JP2013247160A - Arrestor - Google Patents

Abstract

An object of the present invention is to suppress the flashover of an insulating container during a lightning impulse withstand voltage test and improve the reliability of a lightning arrester.
A lightning arrester includes a non-linear resistance element 1 mainly composed of zinc oxide stacked in series, a pair of electrode terminals 2 disposed at both ends of the stacked non-linear resistance element 1, and a non-linear resistance. An internal element including an insulating support 31 arranged along the outer periphery of the element 1 and connecting the pair of electrode terminals 2 is housed in an insulating container 4. The insulating support 31 is configured by filling an insulating material with a powder having a non-linear characteristic of electric resistance.
[Selection] Figure 1

Description

  Embodiments described herein relate generally to a lightning arrester that is connected to a power system and protects electrical equipment from overvoltage.

  The lightning arrester protects the insulation of the facilities and equipment of the system from the overvoltage when an overvoltage such as a lightning surge or a switching surge occurs in the power system. Generally, a lightning arrester has a structure in which a plurality of nonlinear resistance elements mainly composed of zinc oxide are stacked in series inside an insulating container and electrode terminals are fixed at both ends.

  This non-linear resistance element exhibits an insulation characteristic under a normal voltage. However, when an overvoltage is generated in the power system due to a lightning strike or the like and the voltage exceeds a predetermined value, it exhibits conductivity. Therefore, when an overvoltage occurs, a discharge current flows through the lightning arrester, and the overvoltage is limited. Then, as soon as the voltage returns to the normal state, the discharge stops and the original insulation state is restored.

  By the way, the insulating container of the lightning arrester needs to have a withstand voltage performance capable of withstanding a voltage based on the withstand voltage standard. Therefore, the non-linear resistance element is removed from the inside of the insulating container and a lightning impulse withstand voltage test is performed, and an overvoltage equivalent to the withstand voltage test is applied to the insulating container.

  However, in the absence of the non-linear resistance element, the electric field concentrates on the corner of the high-voltage side electrode terminal, and the electric field strength on the inner surface of the insulating container increases, which may cause dielectric breakdown or flashover. For this reason, the insulating container has an allowance in the insulation dimension so that the withstand voltage performance required during the lightning impulse withstand voltage test can be secured.

Japanese Patent Laid-Open No. 2001-291606 JP 2004-165355 A

  In recent years, as with other electrical devices, lightning arresters are required to be compact. In order to make the lightning arrester compact, it is difficult to reduce the size of the insulating container and the electrode terminal, and it is difficult to ensure the required insulating dimensions. In this case, if a lightning impulse withstand voltage test is performed without a nonlinear resistance element, the electric field concentrates at the corners of the electrode terminals, causing a flashover at a voltage lower than the withstand voltage, and achieving the required withstand voltage performance. An unsustainable problem arises.

  In this case, there is a method of relaxing the electric field concentration by applying a non-linear resistance material inside the insulating container, but it is difficult to apply the non-linear resistance material uniformly, and it is easy to achieve sufficient withstand voltage performance in a compact lightning arrester. Couldn't get.

  The present embodiment has been made in view of the above problems. In other words, even in a compact lightning arrester, to suppress flashover due to electric field concentration at the electrode corner during a lightning impulse withstand voltage test, to normally test the withstand voltage performance of the insulating container, and to provide a highly reliable lightning arrester With the goal.

  In order to achieve the above object, the lightning arrester of the present embodiment includes a plurality of non-linear resistance elements mainly composed of zinc oxide stacked in series and a pair of non-linear resistance elements disposed at both ends of the stacked non-linear resistance elements. An internal element including an electrode terminal and an insulating support member that is disposed along the outer periphery of the nonlinear resistance element and connects the pair of electrode terminals is housed in an insulating container. The insulating support is configured by filling an insulating material with a powder having a characteristic of non-linear electrical resistance.

It is sectional drawing which shows the structure of the lightning arrester which concerns on 1st Embodiment. It is a perspective view which shows the structure of the fixing unit of the lightning arrester which concerns on 1st Embodiment. It is a side view of an insulating support. It is a side view which shows the state by which the metal screw was inserted in the both ends of the insulation support body. It is a graph which shows the electrical conductivity and electric field relationship of an insulating support. (A) is an equipotential diagram of the electrode terminal corner | angular part of the lightning arrester in a prior art example, (b) is an equipotential diagram of the electrode terminal corner | angular part of the lightning arrester which concerns on 1st Embodiment. It is a side view of the insulation support body of the lightning arrester which concerns on 2nd Embodiment, (a) shows the state by which the resin with which the nonlinear resistance material was filled was coated on the whole surrounding surface of the insulation support body, (b) is an end. It shows the state of coating only near the part. It is a side view which shows the state by which the metal screw was inserted in the both ends of the insulation support body of Fig.7 (a).

Hereinafter, an embodiment of a lightning arrester will be described with reference to the accompanying drawings.
(First embodiment)
(Constitution)
As shown in FIG. 1, the lightning arrester according to the present embodiment has an internal element housed in a cylindrical insulating container 4. As an internal element, a plurality of nonlinear resistance elements 1 mainly composed of zinc oxide are stacked in series. A pair of electrode terminals 2 are disposed at both ends of the multilayer body of the nonlinear resistance element 1. Specifically, the pair of electrode terminals 2 are an upper high-voltage side electrode terminal 2a and a lower ground-side electrode terminal 2b. The pair of electrode terminals 2 are fixed to the laminated body of the non-linear resistance elements 1 via the fixing unit 3.

  As shown in FIG. 2, the fixed unit 3 includes a pair of disk-shaped conductive plates 32 and 33 and a plurality of columnar insulating supports 31 that connect and support them. The upper conductive plate 32 is disposed between the upper end of the laminate of the high voltage side electrode terminal 2a and the nonlinear resistance element 1, and is fixed to both. The lower conductive plate 33 is disposed between the lower end of the laminated body of the ground side electrode terminal 2b and the nonlinear resistance element 1, and is fixed to both.

  As shown in FIG. 3, the insulating support 31 is made of a non-linear resistance material in which an insulating material is filled with powder having a non-linear characteristic of electric resistance. Examples of the powder having non-linear electrical resistance include zinc oxide and silicon carbide. Examples of the insulating material include resins such as polyethylene and polybutadiene or fiber reinforced plastics (FRP).

  As shown in FIG. 4, metal screws 34 are inserted into both ends of the insulating support 31. The fixing unit 3 is assembled by connecting the metal screws 34 to the fixing brackets provided on the conductive plates 32 and 33.

  The non-linear resistance material constituting the insulating support 31 exhibits insulation in a low electric field, but when the electric field exceeds a certain level, the conductivity rapidly increases and becomes close to the conductor. The conductivity characteristics of the insulating support 31 made of this nonlinear resistance material are shown in the graph of FIG. When the electric field generated in the insulating support 31 by the applied voltage is lower than the electric field E1 in the figure, the conductivity is maintained at about 1E-13, indicating insulation. When the electric field E1 is reached, the conductivity rapidly increases, and thereafter, the conductivity close to the conductor of conductivity 1E-1 is maintained. The voltage that generates the electric field E1 in which the conductivity rapidly increases is called an operation start voltage.

  The operation start voltage of the insulating support 31 varies depending on the filling amount of the powder having a non-linear electric resistance characteristic. In the present embodiment, the filling amount is determined so that the operation start voltage of the insulating support 31 is lower than the flashover voltage of the insulating container 4.

(Function)
The lightning arrester of the present embodiment operates as follows. The lightning impulse withstand voltage test is performed in a state where the nonlinear resistance element 1 is not present inside the insulating container 4 as described above. In the conventional lightning arrester, when a voltage is applied to the lightning arrester, the electric field concentrates on the corner 21 of the high-voltage side electrode terminal 2a, so that the equipotential lines near the corner 21 are dense as shown in FIG. It has become. Due to the concentration of the electric field on the corner 21, the insulating container 4 tends to cause a flashover, and the required withstand voltage performance cannot be maintained.

  Here, in the lightning arrester of the present embodiment, the insulating support 31 exhibits insulation in a low electric field, but exhibits conductivity when exceeding the operation start voltage. The operation start voltage is set to be lower than the flashover voltage of the insulating container 4. Therefore, the insulating support 31 becomes conductive before the insulating container 4 reaches the flashover, and the electric field concentrated on the corner portion 21 of the high-voltage side electrode terminal 2a moves along the columnar insulating support 31 inside the lightning arrester. Is diffused. That is, as shown in FIG. 6B, the equipotential lines 8 near the corners 21 are sparsely distributed. Thereby, the flashover of the insulating container 4 is suppressed.

(effect)
(1) As described in detail above, the lightning arrester of the present embodiment is disposed at both ends of the nonlinear resistance element 1 mainly composed of zinc oxide laminated in series and the laminated nonlinear resistance element 1. The internal element including the pair of electrode terminals 2 and the insulating support 31 arranged along the outer periphery of the nonlinear resistance element 1 and connecting the pair of electrode terminals 2 is housed in the insulating container 4. The insulating support 31 is configured by filling an insulating material with a powder having a non-linear characteristic of electric resistance.

  In this way, by configuring the insulating support 31 with a non-linear resistance material, in the lightning impulse withstand voltage test performed in the absence of the non-linear resistance element 1, the electric field at the corner 21 is relaxed when an overvoltage is applied, and the electric field is further increased. It can be distributed uniformly. Thereby, the flashover of the insulating container 4 can be suppressed, and the withstand voltage performance of the insulating container 4 can be normally tested. For this reason, a compact and highly reliable lightning arrester can be provided.

(2) Furthermore, the insulating support 31 is configured such that its operation start voltage is lower than the flashover voltage of the insulating container 4. Therefore, since the insulating support 31 becomes conductive before the electric field concentrates on the corner portion 21 of the electrode terminal 2 and the flashover occurs in the insulating container 4, the flashover can be reliably suppressed.

(3) The pair of electrode terminals 2 are fixed to both ends of the nonlinear resistance element 1 via the conductive plates 32 and 33, respectively. The insulating support 31 has metal screws 34 inserted into both ends thereof, and is connected to the pair of conductive plates 32 and 33 via the metal screws 34. With this configuration, the conventional lightning arrester provided with an insulating support composed only of an insulating material can be replaced with the insulating support 31 composed of the non-linear resistance material of the present embodiment. A lightning arrester can be provided easily.

(Second Embodiment)
(Constitution)
Next, a second embodiment will be described with reference to FIGS.
In the second embodiment, only differences from the first embodiment will be described, and the same parts as those in the first embodiment will be denoted by the same reference numerals and detailed description thereof will be omitted.

  In the first embodiment, the insulating support 31 is configured by filling an insulating material with a powder having a characteristic of non-linear electrical resistance. In the present embodiment, the insulating support 35 is made of an insulating material such as resin or fiber reinforced plastic (FRP). As shown in FIG. 7, the peripheral surface of the insulating support 35 is covered with a non-linear resistance resin 36 produced by filling a resin with a powder having a non-linear electric resistance characteristic. Examples of the powder having a non-linear electric resistance include zinc oxide and silicon carbide, as in the first embodiment. The powder filling amount is determined so that the operation start voltage of the insulating support 35 is lower than the flashover voltage of the insulating container 4.

  The insulating support 35 covered with the non-linear resistance resin 36 operates in the same manner as the insulating support 31 of the first embodiment. That is, the insulating support 35 exhibits insulation in a low electric field, but exhibits conductivity before the insulating container 4 reaches flashover, and the electric field concentrated on the corner portion 21 of the high-voltage side electrode terminal 2 is insulated. It is diffused along the support 35 into the lightning arrester.

  As described above, the insulating support 35 is made of an insulating material as usual, and the material cost can be reduced by forming only the peripheral surface with a non-linear resistance material. Furthermore, the same effect can be obtained by covering the non-linear resistance resin 36 with respect to an insulating support made of only an existing insulating material.

  As for the range covering the non-linear resistance resin 36, as shown in FIG. 7A, the entire surface of the insulating support 35 is covered, or as shown in FIG. Only the vicinity of the electrode terminal 2a may be covered.

  If the entire surface is covered, the electric field can be distributed more uniformly throughout the lightning arrester. If only the vicinity of the electrode terminal is covered as shown in FIG. 7B, the electric field at the corner can be relaxed pinpointed, and the cost can be reduced.

  As in the first embodiment, the metal screw 34 is inserted into the end portion of the insulating support. However, as a connecting method, the metal screw 34 is first inserted into both ends of the insulating support 35, and thereafter Then, the non-linear resistance resin 36 is covered with a part of the metal screw 34 from the peripheral surface of the insulating support 35. As a result, the metal screw 34 and the insulating support 35 are connected by the non-linear resistance resin 36 without a gap, and the possibility of concentration of the electric field due to the occurrence of the gap can be reduced.

  The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS 1 Nonlinear resistance element 2 Electrode terminal 2a High voltage side electrode terminal 2b Ground side electrode terminal 21 Corner | angular part 3 Fixing unit 4 Insulation container 8 Equipotential lines 31, 35 Insulating support 32, 33 Conductive plate 34 Metal screw 36 Nonlinear resistance resin

Claims (8)

A plurality of non-linear resistance elements mainly composed of zinc oxide stacked in series, a pair of electrode terminals disposed at both ends of the stacked non-linear resistance elements, and an outer periphery of the non-linear resistance elements A lightning arrester configured by housing an internal element including an insulating support for connecting the pair of electrode terminals in an insulating container,
The lightning arrester is characterized in that the insulating support is configured by filling an insulating material with powder having a non-linear characteristic of electric resistance.   The lightning arrester according to claim 1, wherein the insulating support is configured such that an operation start voltage is lower than a flashover voltage of the insulating container.   The pair of electrode terminals are fixed to both ends of the nonlinear resistance element via conductive plates, respectively, and the insulating support is connected to the conductive plate via metal screws inserted at both ends thereof. The lightning arrester according to claim 1 or 2. A plurality of non-linear resistance elements mainly composed of zinc oxide stacked in series, a pair of electrode terminals disposed at both ends of the stacked non-linear resistance elements, and an outer periphery of the non-linear resistance elements A lightning arrester configured by housing an internal element including an insulating support for connecting the pair of electrode terminals in an insulating container,
A lightning arrester characterized in that the insulating support is made of an insulating material, and is coated with a non-linear resistance resin formed by filling a resin with a powder having a non-linear characteristic of electric resistance on a peripheral surface thereof.   5. The lightning arrester according to claim 4, wherein the insulating support coated with the non-linear resistance resin is configured such that an operation start voltage is lower than a flashover voltage of the insulating container.   6. The lightning arrester according to claim 4, wherein the non-linear resistance resin is coated on the entire outer periphery of the insulating support.   6. The lightning arrester according to claim 4, wherein the nonlinear resistance resin is coated only in the vicinity of an electrode terminal on the outer periphery of the insulating support. The pair of electrode terminals are fixed to both ends of the nonlinear resistance element via conductive plates, respectively, and the insulating support is connected to the pair of conductive plates via metal screws inserted at both ends. The lightning arrester according to any one of claims 4 to 7, wherein the insulating support and the metal screw are connected by covering the nonlinear resistance resin.

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