JP4373600B2 - Electrically insulated bus and method for manufacturing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an underground power transmission line, and more particularly, to an electrically insulated bus of the type assembled and laid on site in spite of applying a solid insulator as an insulating medium and a method for manufacturing the same.
[0002]
[Prior art]
Conventionally, in underground power transmission lines, CV cables using a crosslinked polyethylene having an excellent insulating performance as an insulating medium have been applied and have become widespread, and have become mainstream as long-distance lines in Tokyo. At present, the CV cable is required to have a high voltage of 550 kV, and a part of the CV cable has been put into practical use. In recent years, a pipeline air transmission line using SF6 (sulfur hexafluoride) gas as a main insulating medium has been adopted due to the demand for high voltage and large capacity of underground transmission lines. These underground power transmission lines form the basis of social energy distribution, so of course high reliability is required, but also economic and global environmental issues are required, and further reduction and environmental harmony are required. Is desired. Below, the specific structure of a CV cable and a pipe line power transmission line is demonstrated.
[0003]
First, an example of a cross-sectional view of a general structure portion of a CV cable is shown in FIG. As shown in FIG. 6, the CV cable is composed of a stranded conductor 1, an inner semiconductive layer 2, a cross-linked polyethylene insulator 3, and an outer semiconductive layer 4 sequentially disposed around the stranded conductor 1 by extrusion molding. . A metal shield 5 and a vinyl sheath 6 are provided outside the outer semiconductive layer 4 to prevent water permeation.
[0004]
FIG. 7 shows an example of a structure diagram of the connection portion of the CV cable. As shown in FIG. 7, the terminal T of the CV cable is cut and the stranded conductors 1 are connected to each other by a conductor connecting pipe 7. The cross-linked polyethylene insulator 3 and the reinforcing insulator 8 of the terminal T are integrally formed by extruding the cable raw material into the mold using a small extruder at the construction site. Semiconductive layers 9 are respectively provided on the outer circumferences of the conductor connecting pipe 7 and the reinforcing insulator 8, and are integrated with the conductor connecting pipe 7 and the reinforcing insulator 8 by cross-linking. Furthermore, a metal shield 5, a waterproof compound 10 and a protective tube 11 are provided on the outermost periphery to prevent water permeation. In the CV cable having this structure, the insulation thickness of the crosslinked polyethylene insulator 3 is selected according to the voltage class.
[0005]
Next, FIG. 8 shows a sectional view of the structure of the pipeline air transmission line. The in-pipe air transmission line has a coaxial cylindrical structure, and includes a high-voltage conductor 12 through which a high-voltage and large-current flows at the center and a sheath 13 on the outside, and excellent insulation characteristics between the high-voltage conductor 12 and the sheath 13. The SF6 gas 14 is filled. The high voltage conductor 12 is supported in the sheath 13 at intervals of several meters by insulating spacers 15 made of epoxy resin, and constitutes one unit in units of several tens of meters. After this unit is assembled at a factory and transported to the site, the units are connected to form an underground transmission line. Moreover, the universal bellows 16 is arrange | positioned every several tens of meters in order to absorb the thermal expansion and contraction which generate | occur | produces by connecting many units in a tunnel, and the displacement at the time of an earthquake.
[0006]
[Problems to be solved by the invention]
By the way, there are some problems with the above-described underground power transmission lines that are frequently used. First, the CV cable is flexible and can easily cope with curved displacement and ground displacement and is suitable for a long-distance line. On the other hand, the cross-linked polyethylene insulator 3 and the stranded wire conductor 1 are integrally formed. For this reason, there is a restriction on the cross-sectional area of the stranded wire conductor 1, which causes a thermal problem with respect to large current transmission. That is, with a CV cable, the transmission capacity per line is limited, and large-capacity transmission becomes impossible. To compensate for this, power transmission by a large number of lines is required, and the economic efficiency is impaired.
[0007]
On the other hand, for the pipeline air transmission line, the cross-sectional area of the high-voltage conductor 12 can be increased compared to the CV cable, and the heat dissipation is excellent, so that the transmission capacity per line can be increased. is there. Therefore, it is suitable for large capacity underground power transmission lines such as power lines in urban areas. However, there are many connection points at the site, and there is a problem that metal foreign matter is mixed. In particular, the insulating performance of the SF6 gas 14, which is the main insulating medium of the pipeline air transmission line, is significantly reduced with respect to metallic foreign matter, so that countermeasures are required.
[0008]
For example, in order to prevent metallic foreign matter from adhering to the insulating spacer 15, many extra accessories are required, such as providing a particle trap that captures and detoxifies the metallic foreign matter. Naturally, the cost is increased accordingly, and the economic efficiency is impaired. Furthermore, since SF6 gas is also included in the reduction target as a greenhouse gas, there is a possibility that the usage amount will be regulated in the future, such as total amount restriction. Therefore, it may become one of the problems for environmental harmony.
The present invention has been made in consideration of the above points. The purpose of the present invention is to enable high-voltage, large-capacity power transmission, easy maintenance and high reliability, and a reduction in total cost. It is possible to provide an environment-friendly electrical insulation bus and a method for manufacturing the same.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention relates to an electrical insulation bus in which a high voltage conductor for passing a high voltage and a large current is disposed in the axial direction of the inner space of a sheath having a ground potential. It has characteristics.
[0010]
In the first aspect of the present invention , a coaxial cylindrical insulating member is disposed between the high voltage conductor and the sheath, and a predetermined gap is provided between the outer periphery of the high voltage conductor and the coaxial cylindrical insulating member. And a predetermined gap is also formed between the inner wall surface of the sheath and the coaxial cylindrical insulating member, and the high-voltage conductor is connected to the sheath through the potential connection member disposed in each of the predetermined gaps. The high-voltage conductor, the sheath, the coaxial cylindrical insulating member, and the potential connecting member are each configured to be separated and independent in advance.
[0011]
According to the first aspect of the present invention, since the high voltage conductor and the coaxial cylindrical insulating member are separated from each other and independent from each other, the heat generated by energizing the high voltage conductor with a large current is coaxial as in the case of integral molding. Do not transmit directly to the cylindrical insulating member. Therefore, it is possible to improve the reliability of the electrically insulated bus that can perform high-capacity power transmission with high voltage and current. In addition, by providing gaps between the high voltage conductor and the coaxial cylindrical insulating member, and between the coaxial cylindrical insulating member and the sheath, heat transfer from the high voltage conductor can be suppressed, so that a larger current can be applied. In addition, it is possible to improve the thermal reliability of the coaxial cylindrical insulating member.
[0012]
According to a second aspect of the present invention, in the electrically insulated bus according to the first aspect, each of the high-voltage conductor, the coaxial cylindrical insulating member, and the sheath is unitized with a predetermined length within a transport limit. And a unit connection structure in which the units are connected to each other.
According to the invention of claim 2 as described above, the high voltage conductor, the coaxial cylindrical insulating member, and the sheath are unitized, and the unit can be transported and connected. Units can be connected to each other and the whole can be assembled. Therefore, it is possible to realize an electrically insulated bus that can transmit a large amount of power with a high voltage and a large current over a long distance.
[0013]
According to a third aspect of the present invention, in the electrically insulated bus according to the second aspect, the unit connection structure of the high-voltage conductor, the coaxial cylindrical insulating member, and the sheath has an axial direction and a radius for each predetermined length. It includes a displacement countermeasure structure that can absorb the displacement in the direction .
According to the invention described in claim 3 as described above, the high voltage conductor, the coaxial cylindrical insulating member and the sheath each include the displacement countermeasure structure portion capable of absorbing thermal expansion and contraction and seismic displacement, and a highly reliable electric insulated bus. Can be realized.
[0014]
According to a fourth aspect of the present invention, in the electrically insulated bus according to the third aspect, the displacement countermeasure structure portion is a sliding contact structure for the high voltage conductor, a bellows structure for the sheath, and the coaxial cylindrical insulating member. Is characterized by being a contact structure of a rubber-like elastomer material.
According to the fourth aspect of the present invention, the displacement countermeasure structure can absorb thermal expansion and contraction and seismic displacement, and a highly reliable electrically insulated bus can be realized.
[0015]
According to a fifth aspect of the present invention, in the electrically insulated bus according to the first, second, third, or fourth aspect, a dry gas is forcibly enclosed in a gap between the coaxial cylindrical insulating member and the sheath. It is characterized by being.
According to the fifth aspect of the present invention, there is no moisture absorption to the coaxial cylindrical insulating member, and the adverse effect on the insulation performance degradation such as a water tree can be removed, and the insulation reliability of the electrical insulation bus can be improved.
[0016]
According to a sixth aspect of the present invention, in the electrically insulated bus according to the first, second, third, fourth, or fifth aspect, a semiconductive layer is provided on an inner peripheral surface and an outer peripheral surface of the coaxial cylindrical insulating member. The semiconductive layer on the inner peripheral surface is set to the potential of the high-voltage conductor, and the semiconductive layer on the outer peripheral surface is set to the potential of the sheath.
According to the sixth aspect of the present invention, no voltage is applied to the gap between the high voltage conductor and the coaxial cylindrical insulating member and between the coaxial cylindrical insulating member and the sheath. For this reason, even if a metal foreign object enters the gap between the coaxial cylindrical insulating members in the field welding of the high voltage conductor and the sheath, there is no discharge. That is, partial discharge does not occur and insulation reliability can be improved.
[0017]
According to a seventh aspect of the present invention, in the electrically insulated bus according to the sixth aspect, the potential of the high voltage conductor and the potential of the sheath of the coaxial cylindrical insulating member are set by forced connection by the potential connecting member. It is characterized by.
According to the seventh aspect of the present invention, by ensuring the potential of the semiconductive layer at the connection portion between the units of the coaxial cylindrical insulating member, it is possible to prevent a transient voltage from being generated when a surge voltage enters. Thus, it is possible to remove the cause of the insulation deterioration and improve the insulation reliability of the electric insulation bus.
[0018]
According to an eighth aspect of the present invention, in the electrically insulated bus according to the second or third aspect , each unit of the high-voltage conductor is provided with two or more through holes.
According to the eighth aspect of the present invention, thermal convection is possible through the through-hole of the high-voltage conductor, and since a cooling effect is obtained by convection action, there is no direct transmission to the coaxial cylindrical insulating member. The heat resistance reliability of the busbar can be improved.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, one embodiment of the electrically insulated bus according to the present invention will be described in detail with reference to FIGS.
[0020]
(1) Configuration of Electrically Insulated Bus Bar FIG. 1 is an overall configuration diagram of an electrically insulated bus bar according to the present embodiment. Between the high-voltage conductor 12 for passing a high voltage and a large current and a pipe-shaped sheath 13 covering the high-voltage conductor 12, a cylindrical solid insulating structure 17 surrounds the high-voltage conductor 12 on the inner periphery. The main insulating part is formed by being inserted into the surface. FIG. 2 shows a general structure (A in FIG. 1) assembled by connecting the high voltage conductor 12, the sheath 13 and the solid insulation structure 17 unitized to a length that can be transported in a factory. These are CC sectional drawing of a general structure part.
[0021]
The high voltage conductor 12 is configured by connecting the conductor units 12a to each other by conductor welding 12b. The sheath 13 is configured by connecting the pipe units 13a to each other by pipe welding 13b. The solid insulation structure 17 is configured by connecting the insulation structure units 17a to each other with an insulation adhesive 17b. A high-voltage-side semiconductive layer 18 and a ground-side semiconductive layer 19 are provided on the inner and outer peripheral surfaces of the insulating structure unit 17a.
[0022]
The high-voltage potential connecting tube 20 on the inner peripheral surface of the insulating bonding portion 17b of the solid insulating structure 17 is configured to have the same potential as the high-voltage side semiconductive layer 18, and the insulating bonding portion 17b of the solid insulating structure 17 The ground potential connection tube 21 on the outer peripheral surface is configured to have the same potential as the ground side semiconductive layer 19.
Further, the high voltage side gap 22 is formed between the high voltage conductor 12 and the solid insulating structure 17 by the thickness in the radial direction of the high voltage potential connection tube 20, and the thickness in the radial direction of the ground potential connection tube 21. Only the ground-side gap 23 is formed between the solid insulating structure 17 and the sheath 13. Furthermore, the conductor unit 12a is provided with two or more through holes 12c.
[0023]
Next, FIG. 4 shows a displacement countermeasure structure (B in FIG. 1) for thermal expansion and contraction and earthquake displacement. FIG. 5 is a DD cross-sectional view of the displacement countermeasure structure. The high voltage conductor 12 is connected by a slide contact 24 and the sheath 13 is connected by a bellows 25 for each predetermined length in which the conductor units 12a, the pipe unit 13a, and the insulating structure unit 17a are connected to each other. The structure 17 is connected by a rubber-like elastomer member 26. The slide contact 24 is provided with a screw thread, and the conductor unit 12a is provided with a screw hole having the same diameter as the screw thread of the slide contact 24.
[0024]
(2) Manufacturing method An electrically insulated bus having the above-described configuration can be assembled as follows. That is, the conductor unit 12a, the pipe unit 13a, and the insulating structure unit 17a having the high-voltage side semiconductive layer 18 and the ground side semiconductive layer 19 are manufactured in a length that can be transported at the factory. The whole can be assembled by carrying in and connecting to each type of unit.
[0025]
In this case, welding of each conductor unit 12a and the pipe unit 13a can be implemented with an automatic welding machine. Further, after the high voltage potential connecting tube 20 and the ground potential connecting tube 21 are inserted in the insulating structure unit 17a in advance and bonded by the insulating bonding portion 17b, the high voltage side semiconductive layer 18 is formed on the inner peripheral surface. The high-voltage potential connection tube 20 is forcibly fixed to the same potential, and the ground-side semiconductive layer 19 and the ground potential connection tube 21 are forcibly fixed to the same potential on the outer peripheral surface. In this case, the high-voltage potential connecting pipe 20 and the conductor unit 12a have a contact structure so as to have the same potential, and the ground potential connecting pipe 21 and the pipe unit 13a similarly have a contact structure so as to have the same potential. In this state, dry air is sealed by applying pressure to the ground-side gap 23 between the solid insulating structure 17 and the sheath 13. Further, the high-voltage side gap 22 between the high-voltage conductor 12 and the solid insulating structure 17 is provided with a space width of 5 mm or more so that a heat convection can occur.
[0026]
Further, in the displacement countermeasure structure portion, the high voltage conductor 12 is closely connected by a screwing operation of the slide contactor 24, and the sheath 13 is welded with the bellows 25 between the pipe units 13a. In the solid insulation structure 17, the insulation structure units 17a are assembled in advance in a connection type, and a rubber-like elastomer material is poured therein to form a rubber-like elastomer member 26. A semiconductive layer is formed on the inner peripheral surface and the outer peripheral surface of the rubber-like elastomer member 26, and the inner peripheral surface forcibly forms the same potential as the high voltage side semiconductive layer 18 of the insulating structure unit 17a. Forcibly forms the same potential as that of the ground-side semiconductive layer 19 of the insulating structure unit 17a.
[0027]
(3) Operational Effects According to the electrically insulated bus and the manufacturing method thereof according to the present embodiment having the above-described configuration, the following operational effects are obtained. That is, since the high voltage conductor and the solid insulation structure are completely separated and independent, heat generated by energizing the high voltage conductor with a large current is not directly transmitted to the solid insulation structure as in the case of integral molding. And the cross-sectional area of the high-voltage conductor 12 can be enlarged, and high-capacity power transmission with a high voltage and large current is possible.
[0028]
The high voltage conductor 12 and the high voltage side semiconductive layer 18 of the solid insulating structure 17 are at the same potential, and the sheath 13 and the ground side semiconductive layer 19 of the solid insulating structure 17 are also at the same potential. Therefore, the insulation of the high voltage conduction between the high voltage conductor 12 and the sheath 13 is borne only by the solid insulation structure 17. Accordingly, the high-voltage side gap 22 between the high-voltage conductor 12 and the solid insulation structure 17 and the ground-side gap 23 between the sheath 13 and the solid insulation structure 17 are in a non-voltage state. Therefore, even if metal dust generated in the field welding of the conductor unit 12a and the pipe unit 13a exists in the high-voltage side gap 22 and the ground-side gap 23, the insulation characteristics are not affected at all and are harmless. Further, no peeling or cracking occurs due to thermal stress caused by energization of the high voltage conductor 12, and the insulation performance at high temperature is not impaired. That is, since the heat resistance characteristics of the solid insulating structure 17 are determined by the physical properties of the material, the structure has excellent high heat resistance.
[0029]
Furthermore, even if the high-voltage potential connecting tube 20 exists and the high-voltage side gap 22 is a space that is individually sealed, the conductor unit 12a has two or more through holes 12c, so that heat is generated in the high-voltage conductor 12. Has a cooling effect due to the convection action, does not transmit directly to the solid insulating structure 17, and has an excellent structure in terms of heat resistance.
[0030]
(4) Other Embodiments The present invention is not limited to the embodiment as described above, and various other forms can be implemented. For example, the following forms are also included.
That is, if the solid insulation structure 17 and the sheath 13 are formed integrally by eliminating the gap 23, there is no possibility that foreign metal is mixed between the solid insulation structure 17 and the sheath 13, and the insulation reliability can be improved. it can.
In the above embodiment, dry air is used as an example of the dry gas. However, other gases may be used if there is no harmfulness and danger.
Further, if the high-voltage potential connecting pipe 20 is provided with a vent hole and the high-voltage side gap 22 is made as an integrated space having a large volume as much as possible, the convection action due to heat generation of the high-voltage conductor 12 is further enhanced and the cooling effect is improved. Can be improved.
[0031]
【The invention's effect】
As described above, the electrically insulated bus of the present invention can achieve high voltage and large current transmission while ensuring equivalent insulation reliability as compared with the conventional CV cable. In addition, compared with the pipeline air transmission line, while ensuring the equivalent large current carrying performance, there is also no problem of deterioration of insulation reliability for metal foreign objects unique to gas insulation and environmental problems of global warming, Long-distance, high-voltage, high-current underground transmission lines can be realized. Therefore, according to the present invention, high-voltage and large-capacity power transmission is possible, maintenance management and high reliability can be easily ensured, total cost can be reduced, and an environmentally friendly electrical insulated bus can be provided. .
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a typical example of the overall configuration of an electrically insulated bus according to the present invention.
FIG. 2 is a sectional view showing a typical example of a general structure portion of an electrically insulated bus according to the present invention.
FIG. 3 is a cross-sectional view taken along the line CC, showing a typical example of the general structure of the electrically insulated bus according to the present invention.
FIG. 4 is a cross-sectional view showing a typical example of a displacement countermeasure structure portion of an electrically insulated bus according to the present invention.
FIG. 5 is a DD cross-sectional view showing a typical example of a displacement countermeasure structure portion of an electrically insulated bus according to the present invention.
FIG. 6 is a cross-sectional view showing a typical example of a general structure portion of a conventional CV cable.
FIG. 7 is a cross-sectional view showing a typical example of a conventional CV cable connection structure.
FIG. 8 is a cross-sectional view showing a typical example of a conventional pipeline air line.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Stranded wire conductor 2 ... Internal semiconductive layer 3 ... Crosslinked polyethylene insulator 4 ... External semiconductive layer 5 ... Metal shielding 6 ... Vinyl sheath 7 ... ... Conductor connection tube 8 ... Reinforcing insulator 9 ... Semiconductive layer 10 ... Waterproof compound 11 ... Protection tube 12 ... High voltage conductor 12a ... Conductor unit 12b ... Conductor Weld 12c ·· Through hole 13 ··· Sheath 13a ·· Pipe unit 13b ·· Pipe weld 14 ··· SF6 gas 15 ··· Insulating spacer 16 ··· Universal bellows 17 ··· Solid insulating structure 17a ··· Insulating structure unit 17b .. Insulating adhesive 18 ... High voltage side semiconductive layer 19 ... Ground side semiconductive layer 20 ... High voltage potential connection tube 21 ... Ground potential connection tube 22 ... High voltage side air gap 23 ... Ground side air gap 24 ... Slide contact 25 ... Bellows 26 ... Rubber elastomer member T ... CV cable terminal

Claims (8)

In an electrically insulated bus in which a high voltage conductor for passing a high voltage and a large current is arranged in the inner space axial direction of the sheath having a ground potential,
A coaxial cylindrical insulating member is disposed between the high voltage conductor and the sheath,
A predetermined gap is formed between the outer periphery of the high-voltage conductor and the coaxial cylindrical insulating member, and a predetermined gap is also formed between the sheath inner wall surface and the coaxial cylindrical insulating member,
The high voltage conductor is insulated and supported in the sheath via a potential connection member disposed in each predetermined gap, and the high voltage conductor, the sheath, the coaxial cylindrical insulating member, and the potential connection member Are configured in advance so as to be separable and independent from each other.   Each of the high-voltage conductor, the coaxial cylindrical insulating member, and the sheath is unitized with a predetermined length within transport restrictions, and has a unit connection structure in which each unit is connected. The electrically insulated bus according to claim 1.   Each of the unit connection structures of the high-voltage conductor, the coaxial cylindrical insulating member, and the sheath includes a displacement countermeasure structure that can absorb axial and radial displacement for each predetermined length. Item 3. The electrically insulated bus according to Item 2.   4. The displacement countermeasure structure portion has a sliding contact structure for the high-voltage conductor, a bellows structure for the sheath, and a contact structure made of a rubbery elastomer material for the coaxial cylindrical insulating member. Electrically insulated busbar as described.   5. The electrically insulated bus according to claim 1, wherein a dry gas is forcibly enclosed in a gap between the coaxial cylindrical insulating member and the sheath.   A semiconductive layer is provided on the inner peripheral surface and the outer peripheral surface of the coaxial cylindrical insulating member, the semiconductive layer on the inner peripheral surface is at the potential of the high voltage conductor, and the semiconductive layer on the outer peripheral surface is the sheath. 6. The electrically insulated bus according to claim 1, wherein the electrical insulated bus is set to a potential of   The electric insulated bus according to claim 6, wherein the potential of the high-voltage conductor and the potential of the sheath of the coaxial cylindrical insulating member are set by forced connection by the potential connecting member.   4. The electrically insulated bus according to claim 2, wherein each unit of the high voltage conductor is provided with two or more through holes.

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