JP2004080923A - Branch connection structure and its construction method for power transmission branched steel tower - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a branch connection structure that allows branch connection to an underground power cable from an aerial cable without the need for large-scale modification support arms of an existing power transmission steel tower for transmitting power to an underground cable that feeds power to a newly constructed substation, thus dispensing with large-scale modification work, such as construction of a temporary steel tower, improved in mechanical strength, electrical insulation and construction method, and capable of coping with the accidents of the underground cable. <P>SOLUTION: In the aerial cable steel tower having the horizontal support arms 2 arranged at a tower body in a multistep state, a cable end 5, to which the end of the underground cable extending upward from the ground is attached, is attached horizontally to the tower body 1 by a fixing member 6 at a mid-height position between one support arm 2 that supports the corresponding aerial cable and the other support arm 2, immediately below the one support arm; an overhanging member 3 is arranged at the tip of each support arm 2 and a station insulator 4 is hung at the tip; and a jumper line Lj is made to protrude by the station insulator 4, thus constituting the branch connecting structure so that the jumper line Lj is positioned outside of the range of the insulation distance. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a branch connection structure of a power transmission branch tower for branching an underground transmission line from an existing overhead transmission line and transmitting the power, and a method of constructing the branch connection structure.
[0002]
[Prior art]
For the new substation, the method of branching the underground power transmission line from the power transmission tower where the existing overhead power transmission line is erected, and transmitting power can be done by making major modifications to the existing power transmission tower and related equipment. Various proposals and implementations have been made in the past to make it necessary and therefore to make it the minimum necessary work. Such a construction method has undergone a remarkable change according to the times, and until an OF cable (oil Filled Cable) was used as an underground transmission line to be connected to a high-voltage cable such as an overhead transmission line (until 1975). And after the CV cable (crosslinked polyethylene insulated cable) is used, the following changes occur.
[0003]
At the time when the OF cable was used as an underground cable, it was not possible to pull up the underground cable to the upper part of the tower and connect it to the overhead transmission line due to hydraulic pressure. However, the underground cable was connected to the porcelain tube provided at the terminal end from an overhead power transmission line connected to a horizontal support arm above the steel tower using a similar type of connection cable. However, it is necessary to select a position where the connection cable does not interfere with the overhead power transmission line because the existing cable tower is used when lowering the connection arm from the support arm. Therefore, it is necessary to replace the support arm with a longer one.
[0004]
The replacement of the support arm cannot be performed while the power transmission is continued. Therefore, as shown in FIG. 9, after the temporary tower A ′ is constructed near the original tower A, and the overhead transmission line is moved to the temporary tower, Modifications were made by replacing the original support arm of the tower with a longer arm. Substations T is new in the figure, L _B is underground cables (underground transmission lines), L _A is overhead lines, 1 column of towers, B is adjacent tower.
[0005]
Once they become available are CV cable underground cables, since CV cable is a solid insulating structure, it is not necessary to provide a cable termination to the ground, tower underground cable L _B, as shown in FIG. 8 1 can be provided continuously from just below to the top of the tower. In this manner, the upper end of the underground cable L _B is connected to the porcelain bushing of the cable termination 5, cable termination 5 since it is assumed that the mounted vertically on the end of the support arm 2, the support arm 2 has been modified while the close end and overhead transmission lines L _a of the cable termination 5 is no, it is not possible to secure an insulation distance. Therefore, a method has been adopted in which a major modification for lengthening the support arm 2 is performed in the same manner as when an OF cable is used.
[0006]
[Problems to be solved by the invention]
However, the major modification of the tower as described above requires not only the modification of the support arm in any case, but also the site for installing the temporary tower, relocation of the overhead transmission line, return work, construction of the temporary tower, Huge costs, human resources and time are required for removal. This situation is the same even if CV cables can be used as underground cables. However, recently it has become increasingly difficult to secure land for the construction of temporary towers.Therefore, research and development of branch connection structures and construction methods that do not require large modifications of tower support arms or construction of temporary towers have been carried out. It was becoming strongly desired.
[0007]
The present invention has been made in consideration of the above-mentioned various problems in the conventional construction method, and has not greatly modified the support arm of the existing power transmission tower to the underground transmission line for transmitting power to the newly constructed substation, and therefore, has not The branch connection from the overhead transmission line to the underground transmission line can be performed without the need for large-scale remodeling work such as the construction of an underground transmission line, and it is excellent in mechanical strength, electrical insulation performance, construction method, and An object of the present invention is to provide a branch connection structure capable of coping with an accident of an underground power transmission line and a method of constructing the same.
[0008]
[Means for Solving the Problems]
As a means for solving the above-mentioned problems, the present invention provides a multi-stage horizontal support arm on a tower formed by combining columns, and connects overhead transmission lines for locking terminals to each support arm. A jumper line and a station insulator for gripping the jumper line, and a support arm for locking a corresponding overhead transmission line at a cable end of an underground transmission line extending upward from the ground for branch connection from the overhead transmission line. A scaffold longer than the support arm is provided on the support arm immediately below, and the tower is arranged such that the central axis is substantially horizontal at the cable end at an intermediate height between the support arm for locking the overhead power transmission line and the support arm immediately below the support arm. A jumper wire that is attached to the body and provided with a projecting member at the end of the support arm, and a station insulator is suspended at the end of this projecting member and the jumper wire that is gripped is the required insulation distance from the end of the cable end. Than it was a branch connection structure of the power transmission branch towers configured so as to be positioned.
[0009]
According to the branch connection structure of the power transmission branch tower having the above-described configuration, the existing power transmission tower can be modified to branch connect from the overhead transmission line to the underground transmission line and transmit power to the newly installed substation. Currently, CV cables (cross-linked polyethylene insulated cables) are used as underground transmission lines, so CV cables are provided as a continuous line from underground to the top of the tower at the position of the tower, and the terminal is located at the end of the cable. Is fixed to the terminal member.
[0010]
The cable end is generally designed on the assumption that its length is set up vertically, but when installed vertically or down on the support arm of the tower, a part of the tower body of the tower is installed. In addition, the distal end of the cable terminal end where the conductor is exposed to the support arm immediately above or immediately below the support arm where the cable terminal end is installed is too close to be able to secure an insulation distance of a predetermined distance from the distal end. In order to avoid such inconvenience, if the cable end is installed horizontally at the intermediate height between the support arm that supports the corresponding overhead power transmission line and the support arm immediately below, the required insulation distance from the tip end is reduced. The support arm is located at the position corresponding to the condition.
[0011]
However, when the support arm that supports the overhead transmission line is located at the lowest layer, the above “direct support arm” is interpreted as a height position when it is assumed that the support arm is located thereunder. It shall mean providing a scaffold and attaching a cable termination at an intermediate height from that location. The same applies to the “lower supporting arm” in the branch connection method described later. The end of the cable shall be of the type that can be installed horizontally by slightly modifying the conventional type so that internal flashover does not occur in the electric field concentration area inside even if it is installed horizontally. It is assumed that is used.
[0012]
Furthermore, if the cable end is installed horizontally, the insulation distance from the tower body can be ensured. However, as a necessary condition, it is necessary to ensure the insulation distance from the jumper wire. If the jumper wire is connected to the end of the cable end with a lead wire while it is installed in the vertical plane including the overhead power line connected to the end of the support arm, the insulation distance will be reduced when an accident occurs in the underground power line. It is not enough.
[0013]
In the case of an underground power line accident, it takes time to recover, and power transmission via the overhead power line is affected, so it is necessary to disconnect the underground power line from the overhead power line by removing the lead wire connected to the jumper wire Occurs. At this time, even if the lead wire is removed, if the connection point of the jumper wire is located within the required insulation distance from the end of the cable end, the underground power transmission line is not completely disconnected from the overhead power transmission line. In order to cope with such a situation, the station insulator is protruded from the support arm end with an overhang member, and the jumper wire is projected obliquely with the station insulator so that the connection point of the jumper wire is located outside the required insulation distance. It was.
[0014]
In order to obtain the above-mentioned branch connection structure to the underground power transmission line, a construction method is required in which a support arm is modified so as to be capable of branch connection from an overhead transmission line in an existing steel tower. In this method, via a cable termination from a jumper line connecting underground transmission lines to overhead transmission lines that connect overhead transmission lines installed on support arms provided horizontally in multiple stages on a tower body formed by combining columns When branch connection is made, a scaffold longer than the support arm is installed on the lower support arm of the support arm that locks the corresponding overhead transmission line at the cable end, and the work on this scaffold removes the cable end. Attach it to the tower body so that its central axis is substantially horizontal, connect the cable end to the underground power line, and place the station insulator for gripping the jumper wire at a distance from the tower body a predetermined distance from the tip of the support arm A branch connection method of a power transmission branch tower in which the jumper wire is suspended and gripped, and a cable terminal portion is connected to the jumper wire via a lead wire can be provided.
[0015]
In this method, a scaffold longer than the support arm is installed on the support arm immediately below the cable so that the end of the cable is horizontally attached to the tower body between the support arm that supports the corresponding overhead power transmission line and the support arm immediately below it. . On this scaffold, work to hold and move the porcelain tube at the end of the cable horizontally is performed, and the cable end is assembled by assembling the tip of the underground power transmission line fixed to the tower body. At this time, if the porcelain tube is moved horizontally with respect to the support arm supporting the overhead transmission line by the erection rail and the suspending means that moves horizontally by the rail, the work is performed efficiently.
[0016]
The overhanging member is fixedly provided at the tip of the support arm, and the jumper wire is obliquely projected and gripped by the suspended station insulator, and when the lead wire is connected to the cable terminal portion from the jumper wire, a branch connection structure is obtained. can get.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an overall schematic and a main part schematic perspective view of a power transmission branch tower according to an embodiment. The illustrated power transmission branch tower is obtained by partially modifying the existing power transmission tower. The power transmission tower to be remodeled as this power transmission branch tower is the existing power transmission tower that is closest to the new substation and is installed at a position suitable for laying the underground power transmission line, It may be a newly installed power transmission tower.
[0018]
As shown in the figure, a power transmission branch tower A has a plurality of support arms 2 mounted horizontally in a multi-stage manner above a tower 1 constructed by connecting a plurality of columns to a truss structure in the same manner as a general power transmission tower. It is formed Te, the support arm 2 is provided with overhead lines L _a different lengths from each other little by little so as not to overlap vertically, which is laid in a multistage form, can sufficiently support the weight of the overhead transmission line L _a An auxiliary member 2a is provided obliquely downward from the tower body, and its tip is connected to the end of the support arm 2 to reinforce the support arm 2.
[0019]
At the tip of the support arm 2, a projecting member 3 having a U-shape is provided with a predetermined length, and a station insulator 4 is vertically suspended from the tip of the member 3 (in a direction away from the tower 1). . The lower end of the station insulator 4 is connected to the jumper wire L _J, jumper wires L _J is prevented from swaying by wind or earthquake. Thus, existing jumper wires while being held down hanging in a semicircle just below the support arm end, a jumper line L _J in this embodiment is held in a semicircle in an oblique horizontal direction.
[0020]
To the connection to send branched power from the jumper line L _J into the ground power line L _B, the cable terminal portion 5 for fixing the terminal portion of the underground transmission lines L _B, overhead lines of corresponding stage L _A fixing member 6 is fixed to the tower body 1 below the support arm 2 supporting A, at a substantially intermediate height position between the support arm 2 and the support arm 2 immediately below the support arm 2 so that the center axis thereof is substantially horizontal. Mounted through. In addition, a scaffold 7 for mounting the cable terminal portion 5 and the overhang member 3 is installed on the lower support arm 2.
[0021]
The scaffold 7 breaks down after the mounting work, and is left as a permanent member for maintenance and inspection work. Note that the scaffold 7 is omitted in FIG. 1 because the illustration is complicated, and is shown in the detailed view of FIG. When the support arm 2 is located at the lowermost layer, the above “directly below the support arm 2” is understood to be a height position assuming that the support arm 2 is located therebelow, and the scaffold 7 is provided at that position. At the same time, the cable end portion 5 is provided at an intermediate height position between the position and the upper support arm 2, and the overhang member 3 is attached to the lowermost support arm 2.
[0022]
When the cable terminal 5 is attached to the tower 1, the terminals of the cables of each phase of the underground power transmission line extending from the ground are connected to the corresponding cable terminal 5, respectively. connection is made through a lead wire L _l to line L _J. In this case, the jumper line L _J is installed in an oblique horizontal direction so as to pass through the insulation distance within the required range from the distal end of the cable termination 5 and the lead wire L _l is connected to an intermediate position of the semi-circular portion .
[0023]
FIG. 3 shows a schematic structure of the cable terminal section 5. (A) is an assembly side view, and (b) is a main sectional view. FIG. 4 is an exploded view. As shown in the figure, the cable end portion 5 is composed of a porcelain tube 51 made of a polymer material and a cable terminal portion inserted into the inside thereof. Is inserted and fixed so as to protrude from one end of the porcelain tube 51, and the other is largely stripped of the cable sheath and the semiconductive layer to expose the insulator 53, and the rubber unit fixing portion 55 and the rubber unit are provided near the base end thereof. It is inserted and fixed in the insulator tube 51 with the 54 attached.
[0024]
After the cable end is inserted into the insulator tube 51, SF ₆ gas, which is an inert gas, is sealed in the internal gap and sealed. Reference numeral 57 denotes a waterproofing member for protecting a cable end connected to the other end of the insulator tube 51. Incidentally, underground transmission lines L _B is generally the cross-linked polyethylene insulated cables called CV cable is used.
[0025]
The cable end portion 5 having the above-described structure has various characteristics as to whether it has sufficient mechanical strength and electrical insulation performance when mounted horizontally on a steel tower, and whether a polymer insulator tube can be inserted and assembled into a cable terminal. It was adopted as a result of examination. Generally, a porcelain type with sufficient mechanical strength is used as the cable end part from the viewpoint of mechanical strength. However, when installed on a steel tower, external conditions such as wind pressure of 40 m / s and the Great Hanshin-Awaji Earthquake , The compression stress and the tensile stress must be sufficient for the vibration acceleration of 800 gal, and the mounting strength when fixing with the fixing member 6 must be sufficient. The strength of the polymer type insulator tube itself is almost the same as that of the porcelain type, and the polymer type can be used sufficiently.
[0026]
However, when fixing horizontally with the fixing member 6, if the weight is too large, the strength of the fixing structure by the fixing member 6 is insufficient. The polymer type has a total weight of 80 kg in the illustrated example, the porcelain type has a weight of 200 kg, and the polymer type can be supported with a sufficient safety factor by the fixing member 6. However, the porcelain type is not suitable because it is too heavy. It has been adopted.
[0027]
As shown in FIG. 2, a fixing member 6 for fixing the polymer type cable end portion 5 is provided with a parallel side plate 62 in a horizontal direction on an arm tip side of an L-shaped steel material which is a support member of the tower body 1 slightly inclined from vertical. The parallel side plates 62 are fixed, and the C-shaped steel members 63 are fixed to the respective parallel side plates 62. The cable terminal portion 5 is firmly fixed in a cantilever shape by fixing the flange portion at the end of the insulator tube 51 to the C-shaped steel material 63.
[0028]
An operation for forming a power transmission branch tower having a branch connection structure that branches from the overhead transmission line configured as described above to the underground transmission line will be described below. The power transmission branch tower may be formed so as to have the same configuration even when newly installed.However, in the following, the method is mainly applied to the existing power transmission tower, and the method for partially remodeling the constituent members is described below. Will be described. FIG. 6 shows a working structure for fixing the cable terminal 5.
[0029]
As described above, the scaffold 7 is first mounted on the lower support arm 2 for branch connection work to the underground power transmission line, and the temporary rail 8 and the suspension means 9 are also mounted on the upper support arm 2. Is installed. 7 a is a handrail provided on the scaffold 7. The temporary rail 8 and the suspension means 9 are removed after the completion of the construction. The temporary rail 8 and the suspending means 9 are used for the work of attaching the cable terminal 5 horizontally to the tower 1. The temporary rail 8 is temporarily fixed to the support arm 2 by a suitable fixing means such as a wire, a bolt and a nut, and temporary welding.
[0030]
Although not shown in detail, the temporary rail 8 is provided with two C-shaped steel members in parallel, and a method in which a suspension block is mounted on a shaft between the rotating roller and the roller that is movably rotated in the inner groove, or A suspension block is attached by a method of attaching a rotatable roller rotatably rotating so as to sandwich the groove of the H-shaped steel material, and a chain is hung from the suspension block so that the polymer insulator tube 51 of the horizontal cable end portion 5 is suspended. Hanging means 9 is attached. FIG. 7 shows the state of the work of assembling the cable end portion 5 using the temporary rail 8 and the suspension means 9.
[0031]
As shown in (a) of FIG. 7, before assembling the polymer porcelain bushing 51, with respect to C-type steel 63 of the pre-fixed member 6 for fixing the terminal portion relative to the support arm 2 of each stage of the underground transmission lines L _B Work is performed. The terminal portion is attached by exposing the conductor 52 and the insulator 53 in advance and fixing the portion where the rubber unit fixing portion 55 and the waterproofing portion 57 are attached to the C-type steel 63 as described above. Then, the rubber unit 54 is inserted toward the rubber unit fixing portion 55 from the distal end side of the terminal portion.
[0032]
A dedicated insert 10 shown in FIG. 5 is used to insert the rubber unit 54. This inserter 10 combines a pair of bevel gears 11 which engage with each other so that their axes are orthogonal to each other. One of the bevel gears 11 is provided with a rotating handle 12 at the shaft end thereof, and the other bevel gear 11 is provided with a center handle thereof. the threaded rod 13 is screwed into the screw hole is inserted, the end of the threaded rod having a chuck portion 13a which can be fastened to the end of the conductor 52 at the tip of the underground transmission lines L _B. Further, the front end of the frame 14 surrounding the screw rod 13 has an end face for pushing the rubber unit 54.
[0033]
As described above, inserting the rubber unit 54 is attached from the state rubber unit 54 in advance manually in the distal portion of the underground transmission lines L _B is inserted slightly further the insertion tool 10 to the tip portion of the L _B I do. When the handle 12 is rotated proceeds in the direction in which the threaded rod is facing the tip of the L _B, relatively rubber unit 54 is inserted in the opposite direction from the front end of the L _B, abuts against the rubber unit fixing portion 55 located When the insertion is completed, the insertion ends.
[0034]
When pulling the insert loosening the fastening by the chuck 13a, then start inserting operation of inserting the polymer porcelain bushing 51 to the distal end portion of the L _B. As shown in FIG. 7 (a), the suspending means 9 is placed on the temporary rail 8 at an appropriate position outside the end of the support arm 2 and at the position of the center of gravity slightly closer to the base than the center of the length of the polymer insulator 51. The polymer insulator tube 51 is suspended horizontally by the chain of the suspension means 9. (B) also hold the polymer insulator pipes 51 horizontally by hand without using a temporary rail 8 and hanging means 9 as shown in the illustration difficult to balance the porcelain bushing 51 is inserted smoothly into the distal end portion of the L _B It is difficult.
[0035]
However, in this embodiment, the horizontal state of the polymer insulator 51 can be always maintained by using the temporary rail 8 and the suspending means 9, and therefore, the polymer insulator 51 is horizontally moved by the rollers while keeping the horizontal state balanced. Therefore, it inserts the polymer porcelain bushing 51 without damaging the cable insulation 53 to the distal end portion of the L _B. When the insertion of the polymer porcelain bushing 51 is completed, to fix the flange of the end of the porcelain bushing 51 to the fixed member 6, SF ₆ gas 56 is sealed from the outside by means not shown to the porcelain bushing 51.
[0036]
In addition, if the silicon oil enclosed in the insulator tube 51 and the air layer are horizontally installed, the maximum electric field at the electric field concentrated portion and the creepage electric field of the air when the test voltage is applied (JEC3408) are as follows.
Maximum electric field Imp 3.4 kV / mm> Breakdown electric field Imp about 3 kV / mm
AC 0.9kV / mm ≒ AC about 1kV / mm
Since the air layer comes to the electric field concentrated portion and an internal flash occurs, SF ₆ gas is sealed in place of silicon oil to prevent this, but the electric field state in this case is as follows. .
[0037]
Maximum electric field Imp 3.4 kV / mm <creeping breakdown electric field Imp of SF ₆ Approximately 6 kV / mm
AC 0.9kV / mm <AC about 4kV / mm
With such an electric field state, electrical insulation performance can be maintained even in a horizontal state. As another method for preventing the internal flash, a reservoir is disposed above the insulator without supplying SF ₆ gas, the reservoir and the interior of the insulator are connected by an oil supply pipe, and the air layer does not receive an electric field in the insulator. There is also a method in which the inside of the insulator tube is filled with silicone oil by disposing it on the side.
[0038]
After the assembling of the insulator tube 51 is completed, the temporary rail 8 and the suspension means 9 are removed, and then the extension member 3 is attached to the tip of the upper support arm, and the station insulator 4 is attached to the tip. The overhang member 3 is permanently fixed to the tip of the upper support arm by welding. Horizontally the tip of the cable termination 5 mounted as described above is connected through a lead wire L _l jumper line L _J which is gripped by the station insulator 4, thereby overhead lines that are bridged tower The connection work for branch connection from underground to the new substation is completed. The position to be connected to the jumper wires L _J a tip of a cable terminal portion 5 with the lead wire L _l is a predetermined insulation distance outside the supporting arm tip by separating with projecting members 3 stations insulator 4 from the support arm tip It has been placed.
[0039]
This is to make it possible to cope with an underground transmission line accident. When an accident occurs on an underground transmission line for transmitting power to a newly constructed substation, the transmission from the existing substation A to the substation B via the transmission branch tower is affected. Since it takes time to restore the underground transmission line, it is necessary to first restore the transmission from the A → B substation, and it is necessary to disconnect the underground transmission line where the accident occurred from the overhead transmission line. The disconnect is effected by cutting the lead wire L _l for connecting the jumper line L _J cable termination 5.
[0040]
However, when connected as in the conventional connection between overhead transmission line at a position fixing the end of the overhead line to the support arm by jumper wire L _J hanging downwardly between each other of the transmission lines at that position, the cable terminal portion 5 distance close insulation distance between the tip and the jumper line L _J of can not be ensured. Therefore, in order to secure the insulation distance between the jumper line L _J is is protruded station insulator 4 by projecting a flared member 3 from the distal end of the support arm 2, thereby to protrude the jumper wire, lead wire L Thus, the insulation distance from the jumper wire can be obtained even after removing _l .
[0041]
In the above-described embodiment, the overhanging member 3 uses a plate material whose cross section is a letter-shaped. However, as long as the station insulator can be located outside the required insulation distance from the tip of the support arm 2, its cross-sectional shape, The material may be another suitable member.
[0042]
【The invention's effect】
As described in detail above, the branch connection structure of the present invention provides a cable termination portion for fixing a terminal portion of an underground power transmission line with an intermediate height between a support arm of a corresponding overhead power transmission line and a support arm immediately thereunder. At the position, it is fixed horizontally to the tower body, a projecting member is provided from the support arm, the jumper wire is obliquely projected and gripped by a station insulator suspended there, and the insulation distance is secured for the tower body and the jumper wire The branching from the overhead transmission line to the underground transmission line is not required, since the support arm of the tower for overhead power transmission is greatly remodeled, and thus no major rebuilding work such as the construction of a temporary tower is required. It is remarkable that it can be connected, has excellent mechanical strength and electrical insulation performance, and according to the construction method of the present invention, it can cope with an accident of an underground transmission line and can drastically reduce the construction cost. It works
[Brief description of the drawings]
FIG. 1A is an overall schematic diagram of a power transmission branch tower according to an embodiment, and FIG. 1B is an enlarged perspective view of a main part. FIG. 2A is a plan view of a branch connection structure to an underground power transmission line. b) Side view [FIG. 3] (a) Side view, (b) sectional view of cable termination section [FIG. 4] Exploded view of cable termination section [FIG. 5] Schematic configuration view of rubber unit insertion tool ((a)) Indicates an initial operation, and (b) indicates an intermediate operation state.)
6A is a side view and FIG. 7B is a plan view of a working structure for fixing a cable terminal portion. FIG. 7A is an appropriate construction state of an assembling work of a cable terminal portion, and FIG. [Fig. 8] Schematic configuration of a conventional power transmission branch tower [Fig. 9] Schematic diagram of a conventional power transmission branch tower remodeling work [Description of symbols]
DESCRIPTION OF SYMBOLS 1 Tower body 2 Support arm 2a Auxiliary member 3 Overhang member 4 Station insulator 5 Cable terminal end 6 Fixing member 7 Scaffolding 8 Temporary rail 9 Suspension means

Claims (6)

A tower body formed by combining columns is provided with multi-stage horizontal support arms, jumper wires connecting overhead power transmission lines that lock terminals to each support arm, and a station insulator holding this jumper wire. And a scaffold longer than the support arm is provided on the support arm immediately below the support arm for locking the corresponding overhead power line at the cable terminal end of the underground power line extending upward from the ground for branch connection from the overhead power line. At the intermediate height between the support arm for locking the overhead power transmission line and the support arm immediately below the cable, the cable end is attached to the tower so that the central axis is substantially horizontal, and an extension member is provided at the tip of the support arm. The power transmission branch tower is configured such that the jumper wire, which is held by suspending the station insulator at the end of the overhang member, is located outside the required insulation distance from the end of the cable end. Connection structure. Branch connection from the jumper wire connecting underground transmission lines to underground transmission lines that connects overhead transmission lines installed on support arms provided horizontally in multiple stages on a tower body formed by combining columns At the time of installation, a scaffold longer than the support arm is installed on the lower support arm of the support arm that locks the corresponding overhead transmission line at the cable end, and the center axis of the cable end is changed by working on this scaffold. Attach it to the tower so that it is substantially horizontal, connect the cable end to the underground power line, suspend the station insulator for holding the jumper wire at a position away from the tower body by a predetermined distance from the tip of the support arm, and A branch connection method of a power transmission branch tower that grips a jumper wire and connects a cable terminal portion to the jumper wire via a lead wire. A temporary rail is provided above the mounting position of the cable end portion, and a suspending means which is horizontally movable within the rail is provided, and the cable is moved horizontally while the insulator tube at the cable end portion is hung horizontally by the suspending means. 3. The method according to claim 2, wherein the terminal portion is assembled. When suspending the station insulator at a position away from the tower body by a predetermined distance from the tip of the support arm, a projecting member is fixed to the tip of the support arm, and the station insulator is attached to the end of the projecting member. The branch connection method of the power transmission branch tower according to claim 2 or 3. When connecting the end of the underground power transmission line to the cable end portion, the protective layer of the underground power transmission line is peeled off in advance, and a rubber unit is inserted around the outer circumference thereof using an insertion tool. The method for connecting and branching a power transmission branch tower according to any one of claims 2 to 4. A screw shaft having a chuck for gripping the conductor at the end portion is provided in a push frame having a contact surface for mounting a rubber unit at an end portion of the underground power transmission line from which the protective layer has been peeled off so as to be able to protrude and retract. A rubber unit insertion tool configured to engage a gear operating mechanism that is rotated by a handle with a screw shaft and operate the handle to fit and attach a rubber unit to an end of an underground power transmission line.

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