JPH09312204A - Arrester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably block the explosive bursting by using a simple pressure releasing structure. SOLUTION: The arrester comprises a current limiter element having a nonlinear current-voltage characteristic and an insulation tube 2 which houses this element and is sealed at the ends to form a gas-tight space. The end opening of the insulation tube 2 is capped with a bottom-closed sealing metal 10 having a groove 16 of a specified shape to provide a thin wall breakable at the pressure release due to the internal pressure rise of the insulation tube 2. This groove 16 is composed of two concentric annular grooves tied through a radially formed linear groove.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightning arrester, and more particularly, to a lightning arrester attached to an insulator for protecting peripheral equipment of a transmission and distribution line from lightning surge or the like when an abnormal voltage is generated due to lightning surge or the like.

[0002]

2. Description of the Related Art Generally, when an abnormal voltage due to a lightning surge or the like occurs during a lightning strike near an insulator provided on a high-voltage or extra-high-power transmission / distribution line, the peripheral equipment of the transmission / distribution line should be protected from the lightning surge, etc. For protection, a lightning arrester is installed between the ground side and the electric wire side of the above-mentioned insulator.

This lightning arrester is provided with a current limiting element made of ZnO or the like having a non-linear current-voltage characteristic which shows a low resistance to a surge voltage and a high resistance to a normal ground voltage of a transmission and distribution line. Equipped with a structure. This current limiting element is housed in an insulating cylindrical body made of porcelain, and the openings at both ends of the insulating cylindrical body are
The ground-side and wire-side terminal electrodes electrically connected to the current limiting element are sealed to hermetically hold the inside of the insulating tubular body.

In this arrester, when an abnormal voltage due to a lightning surge or the like occurs, the current limiting element has a low resistance value and instantly escapes to the ground, and when the abnormal voltage disappears, the current limiting element has a high resistance value. Then the normal ground voltage is cut off. By this valve action, the peripheral equipment of the transmission and distribution line is protected from lightning surge and the like.

[0005]

However, if a surge voltage exceeding the rating such as direct lightning strike occurs, the current limiting element may fail, in which case an internal arc is generated in the airtight space of the insulating cylindrical body. A large amount of gas is generated by the arc heat, and the internal pressure rises sharply. Due to this rapid increase in internal pressure, internal elements such as a current limiting element explosively break together with the insulating tubular body, and the fragments are scattered around. If such a lightning arrester is explosively destroyed and the fragments are scattered, it may cause personal injury, which is very dangerous and a serious problem.

Therefore, the present invention has been proposed in view of the above problems, and an object thereof is to provide a lightning arrester capable of reliably preventing explosive destruction with a simple pressure release structure. It is in.

[0007]

As a technical means for achieving the above-mentioned object, the lightning arrester of the present invention stores a current limiting element having a non-linear current-voltage characteristic in an insulating cylindrical body, In a lightning arrester in which an opening at both ends of a tubular body is sealed to form an airtight space in the insulating tubular body, at one opening of the insulating tubular body, when pressure is released due to an increase in internal pressure of the insulating tubular body. The invention is characterized in that a bottomed cylindrical sealing metal fitting having a rupturable thin groove formed in a predetermined shape is fitted and fixed.

The thin-walled groove of the sealing member according to the present invention includes two concentric circumferential grooves formed in the center of the bottom surface and a straight groove formed in the radial direction so as to connect the two circumferential grooves. Alternatively, it is preferable that the groove is formed of a polygonal groove formed in the central portion of the bottom surface and a diagonal groove formed so as to connect each vertex of the polygonal groove.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS.
Will be described.

As shown in FIG. 1, the lightning arrester of the present invention is a ZnO having a non-linear current-voltage characteristic which shows a low resistance to a surge voltage and a high resistance to a normal ground voltage of a transmission and distribution line. A plurality of current limiting elements 1 made of, for example, are coaxially laminated, and these current limiting elements 1 are housed in an insulating tubular body 2 made of porcelain. It has a structure in which upper and lower terminal fittings 3 and 4 electrically connected to the element 1 are sealed.

The lightning arrester shown is composed of a plurality of current limiting devices 1.
However, it is also possible to have a structure in which a cooling metal block [not shown] is interposed between the joint surfaces of the plurality of current limiting elements 1. . Further, a structure in which one current limiting element 1 is simply housed in the insulating tubular body 2 is also possible.

Specifically, the sealing structure at the openings at both ends of the insulating tubular body 2 described above is as follows. First, at the upper end opening of the insulating tubular body 2, the upper connecting fitting 6 is connected to the uppermost current limiting element 1 via the compression spring 5, and the upper connecting fitting 6 is attached to the insulating tubular body 2 by the gasket 28. Airtightly fixed,
The upper terminal fitting 3 via the compression spring 29 to the upper connecting fitting 6
Are connected and fixed to the upper end of the insulating tubular body 2 with an adhesive 7. The upper terminal fitting 3 is attached to and electrically connected to the line side electric wire, for example.

Further, in the opening at the lower end of the insulating tubular body 2, a lower connecting fitting 8 is joined to the current limiting element 1 at the lowermost end, and this lower connecting fitting 8 is a feature of the present invention via a connecting plate 9. The sealing metal fitting 10 is joined, and the sealing metal fitting 10 is attached to the gasket 24.
(See FIG. 2) via airtightly fixed to the lower end opening of the insulating tubular body 2. Further, the lower terminal fitting 4 is fixed to the lower end of the insulating tubular body 2 with an adhesive material 11, and a part of the lower terminal fitting 4 is fixed to the lower end opening of the insulating tubular body 2.
By making contact with the peripheral edge of the, electrical connection is made. The lower terminal fitting 4 has a pressure release hole 1 for releasing high-pressure gas in the insulating tubular body 2 when the sealing fitting 10 is broken.
2 are provided. The lower terminal fitting 4 is, for example,
Connected to ground.

The sealing metal fitting 10, which is a feature of the present invention, is shown in FIG.
Also, as shown in FIG. 3, it is a bottomed cylindrical metal member obtained by subjecting a metal plate such as a copper plate to a tin plating or a nickel plating, and has, for example, two concentric circumferential grooves 13 and 14 formed in the center of the bottom surface thereof. And a thin groove 16 composed of a straight groove 15 formed in the radial direction so as to connect the two circumferential grooves 13 and 14. The circumferential grooves 13 and 14 and the linear groove 15 formed in the central portion of the bottom surface have, for example, a V-shaped cross-section, but other cross-sectional shapes such as a U-shape are possible. The circumferential grooves 13 and 14 and the straight groove 15 are coated with an anticorrosive paint to improve water resistance and weather resistance.

Concretely, for example, with respect to the sealing metal fitting 10 having a diameter D of 71 mm and a thickness T [see FIG. 4]: 1 mm, the inner circumferential groove 13 has a diameter d ₁ : 20 mm and is located outside. The circumferential groove 14 has a diameter d ₂ : 40 mm, and the depth t [see FIG. 4] of the circumferential grooves 13 and 14 and the linear groove 15 may be 0.4 mm or less, as shown in FIG. It may be formed to have a thickness of about 0.2 mm. These circumferential grooves 1
The grooves 3 and 14 and the linear groove 15 are formed by, for example, pressing, and the pressing direction can be on either the front side or the back side of the bottom surface.

As described above, in the sealing metal fitting 10, the circumferential groove 1
Since the thin grooves 3 and 14 and the linear groove 15 are locally formed, the thin wall portion locally exists, so that the insulating cylindrical body 2 can be broken at the time of pressure release due to the increase of the internal pressure, and the circumferential groove 13,
The portions 17 and 18 surrounded by 14 and the linear groove 15 are removed.

In the above-mentioned sealing metal fitting 10, the circumferential groove 1
Although the thin groove 16 composed of the grooves 3 and 14 and the straight groove 15 is formed, the present invention is not limited to this, and, for example, FIG.
And a polygonal groove 19 formed in the center of the bottom surface as shown in FIG.
The thin groove 21 may be constituted by a diagonal groove 20 formed so as to connect the respective vertices of the polygonal groove 19,
The portion 22 surrounded by the polygonal groove 19 and the diagonal groove 20 comes off when the pressure is released due to the increase in the internal pressure of the insulating tubular body 2.

As shown in FIG. 2, the sealing metal fitting 10 is fitted and fixed to the opening at the lower end of the insulating tubular body 2. The concrete structure is as follows. That is, the annular projection 23 is formed at the lower end of the insulating tubular body 2, and the insulating tubular body 2 is formed.
The opening end of the sealing metal fitting 10 fitted in the lower end opening of the ring-shaped protrusion 23 is inserted through the gasket 24 such as an O-ring.
It is locked by bending inward so as to cover it.

As described above, the connecting plate 9 interposed between the lower connecting metal fitting 8 and the sealing metal fitting 10 is a circular metal plate extending radially from the central portion thereof as shown in FIG.
It has a punched shape, leaving a connecting portion 26 connected to 5. The connection plate 9 is, for example, a brass metal plate having a diameter D of 50 mm and a thickness of 1 mm, which is punched into the shape described above by press working.

Here, inside the insulating tubular body 2, the current limiting element 1 and the upper and lower connection fittings 6, 8 and The electrical connection of the current limiting element 1 is ensured to improve the electrical characteristics of the current limiting element 1.

The pressure applied by this compression spring 5 is the sealing metal 1
When directly acting on 0, since the thin grooves 16, 21 are formed in the central portion of the bottom surface of the sealing metal fitting 10, the mechanical strength of the portions 17, 18, 22 surrounded by the thin grooves 16, 21 is increased. There is a problem that the strength becomes low.

Therefore, in order to prevent the predetermined pressure applied by the compression spring 5 from directly acting on the sealing metal fitting 10, the sealing metal fitting 1
By disposing the connecting plate 9 directly above 0, and by dispersing the pressing force by the compression spring 5 by the connecting plate 9, the portions 17, 18, surrounded by the thin grooves 16, 21 of the sealing metal fitting 10,
The mechanical strength of 22 is ensured.

As shown in FIG. 2, the lower connecting fitting 8 has a cylindrical lower end contacting the sealing fitting 10 via the connecting plate 9, and a plurality of through holes 27 in the side wall surface near the lower end. Has a structure in which This through hole 27 forms a pressure transmission path at the time of pressure release due to an increase in the internal pressure of the insulating tubular body 2, and as shown by a broken line arrow in the figure, the through hole 27 is provided from the outside of the lower connecting fitting 8 through the through hole 27. The pressure is transmitted to the inside, and the internal pressure is applied to the thin grooves 16 and 2 of the sealing metal fitting 10.
The parts 17, 18 and 22 surrounded by 1 are surely added.

In this lightning arrester, normally, when an abnormal voltage due to a lightning surge or the like occurs, the current limiting element 1 has a low resistance value and instantly escapes to the ground, and when the abnormal voltage disappears, the current limiting element 1 Becomes a high resistance value and shuts off the normal ground voltage. This valve action protects the peripheral equipment of the transmission and distribution line from lightning surges and the like. On the other hand, when a surge voltage exceeding the rating such as a direct lightning strike occurs and the current limiting element 1 fails, an internal arc is generated in the airtight space of the insulating tubular body 2, and a large amount of gas is generated by the arc heat. Internal pressure rises rapidly.

The internal pressure of the insulating tubular body 2 is transmitted from the outside of the lower connecting fitting 8 to the inside thereof through the through hole 27, and when the internal pressure rises to some extent, the internal pressure of the sealing fitting 10 is increased. The thin grooves 16,21, that is, the circumferential grooves 13,14 and the linear grooves 15 (or the polygonal grooves 19 and the diagonal grooves 20) are broken, and the portions 17,18,22 surrounded by the thin grooves 16,21 are Pull out. As a result, the gas generated inside is released to the outside through the withdrawal portion of the sealing metal member 10 to prevent a sudden increase in internal pressure and prevent explosive destruction.

The pressure when the portions 17, 18 and 22 surrounded by the thin grooves 16 and 21 of the sealing metal member 10 are pulled out is about the pressure (breaking pressure) when the insulating cylindrical body 2 is broken. 1/1
0 is good, and the breaking pressure of the insulating tubular body 2 is 360 to 43.
Although it is about 0 atm (kg / cm ² ), the sealing metal fitting 1
Part 17, 18, 22 surrounded by thin grooves 16, 21 of 0
The pressure at the time of withdrawal may be set to about 22 to 46 atm (kg / cm ² ).

Even if the central portion of the bottom surface of the sealing metal fitting 10 is removed as described above, the connecting plate 9 is present immediately above the sealing metal fitting 10. Therefore, the lower connecting metal fitting 8 and the current limiting element 1 are attached to the connecting plate 9. Since the internal elements are supported, they do not fall.

In the above-described embodiment, the structure in which the current limiting element 1 is hermetically housed in the insulating cylindrical body 2 made of porcelain has been described, but the present invention is not limited to this. The current limiting element 1 is housed and arranged in an FRP insulating cylinder (not shown), and a cylindrical insulating jacket (not shown) made of an elastic polymer or EPDM is provided on the outer circumference of the insulating cylinder. It is also possible to have a worn structure.

Further, the sealing metal fitting 10 can be attached not only to the lower end opening of the insulating tubular body 2 but also to the upper end opening of the insulating tubular body 2. Further, when the sealing metal fitting 10 is attached to the lower end opening of the insulating tubular body 2, it can be applied to a lightning arrester of a type that does not include the lower terminal metal fitting 4.

[0030]

According to the present invention, a bottomed cylinder in which a thin groove that can be broken when pressure is released due to an increase in internal pressure of the insulating cylindrical body is formed in one opening of the insulating cylindrical body in a predetermined shape. Caused by internal arc when abnormal voltage due to lightning surge, etc. occurred due to surge voltage exceeding the rating such as direct lightning strike due to the occurrence of abnormal voltage due to lightning surge etc. Even if the internal pressure rises sharply due to gas, the sealing metal fittings will quickly break in the thin groove when the internal pressure rises to some extent. It is possible to prevent such damage before it occurs, and to provide a lightning arrester rich in safety.

Further, the thin groove of the sealing metal fitting can be formed by a simple process such as press working, and the cost can be reduced because a separate component for pressure release is not required. The design depth can be changed by a simple process such as die replacement, and the pressure at the time of releasing the pressure of the sealing metal fitting can be controlled by adjusting the formation pattern and depth of the thin groove.

[Brief description of drawings]

FIG. 1 is a front view including a partial cross-sectional view showing the entire structure of a lightning arrester of the present invention.

FIG. 2 is an enlarged sectional view of an essential part showing a sealing metal member attached to a lower end portion of the insulating tubular body of FIG.

FIG. 3 is a bottom view of the sealing metal fitting of FIG.

FIG. 4 is a partially enlarged cross-sectional view showing a thin groove formed in a sealing metal fitting.

FIG. 5 is a bottom view showing a sealing metal member having a thin groove of another shape.

FIG. 6 is a bottom view showing the connection plate arranged immediately above the sealing metal fitting.

[Explanation of symbols]

 1 Current Limiting Element 2 Insulation Cylindrical Body 10 Sealing Metal Fitting 13 Circumferential Groove 14 Circumferential Groove 15 Straight Groove 16 Thin Groove 19 Polygonal Groove 20 Diagonal Groove 21 Thin Groove

Claims (3)

[Claims] 1. A current limiting element having a non-linear current-voltage characteristic is housed in an insulating cylindrical body, and openings at both ends of the insulating cylindrical body are sealed to form an airtight space in the insulating cylindrical body. In the lightning arrester, a cylindrical bottomed sealing metal fitting having a predetermined shape with a thin groove rupturable at the time of pressure release due to an increase in internal pressure of the insulating tubular body is covered in one opening of the insulating tubular body. A lightning arrester characterized by being fitted and fixed. 2. The thin-walled groove of the sealing member is composed of two concentric circumferential grooves formed in the center of the bottom surface and a straight groove formed in the radial direction so as to connect the two circumferential grooves. The lightning arrester according to claim 1, wherein: 3. The thin groove of the sealing member is composed of a polygonal groove formed in a central portion of a bottom surface and a diagonal groove formed so as to connect each vertex of the polygonal groove. The lightning arrester according to claim 1.