetting resin matrix, and in the case where the content of the acid anhydride-based curing agent exceeds 150 parts by weight or the content of the amine-based curing agent exceeds 50 parts by weight, unreacted curing agent may remain in the thermosetting resin matrix and act as impurities, thereby possibly reducing heat resistance and other physical properties of the thermosetting resin matrix.
The curing accelerator is used to accelerate the curing of the thermosetting resin matrix by the curing agent, and when the curing agent is an acid anhydride-based curing agent, an imidazole-based curing accelerator is preferably used, and when the curing agent is an amine-based curing agent, boron trifluoride ethylamine-based curing accelerator is preferably used.
The content of the imidazole-based curing accelerator may be 1 to 3 parts by weight and the content of the boron trifluoride ethylamine-based curing accelerator may be 2 to 4 parts by weight based on 100 parts by weight of the base resin, and in the case where the content of the imidazole-based curing accelerator is less than 1 part by weight or the content of the boron trifluoride ethylamine-based curing accelerator is less than 2 parts by weight, a completely cured thermosetting resin matrix cannot be obtained, whereas in the case where the content of the imidazole-based curing accelerator exceeds 3 parts by weight or the content of the boron trifluoride ethylamine-based curing accelerator exceeds 4 parts by weight, the curing time is shortened due to a rapid reaction rate, resulting in a rapid increase in the viscosity of the thermosetting resin matrix, and thus there is a problem of a decrease in workability.
The release agent can serve to facilitate molding by reducing friction with a molding die during molding of the thermosetting resin matrix, and zinc stearate or the like can be used, for example.
The release agent may be contained in an amount of 1 to 5 parts by weight based on 100 parts by weight of the base resin, and in the case where the release agent is contained in an amount of less than 1 part by weight, workability of the thermosetting resin matrix may be lowered, whereas in the case where it exceeds 5 parts by weight, workability of the thermosetting resin matrix may not be further improved, and only manufacturing cost may be increased.
The reinforcing fiber may include a carbon fiber, a synthetic fiber, or the like, and in particular, the carbon fiber may possess a tensile strength of 3.5 to 5.0GPa, an elastic modulus of 140 to 600GPa, a thermal expansion coefficient close to 0 or 0 μm/m ℃ or less as a high-strength continuous fiber having a diameter of 3 to 35 μm. In the case where the diameter of the carbon fiber is less than 3 μm, the manufacturing is difficult and thus uneconomical, whereas in the case where it exceeds 35 μm, the tensile strength may be greatly lowered.
The carbon fiber may be surface-treated in order to improve compatibility of the thermosetting resin matrix with a base resin. The coupling agent for treating the surface of the carbon fiber is not particularly limited as long as the surface of the high-strength fiber can be treated, and for example, a titanate coupling agent, a silane coupling agent, a zirconate coupling agent, and the like may be included, and these may be used alone or in combination of two or more.
The surface of the carbon fiber surface-treated with the coupling agent is introduced with a plurality of reactive groups, which react with the polymer resin, thereby preventing a phenomenon of aggregation between the fibers and removing bubbles or defects affecting the physical properties of the final product, so that interfacial bonding property of the high-strength carbon fiber with the thermosetting resin and dispersibility of the high-strength carbon fiber can be improved.
The total volume ratio of the carbon fibers may be 50 to 85%, preferably 75 to 83%, based on the volume of the detection portion removed in the core layer. Here, the total volume ratio of the carbon fiber may be defined as follows.
Total volume ratio (%) = (total volume of carbon fiber/volume of detection portion removed from core layer) ×100 of carbon fiber
Here, in the case where the volume ratio of the carbon fibers is less than 50%, the tensile strength of the central tension line is insufficient, which may cause a reduction in the sag characteristics of the overhead transmission line, whereas in the case where it exceeds 85%, the flexibility of the central tension line is insufficient, which may cause a reduction in the overhead workability of the overhead transmission line, and the agglomeration phenomenon between the carbon fibers increases, which may cause a phenomenon of occurrence of bubbles or cracks inside the core layer, which may greatly reduce physical properties and workability.
On the other hand, the detection unit 120 may include a protection tube 121 and one or more optical fibers 122 inserted into a hollow inside the protection tube 121. The protection tube 121 is not particularly limited if it has a hollow structure into which the optical fiber 122 can be inserted, and for example, an insulating tube or the like composed of a polymer resin having a tensile strength of 60MPa or more, an elongation of 5% or more, a tensile elastic modulus of 2000MPa or more, a bending strength of 90MPa or more, and a bending modulus of 2500MPa or more, preferably polybutylene terephthalate (PBT) or polyvinyl chloride (PVC), preferably polyvinyl chloride (PVC) having a melting point of 100 to 260 ℃ and a glass transition temperature of 80 to 82 ℃ may be used, and a gel compound or the like for protecting the optical fiber 122 may be selectively filled inside the protection tube 121.
On the other hand, as shown in fig. 2, the detecting part 120 may include a gap formed between the protection tube 121 and the optical fiber 122. It is necessary to partially remove the core layer 110 at one end of the center tension line 100 to expose the optical fiber 122 for connection with an OTDR device, and in order to easily expose the optical fiber 122, a bonding force of a degree that the optical fiber 122 and the protection tube 121 can be individually moved is required, so that a gap is formed between the optical fiber 122 and the protection tube 121, which is advantageous in peeling of the optical fiber 122.
In addition, the area of the gap formed between the protection pipe 121 and the optical fiber 122 must satisfy a certain level, and if the gap is too large, it may not be well detected even when the core layer 110 breaks, and if the gap is too small, the optical fiber 122 may break in case of a sag generated in the overhead transmission line. Preferably, a gap in which the duty ratio occupied by the optical fiber 122 is maintained at a level of 50 to 90% may be formed in the space inside the protection tube 121.
In particular, the protective tube 121 may adjust process conditions in the extrusion process of the central tension wire 100, thereby forming an interface layer 121a, which is permeable to the reinforcing fibers and an inner layer 121b, which is impermeable to the reinforcing fibers, included in the core layer 110 at a partial region of the surface as shown in fig. 2 and 3. That is, the interface layer 121a may be a layer formed by mixing the polymer resin constituting the protective layer 121 and the reinforcing fiber. As described above, the interface layer 121a may be formed to enhance the coupling force of the core layer 110 and the protection pipe 121. As a result, the core layer 110 and the detecting portion 120 can be very closely combined with each other to integrally act, and even when the core layer 110 breaks, the core layer 110 and the protection tube 121 remain combined, so that the impact can be transmitted to the optical fiber 122 in the detecting portion 120 as completely as possible, and thus whether the core layer 110 breaks can be detected more accurately.
Here, the interface layer 121a is formed by penetrating the reinforcing fibers into a polymer resin forming the protective tube 121, and the length occupied by the interface layer may be 60% or more based on the outer circumference of the protective tube 121 in any cross section of the protective tube 121.
In addition, it is preferable that the interface layer 121a may include a region having a thickness of 5 μm or more in any cross section of the protection pipe 121, and more preferably, the average thickness of the interface layer 121a may be 5 μm or more, for example, 5 μm to less than the entire thickness of the protection pipe 121.
Here, as shown in fig. 4, the average thickness of the interface layer 121a may be a value obtained by measuring and averaging thicknesses of a horizontal line, a vertical line, a diagonal line forming an angle of 45 ° with the horizontal line, and eight points where the diagonal line forming an angle of 135 ° with the horizontal line intersects the interface layer 121a, which pass through the center of the detection portion 120.
Here, the interface layer 121a does not include a region having a length of less than 60% or a thickness of 5 μm or more based on the entire circumference of the outer periphery of the protection tube 121, or in the case where the average thickness is less than 5 μm, the tight bonding between the protection tube 121 and the core layer 110 is insufficient to cause the core layer 110 and the detection part 120 to act alone, so that it may be difficult to accurately detect whether the core layer 110 is broken. That is, even if the core layer 110 receives an impact and the core layer 110 breaks, the impact cannot be transmitted to the optical fiber 122 in the detection portion 120, and thus it may not be possible to detect whether the core layer 110 breaks.
To form such an interface layer 121a, the core layer 110 extruded outside the protection tube 121 may be cured at a specific curing condition, for example, at a curing temperature of 50 to 250 ℃, preferably 150 to 200 ℃, and at a curing speed of 0.5 to 2.0mpm, preferably 0.6 to 1.2mpm, so that the reinforcing fibers inside the core layer 110 may at least partially penetrate the protection tube 121.
Before or after the clamping operation of the end of the overhead transmission line on the pylon, as shown in fig. 5 and 6, the operator can connect the optical fiber 122 exposed at one end of the central tension line with the OTDR device.
In order to detect whether or not the center tension line 100 is broken after the overhead transmission line is installed in the pylon, a hole 310 or the like for exposing the optical fiber 122 to the outside may be provided in the clamp 300 connected to the end of the overhead transmission line, and in this case, the optical fiber 122 may be placed in the hole 310 and exposed to the outside, and then a sealing material such as grease may be placed in the other hole 320 included in the clamp 300, thereby preventing penetration of moisture or the like. Accordingly, the optical fiber 122 exposed to the outside can be connected to an OTDR device through the hole 310, so that whether the center tension line 100 is broken or not can be detected. Fig. 7 is a schematic diagram showing an example of detecting whether the center tension line is damaged in a manner of OTDR (Optical Time Domain Deflectometers).
As shown in fig. 7, by inputting an optical signal in a state in which an optical fiber exposed from one end of a cable is connected to an optical fiber connector cable by an OTDR measuring instrument and recovering an optical signal reflected from the other end of the optical fiber again, it is possible to measure an optical loss caused by breakage of the optical fiber or the like, and to measure whether or not the optical fiber is broken or a broken position, and since such breakage of the optical fiber or the like occurs due to breakage of a central tension line, it is possible to detect not only whether or not the central tension line is broken but also a broken position based on a measured value of the optical fiber.
That is, in the case of a normal central tension line, the change in the magnitude of the signal occurs at the end of the central tension line forming the grip, but in the case of a break occurring in the middle of the central tension line, the change in the magnitude of the signal occurs at the position where the break occurs. That is, the fracture occurrence position can be identified as the end of the center tension line. Therefore, it is possible to detect whether or not the center tension line is broken and the broken position by identifying the change in the magnitude of the signal and the position where the change occurs.
On the other hand, in the case of the conventional technique in which the optical fiber is directly buried in the center tension line without an additional protection tube, since there is no method of exposing the optical fiber from one end of the center tension line, the OTDR device cannot be applied, and therefore, it is only possible to simply detect whether the optical fiber is broken or not, and the broken position cannot be detected.
Here, in an arbitrary cross section of the central tension line, the entire sectional area of the detecting portion 120 may be 1 to 12% based on the total sectional area of the core layer 110. For example, in any cross section of the center tension line, the entire diameter of the detecting portion 120 may be 0.9 to 3.0mm. When the cross-sectional area ratio of the detection portion 120 is less than 1%, the detection portion 120 is not affected even when the core layer 110 is broken, and it is difficult to detect breakage of the center tension line, and when the cross-sectional area ratio of the detection portion 120 exceeds 12%, the tensile strength of the core layer 110 is greatly reduced.
Here, the tensile strength of the center tension line including the detection portion needs to be 2,800mpa or more to ensure a sag characteristic that prevents the overhead transmission line from sagging downward.
Fig. 8 is a view schematically showing an embodiment of the positional correlation of the detection portion in the core layer in the center tension line for an overhead transmission line shown in fig. 2.
As shown in fig. 8, in the core layer 110 of the central tension line 100, a relationship between a maximum distance b and a minimum distance a among distances from the detection portion 120 to the surface of the core layer 110 may satisfy the following equation 1.
[ mathematics 1]
0.ltoreq.b-a.ltoreq.50% of the outer diameter of the core layer
Here, among the distances between the surface of the detecting portion 120 and the surface of the core layer 110, the longest distance b and the shortest distance a are the longest distances b and the shortest distances a.
Specifically, as shown in a of fig. 8, in the case where the difference between the maximum distance b and the minimum distance a is 50% or less of the outer diameter of the core layer 110, that is, in the case where the eccentricity of the detection portion 120 within the core layer 110 is a certain level or less, the breakage detection of the center tension line 100 based on the detection portion 120 can be stably performed, while the decrease in the tensile strength of the center tension line 100 can be minimized, and the optical fiber 122 can be more easily exposed from the core layer 110. More preferred embodiments are those in which there is no difference between the maximum distance b and the minimum distance a, and in which there is no eccentricity of the detection portion 120 in the core layer 110. As shown in b of fig. 8, in the case where the difference between the maximum distance b and the minimum distance a exceeds 50% of the outer diameter of the core layer 110, that is, in the case where the detection portion 120 is eccentric to one side beyond a certain level within the core layer 110, it is difficult to stably perform breakage detection of the central tension line 100 based on the detection portion 120, the tensile strength of the central tension line 100 may be greatly lowered, and it is difficult to expose the optical fiber 122 from the core layer 110.
On the other hand, the cover layer 130 may be included in the center tension wire 100, but may be included in a conductor together with an aluminum wire 200 described later.
The cover layer 130 may additionally suppress damage to the wire caused by contact and friction between the core layer 110 and the wire, and may be configured to be electrically connected to the wire disposed around the center tension wire 100 when it is made of a metal material having excellent electrical conductivity, for example, 55 to 64% iacs, preferably the same aluminum material as the wire, thereby reducing the overall resistance of the overhead transmission line, and as a result, may additionally perform a function of increasing the power transmission amount.
Here, the thickness of the cover layer 130 may be 0.3 to 2.5mm, and in the case where the thickness of the cover layer 130 is less than 0.3mm, the effect of reducing the overall resistance of the overhead transmission line is not obvious, whereas in the case where the thickness exceeds 2.5mm, there is a problem that it is difficult to manufacture the central tension line 100, and the tensile strength of the central tension line 100 is reduced and the low sag characteristic cannot be achieved based on the central tension line 100 having the same outer diameter, because the outer diameter of the core layer 110 is reduced.
In the case where the center tension wire 100 further includes the cover layer 130, as shown in fig. 9, a gap 140 may be formed between the core layer 110 and the cover layer 130. The cover layer 130 may be formed by a method of continuously extruding (conform extrusion) a metal rod (rod) such as aluminum or welding a metal tape such as aluminum, etc., and in particular, the cover layer 130 may be formed by continuously extruding an aluminum rod, and thus the cover layer 130 may be formed by a long distance technique, so that not only may the production efficiency be improved, but also the formation and adjustment of the gap 140 may be facilitated.
In addition, in the case of continuous extrusion, since the cover layer 130 having a continuously formed surface without a joint such as a welded portion can be formed, it is possible to prevent the joint portion from being broken and to generate galvanic corrosion due to bending stress (bonding stress) acting on the center tension line 100 after the center tension line 100 or the overhead transmission line provided with the center tension line 100 is manufactured, erected, or erected.
The cover 130 and the gap 140 may be formed by extruding a metal material into a tube shape. Specifically, the size of the gap 140 may be adjusted by extruding the metal material surrounding the cover layer 130 and having an inner diameter larger than the outer diameter of the cover layer 130 into a tube shape and then forming the cover layer 130 by stepwise diameter reduction, for example, the total sectional area of the gap 140 may be about 0.15 to 7.1mm 2 。
Accordingly, not only can degradation of the core layer 110 be prevented by suppressing heat transfer to the core layer 110 when continuously extruding the aluminum rod for forming the cover layer 130, but also in the case where bending stress is applied to the center tension wire 100 for an overhead transmission line, the gap 140 allows the core layer 110 and the cover layer 120 to act alone, so that most of the bending stress may be applied to the core layer 110 including a fiber reinforced plastic wire having a relatively high tensile strength to achieve low sag characteristics of an overhead transmission line, while suppressing breakage of a spool, a drum, a pulley, or the like for manufacturing or setting up an overhead transmission line when crimping the center wire 100 by minimizing stress applied to the cover layer 130 composed of an aluminum material having a relatively low tensile strength.
Fig. 10 is a diagram schematically illustrating a cross-sectional structure related to one embodiment of the overhead transmission line of the present invention including the center tension line illustrated in fig. 2.
As shown in fig. 10, the overhead transmission line of the present invention is formed by arranging a plurality of conductors twisted by aluminum alloy or aluminum wires 200 around the center tension line 100.
The aluminum wire 200 may be composed of 1000 series aluminum or aluminum-zinc alloy such as 1050, 1100, 1200, etc., and the tensile strength before heat treatment may be about 15 to 25kgf/mm 2 And an elongation of less than about 5%, the tensile strength after heat treatment may be less than about 9kgf/mm 2 And an elongation of about 20% or more.
In addition, the section of the aluminum wire 200 is trapezoidal, and the occupation ratio of the conductor is significantly increased compared with the conventional aluminum wire of the conventional overhead transmission line with a circular section, thereby maximizing the power transmission amount and efficiency of the overhead transmission line. For example, the area ratio of a conductor including an aluminum wire having a circular cross section may be about 75%, whereas the area ratio of a conductor including an aluminum wire having a trapezoidal cross section may be about 95% or more.
The aluminum wire 200 may be formed in a trapezoid shape in cross section by continuous extrusion or wire drawing processing using a trapezoid die. The aluminum wire 200 may be naturally heat-treated during extrusion in the case of being formed by continuous extrusion, and thus does not require additional heat treatment, but is subsequently heat-treated in the case of being formed by a wire drawing process.
The aluminum wire 200 may be heat-treated during continuous extrusion or may be subsequently heat-treated after drawing, so that a region formed inside an aluminum structure and interfering with stress concentration of an electron flow due to thermal deformation or the like during extrusion or drawing may be released, and thus the electrical conductivity of the aluminum wire 200 may be improved, and as a result, the power transmission amount and the power transmission efficiency of the overhead power transmission line may be improved.
The cross-sectional area and number of the aluminum wires 200 may be appropriately selected according to the specification of the overhead transmission line, for example, the cross-sectional area of the aluminum wires 200 may be 3.14 to 50.24mm 2 In the case of converting the aluminum wire 200 having a trapezoid cross section into an aluminum wire having the same cross section and a circular cross section, the converted aluminum wire may have a cross-sectional diameter of 2 to 8mm.
In addition, the number of the aluminum wires 200 may be, for example, 12 to 40, and preferably, may have a multi-layer structure including eight in the core layer and twelve in the cover layer.
As described above, the aluminum wire 200 may be heat-treated to improve electrical conductivity, but when the heat treatment is performed, the surface is softened and weakened to be easily scratched, so that a plurality of scratches are generated on the surface of the aluminum wire 200 due to external pressure or impact during the manufacturing, transportation, and erection of the overhead transmission line, and thus corona discharge occurs to cause high frequency noise when the overhead transmission line is used.
Therefore, the aluminum wire 200 may have a surface hardness-enhancing layer formed on the surface thereof in order to suppress the occurrence of surface scratches. Preferably, the surface hardness enhancing layer may have a thickness of 5 μm or more, preferably more than 10 μm and 50 μm or less. When the thickness of the surface hardness enhancement layer is less than 5 μm, since the surface hardness of the aluminum wire 200 cannot be sufficiently increased, a plurality of scratches may be generated on the surface of the aluminum wire 200 due to external pressure, impact, or the like during the manufacturing, transfer, erection, or the like of the overhead transmission line, whereas when the thickness exceeds 50 μm, the surface hardness enhancement layer may be locally broken or ruptured when the overhead transmission line is curled around a bobbin or the like.
Also, the aluminum wire 200 may form the surface hardness reinforcing layer on the surface thereof, so that the tensile strength of the overhead transmission line may be further improved, and as a result, the sag (sag) of the overhead transmission line may be further suppressed.
The surface hardness enhancing layer may be formed on the surface of the entire plurality of aluminum wires 200 constituting the overhead transmission line, preferably on the entire surface of each of the aluminum wires 200 present in the outermost coating layer among the plurality of aluminum wires 200, and more preferably on the outer side surface forming the outer circumference of the overhead transmission line among the surface of each of the aluminum wires 200 present in the outermost coating layer.
The surface hardness-enhancing layer is not particularly limited as long as it can enhance the hardness of the surface of the aluminum wire 200 and thus can suppress the occurrence of scratches, and may include, for example, an aluminum oxide film formed by anodic oxidation (anodic) treatment, a gold plating film of nickel (Ni), tin (Sn), or the like.
Specifically, the anodic oxidation treatment method of the surface of the aluminum wire 200 may include: degreasing (cleaning) to remove organic contaminants such as grease present on the surface of the aluminum wire 200; washing (washing) the surface of the aluminum wire 200 with clean water; etching (etching) to remove alumina present on the surface of the aluminum wire 200 with sodium hydroxide; ash removal (desmutting), which dissolves and removes alloy components remaining on the surface of the aluminum wire 200 after etching; washing (washing) the surface of the aluminum wire 200 again with clean water; an anodic oxidation treatment (anodic) for applying a voltage of 20 to 40V and performing in order to form a dense and stable aluminum oxide film on the surface of the aluminum wire 200; washing (washing) the surface of the aluminum wire 10 again with clean water; and drying (drying), air drying at normal temperature, and the like.
In the case where the surface hardness enhancing layer includes an alumina coating film treated by anodic oxidation, the alumina coating film is excellent in insulation properties, so that power loss can be reduced based on the insulation effect between the aluminum wires 200, and Joule (Joule) heat generated in electric power transmission can be rapidly discharged to the atmosphere by the high radiation properties of the alumina coating film, whereby current capacity can be increased.
In addition, the surface hardness enhancement layer may be coated with a polymer resin such as a fluororesin. The polymer resin can impart a superhydrophobic effect on the alumina coating, so that dust or pollutants in the atmosphere can be inhibited from being adsorbed on the surface of the overhead transmission line, or snow accumulation or icing in winter can be inhibited.
The surface hardness enhancement layers may each include an alumina coating film treated by anodic oxidation, a gold plating coating film of nickel (Ni), tin (Sn), or the like. In the case where the surface hardness enhancement layers each include an alumina coating and a gold plating coating, the alumina coating may be disposed at a lower portion and the gold plating coating may be disposed at an upper portion of the alumina coating, and the thickness ratio of the alumina coating to the gold plating coating may be about 3:1 to 5:1.
In the case where the thickness ratio of the aluminum oxide film to the gold-plated film is 3:1 to 5:1, the surface hardness of the aluminum wire 200 can be sufficiently increased by the aluminum oxide film which is relatively thick and has a relatively excellent effect of improving the surface hardness, and localized breakage, etc. of the surface hardness enhancing layer in the case where the overhead transmission line is curled on a reel, etc. can be effectively suppressed by the gold-plated film which is disposed outside and has a relatively low risk of breakage, etc. due to bending.
Examples (example)
1. According to the rupture test of the interface layer formation
The curing conditions of the core layer were adjusted differently so that a breaking test was performed by performing a bending test on the center tensile line sample in the case where the protective tube at least partially forms an interface layer that is permeated with carbon fibers and in the case where the interface layer is not formed, respectively.
Here, as shown in fig. 11, a center tension line having a length of 90m was used, and the core layer was connected to a bending test jig and a bending force was applied to reduce the bending height from 700mm to 300 mm.
At one end of the center tensile line sample of the present invention, where the interface layer was formed, the breaking test was performed by partially removing the core layer and exposing the optical fiber and performing the bending test in a state of being connected to the OTDR device, and OTDR test data was shown in fig. 11. As shown in fig. 11, in the case where the central tension line is not broken, as shown in the upper graph of fig. 11, the magnitude of the signal is changed at the end of the central tension line forming the grip, but in the case where the bending at the bending height of 380mm causes the breakage at the middle of the central tension line, the magnitude of the signal is changed at the place where the breakage occurs. That is, it was confirmed that the optical fibers are broken together also at the time of breaking the central tension line, so that it is possible to detect whether the central tension line is broken.
On the other hand, a breaking test was performed by performing a bending test on a center tensile line sample on which no interface layer was formed, and light was irradiated to an optical fiber at one end and whether or not the optical fiber was broken was observed by an optical microscope at the other end, the result of which is shown in fig. 12. As shown in fig. 12, it was confirmed that although the core layer of the central tension line was broken, the optical fiber was not broken, and it was impossible to detect whether the central tension line was broken.
2. Center tension line tensile strength evaluation based on cross-sectional area ratio of detection portion
Tensile strength was measured after manufacturing center tensile line samples with the specifications shown in table 1 below. The tensile strength of the center tension line including the detection portion is 2,800MPa or more, so that the sag characteristic of the overhead transmission line can be ensured.
TABLE 1
As described in table 1, it was confirmed that the ratio of the core layer cross-sectional area to the detection section cross-sectional area of the center tension line of the present invention was adjusted to 1 to 12%, thereby securing a sufficient tensile strength of 2,800mpa or more.
However, in the case of comparative examples 1 to 7 in which the ratio of the cross-sectional area of the core layer to the cross-sectional area of the detection portion exceeded 12%, it was confirmed that the tensile strength did not reach 2,800mpa, and the function as a center tension line having sufficient relaxation characteristics could not be achieved.
While the present invention has been described with reference to the preferred embodiments thereof, it will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit of the invention as set forth in the appended claims. Therefore, as long as the modified embodiments substantially include the constituent elements of the claims of the present invention, they should be regarded as falling within the technical scope of the present invention.
Claims (19)
1. A center tension line for an overhead transmission line, comprising:
a core layer comprising a fiber reinforced plastic comprising reinforcing fibers in a thermoset resin matrix; and
a detection part inserted into the core layer and comprising more than one optical fiber and a protection tube surrounding the optical fiber,
the protection tube includes: an interfacial layer for enhancing fiber penetration included in the core layer; and an inner layer that is impermeable to the reinforcing fibers.
2. The center tension line for an overhead transmission line according to claim 1, wherein,
the interfacial layer is a layer formed by mixing the polymer resin constituting the protective layer and the reinforcing fiber.
3. The center tension line for overhead transmission line according to claim 2, wherein,
In any cross section of the protective tube, the length occupied by the interface layer is 60% or more based on the outer circumference of the protective tube.
4. The center tension line for overhead transmission line according to claim 2, wherein,
in any cross section of the protective tube, the interface layer includes a region having a thickness of 5 μm or more.
5. The center tension line for overhead transmission line according to claim 2, wherein,
in any cross section of the protective tube, the average thickness of the interface layer is 5 μm or more.
6. The center tension wire for an overhead transmission line according to any one of claims 1 to 5, wherein,
in any cross section of the center tension line, the ratio of the cross sectional areas of the detection portions, that is, the cross sectional area ratio is 1 to 12% based on the cross sectional area of the core layer.
7. The center tension line for an overhead transmission line according to claim 6, wherein,
the tensile strength of the center tensile line including the detection portion is 2,800mpa or more.
8. The center tension line for an overhead transmission line according to claim 7, wherein,
the following formula 1 is satisfied,
Mathematics 1
0.ltoreq.b-a.ltoreq.50% of the outer diameter of the core layer
In the above-mentioned formula 1, a reference numeral,
b refers to the longest distance, i.e. the largest distance,
a refers to the shortest distance, i.e., the smallest distance, among the distances between the surface of the detection portion and the surface of the core layer.
9. The center tension wire for an overhead transmission line according to any one of claims 1 to 5, wherein,
the protective tube is an insulating tube composed of a polymer resin having a tensile strength of 60MPa or more, an elongation of 5% or more, a tensile elastic modulus of 2000MPa or more, a flexural strength of 90MPa or more, a flexural modulus of 2500MPa or more, a melting point of 100 to 260 ℃ and a glass transition temperature of 80 to 82 ℃.
10. The center tension line for an overhead transmission line according to claim 9, wherein,
the high polymer resin is polyvinyl chloride PVC or polybutylene terephthalate PBT.
11. The center tension wire for an overhead transmission line according to any one of claims 1 to 5, wherein,
the reinforcing fibers may comprise carbon fibers and,
the carbon fiber includes a high-strength continuous fiber having a diameter of 3 to 35 μm, a tensile strength of 3.5 to 5.0Gpa, an elastic modulus of 140 to 600Gpa, and a thermal expansion coefficient of 0 μm/m ℃ or less.
12. The center tension line for an overhead transmission line according to claim 11, wherein,
the total volume ratio of the carbon fibers is 50 to 85% based on the volume excluding the detection portion in the core layer,
here, the total volume rate of the carbon fiber is defined as follows:
total volume ratio (%) = (total volume of carbon fiber/volume of core layer except for detection portion) ×100.
13. The center tension wire for an overhead transmission line according to any one of claims 1 to 5, wherein,
the thermosetting resin matrix comprises a base resin having a glass transition temperature Tg of 205 ℃ or higher.
14. The center tension line for an overhead transmission line according to claim 13, wherein,
the base resin includes an epoxy resin.
15. The center tension wire for an overhead transmission line according to any one of claims 1 to 5, wherein,
the detection portion includes a gap formed between the protection tube and the optical fiber.
16. The center tension wire for an overhead transmission line according to any one of claims 1 to 5, wherein,
also included is a cover layer surrounding the core layer and composed of a metallic material having an electrical conductivity of 55 to 64% iacs.
17. The center tension line for an overhead transmission line according to claim 16, wherein,
the metal material comprises an aluminum material,
the thickness of the cover layer is 0.3 to 2.5mm.
18. The center tension line for an overhead transmission line according to claim 17, wherein,
a gap is formed between the core layer and the cover layer.
19. An overhead power transmission line, comprising:
a center tension line for an overhead transmission line as claimed in any one of claims 1 to 5; and
and a conductor formed by twisting a plurality of aluminum alloys or aluminum wires arranged around the center tension wire for the overhead transmission line.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR10-2021-0069925 | 2021-05-31 | ||
| KR1020220064430A KR20220162070A (en) | 2021-05-31 | 2022-05-26 | Central tension member for an overhead cable with a function detecting damage and the overhead cable comprising the same |
| KR10-2022-0064430 | 2022-05-26 | ||
| PCT/KR2022/007549 WO2022255735A1 (en) | 2021-05-31 | 2022-05-27 | Central tension line for overhead power transmission cable having damage detection function and overhead power transmission cable comprising same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117461096A true CN117461096A (en) | 2024-01-26 |
Family
ID=89580420
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202280038817.0A Pending CN117461096A (en) | 2021-05-31 | 2022-05-27 | Center tension line for overhead transmission line with breakage detection function and overhead transmission line comprising same |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117461096A (en) |
-
2022
- 2022-05-27 CN CN202280038817.0A patent/CN117461096A/en active Pending
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