JP2015191788A - Optical fiber composite overhead earth wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber composite overhead earth wire which allows incorporation of optical core wires having a low heatproof temperature.SOLUTION: An optical fiber composite overhead earth wire includes an optical unit part having an optical core wire in which optical fiber element wires are arranged and an earth wire part provided outside the optical unit part, and the earth wire part includes first element wires of a conductivity of 50% IACS or higher and second element wires having a melting energy per unit length of higher than 550 J/cm.

Description

  The present invention relates to an optical fiber composite ground wire.

  In the overhead power transmission line, an overhead ground line for protecting the power line from direct strikes caused by lightning strikes and flowing current caused by lightning strikes to the ground is installed on the top of the steel tower, which is the upper part of the power line that becomes the main transmission line. In recent years, an optical fiber composite ground wire (hereinafter also referred to as OPGW) in which an optical fiber is incorporated so that the overhead ground wire can also serve as an information transmission line has been developed (for example, Patent Document 1).

Japanese Utility Model Publication No. 6-68237 Japanese Patent No. 5255931

  In OPGW, an induced current is induced in the OPGW by the current of the power line, so the OPGW may constantly generate heat. Further, in OPGW, there is a possibility that the strands may be melted or disconnected due to direct lightning strikes. Further, when the power line has a ground fault, the power line and the OPGW form a closed circuit, and a ground fault current flows through the OPGW, so that the OPGW may instantaneously generate heat.

  For this reason, the optical fiber core incorporated in the conventional OPGW has been configured to always withstand 150 ° C. and instantaneously 300 ° C. as described in Patent Document 1, for example. Such an optical fiber having high heat resistance is limited to the use of OPGW, and is rarely used in other fields, so that it is expensive.

  An object of the present invention is to provide an optical fiber composite ground wire capable of incorporating an optical fiber having a low heat-resistant temperature.

According to one aspect of the invention,
An optical unit having an optical core in which an optical fiber is provided;
A ground wire provided outside the light unit;
Have
The ground wire portion is
A first strand having a conductivity of 50% IACS or higher;
A second strand having a melting energy per unit length greater than 550 J / cm;
An optical fiber composite ground wire is provided.

According to another aspect of the invention,
An optical unit having an optical core in which an optical fiber is provided;
A ground wire provided outside the light unit;
Have
The ground wire portion is
A first ground layer provided outside the optical unit;
A second ground layer provided outside the first ground layer;
Have
An optical fiber composite ground wire is provided in which the conductivity of the first ground layer is higher than the conductivity of the second ground layer.

  ADVANTAGE OF THE INVENTION According to this invention, the optical fiber composite overhead ground wire which can incorporate the optical core wire with low heat-resistant temperature is provided.

It is sectional drawing orthogonal to the axial direction of the optical fiber composite overhead ground wire which concerns on 1st Embodiment of this invention. It is sectional drawing orthogonal to the axial direction of the optical fiber strand which concerns on 1st Embodiment of this invention. (A) is sectional drawing orthogonal to the axial direction of the optical unit part which concerns on 1st Embodiment of this invention, (b) is sectional drawing orthogonal to the axial direction of the optical unit part which concerns on the modification 1. is there. (A) is sectional drawing orthogonal to the axial direction of the optical unit part which concerns on the modification 2, (b) is sectional drawing orthogonal to the axial direction of the optical unit part which concerns on the modification 3. FIG. It is the figure which looked at the overhead structure of the optical fiber composite overhead ground wire and the power line in the steel tower from the axial direction of the optical fiber composite overhead ground wire. It is sectional drawing orthogonal to the axial direction of the optical fiber composite overhead ground wire which concerns on 2nd Embodiment of this invention. It is sectional drawing orthogonal to the axial direction of the optical fiber composite overhead ground wire which concerns on 3rd Embodiment of this invention. It is sectional drawing orthogonal to the axial direction of the optical fiber composite overhead ground wire which concerns on a comparative example.

<First Embodiment of the Present Invention>
(1) Structure of optical fiber composite ground wire The optical fiber composite ground wire according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view orthogonal to the axial direction of the optical fiber composite ground wire according to the present embodiment.

  The optical fiber composite ground wire (OPGW) 10 according to the present embodiment is a light having a low heat-resistant temperature by increasing the electrical conductivity while maintaining the lightning resistance (melting resistance against lightning strike). It is configured so that the core 200 can be incorporated. Details will be described below.

  In the following, the optical fiber composite ground wire 10 of the present embodiment is abbreviated as OPGW10. In the following, the “axial direction” of OPGW 10 refers to the longitudinal direction (extending direction) of OPGW 10, and the “radial direction” of OPGW 10 refers to the direction perpendicular to the axial direction of OPGW 10, that is, the short direction of OPGW 10. The “circumferential direction” of the OPGW 10 refers to a direction along the outer periphery of the OPGW 10. The “inner peripheral surface” refers to a surface on the center side, and the “outer peripheral surface” refers to a surface on the opposite side to the inner peripheral surface.

(Optical unit)
As shown in FIG. 1, an optical unit unit 20 is provided at the center of the OPGW 10. An optical fiber core 200 having an optical fiber 100 is provided inside the optical unit 20. The details of the optical unit 20 that can be incorporated into the OPGW 10 of this embodiment will be described later.

(Ground line)
A ground wire portion 30 is provided outside the optical unit portion 20. The ground wire portion 30 protects the power line (50) and the optical core wire 200 from lightning strikes, suppresses a temperature rise caused by an induced current and a ground fault current within a predetermined range, and bears the tension of the OPGW 10 during overhead wiring. Configured to function as. The ground wire portion 30 has at least two types of strands, and is composed of, for example, a first strand 320 made of a material having high conductivity and a material having lightning resistance (melting resistance against lightning strike). A second strand 420.

  In the present embodiment, the ground wire portion 30 includes two or more layers, and includes a first ground wire layer 300 and a second ground wire layer 400. A first strand 320 and a second strand 420 are provided in the first ground layer 300 and the second ground layer 400, respectively. Hereinafter, each layer of the ground wire portion 30 will be described.

  The first ground layer 300 is provided outside the optical unit unit 20. The first ground wire layer 300 is provided by twisting a plurality of first strands 320 together.

  Here, the conductivity of the first ground layer 300 is higher than the conductivity of a second ground layer 400 described later provided outside the first ground layer 300.

  In the present embodiment, the conductivity of the first strand 320 provided in the first ground layer 300 is 50% IACS or more. Note that the unit of conductivity “% IACS” is a ratio of conductivity when the conductivity of international standard soft copper (International Annealed Copper Standard) is 100%. In the present embodiment, since the conductivity of the first strand 320 is 50% IACS or more, Joule heat is induced in the first strand 320 due to the induced current induced from the power line (50) or the current at the time of ground fault. Is suppressed. Thereby, the temperature rise of OPGW10 is suppressed. Therefore, the heat resistant temperature of the optical fiber 200 incorporated in the OPGW 10 can be lowered.

  Specifically, the first strand 320 is, for example, a heat resistant aluminum alloy wire (TAL), a super heat resistant aluminum alloy wire (ZTAL), a special heat resistant aluminum alloy wire (XTAL), or a high strength heat resistant aluminum alloy wire (KTAL). It consists of at least one. For heat-resistant aluminum alloy wires (TAL), super heat-resistant aluminum alloy wires (ZTAL), special heat-resistant aluminum alloy wires (XTAL) and high-strength heat-resistant aluminum alloy wires (KTAL), please refer to the “Aerial Power Transmission Regulations” issued by the Japan Electric Association. Have been described. The electrical conductivity of heat resistant aluminum alloy wire (TAL), super heat resistant aluminum alloy wire (ZTAL), special heat resistant aluminum alloy wire (XTAL), and high strength heat resistant aluminum alloy wire (KTAL) is 60% IACS, 60% IACS, 58% IACS, 55% IACS. The 1st strand 320 of this embodiment is a heat-resistant aluminum alloy wire (TAL), for example.

  The second ground layer 400 is provided outside the first ground layer 300. The second ground wire layer 400 is provided by twisting a plurality of second strands 420 together.

  Here, it is known that the lightning resistance of a strand can be evaluated by the melting energy per unit length of the strand defined as the energy for completely melting the strand (for example, Patent Document 2). When the target value of summer lightning charge resistance is 200 C, the melting energy per unit length of the wire is about 380 J / cm, and when the target value of winter lightning charge resistance is 300 C, The melt energy per unit length is about 550 J / cm.

  Further, the melting energy E per unit length of the strand is obtained by the following formula (1).

Where C is the specific heat of the material constituting the strand, T ₀ is room temperature, T is the melting point of the strand, δ is the melting heat of the strand, and W is the weight per unit length of the strand.

  In the present embodiment, the melting energy per unit length of the second strand 420 obtained by the equation (1) is greater than 550 J / cm. That is, the melting energy per unit length of the second strand 420 is larger than the target value of the melting energy per unit length of the strand due to winter lightning. Thereby, the 2nd strand 420 comes to have the target lightning resistance.

  Specifically, in this embodiment, the 2nd strand 420 consists of an aluminum covering steel wire (AC wire), for example. The 2nd strand 420 has the steel wire 440 which consists of steel, and the coating layer 460 which is provided in the outer side of the steel wire 440 and consists of aluminum.

  Here, when the 2nd strand 420 is an AC line, the fusion energy E per unit length of the 2nd strand 420 is calculated | required by the following formula | equation (2).

Where C _Al is the specific heat of aluminum, C _Fe is the specific heat of steel, T ₀ is room temperature, T ₁ is the melting point of aluminum, T ₂ is the melting point of steel, δ _Al is the heat of fusion of aluminum, and δ _Fe is the heat of fusion of steel , W _Al is the weight per unit length of the coating layer 460 made of aluminum, and W _Fe is the weight per unit length of the steel wire 440 made of steel.

  More specifically, in the present embodiment, when the second strand 420 is made of an AC line, for example, the conductivity of the second strand 420 is lower than the conductivity of the first strand 320 and is 40% IACS. is there. Note that an AC line having a conductivity of 40% IACS is referred to as “40AC”. Moreover, the diameter of the 2nd strand 420 is 4.0 mm or more. In addition, the area ratio of the coating layer 460 made of aluminum at 40AC is 62%. In this case, the melting energy E per unit length of the 2nd strand 420 becomes 563.4 J / cm or more from Formula (2). Therefore, the melting energy per unit length of the second strand 420 becomes larger than the melting energy per unit length of the strand due to winter lightning, and the second strand 420 has the target lightning resistance.

  In order to set the melting energy E per unit length of the second strand 420 to 550 J / cm, when the second strand 420 is 40AC, the diameter of the second strand 420 is 4. When the second strand 420 is 27 AC, the diameter of the second strand 420 is 3.5 mm or more. When the second strand 420 is 14 AC, the diameter of the second strand 420 is 3. It needs to be 2 mm or more. Moreover, when the 2nd strand 420 is a deformed line | wire, such as a cross-sectional sector, each of the steel wire 440 and the coating layer 460 so that the fusion energy E per unit length of the 2nd strand 420 may be 550 J / cm. It is necessary to set the cross-sectional area.

  The electrical resistance per unit length (as a whole) of the OPGW 10 configured as described above is, for example, 0.140 Ω / km or less. Thereby, the constant temperature of OPGW10 can be 100 degrees C or less, and instantaneous temperature can be 200 degrees C or less. Therefore, the heat resistant temperature of the optical fiber 200 incorporated in the OPGW 10 can be lowered.

(Specific dimensions)
As specific dimensions of the OPGW 10, the diameter of the optical unit 20 is 2 mm or more and 7 mm or less, for example, 4.5 mm.

  The diameter of the 1st strand 320 in the 1st ground layer 300 of ground wire part 30 is 2 mm or more and 7 mm or less, for example, is 4.5 mm. The number of the first strands 320 in the first ground layer 300 is 4 or more and 14 or less, for example, 6.

  The diameter of the 2nd strand 420 in the 2nd ground wire layer 400 of ground wire part 30 is 3.2 mm or more and 7 mm or less, for example, is 4.5 mm. The number of the second strands 420 in the second ground layer 400 is 6 or more and 20 or less, for example, 12.

(2) Configuration of Optical Unit As described above, the OPGW 10 according to the present embodiment increases the electrical conductivity while maintaining the lightning resistance (melting resistance due to lightning strike), so that the optical fiber 200 having a low heat resistance temperature can be obtained. Configured to be incorporated. For example, the heat-resistant temperature of the optical fiber 200 incorporated in the OPGW 10 of the present embodiment can be constantly 100 ° C. or higher and lower than 150 ° C., or instantaneously 200 ° C. or higher and lower than 300 ° C. More preferably, the heat-resistant temperature of the optical fiber 200 incorporated in the OPGW 10 of the present embodiment can be constantly 100 ° C. and instantaneous 200 ° C. Thus, the optical unit part 20 which has the optical core 200 with low heat-resistant temperature is comprised as follows, for example.

  First, the optical fiber 100 provided inside the optical fiber 200 will be described.

  Here, FIG. 2 is a cross-sectional view orthogonal to the axial direction of the optical fiber 100 according to the present embodiment. As shown in FIG. 2, the optical fiber 100 includes an optical fiber 110 and fiber coating layers (140 and 150 described later) that cover the optical fiber 110.

  The optical fiber 110 has a core 120 and a clad 130. For example, the core 120 is made of pure quartz glass, and the cladding 130 is made of fluorine-added quartz glass. The optical fiber 110 is, for example, a single mode optical fiber.

  In this embodiment, the fiber coating layer is composed of, for example, two layers. For example, the first fiber coating layer 140 is provided so as to cover the outside of the optical fiber 110, and the second fiber coating layer 150 is provided so as to cover the outer periphery of the first fiber coating layer 140.

  Moreover, the 1st fiber coating layer 140 and the 2nd fiber coating layer 150 contain an ultraviolet curing silicone resin, for example. The heat resistant temperatures of the first fiber coating layer 140 and the second fiber coating layer 150 are always 100 ° C. or more and less than 150 ° C., instantaneous 200 ° C. or more and less than 300 ° C., more preferably 100 ° C. instantaneous 200 ° C.

  Next, the optical fiber 200 will be described. A bundle of a plurality of optical fiber strands 100 is referred to as an optical core wire 200.

  Here, FIG. 3A is a cross-sectional view orthogonal to the axial direction of the optical unit section according to the present embodiment. As shown in FIG. 3A, the optical fiber 200 is a so-called fixed three-core optical fiber. That is, the optical core wire 200 includes an optical fiber strand 100 that is twisted together and a strand covering layer 210 that is provided so as to cover the outer periphery of the optical fiber strand 100.

  The strand covering layer 210 includes, for example, a fluorine-based resin. In the present embodiment, the heat resistance temperature of the wire covering layer 210 is always 100 ° C. or more and less than 150 ° C., instantaneously 200 ° C. or more and less than 300 ° C., more preferably 100 ° C. instantaneously 200 ° C.

  As described above, in this embodiment, the optical fiber 100 and the optical fiber 200 can be made of a material having a low heat-resistant temperature.

  Next, the optical unit unit 20 will be described.

  As shown in FIG. 3A, the optical unit portion 20 of this embodiment is a so-called spacer type, and has a spacer 280 at the center. The spacer 280 is provided with a groove (not shown) recessed from the outer peripheral side toward the center. The said groove part is provided in the outer periphery of the spacer 280 helically along the axial direction, for example. Here, the spacer 280 is provided with, for example, three grooves. The spacer 280 is made of aluminum, for example.

  In the groove portion of the spacer 280, the optical fiber 200 having the optical fiber 100 described above is inserted. A protective tube 290 is provided so as to cover the outer periphery of the spacer 280. The protective tube 290 is made of aluminum, for example.

(Specific dimensions)
As specific dimensions of the optical fiber 100, for example, the diameter of the optical fiber 110 is 0.125 mm. The thickness of the first fiber coating layer 140 is 0.01 mm or more and 0.11 mm or less, and the thickness of the second fiber coating layer 150 is 0.01 mm or more and 0.11 mm or less. That is, the diameter of the optical fiber 100 is 0.165 mm or more and 0.56 mm or less.

  As specific dimensions of the optical fiber 200, for example, the thickness of the strand covering layer 210 is 0.05 mm or more and 0.15 mm or less. That is, the diameter of the optical fiber 200 is 0.46 mm or more and 1.5 mm or less.

  As specific dimensions of the optical unit section 20, for example, the diameter of the spacer 280 of the optical unit section 20 is 2 mm or more and 7 mm or less, and the thickness of the protective tube 290 is 0.1 mm or more and 1.0 mm or less. The diameter of the optical unit 20 is 2.2 mm or more and 9 mm or less, for example, 4.5 mm.

(3) Overhead structure of optical fiber composite overhead ground wire (Power line overhead conditions)
Here, the overhead line conditions of the power line 50 of the present embodiment will be described with reference to FIG. FIG. 5 is a view of the overhead structure of the optical fiber composite ground wire and the power line in the steel tower as viewed from the axial direction of the optical fiber composite ground wire. As shown in FIG. 5, the OPGW 10 of this embodiment is provided with the power line 50. Hereinafter, how the overhead line condition of the power line 50 affects the induced current induced in the OPGW 10, the current flowing through the OPGW 10 in the event of a ground fault, and the like will be described together with the overhead line condition of the power line 50.

  When the nominal voltage of the power line 50 provided alongside the OPGW 10 is 187 kV or higher, the current of the power line 50 is large and the induced current induced in the OPGW 10 is large. In this case, the OPGW 10 is so-called directly grounded. That is, the neutral point of the three-phase alternating current and the ground are directly connected, and a large ground fault current flows through the OPGW during a ground fault. For example, in this embodiment, the nominal voltage of the power line 50 is 500 kV.

Moreover, since the current capacity of the power line 50 increases as the size of the power line 50 increases, the induced current induced in the OPGW 10 increases. For example, the nominal cross-sectional area of the power line 50 is not less than 120 mm ^{2 and not} more than 1520 mm ^{2. In} the present embodiment, the nominal cross-sectional area of the power line 50 is 410 mm ² as a standard condition applied in Japan.

  In addition, when the heat resistant temperature of the power line 50 is high, the current capacity of the power line 50 increases, so that the induced current induced in the OPGW 10 increases. For example, in the present embodiment, the power line 50 is a heat-resistant steel core aluminum stranded wire (TACSR) that is widely used in Japan.

  Further, when the number of conductors per phase of the power line 50 increases, the current capacity per phase of the power line 50 increases, so that the induced current induced in the OPGW 10 increases. For example, the number of conductors 500 per phase of the power line 50 is 1 or more and 8 or less, and in this embodiment, the number of conductors per phase of the power line 50 is four. In the case of a large line having four conductors per phase of the power line 50, two OPGWs 10 are provided, for example.

  The phase arrangement of the power line 50 also affects the induced current of the OPGW 10.

  As shown in FIG. 5, two power lines (power transmission main lines) 50 of three-phase alternating current are installed on the steel tower 80. If the left power line 50 in the figure is the first line 51a, 51b, 51c and the right power line 50 is the second line 52a, 52b, 52c, the phase arrangement of the three phases of each power line 50 can be determined independently.

  If the first line 51a, 51b, 51c and the second line 52a, 52b, 52c are arranged in the same phase (two-line in-phase arrangement), the induced current induced in the OPGW 10 increases. Therefore, in many cases, the induced current induced in the OPGW is reduced by arranging the first and second lines in opposite phases. In the present embodiment, for example, a two-line in-phase arrangement is used as a severe condition for increasing the induced current.

  Under the overhead line conditions of the power line 50 as described above, the constant temperature of the OPGW 10 may easily increase due to the induced current induced in the OPGW 10. Furthermore, there is a possibility that the instantaneous temperature of the OPGW 10 is likely to rise due to a large ground fault current flowing through the OPGW 10 in a superimposed manner. In the present embodiment, the ground wire portion 30 of the OPGW 10 is composed of two or more layers, and the first strand 320 having high conductivity is provided on the ground wire portion 30 as described above, thereby reducing the electrical resistance of the OPGW 10. be able to. Therefore, even under the overhead condition of the power line 50 as described above, it is possible to suppress a constant temperature increase due to the induced current and an instantaneous temperature increase due to a large ground fault current.

(OPGW overhead condition)
The OPGW 10 of the present embodiment is wired to the top of the steel tower 80 via a connection clamp (not shown). As described above, two OPGWs 10 are provided, for example. The OPGW 10 of this embodiment is wired to satisfy the following conditions, for example.

  During transmission of the power line 50, the temperature of the OPGW 10 (of the ground wire portion 30) that rises due to the Joule heat of the induced current induced from the power line 50 is 100 ° C. or less.

  The maximum working tension of the OPGW 10 is set so that the sag of the OPGW 10 is 80% of the sag of the power line 50 when the temperature of the power line 50 is the lowest temperature (for example, −15 ° C.). At this time, it is stipulated in the technical standard (referred to as “electric technology”) of electrical equipment that the safety factor of the maximum working tension of OPGW10 with respect to the tensile load of OPGW10 is 2.5 or more. The safety factor is, for example, 2.8 in view of the tolerance for the difference or the like (in other words, the maximum working tension of OPGW10 is 1 / 2.8 times the tensile load of OPGW10).

  Further, the current of the OPGW 10 at the time of the ground fault and the energization time to the OPGW 10 are determined by the line design. For example, when the current of the OPGW 10 at the time of ground fault is 32 kA and the energization time to the OPGW 10 is 0.34 seconds, the instantaneous (arrival) temperature of the OPGW 10 (at the ground wire portion 30) is 200 ° C. or less. The sag of OPGW 10 when the temperature of OPGW 10 becomes the instantaneous temperature is equal to or less than the sag of power line 50.

(4) Manufacturing method of optical fiber composite ground wire Next, the manufacturing method of OPGW10 which concerns on this embodiment is demonstrated.

(Optical fiber forming process)
First, the optical fiber 110 is formed by melting and stretching the optical fiber preform in a heating furnace using an optical fiber drawing machine. Next, the first optical fiber coating layer 140 and the second optical fiber coating layer 150 are formed by coating the outer periphery of the stretched optical fiber 110 with an ultraviolet curable silicone resin and irradiating ultraviolet rays twice in sequence. . The intermediate body of the optical fiber 100 formed in this way is wound around a metal bobbin, and this bobbin is put into a thermostatic bath and subjected to heat treatment at 120 ° C. for 30 minutes, for example. Thus, the optical fiber strand 100 is formed.

(Optical fiber forming process)
For example, three optical fiber strands 100 are twisted, and a strand covering layer 210 containing, for example, a fluorine-based resin is formed so as to cover the outer periphery of the optical fiber strand 100. Thereby, the optical fiber 200 is formed.

(Optical unit formation process)
A spacer 280 having a spiral groove formed in the axial direction is prepared in advance, and the optical fiber 200 is inserted into the groove of the spacer 280. Next, a protective tube 290 is formed by continuously welding and extending the joint between the tapes by attaching a tape made of aluminum to the outside of the spacer 280 through which the optical fiber 200 is inserted into the groove. To do. Thus, the optical unit portion 20 is formed.

(First strand formation process)
A first wire 320 made of a heat-resistant aluminum alloy (TAL) is formed by a wire drawing machine using a wire drawing die having a circular opening.

(Second strand forming process)
Using a wire drawing die having a circular opening, a wire rod for steel wire 440 made of steel is formed by a wire drawing machine. Next, the wire for steel wire to be the steel wire 440 is coated with aluminum to be the coating layer 460 by a hot extrusion method to form a composite wire. Next, by drawing the obtained composite wire with a wire drawing machine, a second strand 420 made of AC wire is formed.

(Twisting process)
Next, the first ground wire layer 300 is formed by twisting, for example, six first strands 320 so that the optical unit portion 20 is arranged at the center and the outer periphery of the optical unit portion 20 is covered. Next, the second ground layer 400 is formed by twisting, for example, twelve second strands 420 so as to cover the outer periphery of the first ground layer 300.

  As described above, the OPGW 10 according to this embodiment is manufactured.

(5) Effects according to the present embodiment According to the present embodiment and its modifications, the following one or more effects are achieved.

(A) According to the present embodiment, the ground wire portion 30 provided outside the optical unit portion 20 has the first strand 320 having a conductivity of 50% IACS or more and the melting energy E per unit length. A second strand 420 that is larger than 550 J / cm. Accordingly, the optical fiber 100 having a low heat-resistant temperature can be incorporated into the OPGW 10 by increasing the conductivity of the OPGW 10 while maintaining the lightning resistance of the OPGW 10 (melting resistance against lightning).

  Here, the conventional OPGW is considered as a comparative example.

  In OPGW, an induced current is induced in the OPGW by the current of the power line, so the OPGW may constantly generate heat. Further, in OPGW, there is a possibility that the strands may be melted or disconnected due to a direct lightning strike. Further, when the power line has a ground fault, the power line and the OPGW form a closed circuit, and a ground fault current flows through the OPGW, so that the OPGW may instantaneously generate heat.

  Therefore, in the conventional OPGW, all the strands in the ground wire portion are constituted by AC wires that are less likely to be broken by melting or melting when subjected to a lightning strike. However, since all the strands in the ground wire portion are composed of AC wires, the conductivity of the OPGW so far has been low. For this reason, in the past OPGW, the temperature of the OPGW was likely to rise due to the Joule heat of the induced current induced from the power line.

  Therefore, the optical core wire incorporated in the conventional OPGW has been configured to always withstand 150 ° C. and instantaneously 300 ° C. as described in Patent Document 1 described above, for example. For example, in conventional optical fiber strands incorporated in OPGW, in order to increase the heat-resistant temperature, the fiber coating layer is composed of two layers of a silicone resin layer and a fluorine resin layer, The layer was made of polyimide resin. Moreover, the strand covering layer in the optical core was made of a fluorine resin having a high heat resistance temperature. Such an optical fiber having high heat resistance is limited to the use of OPGW, and is rarely used in other fields, so that it is expensive.

  On the other hand, according to the present embodiment, since the conductivity of the first strand 320 constituting the ground wire portion 30 is 50% IACS or more, the first strand 320 is induced from the power line (50). Generation of Joule heat due to induced current or ground fault current is suppressed. Thereby, the temperature rise of OPGW10 is suppressed. Specifically, as an example in which the second strand 420 has a melting energy of 550 J / cm or more, when the diameter is 40 AC having a diameter of 4.0 mm, the conductivity of the first strand 320 is 50% IACS or more. Accordingly, the equivalent conductivity of the OPGW 10 as a whole can be set to 44% IACS or more, and the constant temperature of the OPGW 10 can be set to 100 ° C. or less and the instantaneous temperature can be set to 200 ° C. or less. Therefore, the heat-resistant temperature of the optical fiber 200 incorporated in the OPGW 10 can be made lower than the heat-resistant temperature of the optical fiber bundle incorporated in the OPGW so far.

  Moreover, the melting energy per unit length of the 2nd strand 420 which comprises the ground wire part 30 is larger than 550 J / cm. That is, the melting energy per unit length of the second strand 420 is larger than the melting energy per unit length of the strand due to winter lightning. Thereby, the 2nd strand 420 comes to have lightning resistance. Therefore, even during a lightning strike, the second strand 420 is suppressed from melting and can continue to bear the tension of the OPGW 10.

  As described above, the first strand 320 is provided in the ground wire portion 30 of the OPGW 10 to increase the conductivity of the OPGW 10, thereby suppressing the temperature rise of the OPGW 10. By providing the second strand 420, the OPGW 10 Lightning resistance is ensured. Thereby, the optical fiber 200 having a low heat resistant temperature can be incorporated into the OPGW 10. Therefore, in the present embodiment, it is possible to avoid the use of an expensive optical fiber having a high heat resistant temperature, and it is possible to suppress an increase in the manufacturing cost of the OPGW 10.

(B) According to this embodiment, the nominal voltage of the power line 50 provided alongside the OPGW 10 is 187 kV or more. At this time, the ground wire portion 30 of the OPGW 10 is composed of two or more layers.

  Here, as a comparative example, consider a case where the nominal voltage of the power line provided alongside the OPGW is 66 kV or more and 154 kV or less. In the case of this comparative example, the power line current is small and the induced current induced in the OPGW is small. The OPGW of the comparative example is so-called resistance ground. That is, a large electric resistance is inserted between the neutral point of the three-phase alternating current and the ground, and the current of the OPGW at the time of the ground fault is suppressed. Therefore, in the OPGW of the comparative example, the ground wire portion can be configured by only one layer having high electric resistance, and the heat resistance temperature of the OPGW is set to about 90 ° C. continuously and about 120 ° C. instantaneously. Thus, the heat resistant temperature of the OPGW may be lowered due to the difference in the nominal voltage of the power line and the difference in the grounding method.

  On the other hand, when the nominal voltage of the power line 50 provided alongside the OPGW 10 is 187 kV or more, as described above, the current of the power line 50 is large, and the induced current induced in the OPGW 10 is large. In this case, the OPGW 10 is so-called directly grounded. That is, the neutral point of the three-phase alternating current and the ground are directly connected, and a large ground fault current flows through the OPGW during a ground fault. Therefore, when the nominal voltage of the power line 50 is 187 kV or higher, the constant temperature of the OPGW 10 is likely to rise due to the induced current induced in the OPGW 10, and the instantaneous temperature of the OPGW 10 may easily rise due to the flow of a large ground fault current. There is.

  Therefore, according to the present embodiment, the ground wire portion 30 of the OPGW 10 is configured with two or more layers, and the first strand 320 having high conductivity is provided in the ground wire portion 30 as described above, so that the OPGW 10 as a whole is provided. The electrical resistance can be reduced. Thereby, even if it is a case where the nominal voltage of the electric power line 50 is 187 kV or more, the continuous temperature rise by an induced current and the instantaneous temperature rise by a big ground fault current can be suppressed. Therefore, this embodiment is particularly effective when the nominal voltage of the power line 50 is 187 kV or higher.

(C) According to the present embodiment, the ground wire portion 30 includes a first ground wire layer 300 in which a plurality of first strands 320 are twisted on the outside of the optical unit portion 20, and the first ground wire layer 300. A second ground wire layer 400 provided with a plurality of second strands 420 twisted together.

  Here, as a comparative example, contrary to the present embodiment, the first strand having high conductivity is provided in the second ground layer located outside the ground wire portion, and is located inside the ground wire portion. Consider the case where a second strand having lightning resistance is provided in the first ground layer. When the OPGW receives a lightning stroke, the arc current of the lightning stroke first reaches the outer layer (second ground layer) of the ground line portion. Since the 1st strand with high conductivity provided in the 2nd ground layer does not have sufficient lightning resistance, the 1st strand of the 2nd ground layer may blow out.

  On the other hand, according to the present embodiment, the first ground layer 300 composed of the first strands 320 having high conductivity is the second ground wire composed of the second strands 420 having lightning resistance. Covered by layer 400. When the OPGW 10 receives a lightning stroke, the first ground layer 300 including the first strands 320 having low lightning resistance is protected by the second ground layer 400. Therefore, it can suppress that the 1st strand 320 of the 1st ground wire layer 300 blows out.

(D) According to this embodiment, specifically, the electrical resistance per unit length (as a whole) of the OPGW 10 is 0.140 Ω / km or less. Thereby, the constant temperature of OPGW10 can be 100 degrees C or less, and instantaneous temperature can be 200 degrees C or less. Therefore, the heat resistant temperature of the optical fiber 200 incorporated in the OPGW 10 can be lowered.

<Modification of this embodiment>
In the first embodiment described above, the case where the optical core 200 is a so-called fixed three-core optical core is described, but the present invention is not limited to this. For example, the configuration of the optical fiber core and the optical unit section as in the following modification is conceivable. The configuration of the optical fiber 100 is the same as that of the first embodiment. In the following modification, only elements different from the first embodiment will be described, and description of elements substantially the same as those described in the first embodiment will be omitted.

(Modification 1)
FIG. 3B is a cross-sectional view orthogonal to the axial direction of the optical unit section according to the present embodiment. As shown in FIG. 3B, the optical core 202 of the first modification is a so-called fixed 6-core batch optical core.

  A central inclusion 222 is provided at the center of the optical fiber 202. The central inclusion 222 is made of, for example, FRP. For example, six optical fiber strands 100 are twisted outside the center inclusion 222. Moreover, the strand covering tape 232 is provided so that the outer periphery of the optical fiber strand 100 may be covered. The strand covering tape 232 includes, for example, a fluorine resin.

  In addition, for example, five grooves are provided in the spacer 282 of the optical unit 22 of the first modification. The optical fiber 202 is inserted into each of the groove portions of the spacer 282.

  Like the modification 1, the optical unit part 22 may have more optical fiber strands 100 than the optical unit part 20 of 1st Embodiment.

(Modification 2)
FIG. 4A is a cross-sectional view orthogonal to the axial direction of the optical unit section according to the second modification. As shown in FIG. 4A, the optical fiber 204 of the second modification is a so-called non-fixed batch optical fiber.

  A tension member 224 is provided at the center of the optical fiber 204. The tension member 224 is made of, for example, FRP. For example, twelve optical fiber strands 100 are twisted outside the tension member 224. Moreover, the strand covering layer 214 is provided so that the outer periphery of the optical fiber strand 100 may be covered. The strand covering layer 214 includes, for example, a fluorine resin.

  Further, in the optical unit 24 of the second modification, the optical fiber 204 is inserted through the protective tube 290 with a gap. In the case of the modification 2, the protective tube 290 may be made of stainless steel or steel in addition to the case of being made of aluminum. Further, the protective tube 290 may be a stainless steel tube coated with aluminum.

  According to the second modification, the optical fiber 204 can move in the protective tube 290, so that the optical fiber 204 can be exchanged.

(Modification 3)
FIG. 4B is a cross-sectional view orthogonal to the axial direction of the optical unit section according to Modification 3. As shown in FIG. 4B, the optical fiber core 206 of the third modification is also a so-called non-fixed batch optical fiber, similarly to the second modification.

  A central inclusion 226 is provided at the center of the optical fiber 206. The central inclusion 226 is made of, for example, FRP. For example, six optical fiber strands 100 are twisted outside the central inclusion 226. In addition, a strand covering layer 216 that functions as a tension member is provided so as to cover the outer periphery of the optical fiber strand 100. The strand covering layer 216 is made of, for example, FRP.

  Further, in the optical unit portion 26 of the third modification, as in the second modification, the optical fiber 204 is inserted through the protective tube 290 with a gap.

  A tension member may be provided outside the optical fiber strand 100 as in the optical unit portion 26 of the third modification.

<Second Embodiment of the Present Invention>
A second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a cross-sectional view orthogonal to the axial direction of the optical fiber composite ground wire according to the present embodiment.

  This embodiment is different from the first embodiment in the configuration of the first ground layer 302. Hereinafter, only elements different from those of the first embodiment will be described, and elements substantially the same as those described in the first embodiment are denoted by the same reference numerals and description thereof will be omitted.

(1) Structure of optical fiber composite aerial ground wire As shown in FIG. 6, in the OPGW 12 of the present embodiment, the first ground wire layer 302 provided on the outside of the optical unit section 20 has, for example, a fan-shaped cross section. A first strand 322 is included. The first strand 322 has a side surface along the radial direction. Note that “along the radial direction” can be rephrased as “provided in a direction having a radial component”. The plurality of first strands 322 twisted together with the first ground layer 302 are in contact with each other on the side surface (surface contact). Thereby, in the 1st ground wire layer 302, the 1st strand 322 is filled densely.

  The inner peripheral surface of the first ground wire layer 302 formed by providing a plurality of first strands 322 aligned in the circumferential direction forms a curved surface along the outer peripheral surface of the protective tube 290 of the optical unit unit 20. . The inner peripheral surface of the first ground layer 302 is in contact with the protective tube 290 of the optical unit unit 20 (surface contact).

(2) Effects According to the Present Embodiment According to the present embodiment, the plurality of first strands 322 twisted together with the first ground wire layer 302 are in contact with each other on the side surface (surface contact). In the first ground layer 302, the first strands 322 are densely filled. The cross-sectional area of the 1st strand 322 in the 1st ground wire layer 302 can be enlarged, and the electrical resistance of the 1st ground wire layer 302 can be made low. In the first ground layer 302, the generation of Joule heat due to the induced current induced from the power line (50) or the current at the time of the ground fault is further suppressed. Therefore, the temperature rise of OPGW10 can be suppressed stably.

<Third embodiment of the present invention>
A third embodiment of the present invention will be described with reference to FIG. FIG. 7 is a cross-sectional view orthogonal to the axial direction of the optical fiber composite ground wire according to the present embodiment.

  This embodiment differs from the first embodiment in the configuration of the second ground layer 404. Hereinafter, only elements different from those of the first embodiment will be described, and elements substantially the same as those described in the first embodiment are denoted by the same reference numerals and description thereof will be omitted.

  As shown in FIG. 7, in the OPGW 14 of the present embodiment, the number of the second strands 424 in the second ground layer 404 is smaller than the number of the second strands of the first embodiment, for example, 10 It is a book. Moreover, the diameter of the 2nd strand 424 is larger than the diameter of the 2nd strand of 1st Embodiment, for example, is 5.3 mm.

  According to the present embodiment, as described above, even when the number of the second strands 424 is small and the diameter of the second strands 424 is large, the same effect as the first embodiment can be obtained. .

<Other Embodiments of the Present Invention>
As mentioned above, although embodiment and modification of this invention were described concretely, this invention is not limited to the above-mentioned embodiment and modification, and can be variously changed in the range which does not deviate from the summary.

  In the above-described embodiment, the case where the ground wire portion 30 of the OPGW 10 is configured by two layers (the first ground wire layer 300 and the second ground wire layer 400) has been described, but the ground wire portion of the OPGW has three or more layers. You may have a ground wire layer.

In the above-described embodiment, the case where the second strand 420 of the OPGW 10 is made of an AC wire has been described. However, if the melting energy per unit length of the second strand is larger than 550 J / cm, the second strand May be other than AC lines. For example, the second strand may be an aluminum-coated invar wire. In this case, in order to obtain the melting energy of the aluminum-coated invar wire, in formula (2), C _Fe is the specific heat of the invar, T ₂ is the melting point of the invar, δ _Fe is the heat of melting of the invar, and W _Fe is the steel made of invar. What is necessary is just to substitute for the weight per unit length of a line part.

  Moreover, although the above-mentioned embodiment demonstrated the case where the 1st strand 320 consists of a heat-resistant aluminum alloy, if the electrical conductivity is 50% IACS or more, the 1st strand will consist of an aluminum covering steel wire. Also good.

  In the above-described embodiment, the case where the cross section of the second strand 420 constituting the second ground layer 400 is circular has been described. However, the cross section of the second strand constituting the second ground layer is a fan shape. It may be an irregular shape.

  In the above-described embodiment, the case where the optical unit unit 20 includes the protective tube 290 has been described. However, the optical unit unit may not include the protective tube.

  Moreover, although the above-mentioned embodiment demonstrated the case where the fiber coating layer of the optical fiber strand 100 was provided with two layers (140,150), the fiber coating layer of an optical fiber strand may be only one layer. .

  Moreover, although the above-mentioned embodiment demonstrated the case where the strand covering layer 210 was provided so that the outer periphery of the optical fiber strand 100 of the optical fiber 200 could be covered, an optical fiber strand is covered with a strand covering layer. You may accommodate in the groove part of a spacer in the state which is not broken. Also in the modified examples 3 and 4, the optical fiber strand may be accommodated in the protective tube in a state where it is not covered with the strand covering layer.

(1) Configuration of OPGW As shown in Table 1 below, the OPGW of Sample 1 corresponding to the first embodiment shown in FIG. 1 was designed, and 4 conductors per phase of 500 kV, TACSR 410 mm ² , We examined (evaluated) the temperature, sag characteristics, etc. when the power lines were arranged in two lines in phase.

  Further, as shown in Table 2 below, the OPGW of Sample 2 corresponding to the second embodiment shown in FIG.

  Further, as shown in Table 3 below, the OPGW of Sample 3 corresponding to the third embodiment shown in FIG.

  Further, as an example of the OPGW that has been used so far, the OPGW of the comparative example was examined as follows.

  Here, FIG. 8 is a cross-sectional view orthogonal to the axial direction of the optical fiber composite ground wire according to the comparative example. As illustrated in FIG. 8, the OPGW 90 of the comparative example includes an optical unit portion 92 and a ground wire portion 93. The configuration of the ground wire portion 93 is different from that of the first embodiment, and all the strands (932, 942) in the ground wire portion 93 are configured by AC lines. For example, the first ground layer 930 has a first strand 932 whose section is made of a fan-shaped AC line, and the second ground layer 940 has a second strand 942 whose section is made of an AC line having a circular shape. .

  As shown in Table 4 below, for the OPGW of the comparative example shown in FIG.

  Further, as shown in Table 5 below, in addition to the samples 1 and 2 described above, the configurations of the optical unit portion and the ground wire portion are the same as those of the samples 1 and 2, and the cross-sectional areas are different (that is, electrical resistance The OPGWs of Samples 4, 5, and 6 were designed, and normal and instantaneous reached temperatures under the same conditions as Sample 1 were examined.

(2) Details of Evaluation Contents The following evaluation was performed on the above-described sample and the OPGW of the comparative example.

  The constant temperature of each OPGW of the sample and the comparative example was evaluated when a current of 4824 A per phase was passed through the power line provided. At this time, an induced current (482.4 A) corresponding to 10% of the current flowing per phase of the power line is induced in each ground line portion.

  Further, the instantaneous (arrival) temperatures of the OPGW of the sample and the comparative example were evaluated when a ground fault occurred in the power line 50, the current was 32 kA, and the energization time to the OPGW 10 was 0.34 seconds.

(3) Evaluation Results As shown in Table 4, the OPGW of the comparative example always had a temperature of 114 ° C and an instantaneous temperature of 259 ° C. For this reason, it turns out that the heat-resistant temperature of the optical fiber incorporated in the OPGW of the comparative example is required to be constantly 150 ° C. and instantaneously 300 ° C.

  On the other hand, as shown in Tables 1 to 3, in Samples 1 to 3, the constant temperature of OPGW is 96 ° C., 92 ° C., and 95 ° C., and the instantaneous temperature of OPGW is 184 ° C. and 167 ° C., respectively. And 176 ° C. That is, in any of Samples 1 to 3, the OPGW temperature was always 100 ° C. or lower and instantaneously 200 ° C. or lower. Therefore, it can be seen that the heat-resistant temperature of the optical fiber incorporated in the OPGWs of Samples 1 to 3 can be lower than the heat-resistant temperature of the optical fiber incorporated in the conventional OPGW of the comparative example.

  Note that the constant temperature and instantaneous temperature of the OPGW of Sample 2 were the lowest. In the OPGW of Sample 2, the cross section of the first strand in the first ground layer was formed in a fan shape, and the cross-sectional area of the first strand was large. Therefore, in the OPGW of sample 2, the conductivity of the first ground layer (equivalent conductivity of OPGW) can be increased. In the first ground layer, the induced current induced from the power line, the current at the time of the ground fault It is considered that the constant temperature and instantaneous temperature of the OPGW of Sample 2 could be lowered by further suppressing the generation of Joule heat due to.

  As shown in Table 5, as the cross-sectional area of OPGW increases (that is, as the electrical resistance per unit length of OPGW decreases), the constant temperature and instantaneous temperature of OPGW decrease. In particular, in Samples 1 and 2 in which the electrical resistance per unit length of OPGW was 0.140 Ω / km or less, the temperature of OPGW was always 100 ° C. or less and instantaneously 200 ° C. or less. Therefore, it is considered that the electric resistance per unit length of OPGW is preferably 0.140 Ω / km or less.

  As described above, according to the present invention, it is possible to provide an OPGW that can incorporate an optical fiber having a low heat-resistant temperature.

10 Optical fiber composite ground wire (OPGW)
20, 22, 24, 26 Optical unit 30 Ground line 50 Power line (power transmission main line)
51a, 51b, 51c No. 1 line 52a, 52b, 52c No. 2 line 80 Steel tower 100 Optical fiber strand 110 Optical fiber 120 Core 130 Cladding 140 First fiber coating layer 150 Second fiber coating layer 200, 202, 204, 206 Optical fiber core 210, 214, 216 Wire covering layer 222, 226 Central inclusion 224 Tension member 232 Wire covering tape 280, 282 Spacer 290 Protective tube 300 First ground layer 320, 322 First strand 400, 404 Second ground wire Layers 420 and 424 Second strand 440 Steel wire 460 Coating layer 500 Conductor

Claims (11)

An optical unit having an optical core in which an optical fiber is provided;
A ground wire provided outside the light unit;
Have
The ground wire portion is
A first strand having a conductivity of 50% IACS or higher;
A second strand having a melting energy per unit length greater than 550 J / cm;
An optical fiber composite ground wire characterized by comprising: The ground wire portion is
A first ground layer provided by twisting a plurality of the first strands on the outside of the optical unit portion;
A second ground layer provided by twisting a plurality of the second strands outside the first ground layer;
The optical fiber composite ground wire according to claim 1, wherein The first strand has a side surface along a radial direction,
3. The optical fiber composite ground wire according to claim 2, wherein the plurality of first strands twisted together with the first ground layer are in contact with each other at the side surface. The electrical resistance per unit length is 0.140 ohm / km or less, The optical fiber composite ground wire of any one of Claims 1-3 characterized by the above-mentioned. The optical fiber composite ground wire according to any one of claims 1 to 4, wherein the second strand is made of an aluminum-coated steel wire. The conductivity of the second strand is lower than the conductivity of the first strand,
The diameter of the said 2nd strand is 3.2 mm or more, The optical fiber composite overhead ground wire of Claim 5 characterized by the above-mentioned. The said 1st strand consists of at least any one of a heat resistant aluminum alloy wire, a super heat resistant aluminum alloy wire, a special heat resistant aluminum alloy wire, and a high strength heat resistant aluminum alloy wire, The any one of Claims 1-6 characterized by the above-mentioned. An optical fiber composite ground wire according to the item. The optical fiber composite ground wire according to any one of claims 1 to 6, wherein the first strand is made of an aluminum-coated steel wire. 9. The optical fiber composite ground wire according to claim 1, wherein the heat-resistant temperature of the optical fiber is always 100 ° C. or higher and lower than 150 ° C., and instantaneously 200 ° C. or higher and lower than 300 ° C. 9. . The optical fiber is
Optical fiber,
A coating layer that coats the optical fiber and contains an ultraviolet curable silicone resin;
The optical fiber composite overhead ground wire according to any one of claims 1 to 9, characterized by comprising: An optical unit having an optical core in which an optical fiber is provided;
A ground wire provided outside the light unit;
Have
The ground wire portion is
A first ground layer provided outside the optical unit;
A second ground layer provided outside the first ground layer;
Have
An optical fiber composite ground wire, wherein the electrical conductivity of the first ground layer is higher than the electrical conductivity of the second ground layer.

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