JPH0129934Y2 - - Google Patents

Description

[Detailed description of the invention] This invention limits or blocks the follow-on flow of AC caused by lightning flashovers in power transmission and distribution lines using insulated wires, thereby eliminating disconnection and damage to the insulators, protecting the lines and preventing ground faults. This relates to a lightning disconnection prevention unit that restores insulation on its own to prevent power outages.

Conventionally, when shock overvoltage caused by lightning surges is applied to power transmission and distribution lines using insulated wires, the insulation coating of the wires breaks through and flashover occurs in the insulator, and the resulting AC follow-on arc causes the wires to melt. Damage occurred, including damage to the insulators. In addition, even if the wire did not break, the insulator did not have the ability to restore its insulation on its own, and ground fault relays and equipment at the substation were activated to cut off the following current, resulting in a power outage to the line. Therefore, JP-A-55
- As in the invention described in Publication No. 136412, a current-limiting element containing a current-limiting element made of a material with non-linear voltage-current characteristics is interposed in the energizing-side arcing horn attached to the cap fitting of the clamp-top insulator. There are also known devices that limit or block the follow-up current associated with lightning flashovers, prevent wire breakage and damage to the insulator, and allow the insulator device to restore insulation on its own to prevent line power outages. However, in this invention, in order to clamp the electric wire and connect it to the arcing horn on the energized side, it is necessary to strip off the insulation coating. Therefore, it is necessary to install an insulating cover, which takes time to install the pole, and if the insulating cover is installed, birds may use their beaks to eat insects and use themselves as a medium to cause ground faults. There was a risk of damage from birds and stress corrosion of the core wire due to rainwater entering the inside of the insulating cover. moreover,
The above-mentioned invention relates to a clamp-top insulator, and in power distribution lines where tight-top insulators, which grip electric wires with their insulation coatings still attached, are the majority, when the current-limiting element described above is installed on an existing line, the line can be cut off during power outage. Various problems remained, including the need to replace the insulator, which made it impractical.

Furthermore, in Japanese Patent Application Laid-Open No. 50-41088, an air gap is formed between an insulated wire and an intermediate electrode attached to a current limiting unit, and the intermediate electrode is formed in an arc shape or the like to partially cover the creeping surface of the insulator. A gap device with a current limiter is disclosed. This device is more practical than the previous case where it is installed on the power supply side, but for example, it has the ability to capture flashover caused by lightning surges and is a simple means of installation on existing equipment on power lines. No particular consideration was given.

The present invention was completed with the aim of providing a lightning disconnection prevention unit that solves the above-mentioned problems, and the present invention will be described in detail below with reference to the illustrated embodiments.

Reference numeral 1 denotes a grounding fitting such as a grounding arm; a tight-tipped insulator body 2 is fastened and fixed to the grounding fitting 1 with a base fitting 6a and a pin fitting 6b which are integrally fixed to the grounding side end of the grounding fitting 1; A wire receiving groove 3a is provided on the circumferential surface of the head 3 of the insulator body 2, and the covered wire 4 is inserted into the wire receiving groove 3a without removing the insulation coating 4b, and the bound wire 5
It is fixedly supported by the head 3 with a . 7 is a conventionally known current limiting element 7a which is made of a material with non-linear voltage-current characteristics such as silicon carbide or zinc oxide, and has electrode surfaces formed by welding a metal such as aluminum to both end surfaces of the main body. Side electrode 7b and ground side electrode 7
A current-limiting element is a current-limiting element formed by sandwiching the two electrodes between the electrodes 7b and 7b, and covering only the tips of the electrodes with a pleated insulator 7d made of rubber or synthetic resin. As shown in FIG. 2, a C-ring-shaped intermediate electrode 8 is made of a highly flexible and thin metal wire such as aluminum alloy or brass and has an inner diameter sufficient to surround the insulator body 2 in an annular shape at a predetermined distance. As is clear, it is mounted substantially horizontally with the mounting end 8b bent into a long U-shape and formed to protrude. The intermediate electrode 8 is formed by bending the tip portions of a pair of arcuate arm portions 8a, 8a that form a ring following the opening portion, that is, the long U-shaped mounting end portion 8b, to the outside to form an opening. The distance between the openings 8d formed by forming the arm end portions 8c, 8c so that the arcuate portions face each other is always smaller than the body diameter of the insulator body 2, but when necessary Due to the elasticity of the material, the opening 8d can be enlarged to pass through the body of the insulator body 2, and the intermediate electrode 8 has an air gap between it and the insulated wire 4 supported by the bind wire 5. They are arranged in parallel to cover the grounding fitting 1 with a gap in between, and the mounting end portion 8b is connected and fixed to the power-supplying side electrode 7b by a holding plate 9 and a bolt 10. On the other hand, the ground side electrode 7c of the current limiting element 7 is connected to the insulator body 2.
While holding the base metal fitting 6a on the grounding side, tighten the bolt 12.
Two-piece band fitting 11 that is tightened and fixed by
are connected and fixed with bolts 13. The band fitting 11 is provided with a hinge portion 11a in an annular portion so that it can be opened and closed.

Further, as shown in FIG. 2, the intermediate electrode 8 and the base metal fitting 6a are arranged so that their mutual rings are concentric with the insulator body 2, so that the insulator body 2 and the intermediate electrode can be connected to each other regardless of the mounting direction to the insulator. 8 is kept constant.

With this structure, the insulated wire 4 is held by the bind wire 5 with the insulation coating 4b attached to the head 3 of the insulator body 2 attached to the grounding fitting 1 without exposing the core wire 4a. When an impact overvoltage is applied to the line due to a lightning surge, the insulation coating 4b of the insulated wire 4 is broken through, and discharge is emitted from the core wire 4a or the binding wire 5, passes through the air gap, and is captured by the intermediate electrode 8. This intermediate electrode 8 is in the shape of a C ring, and is surrounded almost all the way around the insulator body 2 while maintaining a constant distance from the circumferential surface of the insulator body 2, that is, a constant horn coordinate, and runs parallel to the insulated wire 4. Because of this arrangement, the capture range of the flashover voltage is wide, and it can be installed in any direction even in irregular pole mounting conditions, such as when wires are placed at arbitrary horizontal angles at the gripping point. Become. In addition, unstable flashover paths caused by excessive and steep lightning surges or uneven staining of the insulator surface can be sufficiently covered, and a stable discharge path is formed to provide a reliable trapping function. The lightning surge captured in the intermediate electrode 8 in this way is transferred to the current limiting element 7
It is discharged from the current-applying side electrode 7b via the current-limiting element 7a and the grounding-side electrode 7c, but when an impact overvoltage is applied to the current-limiting element 7a, the current-limiting element 7
Due to the non-linearity of the voltage-current characteristics, a reduces its resistance value to allow the large current of the lightning surge to pass through, and after the impact overvoltage disappears, it restores its resistance value to immediately limit and interrupt the following discharge and prevent lightning disconnection. The unit quickly restores insulation. Therefore, no follow-on arc occurs,
Damages such as wire breakage and insulator damage are reliably prevented, and since the insulator device instantly recovers its insulation due to the air gap after the impact overvoltage is discharged, the ground fault relays and equipment at the substation do not operate, and the line remains intact. Power outages can be avoided. Furthermore, in the present invention, by attaching the current limiting element 7 and the intermediate electrode 8 to the base metal fitting 6a on the ground side of the insulator body 2 using the two-piece band metal fitting 11 that can be opened and closed, it is possible to create a tight-fit insulator that tightens the mass in the distribution line. Easy to use. Further, the intermediate electrode 8 has an opening 8d shaped like a C ring that can be expanded by utilizing the elasticity of a thin metal wire, and has arm tips 8c formed as arc-shaped ends facing each other, and a long U. Mounting end 8 that protrudes in a letter shape
b, and furthermore, the insulator body 2 can be surrounded in an annular shape that is most desirable in terms of the trapping performance, and the opening 8d can more easily add elasticity to the long U-shaped mounting end 8b. The diameter of the body of the insulator body 2 can be reduced to the minimum limit that can further ensure the catching of the insulator, and the opposing arcuate ends are designed to allow the opening to pass smoothly through the insulator body 2 without damaging it. If the wire is pressed against the trunk of the insulator body 2 while holding the wire, the opening will be expanded and the wire can be freely passed through the cross section and installed. In addition, since it returns to its original shape due to its elasticity after passing, it is possible to carry out repair work on existing tight-tip insulators in a short time by using the existing equipment as is, without having to modify the energized parts of the line or causing a power outage. . In addition, the intermediate electrode 8 limits and blocks follow-on arcs and has almost no melting damage, so it can be molded from a thin metal wire with a diameter of several millimeters, making it possible to mass-produce uniform products at low cost using a simple mold. In addition, it is lightweight and easy to handle, and because it is elastic, it easily absorbs external force even if it accidentally hits the insulator or surrounding column fittings, causing damage to the insulator or connected current limiting elements. It also has the advantage of being less frequent.
In addition, there is no need to strip the insulation coating of the wire or attach an insulation cover as in the conventional method, making the overall installation of the pole easier.In addition, since the insulation cover is not attached, there is no risk of bird damage caused by birds that prey on insects. does not induce
Since the core wire 4a is not exposed while the electric wire is still covered with the insulation coating 4b, there are various advantages such as completely eliminating the risk of stress corrosion caused by rainwater.

As is clear from the explanation of the above embodiments, the present invention is not only highly effective in maintaining the stability of power transmission and distribution lines, but also can be easily expanded by simply pressing the opening of the intermediate electrode against the body of the insulator during installation. Therefore, it has great practical value as a lightning disconnection prevention unit that can be easily installed on poles.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view showing an embodiment of the present invention applied to a high-voltage solid insulator, and FIG. 2 is a partially cutaway plan view. 1: Grounding metal fitting, 2: Insulator body, 4: Insulated wire,
6a: Base metal fitting, 7: Current-limiting element, 7b: Power supply side electrode, 7c: Grounding side electrode, 8: Intermediate electrode, 8a:
Arm portion, 8b: mounting end portion, 8c: arm tip portion, 8d: opening portion, 11: band metal fitting.

Claims (1)

[Scope of utility model registration request] Lightning of an electric line, in which an air gap is formed via an intermediate electrode 8 between an insulated wire 4 supported on an insulator body 2, and a current limiting element 7 with non-linear voltage-current characteristics is provided on a grounding fitting 1. In the disconnection prevention unit, the intermediate electrode 8 has a long U-shaped mounting end 8b formed of a highly flexible metal wire, a pair of arc-shaped arm parts 8a, 8a, and a pair of arc-shaped arms 8a, the tips of which are removed. It consists of arm tip parts 8c, 8c bent toward the side, and the arm tip parts 8c, 8
An opening 8d having a width smaller than the diameter of the body of the insulator body 2 is provided between the current-limiting element 7 and the current-applying side electrode 7b.
The current limiting element 7 is attached concentrically to the insulator body 2 and the band fitting 11, and the current limiting element 7 is connected to the base metal fitting 6a on the ground side of the insulator body 2 via the ground side electrode 7c to the two-split band fitting 11 which can be opened and closed. A lightning disconnection prevention unit characterized by being installed.