JPH0773084B2 - Lightning arrester - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a lightning arrester for preventing explosion / scattering when a lightning surge exceeding a rating arrives at a lightning arrester installed on a distribution line or the like. is there.

2. Description of the Related Art In recent years, many lightning arresters have been installed in power distribution lines for the purpose of protecting various devices from abnormal voltage such as lightning surge.

In FIG. 5 showing the structure of the conventional lightning arrester (1),
(2) is a magnetic insulating container, which has a cylindrical shape with umbrella-shaped projections provided in multiple stages on the outer periphery. (3) (3) is a current limiting element that is stacked and housed in an insulating container, and is mainly zinc oxide, which has low resistance to surge voltage and high resistance to normal ground voltage of distribution lines. A resistor having excellent nonlinearity as a component is used. (4) and (5) are a ground side terminal and an electric wire side terminal, which seal and seal the upper and lower openings of the insulating container (2) while being electrically connected to the current limiting element.

The lightning arrester (1) is mounted in such a manner that, for example, a mounting bracket (7) fixed to a band (6) wound around an insulating container (2) is fixed to a wire arm of a utility pole, and a ground side terminal (4) is attached. Is generally grounded by a grounding wire, and the wire-side terminal (5) is electrically connected to a distribution line by a connecting wire.

In the lightning arrester (1) in the attached state, the current limiting element has a high resistance value with respect to the normal ground voltage of the distribution line, and interrupts this. However, when an abnormal voltage such as a lightning surge occurs, the current limiting element has a low resistance value and is released to the ground.
When the abnormal voltage on the line disappears, the current limiting element returns to a high resistance value and cuts off the normal ground voltage again. The above operation protects the peripheral equipment of the distribution line from lightning surges.

Problems to be Solved by the Invention When a surge voltage exceeding the rating such as direct lightning strikes the above-mentioned conventional lightning arrester (1), the current limiting element may be destroyed. In this case, the destruction mode is through fracture, creeping path, or the like, but in any case, a large amount of gas is generated by the arc heat, and the internal pressure of the lightning arrester (1) rapidly rises.

Thus, the conventional lightning arrester (1) has a sealed structure with a magnetic insulating container in consideration of the weather resistance of the current limiting element.
Therefore, if the internal pressure rises rapidly, the magnetic insulating container may explode or scatter around. This is particularly problematic when used in urban areas, since the possibility of personal injury increases.

JP-A-62-139301 discloses a lightning arrestor in which a lightning arrester element is housed in an insulating cylinder having pressure release holes and electrodes provided at both ends, and an outer insulator is molded by resin molding. .

However, in the invention of this publication, the resin is filled by the resin mold so as to fill the internal gap. Therefore, the gas pressure generated when the lightning protection element breaks acts on the insulating cylinder integrated with the filling resin, and the insulating cylinder may be broken or scattered before the resin in the pressure release hole portion is broken. Therefore, although the reinforcing ring is provided on the insulating cylinder, there is a problem that the cost becomes high due to the complicated structure.

Means for Solving the Problems The present invention has been made in view of the above conventional problems, and means for solving the problems include an insulating cylinder containing a current limiting element in a state where a space is formed inside. In the lightning arrester including a pair of electrodes fixed to the openings of both ends of the insulating cylinder while being electrically connected to the current limiting element, and a sheath insulator covering the outer circumference of the insulating cylinder, Occurs when the current limiting element is broken by forming a pressure hole or slit and forming the jacket insulator by a tubular elastic insulator that is fitted and fixed to the outer periphery of the insulating cylinder from the outside. The gas pressure to be applied is directly applied to the outer insulator through the internal space and the pressure release hole or slit of the insulating cylinder.

Action When the current limiting element is destroyed and a large amount of gas is generated, the gas pressure passes through the pressure releasing hole or slit and directly acts on the jacket insulator. Then, it is released into the atmosphere by breaking a part of the elastic outer jacket insulator or through a gap between the outer jacket insulator and an insulating cylinder formed by extending the outer jacket. Therefore, explosion and scattering of the lightning arrester is prevented.

Examples The present invention will be described below with reference to Examples.

In the lightning arrester (11) according to one embodiment of the present invention shown in FIG. 1, (12) is an insulating cylinder, which is formed by molding an insulating material such as reinforced plastic (FPR) into a cylindrical shape, as shown in FIG. The circular pressure relief holes (13) (13) ... have been opened. (14) (1
4) is a current limiting element that is housed in a stacked manner inside the insulating cylinder (12), and is mainly composed of zinc oxide, etc., which has a low resistance value against lightning surge and cuts off the normal ground voltage of the distribution line. A resistor having a cylindrical shape is used.
(15) (15) is a pair of electrodes. A male screw (15b) is projected and formed on one surface of a base (15a) having the same outer diameter as that of the insulating cylinder (12), and the insulating cylinder (12) is formed on the other surface. ) (15)
c) is formed stepwise. Numerals (16), (16) ... Are positioning pins for fixing the electrodes (15), (15) to the insulating cylinder (12). Reference numeral (17) is a compression spring, (18) is a spring receiver, and (19) is a strip-shaped conductor plate fixed by being hooked on both ends of the compression spring (17).
A reliable electrical connection is made between 5) and the current limiting element (14) (14). (20) (20) is a plain washer, (21) (21) is a nut, and these connect the male wires (15b) (15b) of the electrode with a connecting wire (not shown) extending from the distribution line and the ground conductor. It Reference numeral (22) is a cylindrical jacket insulator having an umbrella-shaped protrusion (22a) (22a) ...
And the adhesive (2) so as to cover the outer periphery of the electrode base (15a).
It is fixed by 3). The material of the jacket insulator (22) may be an insulating material having elasticity, and for example, an elastic resin material such as silicone rubber, ethylene rubber, propylene rubber, EPR, or elastic epoxy resin can be used. In particular, if you use a tube-shaped product that has the property of shrinking when exposed to the outside air or the property of shrinking when heated, the work of fitting and fixing to the insulating tube (12) can be done easily, which is convenient for production. Is.

Next, an example of assembling the lightning arrester (11) will be described.

First, one electrode (15) is fitted into the insulating cylinder (12), and the positioning pin (16) is inserted into the pin holes (12a) (15d) provided at the corresponding positions of the insulating cylinder (12) and the electrode (15). ) And fix it. Next, the current limiting element (14) (14), the spring receiver (18), the compression spring (17) to which the strip-shaped conductor plate (19) is fixed are inserted, the other electrode (15) is fitted, and the positioning pin Insert (16) in the same manner and assemble as shown in FIG. Next, an outer jacket insulator (22) made of a silicone-based heat-shrinkable tube is prepared, an adhesive (23) is applied to the inner surface of the outer jacket insulator (22), and then the insulating cylinder (12) and Fit so as to cover the outer periphery of the base portion (15a) of the electrode. Finally, by putting it in a heating furnace and heating it under a predetermined temperature condition for a predetermined time, the outer cover insulator (22) is thermally contracted, and at the same time, the adhesive agent (23) is cured and the outer periphery of the insulating cylinder (12) is covered. It is closely attached and fixed.

As described above, by connecting the assembled arrester (11) between the distribution line and the ground conductor, the built-in current limiting element (14) (1
By the function of 4), the normal ground voltage of the distribution line is cut off,
The lightning surge can be released to the ground and the peripheral equipment of the distribution line can be protected from the lightning surge. When a surge voltage exceeding the rating of the arrester arrives and the current limiting element (14) (14) is destroyed and the internal pressure of the arrester (11) suddenly increases, the insulating cylinder (12) This gas pressure directly acts on the jacket insulator (22) through the pressure release hole (13) provided. For this reason, a hole is opened in the corresponding portion of the jacket insulator (22), or the jacket insulator (22) is peeled outward to form a gap with the insulating cylinder (12). Then, gas is ejected from the holes or the gap toward the atmosphere. Therefore, the internal pressure is reduced and the explosion or scattering of the lightning arrester (11) is prevented.

The pressure release hole formed in the insulating cylinder (12) is not limited to the circular shape shown in FIG. 2, but may be an arbitrary shape such as an ellipse. In short, this pressure relief hole is
As long as it has a size that can directly act on the jacket insulator (22) without significantly deteriorating the mechanical strength of the above, and without weakening the gas pressure that is suddenly generated inside, such as the fourth example. It may be a slit hole (24) as shown in the figure. In the embodiment shown in FIG. 4, the pressure release hole is a slit hole (24).
2 is exactly the same as that shown in FIG.

Effect of the Invention According to the present invention, a pressure release hole is formed in an insulating cylinder that holds a current limiting element, so that gas pressure generated inside directly acts on an outer insulator made of an elastic material, and a local breakage of the outer insulator causes local damage. By forming a pressure release path to release gas pressure to the atmosphere and lower the internal pressure, it is possible to prevent the lightning arrester from exploding and scattering. Therefore, the safety of this type of arrester can be improved, and maintenance and management of the distribution line and the like can be performed more easily than before. In particular, the present invention obtains an effective valve action by a simple combination of selecting the material of the jacket insulator as an elastic material and forming a hole in the insulating cylinder, so that the structure is extremely simple and the manufacturing cost is low. It has the advantage that it can.

[Brief description of drawings]

FIG. 1 is a front view of a lightning arrester which is an embodiment of the present invention. 2 and 3 are front views showing the lightning arrester shown in FIG. 1 with the outer insulation removed, and FIG. 3 shows the left half in cross section. FIG. 4 is a front view showing the shape of the insulating cylinder of another embodiment of the present invention. FIG. 5 is a sectional view showing a conventional lightning arrester. (11) …… Lightning arrester, (12) …… Insulation cylinder, (13) (24)…
… Pressure release hole, (14) …… Current limiting element, (15) …… Electrode, (2
2) …… Insulator insulation, (23) …… Adhesive.

Claims (1)

[Claims] 1. An insulating cylinder containing a current limiting element in a state where a space is formed inside, a pair of electrodes fixed to openings of both ends of the insulating cylinder electrically connected to the current limiting element, In a lightning arrester including an outer jacket covering the outer circumference of a cylinder, a pressure releasing hole or a slit is formed in the outer cylinder, and the outer jacket is fixed by fitting the outer jacket on the outer circumference of the outer cylinder. It is composed of a cylindrical elastic insulating material, and the gas pressure generated when the current limiting element is broken is directly applied to the outer insulator through the internal space and the pressure release hole or slit of the insulating cylinder. Lightning arrester characterized by doing so.