JPH0766013A - Support insulator - Google Patents

Abstract

PURPOSE:To increase a discharge withstand current rating by composing the main body of a support insulator of a cast resin filled with inorganic grains having nonlinear characteristics and augmenting the grain size of the inorganic grains on the main conductive member side or reducing the fill of the inorganic grains on the sealed vessel side. CONSTITUTION:Inorganic grains mainly comprising zinc oxide are sorted into inorganic grains a-e (a: 0.1-0.5mm, b: 0.5-1.0mm, c: 1.0-3.0mm, d: 3.0-5.0mm, e: 5.0-10.0mm). An epoxy resin is filled with each inorganic grain a-e, and five kinds of mixed resins A-E are injected into a casting mold for an indicating insulator, thus manufacturing the main body 10a of a support insulator. The mixed resins A-E are used in such a manner that the height of the main body 10a is divided into five equal parts and different parts each with 1/5 the height are employed for the mixed resins A, B, C in order starting with the sealed vessel 1 side. When the mixed resins A-E are thermost, conductive connecting sections 9 are disposed on both end faces of the main body 10a, and the main body 10a and the connecting sections 9 are unified, thus constituting the support insulator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support insulator having a function as a lightning arrester.

[0002]

2. Description of the Related Art Generally, in a power system, an overvoltage protection device such as a lightning arrester is used to remove an overvoltage superimposed on a normal voltage to protect the power system and electric equipment. The conventional connection between the arrester and the main circuit is configured as shown in FIG. The main circuit conductor 2 forming the main conductive portion in the closed container 1 is supported in an insulated state in the closed container 1 by a pillar-shaped support insulator 3 made by casting epoxy resin. A branch conductor 4 branched from the main circuit conductor 2 penetrates an insulating spacer 5 arranged in the closed container 1, and a lightning arrester container 6 connected to the closed container 1 via the insulating spacer 5.
It projects inside. A non-linear resistor 7 is placed in the arrester container 6.
Is housed, and this laminated body is electrically connected to the branch conductor 4 protruding into the lightning arrester container 6.

As described above, there is a problem that the branch conductor 4 is required to connect the conventional lightning arrester to the main circuit, and the device becomes large in size by the size of the lightning arrester container 6.
In order to solve this problem, a support insulator having a function as a lightning arrester has been filed (Japanese Utility Model Laid-Open No. 3-1607). This supporting insulator is connected to the main circuit as shown in FIG. That is, a laminated body in which the non-linear resistors 7 are laminated is embedded in an epoxy resin 8, and conductive connecting portions 9 are provided on both end faces of the laminated body to form a support insulator, and the support insulator is interposed therebetween. To connect the main circuit conductor 2 and the closed container 1. Therefore, when an overvoltage is applied to the main circuit conductor 2,
An electric path including the connecting portion 9, the non-linear resistor 7, the connecting portion 9, and the closed casing 1 is formed, and the main circuit can be protected from overvoltage.

As described above, by using the support insulator integrated with the non-linear resistor, it is possible to reduce the number of components as compared with the case of connecting a lightning arrester using a lightning arrester container as in the related art, and to connect the lightning arrester. The part can be miniaturized.

However, the electric field strength in the closed container in which the supporting insulator is arranged differs between the main circuit conductor side and the closed container side, and an electric field is generated at the edge portion of the non-linear resistor on the main circuit conductor side where the electric field strength is high. Concentrates. Despite this, in the conventional support insulator, since the non-linear resistors are uniformly laminated and used, there is a problem that dielectric breakdown easily occurs at the edge portion of the non-linear resistors on the main circuit conductor side. there were.

When an overvoltage is applied to the main circuit and a large current flows through the non-linear resistor in the support insulator, mechanical stress is generated at the boundary between the edge portion of the non-linear resistor and the casting resin. This mechanical stress is not uniform in the supporting insulator and becomes maximum at the boundary between the edge portion of the non-linear resistor on the closed container side and the casting resin. For this reason, there has been a problem that when a large current flows, the support vessel side of the support insulator is easily destroyed. In order to improve the mechanical strength of such a support insulator, it is necessary to enlarge the support insulator, and it is necessary to form a recess in the closed container 1 to dispose the support insulator. In addition, there is a problem that the shape is complicated.

[0007]

As described above, in the conventional support insulator having a function as a lightning arrester, dielectric breakdown is likely to occur at the edge portion of the non-linear resistor on the main circuit conductor side due to concentration of electric field strength. There was a problem. In addition, the boundary between the edge portion of the non-linear resistor on the closed container side and the casting resin is easily broken due to mechanical stress generated when a large current flows, and in order to prevent damage, the support insulator must be enlarged. did not become. Therefore, an object of the present invention is to provide a small-sized support insulator having the function of a lightning arrester which is excellent in insulation and mechanical strength.

[0008]

In order to achieve the above object, in the present invention, the first invention is arranged between a closed container and a main conductive portion, and the main conductive portion is supported in the closed container. In the support insulator, the main body of the support insulator is composed of a casting resin filled with inorganic semiconductor particles having a non-linear voltage-current characteristic, and conductive connecting portions are provided on both end faces of the main body, and the connecting portion is formed. Provided is a support insulator characterized in that the closed container and the main conductive portion are connected via the. Further, as a second invention, the particle diameter of the inorganic semiconductor particles changes according to the distance from the main conductive portion, and the particle diameter in the vicinity of the main conductive portion is larger than the particle diameter in the vicinity of the closed container. A support insulator characterized by the above is provided. Further, as a third invention, the filling amount of the inorganic semiconductor particles changes according to the distance from the main conductive portion, and the filling amount near the main conductive portion is larger than the filling amount near the closed container. A support insulator characterized by the above is provided. The inorganic semiconductor particles preferably contain zinc oxide as a main component.

[0009]

The inorganic semiconductor particles (hereinafter referred to as inorganic particles) filled in the casting resin function as a non-linear resistor, and give the support insulator the property of a lightning arrester. In addition, by increasing the particle size of the inorganic particles on the main conductive portion side, it is possible to alleviate the electric field concentration and improve the insulating properties of the supporting insulator. By increasing the filling amount of inorganic particles on the main conductive part side and decreasing it on the closed container side, while maintaining the function as a lightning arrester,
It becomes a supporting insulator whose mechanical strength does not easily decrease even when a large current flows.

[0010]

EXAMPLE A first example of the present invention will be described with reference to FIG. 1 and Table 1. For example, bismuth oxide, antimony oxide, etc. are added as additives to the zinc oxide, which is the main component, and further water and organic bainidae are added and mixed in a mixing device. The mixture obtained is dried, for example 100 μm in diameter.
The granulated powder of about m is produced, and this granulated powder has a diameter of 0.5 to 10 m.
m is molded into a substantially spherical shape. In order to remove the organic binders from the obtained molded product, the molded product is calcined at, for example, 500 ° C. and further calcined at 1200 ° C. in air to obtain inorganic particles.

The obtained inorganic particles are classified into inorganic particles a to e according to the particle size as follows. a: 0.1 to 0.5 mm b: 0.5 to 1.0 mm c: 1.0 to 3.0 mm d: 3.0 to 5.0 mm e: 5.0 to 10.0 mm The respective inorganic particles a to e are filled in an epoxy resin to obtain five types of The mixed resins A to E are poured into a casting mold for a supporting insulator to prepare a supporting insulator body 10a shown in FIG. As the mixed resins A to E, the height of the main body 10a is divided into five equal parts, and the mixed resin A and the mixed resin B which are different from each other in order from the side of the closed container 1 are used. When the mixed resins A to E are thermoset, conductive connecting portions 9 are provided on both end surfaces of the main body 10a, and the main body 10a and the connecting portions 9 are integrated to form a support insulator. Since the epoxy resin shrinks when it is heat-cured, the filled inorganic particles a to e come into close contact with each other to act as a nonlinear resistor.

Next, the operation and effect of this embodiment will be described. A shock current having a waveform of 4/10 μs was applied to the supporting insulator of this example at intervals of 3 minutes, and the number of times 50% of the supporting insulator was destroyed (hereinafter referred to as 50% number of times of destruction) was measured. .

[0013]

[Table 1]

When a shock current of 30 kA was used, the conventional supporting insulator shown in FIG. 3 had a 50% failure frequency of 20.2 times, whereas this embodiment had a frequency of 21.4 times. When a shock current of 40 kA is used, the conventional support insulator is 9.5
In this embodiment, 18.6 times, and in the case of using a shock current of 50 kA, the conventional number is 6.8 times.
It was 14.1 times.

The reason why the electrical characteristics of the supporting insulator are improved in this embodiment is considered as follows. In the conventional support insulator in which the laminated non-linear resistors are embedded in the epoxy resin, the electric field is likely to be concentrated on the edge portion of the non-linear resistor, and the electric field strength increases as the electric circuit is closer to the main circuit conductor. Therefore, if an abnormal voltage is generated in the main circuit conductor, dielectric breakdown occurs at the edge portion of the non-linear resistor near the main circuit conductor, and the discharge withstand capability decreases.

On the other hand, in the supporting insulator of the present embodiment, the inorganic resin particles a to e are filled in the epoxy resin instead of the non-linear resistor formed in the shape of a disk.
The insulating characteristics of the mixed resins A to E can be changed according to the strength of the electric field strength, and an excellent discharge withstand capability can be obtained without overdesigning.

The particle diameters of the inorganic particles a to e are not limited to those of this embodiment, and the same action and effect can be obtained as long as the main component is not limited to zinc oxide and has non-linear characteristics. Of course.

Next, a second embodiment of the present invention will be described with reference to FIG. 2, Table 1 and Table 2. Water and organic binders are added to the same raw material as in the first embodiment containing zinc oxide as a main component and mixed in a mixing device, and the resulting mixture is dried to form a granulated powder of, for example, about 0.5 to 1.0 mm. create. The granulated powder is calcined in air at, for example, 500 ° C. and then at 1200 ° C. to obtain inorganic particles. The inorganic particles thus obtained and the epoxy resin are mixed in the following proportions to prepare mixed resins E to I.

[0019]

[Table 2]

The mixed resins E to I are poured into a casting metal for a supporting insulator to prepare a supporting insulator body 10b shown in FIG.
The height of the main body 10b is divided into five equal parts, and five kinds of mixed resins E to I are sequentially injected from the closed container 1 side in the order of ⅕, such as mixed resin E and mixed resin F. When thermosetting the main body 10b, conductive connecting portions 9 are provided on both end surfaces of the main body 10b, and the main body 10b and the connecting portions 9 are integrated to form a support insulator. Since the epoxy resin shrinks when it is thermoset, the filled inorganic particles come into close contact with each other to act as a nonlinear resistor.

Next, the operation and effect of this embodiment will be described. Table 1 shows the number of 50% breakdowns when an impact current of 4/10 μs waveform was applied to the support insulator of this example at intervals of 3 minutes. When 30kA is used as the shock current,
The number of times of 50% destruction of the conventional supporting insulator was 20.2 times, whereas this example was 20.8 times. Also, the impact current is 40
When kA was used, the conventional supporting insulator was 9.5 times, whereas in the present embodiment, it was 19.2 times, and the impact current was 50 k.
When A was used, it was 6.8 times in the past and 15.5 times in this example.

The reason why the electrical characteristics of the supporting insulator are improved in this embodiment is considered as follows. In a conventional support insulator in which a laminated body of non-linear resistors is embedded in epoxy resin, a large current flows through the non-linear resistors, and mechanical stress occurs at the boundary between the edge of the non-linear resistors and the casting resin. . Since this mechanical stress is maximum at the boundary on the side of the closed container,
If a large current flows continuously, the side of the supporting insulator in the closed container is easily broken.

On the other hand, in the supporting insulator of this embodiment, the use of the non-linear resistor formed in the shape of a disk is stopped and the inorganic particles are filled in the epoxy resin. Therefore, there is no edge where large mechanical stress concentrates, and the amount of epoxy resin is increased in the vicinity of the closed container by reducing the filling amount of inorganic particles, improving the mechanical strength without increasing the size of the supporting insulator. You can This embodiment can not only provide a support insulator having an excellent discharge withstanding by improving the mechanical strength, but also because the support insulator does not need to be upsized, the size and shape of the device can be increased without forming a recess in the closed container. It is possible to prevent the complication of the above and increase of the cost associated therewith.

The filling amount of the inorganic particles is not limited to this embodiment, and may be any amount as long as the inorganic particles are in close contact with each other depending on the distance from the main circuit conductor. In addition, although the inorganic particles containing zinc oxide as the main component have been shown in this example, it is needless to say that the same effect can be obtained as long as the particles have nonlinear characteristics.

[0025]

As described above, in the present invention, the main body of the support insulator is made of the casting resin filled with the inorganic particles having the non-linear characteristic, and the particle size of the inorganic particles is increased on the main conductive portion side, Alternatively, by reducing the filling amount of the inorganic particles on the closed container side, it is possible to provide a small-sized supporting insulator having excellent discharge withstand capability.

[Brief description of drawings]

FIG. 1 is a sectional view of a support insulator showing a first embodiment of the present invention.

FIG. 2 is a sectional view of a support insulator showing a second embodiment of the present invention.

FIG. 3 is a sectional view of a conventional support insulator.

FIG. 4 is a cross-sectional view showing a connecting portion between a conventional lightning arrester and a main circuit.

[Explanation of symbols]

1 ... Airtight container, 2 ... Main circuit conductor, 9 ... Connection part, 10a, 10
b ... The main body of the support insulator.

Claims (3)

[Claims] 1. A support insulator which is disposed between a closed container and a main conductive part and supports the main conductive part in the closed container, wherein the main body of the support insulator is an inorganic semiconductor particle having a non-linear voltage-current characteristic. A support insulator characterized in that it is made of a casting resin filled with, conductive connection parts are provided on both end faces of the main body, and the closed container and the main conductive part are connected via the connection parts. . 2. The casting resin is filled with the inorganic semiconductor particles having different particle diameters, and the particle diameter of the inorganic semiconductor particles becomes larger in the vicinity of the main conductive portion. Support insulator. 3. The supporting insulator according to claim 1, wherein the filling amount of the inorganic semiconductor particles is increased as it is closer to the main conductive portion.