JP2004071972A - Lightning arrester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure the successful bonding of an internal element component by improving twisting strength without causing the reduction of operability and the cost increase of a product. <P>SOLUTION: This lighting arrester is obtained by sandwiching a current limiting element 1 having nonlinear current voltage characteristic between a pair of terminal electrodes 2 and 3, disposing them coaxially, fixing terminal electrodes 2 and 3 to both of the ends of a plurality of insulation rods 4 arranged around it, and covering the outer peripheral surfaces of the current limiting element 1 and the electrodes 2 and 3 with an insulating outer cover 5. The arrester is provided with a structure of connecting a conductive spacer 9 to the end face of the element 1 opposing the one electrode 3 and inserting a conductive pressurizing screw 15 through the electrode 3 to press the spacer 9 with the screw tip part of it to compress an internal element component including the element 1 in the axial direction. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a lightning arrester for protecting peripheral facilities of transmission and distribution lines from surges or the like when an abnormal voltage occurs due to, for example, a lightning surge or a switching surge.
[0002]
[Prior art]
Generally, when an abnormal voltage occurs due to a lightning surge due to lightning strikes on high-voltage or extra-high-voltage transmission and distribution lines and their vicinity, and switching surges caused by switching in and out of switches and circuit breakers, the vicinity of transmission and distribution lines In order to protect the equipment from surges, a lightning arrester is installed between the wire side of the transmission and distribution line and the ground side.
[0003]
This lightning arrester has a structure provided with a current limiting element made of ZnO or the like having a non-linear current-voltage characteristic showing low resistance to surge voltage and high resistance to normal ground voltage of transmission and distribution lines. I do. This current limiting element is sandwiched between a pair of terminal electrodes, and they are arranged coaxially.A plurality of insulating rods are arranged around the current limiting element, and terminal electrodes are fixed to both ends of the insulating rods. There is a structure in which an insulating jacket is attached to an outer peripheral surface of an electrode (see Japanese Patent Application Laid-Open No. 63-31602).
[0004]
In a lightning arrester, normally, the current limiting element has a high resistance and insulates the wire side and the ground side.However, if an abnormal voltage occurs due to a surge or the like, the current limiting element becomes a low resistance and instantaneously reduces this. When the abnormal voltage is extinguished and the current limiting element becomes high resistance, the current flowing to the ground is cut off. By this valve action, the peripheral equipment of the transmission and distribution line is protected from abnormal voltages such as lightning surge and switching surge.
[0005]
On the other hand, if an abnormal voltage, such as a direct lightning strike that exceeds the performance of the lightning arrester, occurs, the current-limiting element may fail.In this case, an internal arc is generated between the terminal electrodes, and a large amount of gas is generated by the arc heat. This causes the internal pressure to rise sharply. When the internal pressure rises sharply, the insulating jacket is easily broken and the arc is discharged to the outside to generate an external arc, thereby extinguishing the internal arc. Thus, it is possible to prevent the lightning arrester from being explosively destroyed due to a sudden increase in the internal pressure and the fragments thereof being scattered around.
[0006]
[Problems to be solved by the invention]
By the way, the conventional lightning arrester has a mechanical strength based on a structure in which an internal element component including a current limiting element is supported by a plurality of insulating rods, and therefore, a high tensile strength can be secured. However, when the lightning arrester is mounted on the wire side and the ground side of the transmission and distribution line, the torsion force when tightening the terminal bolts for mounting the device causes slippage between the internal element parts, and the entire device is resistant to torsion. May be twisted and deformed.
[0007]
Means for increasing the tightening force of the insulating rods described above to secure the mutual contact force of the internal element parts is also conceivable.However, in order to obtain a good joining state of the internal element parts, each of the plurality of insulating rods must be It must be tightened evenly, which causes a problem that the workability is reduced and the cost of the product is increased.
[0008]
Further, the conventional lightning arrester has a structure in which the internal element parts are axially compressed by an elastic member such as a coil spring or a disc spring. Since the polymer material of the body pushes back the elastic member, the polymer material may enter between the current limiting element and the terminal electrode, which are internal element parts, and may cause conduction failure. And so on.
[0009]
In order to prevent this conduction failure, means for securing conductivity between the internal element parts by joining the internal element parts with a conductive bonding material (such as solder or conductive adhesive) may be considered. However, the use of the above causes a problem that the cost of the product is increased.
[0010]
Therefore, the present invention has been proposed in view of the above problems, and its object is to improve the torsional strength without causing a reduction in workability and an increase in product cost, and to improve the internal element parts. An object of the present invention is to provide a lightning arrester capable of ensuring a good connection state.
[0011]
[Means for Solving the Problems]
As a technical means for achieving the above object, the present invention provides a current limiting element having a non-linear current-voltage characteristic, sandwiching the current limiting element between a pair of terminal electrodes, arranging them coaxially, and disposing them around the terminal. In a lightning arrester having the terminal electrodes fixed to both ends of the plurality of insulating rods and an insulating jacket attached to the outer peripheral surfaces of the current limiting element and the terminal electrodes, a current limiting element facing at least one of the terminal electrodes is provided. A conductive spacer is joined to the end surface of the terminal, and a conductive pressing screw is screwed into the terminal electrode, and the spacer is pressurized at the screw tip, so that the internal element parts including the current limiting element can be compressed in the axial direction. It is characterized by having.
[0012]
Here, the term "at least one terminal electrode" means that the structure in which the internal element component is axially compressed by the pressing screw via the spacer is any one of a pair of (electrode side and ground side) terminal electrodes. It means that it is provided on one or both terminal electrodes. The internal element parts including the current limiting element include a spacer, a disc spring, and the like in addition to the current limiting element. In addition, the current limiting element sandwiched between the pair of terminal electrodes includes a plurality of current limiting elements arranged in an axial shape.
[0013]
In the present invention, by providing a structure in which the internal component is axially compressed by the pressing screw via the spacer, the frictional force between the internal component can be increased by the compression load. When installing on the electric wire side and the ground side of the power transmission and distribution line, it is possible to suppress the occurrence of slip between the internal element parts of the lightning arrester due to the torsion force when tightening the terminal bolts for installing the device, and the torsion resistance of the lightning arrester Improvement can be achieved. In addition, since the degree of adhesion in the joined state of the internal element parts can be improved by the compressive load acting on the internal element parts by the pressing screw, the polymer material of the insulating outer body is reduced when the insulating outer body is formed. It is possible to suppress the occurrence of conduction failure due to intrusion between the internal element parts.
[0014]
It is preferable that the spacer in the above configuration of the present invention has a shape in which rotation around the axis can be restricted by contacting the outer peripheral surface with the insulating rod. With this configuration, even if a torsion force is applied to the lightning arrester, the outer circumferential surface of the spacer abuts on the insulating rod, thereby preventing the spacer from rotating around the axis. Here, the “shape in which rotation around the axis can be restricted by abutting on the insulating rod” means a shape provided with a notch into which the insulating rod is fitted, a shape provided with a through hole through which the insulating rod is inserted, and the like. In addition to the above-described notches and through holes, a polygonal shape such as a quadrilateral in which the outer shape of the spacer itself is inscribed in the insulating rod is also effective.
[0015]
Here, when a torsion force is applied to the lightning arrester, the first slip occurs between the terminal electrode and the spacer.If the shape of the spacer is as described above, the position of the spacer with respect to the insulating rod is constant. Therefore, no slip occurs between the terminal electrode and the spacer even when a torsional force is applied.
[0016]
It is preferable that at least the end face of the spacer in the above configuration of the present invention that comes into contact with the current limiting element is roughened. By doing so, the frictional force in the joint state between the spacer and the current limiting element can be increased, and the torsion resistance of the lightning arrester can be improved. As a means for roughening the end face in contact with the current limiting element, a conductive material such as a metal (for example, aluminum) can be sprayed or formed by machining such as pressing or cutting.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
1 and 2 show an embodiment of the present invention. The lightning arrester of this embodiment has a plurality of current limiting elements made of ZnO or the like having a non-linear current-voltage characteristic showing low resistance to surge voltage and high resistance to normal ground voltage of transmission and distribution lines. 1 and a pair of terminal electrodes 2 and 3 on the electric wire side and the ground side at both ends of the current limiting element 1 are arranged coaxially, and three or more (six in the figure) insulating rods 4 are surrounded therearound. The terminal electrodes 2 and 3 are fixed to both ends of the insulating rod 4 arranged in parallel to the axial direction, and the insulating jacket 5 is attached to the outer peripheral surfaces of the current limiting element 1 and the terminal electrodes 2 and 3. Have.
[0018]
In this lightning arrester, normally, the current limiting element 1 has a high resistance and insulates the electric wire side from the ground side. However, when an abnormal voltage due to a surge or the like occurs, the current limiting element 1 becomes a low resistance and has a low resistance. If the abnormal voltage disappears instantaneously and the abnormal voltage disappears, the current limiting element 1 becomes high resistance and cuts off the current flowing to the ground. By this valve action, the peripheral equipment of the transmission and distribution line is protected from abnormal voltages such as lightning surge and switching surge.
[0019]
On the other hand, if an abnormal voltage such as a direct lightning strike that exceeds the performance of the lightning arrester occurs, the current limiting element 1 may fail. In this case, an internal arc is generated between the terminal electrodes 2 and 3 and the heat generated by the arc is generated. A large amount of gas is generated and the internal pressure rises sharply. When the internal pressure rises sharply, the insulating jacket 5 is easily broken and the arc is discharged to the outside to generate an external arc, thereby extinguishing the internal arc. This prevents the lightning arrester from being explosively destroyed due to a sudden increase in internal pressure and the fragments thereof from being scattered around.
[0020]
The following structure is applicable as a means for fixing the insulating rod 4 to the terminal electrodes 2 and 3. Although not shown, first, an axial through hole or a notch is formed in each of the terminal electrodes 2 and 3, and an end portion of the insulating rod 4 is subjected to a screw process so that the through holes or the notches of the terminal electrodes 2 and 3 are formed. There is a structure in which the insulating rod 4 is inserted and the end of the insulating rod 4 is screwed. Second, an axial through hole or a concave hole is formed in each of the terminal electrodes 2 and 3, and an insulating rod 4 is inserted into the through hole or the concave hole. There is a structure for caulking the end of No. 4. In this caulking structure, an adhesive may be applied to the portion where the insulating rod 4 has been inserted into the through hole or the concave hole together with the caulking to bond the two together. Third, as shown in FIG. 1, the axial recesses 6, 7 of the terminal electrodes 2, 3 are formed, and an adhesive (not shown) is applied to the end of the insulating rod 4. Is inserted into the recessed holes 6 and 7 of the terminal electrodes 2 and 3 and bonded. In the illustrated lightning arrester, the one that employs the third fixing means among the three fixing means described above is illustrated.
[0021]
The insulating rod 4 may be, for example, an FRP rod made by impregnating resin into a bundle of insulating fibers (for example, glass fiber or aramid fiber) parallel to the axial direction of the lightning arrester, or insulating fiber impregnated with resin. Use an FRP bar or the like obtained by rolling the cloth into a bar shape and hardening it.
[0022]
The insulating jacket 5 is made of a polymer material having excellent insulation and weather resistance, such as silicon rubber, EP rubber, EVA, or epoxy, and is integrally formed on the outer peripheral surfaces of the current limiting element 1 and the terminal electrodes 2 and 3. I do. In addition to the integral molding, for example, a structure in which a tube formed body with or without folds, such as silicon rubber, EP rubber, or EVA, is placed on the outer peripheral surfaces of the current limiting element 1 and the terminal electrodes 2 and 3 by thermal contraction or other means. It may be. The internal space of the insulating jacket 5 may be filled with an organic insulating material such as a gel or rubber. By filling the internal space of the insulating jacket 5 with the organic insulating material as described above, it is possible to prevent moisture from entering from the outside and to secure airtightness for a long time.
[0023]
Between the terminal electrode 2 on the ground side and the current limiting element 1, a disc spring 8 for ensuring conductivity at all times, and a conductive spring for ensuring contact between the disc spring 8 and the current limiting element 1. The spacer 9 is interposed. A conductive spacer 9 is also arranged between the terminal electrode 3 on the electric wire side and the current limiting element 1 so as to be in close contact with the current limiting element 1. An inner end face of each spacer 9, that is, an end face 10 that contacts the current limiting element 1 is made rough. As a means for roughening the inner end face 10 of the spacer 9, a conductive material such as metal (for example, aluminum) may be sprayed, or irregularities may be formed by machining such as pressing or cutting.
[0024]
As shown in FIG. 2, a plurality of (six in the figure) cutouts 11 are formed at equal intervals in the circumferential direction of the outer peripheral surface of the spacer 9 arranged on the ground side and the electric wire side. By fitting the insulating rod 4 into the shaft 11, rotation around the axis of the spacer 9 can be restricted. In consideration of the assembly of the internal element parts of the lightning arrester, if the notch 11 is formed in the spacer 9, the plurality of current limiting elements 1 are arranged coaxially and the spacer 9 is arranged. Since it is only necessary to fit the insulating rod 4 into the notch 11 of the spacer 9, it is preferable in that the assembling work becomes easy.
[0025]
In this embodiment, the notch 11 is formed in the spacer 9. However, a structure in which a through hole is formed in the spacer 9 and the insulating rod 4 is inserted into the through hole may be used. Further, the outer shape of the spacer 9 is not limited to the disk shape, but may be a rectangular plate shape. For example, a rectangular spacer 9a having a notch 11a as shown in FIG. 3A, a rectangular spacer 9b having a through hole 11b as shown in FIG. As shown in ()), a rectangular spacer 9c having a size inscribed in the insulating rod 4 may be used. All of the spacers 9, 9a to 9c having these shapes are restricted from rotating around the axis by contacting the insulating rod 4. The spacers 9, 9a to 9c are not limited to the plate shape, but may be a block shape.
[0026]
Further, as shown in FIG. 1, the disc spring 8 arranged between the terminal electrode 2 on the ground side and the spacer 9 can be arranged on the electric wire side. In that case, it is necessary to interpose a disc spring between the two spacers. When the disc spring 8 arranged on the ground side is omitted, if the inner end surface 12 of the terminal electrode 2 on the ground side is roughened, the spacer 9 on the ground side is omitted and the terminal electrode 2 on the ground side is omitted. Can be directly bonded to the current limiting element 1, and since the inner end surface 12 of the terminal electrode 2 is rough, the electrical and mechanical connection with the current limiting element 1 is assured. Become. As a means for roughening the inner end surface 12 of the ground-side terminal electrode 2, a conductive material such as metal (for example, aluminum) is sprayed, or irregularities are formed by machining such as pressing or cutting. Just fine.
[0027]
When the lightning arrester is mounted on the wire side and the ground side of the power transmission and distribution line, if the torsion force is applied when tightening the terminal bolts for mounting the device, the first slip that occurs between the internal element parts is the terminal electrode 2 (dish). Between the spring 8) and the spacer 9, and between the terminal electrode 3 (pressing screw 15) and the spacer 9, the insulating rod 4 fixed to the terminal electrodes 2 and 3 is in a state fitted in the notch 11 of the spacer 9. Therefore, the position of the spacer 9 with respect to the insulating rod 4 becomes constant, and the spacer 9 is caught by the insulating rod 4 and rotation around the axis is prevented. The torsion resistance of the device can be improved.
[0028]
In addition, since the end face 10 of the spacer 9 which is in contact with the current limiting element 1 is roughened, the frictional force in the joint state between the spacer 9 and the current limiting element 1 can be increased, and even if a torsional force is applied, 9 and the current limiting element 1 become less slippery, and in this respect, the torsion resistance of the lightning arrester can be improved. In addition, since each of the plurality of current limiting elements 1 is formed with a rough surface by metal spraying of, for example, aluminum or the like, each of the current limiting elements 1 is hard to slip between the current limiting elements 1.
[0029]
On the other hand, a screw hole 14 is formed in the center of the terminal electrode 3 on the electric wire side in the axial direction, and a pressing screw 15 having conductivity is screwed into the screw hole 14 and the screw tip is connected to the terminal electrode 3. Protruding from the end surface of the terminal electrode 3 and abut against the spacer 9 facing the terminal electrode 3. A screw having a hexagonal hole 16 at the rear end (a screw with a hexagonal hole) is used as the pressing screw 15 so that the terminal electrode 3 can be easily screwed after being inserted into the screw hole 14. The structure of the pressing screw 15 may be provided on the terminal electrode 2 on the ground side. In this case, the disc spring 8 may be interposed between the terminal electrode 3 on the electric wire and the spacer 9.
[0030]
By screwing the pressing screw 15, the spacer 9 is pressed in the axial direction to compress the current limiting element 1. Thereby, electrical and mechanical between the current limiting elements 1, between the current limiting element 1 and the spacer 9, between the disc spring 8 and the spacer 9 and the terminal electrode 2, and between the pressing screw 15 and the spacer 9 and the terminal electrode 3. A secure joint is ensured. If the pressing screw 15 is screwed in until the disc spring 8 arranged between the terminal electrode 2 on the ground side and the spacer 9 is completely compressed, the pressing force by the pressing screw 15 and the elastic force by the disc spring 8 are always increased. Because of the function, the electrical and mechanical joining state of the internal element parts can be further ensured.
[0031]
Since the frictional force between the internal component parts can be increased by the compression load generated by the screwing by the pressing screw 15, when mounting the lightning arrester on the wire side and the ground side of the transmission and distribution line, the terminal bolts for mounting the device are required. The occurrence of slippage between the internal component parts due to the torsional force at the time of tightening can be suppressed, and the torsion resistance of the lightning arrester can be improved. In addition, the rigidity of the lightning arrester increases due to the increase in the compressive force of the pressing screw 15, and the bending resistance can be improved.
[0032]
As described above, by securing the compressive force in the axial direction by the pressing screw 15, it is possible to obtain a greater compressive force in the axial direction than in the case of an elastic member such as a coil spring or a disc spring in the conventional device. As a result, the degree of adhesion of the internal element components including the current limiting element 1 in the joined state can be improved, and the disc spring 8 disposed between the terminal electrode 2 on the ground side and the spacer 9 is pressed until it is completely compressed. If the screw 15 is screwed in, there is no room for the disc spring 8 to return due to the pressure due to the integral molding of the insulating casing 5, so that the polymer material of the insulating casing 5 penetrates between the internal element parts and conducts. The occurrence of defects can be prevented.
[0033]
FIG. 4 shows another embodiment of the present invention, which is a lightning arrester having a larger number of current limiting elements 1 than the embodiment of FIG. The lightning arrester of this embodiment has a structure in which a conductive spacer 17 is also interposed at an intermediate position between a plurality of current limiting elements 1 arranged. In the case of this spacer 17, since it is arranged at an intermediate position between a plurality of current limiting elements, since the current limiting element 1 is joined above and below it, both end faces 13 in contact with the current limiting elements 1 are roughened. And
[0034]
By making the both end surfaces 13 of the spacer 17 that are in contact with the current limiting element 1 rough, the frictional force in the joined state between the spacer 9 and the current limiting element 1 can be increased, and even if a torsional force is applied, the spacer 9 can be used. And the current limiting element 1 becomes less slippery, and in this regard, the torsion resistance of the lightning arrester can be further improved.
[0035]
By providing the intermediate spacer 17 in this manner, even if the lightning arrester is elongated in the axial direction, it is possible to ensure an improvement in the torsional strength, and to limit the current limiting element inside the lightning arrester due to an excessive lightning surge or the like. It is also possible to improve the pressure release performance when an internal arc is generated due to failure of the device 1.
[0036]
In other words, while the pressure between the insulating rods 4 may be widened due to the pressure release when the internal arc is generated, the internal element parts may be scattered. On the other hand, if the spacer 17 is interposed at the intermediate position of the current limiting element 1, 17, the spread between the insulating rods 4 can be prevented, and the scattering of the internal element parts can be prevented. In consideration of the point where such a function is exhibited, a through hole 18 is formed in the spacer 17 as shown in FIG. Is preferable.
[0037]
【The invention's effect】
According to the present invention, a conductive spacer is joined to the end face of the current limiting element facing at least one terminal electrode, a conductive pressing screw is inserted into the terminal electrode, and the spacer is applied at the tip of the screw. By compressing the internal element parts including the current limiting element by compressing them, the frictional force between the internal element parts can be increased by the compressive load. In addition, the occurrence of slippage between the internal element parts due to the torsion force can be suppressed, and the torsion resistance, rigidity, and bending resistance of the lightning arrester can be improved.
[0038]
In addition, since the degree of adhesion in the joined state of the current limiting element can be improved by a compressive load acting on the internal element component by the pressing screw, the polymer material of the insulating outer body is reduced when the insulating outer body is formed. Since it is possible to prevent the occurrence of conduction failure due to intrusion between the internal element parts, it is possible to improve reliability and provide a high-quality lightning arrester.
[0039]
If the spacer has a shape in which rotation around the axis can be restricted by contacting the outer peripheral surface of the spacer with the insulating rod, the position of the spacer with respect to the insulating rod becomes constant even if a torsion force is applied to the lightning arrester, Slip does not occur between the terminal electrode and the spacer, and the torsional strength is further improved. If at least the end face of the spacer that contacts the current limiting element is made rough, the frictional force in the joint state between the spacer and the current limiting element can be increased, and the torsional strength can be further improved.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an embodiment of a lightning arrester according to the present invention.
FIG. 2 is a sectional view taken along line AA of FIG.
FIGS. 3A to 3C are cross-sectional views showing three examples of spacers applicable to the lightning arrester of the present invention.
FIG. 4 is a cross-sectional view showing another embodiment of the present invention.
FIG. 5 is a sectional view taken along the line BB of FIG. 4;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Current limiting element 2 and 3 Terminal electrode 4 Insulating rod 5 Insulating jacket 9 Conductive spacer 10 End face 15 which contacts current limiting element 15 Conductive pressing screw

Claims (3)

A current-limiting element having a non-linear current-voltage characteristic is sandwiched between a pair of terminal electrodes to arrange them coaxially, and the terminal electrodes are fixed to both ends of a plurality of insulating rods arranged therearound, In the lightning arrester having an insulating jacket attached to the outer peripheral surfaces of the current limiting element and the terminal electrode, a conductive spacer is joined to an end face of the current limiting element facing at least one of the terminal electrodes, and a conductive material is connected to the terminal electrode. A lightning arrester characterized in that internal component parts including a current limiting element can be compressed in the axial direction by inserting a flexible pressing screw and pressurizing the spacer at the tip of the screw. 2. The lightning arrester according to claim 1, wherein the spacer has a shape capable of restricting rotation around an axis by contacting an outer peripheral surface of the spacer with an insulating rod. 3. The lightning arrester according to claim 1, wherein the spacer has at least an end surface in contact with the current limiting element having a rough surface.

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