JP4260553B2 - Power cable termination connection - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power cable termination connection, and more particularly to an air termination connection of a high voltage power cable.
[0002]
[Prior art]
For example, Japanese Patent Application Laid-Open No. H10-133707 discloses a conventional end-of-air connection portion of a power cable.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-51938
This air termination connection part is comprised by the cable, the soot pipe surrounding the termination | terminus of a cable, and the electric field shielding internal insulator which performs internal reinforcement insulation. The electric field shielding internal insulator is composed of a combination of an epoxy seat and a rubber pre-mold insulator (generally, an integrated unit composed of an ethylene propylene rubber (EPR) insulator and a semiconductive layer), Insulation performance is ensured by compressing the pre-mold insulator using a spring unit.
[0005]
FIG. 4 shows another structural example of the air termination connection portion using the electric field shielding internal insulator. In FIG. 4, the end portion (upper side of the drawing) of the cable 24 is inserted into the soot tube 12 installed at a predetermined position by a support insulator 25. The soot tube 12 is made of porcelain or polymer. In the soot tube 12, the cable conductor 7 from which the covering portion of the cable 24 is removed is compression-connected to the conductor lead bar 1. The soot pipe 12 is covered with an upper lid through the soot pipe upper packing 5, and the conductor lead bar 1 is drawn out into the atmosphere through the airtight seal packing 6 from the center, and is connected to the overhead wire or other equipment with lead wires. Connected. The hermetic seal packing 6 is fastened to the upper lid by the packing fastening metal fitting 4, and the conductor lead-out dedicated 1 is fixed by the conductor fixing lock nut 3 at the upper part of the tub tube 12, and these are covered by the rain cover 2.
[0006]
The electric field control of the air termination connection portion is controlled within the allowable electric field strength by inserting the plug-in unit rubber insulator 13 on the cable insulator 11 from which the cable outer shielding layer 21 in the soot tube 12 is removed. Is done. Further, a gas 9 layer is provided in the upper part of the soot pipe 12, and the pressure change due to the expansion and contraction due to the temperature of the insulating oil 10 below it is absorbed by this gas 9 layer and kept below the allowable internal pressure value of the soot pipe 12. It is like that. Further, the connection portion between the cable conductor 7 and the conductor lead bar 1 is covered with an upper conductor hermetic seal 8 for hermetically sealing them. In some cases, the insulating pipe 10 is entirely used as the insulating gas without using the insulating oil 10.
[0007]
An oil stop or gas stop process is applied to the lower part of the soot pipe 12 so that the insulating oil 10 or the gas 9 in the soot pipe 12 does not leak to the lower cable side. As shown in FIGS. 4 and 5 (enlarged view of portion A in FIG. 4), the general structure is that a cylindrical oil (or gas) fastener 15 (hereinafter referred to as “oil fastener”) is a cable. Inserted into the outer shielding layer 21, the upper and lower portions of the metal fitting 15 are sealed by tape processing or the like to form the oil metal fitting upper seal 14 and the oil metal fitting lower seal 20. Further, the gap between the oil stopper 15 and the mounting flange 18 is sealed with a packing 17 fixed to the mounting flange 18 by a packing fastening metal 16. The mounting flange 18 is connected to the soot tube 12 via a soot tube lower packing 19. Further, a protective metal fitting 22 is attached to the lower portion of the terminal connection portion to protect the cable outer shielding layer 21, and further, a lower seal 23 is provided to block the outside from the outside.
[0008]
In general, in the structure of the conventional oil clamp 15 shown in FIG. 5, the internal pressure is always used in the range of about 0 to 0.3 MPa. If the internal pressure exceeds this level, the oil stopper 15 may move in the vertical direction (vertical direction in the figure) due to the internal pressure. In this case, for example, as shown in FIG. 6, a stopper 15b is attached to the oil stopper 15a. It is necessary to provide it.
[0009]
[Problems to be solved by the invention]
In recent years, there has been an increasing demand for connecting directly from underground power transmission towers to underground power cables. At that time, the most cost-effective thing is to pull the cables up to the tower and connect the cable to the air terminal on the tower. This is a method in which a section is provided and directly connected from an overhead line by a jumper line. In this case, it is required to reduce the weight of the terminal connection part and to make it advantageous in designing the strength of the steel tower. In the case of installation on a steel tower, it is necessary to prevent explosions and explosions in the event of a ground fault because of its high altitude. Polymer rods are lighter than porcelain rods and have less cracking and scattering.
[0010]
However, even when a polymer is used as the soot pipe, in the case of a ground fault in the soot pipe 12, the pressure in the soot pipe 12 cannot be controlled, and there is a possibility of explosion explosion (solid debris and insulating oil scattering, ignition). was there. Further, the power cable terminal connection portion in Patent Document 1 has the same problem.
[0011]
Accordingly, an object of the present invention is to provide a power cable termination connection portion that can prevent explosion and scattering of a soot pipe and other members due to an increase in internal pressure during a ground fault.
[0012]
Further, in recent years, there is a demand for a simple structure that is lightweight and easy to install (attach and assemble) in a power cable terminal connection.
[0013]
Accordingly, another object of the present invention is to provide a simple pressure release structure with a small number of parts without using a complicated device or structure even for a high internal pressure generated during a ground fault.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, the power cable termination connecting portion of the present invention includes a soot tube that inserts the end portion of the power cable, and insulating oil or insulating gas filled around the power cable in the soot tube. A leakage prevention fitting provided to be inserted through the power cable at a boundary between the power cable and the soot tube where the power cable is inserted into the soot tube, and preventing the insulating oil or the insulating gas from leaking to the outside of the soot tube; In the terminal cable connecting portion for power cable, a flange portion is provided on the leakage prevention metal fitting, and a gap between the flange portion and a mounting flange connected to the soot tube is sealed so that the power cable and the soot tube are connected. was hermetically sealed, and the lower side of the flange portion in the power cable side end portion outside of the porcelain bushing, through a pedestal attached to the lower side of the mounting flange Serial provided stoppers for preventing leakage fitting, the stopper is to porcelain tube internal pressure of less than 1MPa, to prevent the leakage prevention fitting is moved downward in the vertical direction, deformation and the porcelain bushing inner reaches above the internal pressure 1MPa The leakage prevention fitting is moved downward in the vertical direction to release the internal pressure of the soot tube into a protection fitting connected to the soot tube.
[0015]
It is desirable that the protrusion of the flange portion has a dimension of 10 mm or more.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a power cable termination connecting portion of the present invention will be described with reference to the drawings.
[0018]
The overall structure of the power cable termination connection portion according to the present embodiment is basically the same as that of the conventional power cable termination connection portion shown in FIG. The structure shown is different, and is configured as shown in FIG.
[0019]
In FIG. 1, a flange portion 28 a is provided at a location where the oil stopper 28 abuts against the packing 17, and the outer diameter of the oil stopper 28 at this portion is increased, so that from the side of the soot pipe (upper side in the figure). The inner pressure receiving area is formed to be large.
[0020]
For example, the outer diameter of the cable outer shielding layer 21 is d ₁ , the outer diameter of the oil stopper 15 having no conventional flange portion shown in FIG. 5 is d ₂ , and the oil stopper 28 of the present embodiment shown in FIG. When the outer diameter of the flange portion 28a is d ₃ , specifically d ₁ = 90 mm, d ₂ = 100 mm, and d ₃ = 130 mm, FIG. 1 (structure according to this embodiment) is compared with FIG. 5 (conventional structure). The pressure multiple P received by the flange surface by
P = (d ₃ ² -d ₁ ² ) / (d ₂ ² -d ₁ ² )
P = 4.63
Thus, the internal pressure receiving sensitivity can be increased by 4.33 times that of the conventional structure.
[0021]
The oil stopper 28 can be formed of a non-magnetic metal, and the dimension of the protrusion (d ₃ -d ₂ ) by the flange portion 28 a is preferably 10 mm or more from the viewpoint of the above-mentioned pressure sensitivity. More preferably, it is 10 to 50 mm in view of the outer diameter restriction of the terminal connection structure.
[0022]
Further, a stopper 27 is provided on the lower side of the mounting flange 18 via a pedestal 26. The stopper 27 is made of a non-magnetic metal or hard plastic. The stopper 27 does not deform under normal use conditions of the inner side of the tub tube, and functions effectively, and is strong enough to deform when a high internal pressure is generated due to a ground fault. Is designed. Moreover, it is desirable to provide the stopper 27 not only at one place as shown in the figure but also at a plurality of places, for example, four places.
[0023]
FIG. 2 shows a pressure release operation situation when a ground fault occurs and a high internal pressure is instantaneously generated (for example, 4 MPa). The oil stopper 28 receives a force in the M direction in the figure due to the internal pressure due to the ground fault, and bends the stopper 27 and moves downward. For this reason, insulating oil and gas on the side of the soot pipe are sprayed into the lower space as indicated by the broken arrow F, so that the pressure inside the soot pipe can be made less than the internal pressure breakdown strength of the soot pipe, preventing phenomena such as explosion scattering and ignition. it can.
[0024]
In the structure of this embodiment, since the pressure in the vertical tube during normal use is about 0 to 0.5 MPa, the strength of the stopper 27 is preferably about 1 MPa. When the internal pressure of the soot pipe becomes 1 MPa or more, the stopper 27 is deformed and the oil clamp 28 can be moved downward in the vertical direction. However, it is also possible to change the stopper deformation strength according to conditions such as the structure of the terminal connection portion and the ground fault current, and set conditions other than 1 MPa. Further, the internal pressure at the time of the ground fault test reached 4 MPa or more in the case of the terminal connection part for 154 kVXLPE cable, but it was confirmed by the test that the structure of this embodiment can completely prevent explosion and scattering.
[0025]
As described above, in the power cable termination connection portion of the present embodiment,
(A) By providing only the stopper 27 for the oil clamp 28, explosion and scattering of the soot pipe and other members due to an increase in internal pressure during a ground fault can be prevented with a simple structure.
(B) Although the oil stopper 28 functions as a seal metal fitting at normal internal pressure, it functions as a pressure relief metal fitting at the time of a ground fault, thus preventing an increase in the number of parts by combining multiple functions with one component. it can.
(C) Since the flange 28a is provided in the oil stopper 28 and the outer diameter is increased to increase the pressure receiving area, the oil stopper 28 can be easily moved downward in the vertical direction in accordance with the pressure change in the vertical pipe 12. Can do.
[0026]
In addition, the other embodiment of the termination | terminus connection part for electric power cables of this invention is shown in FIG. In this cable terminal connection portion, a flange portion 29a is provided below the oil clamp 29, and the oil clamp lower seal 20 shown in FIG. 1 is omitted. Also in this embodiment, the same effect can be obtained by the same operation as the cable terminal connection portion shown in FIG.
[0027]
【The invention's effect】
According to the power cable terminal connection portion of the present invention, the following effects can be obtained.
(1) Compared to the conventional structure, the only additional part is a stopper, and despite the extremely simple structure, explosion explosion due to high internal pressure during a ground fault can be prevented.
(2) For this reason, it becomes possible to safely install the cable terminal connection portion on the overhead power transmission line tower, and there is an invaluable merit in terms of cost. Further, in the case of installation on the ground as in the prior art, the safety is further improved, and it can be used in places where there is a concern about conventional installation such as near a house.
(3) Although it can be used for all types of soot pipes, it is particularly suitable for installation on a steel tower of a polymer soot pipe type cable terminal connection portion, and further, its advantages can be utilized.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view showing an embodiment of a power cable termination connecting portion of the present invention.
FIG. 2 is a partial cross-sectional view showing a pressure release operation situation at the time of a ground fault in one embodiment of the power cable terminal connection portion of the present invention.
FIG. 3 is a partial cross-sectional view showing another embodiment of the power cable terminal connection portion of the present invention.
FIG. 4 is a cross-sectional view showing a conventional power cable termination connection.
5 is an enlarged cross-sectional view of a portion A indicated by a broken line in FIG.
FIG. 6 is an enlarged cross-sectional view showing another example of a portion A of a conventional power cable terminal connection portion.
[Explanation of symbols]
7 Cable conductor 9 Gas 10 Insulating oil 11 Cable insulator 12 碍 pipe 15 Oil clamp (leakage prevention bracket)
17 Packing 18 Mounting flange 21 Cable outer shielding layer 24 Cable 27 Stopper 28 Oil clamp (leakage prevention bracket)
28a Flange 29 Oil stopper (Leakage prevention bracket)
29a Flange

Claims (2)

A power cable, a soot tube that inserts a terminal portion of the power cable, an insulating oil or an insulating gas filled around the power cable in the soot tube, and a power cable / in which the power cable is inserted into the soot tube In the terminal connection part for a power cable, the leakage preventing metal fitting is provided to be inserted through the power cable at a soot boundary portion and prevents the insulating oil or the insulating gas from leaking outside the soot pipe. A flange portion is provided on the metal fitting, and a gap between the flange portion and a mounting flange connected to the soot tube is sealed, and the power cable and the soot tube are hermetically sealed, and the power cable side end of the soot tube in lower side of the flange portion at outer side, a stopper for the leakage prevention fitting provided through the pedestal attached to the lower side of the mounting flange, said stopper Prevents the leak-proof fitting from moving downward in the vertical direction up to an internal pressure of less than 1 MPa, and deforms when the internal pressure of the pipe reaches an internal pressure of 1 MPa or more and moves the leak-proof fitting in the vertical direction downward. The power cable terminal connection part is characterized in that the internal pressure of the soot pipe is released into a protective metal fitting connected to the soot pipe.   The end connection portion for a power cable according to claim 1, wherein the projection of the flange portion has a dimension of 10 mm or more.

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