JPH0963807A - Arrester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce weight of the whole of an arrester and assembling manhours, in an arrester which dispenses with an upper and a lower bursting devices and bursts gas from the side surface. SOLUTION: A circular arc insulating bar 3 is fixed on a lower electrode 2, ZnO elements 4 are stacked in the insulating bar 3, and an electrode 1 is mounted above the ZnO elements 4. The electrode 1 is fixed to the tip part of the circular arc type insulating bar 3 with a screw 13 or the like. The part except the outer end surfaces of the upper and the lower electrodes 1, 2 are covered with a rubber jacket 14, and caps 8, 9 are mounted on both of the electrodes. Parts of ring trenches 1a, 2a arranged on the electrodes are compressively molded with a roll, from the outside of the caps, built in a unified body and hermetically sealed. Moisture caused by water vapor penetration through the rubber jacket is absorbed with desiccant 12.

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 having a pressure release function for preventing explosion / scattering when the internal pressure of the lightning arrester rises.

[0002]

2. Description of the Related Art A current lightning arrester is basically a sintered body containing zinc oxide as a characteristic element (hereinafter referred to as ZnO).
Element), an insulating container for hermetically housing the ZnO element, a pressure release mechanism and an electrode. This lightning arrester is installed in a power transmission or distribution line or a protective device, and when an abnormal voltage such as a lightning surge occurs, the ZnO element shows a low resistance value and releases the abnormal voltage to the ground, and the abnormal voltage from the line is generated. When it disappears, the ZnO element returns to a high resistance value and maintains the normal commercial frequency ground voltage.

A lightning arrester protects a protected line or equipment from an abnormal voltage by such an action.
When a non-responsible load such as a direct lightning strike is applied, the lightning arrester causes internal flashing or piercing destruction, and an arc is generated inside. The arc energy expands the internal gas, and at the same time, gas is generated from the internal elements such as the ZnO element to increase the internal pressure. Also, the inside of the insulating container is rapidly heated. If this internal flash state continues, the internal pressure rises depending on the arc energy, which may cause explosion and scattering. Furthermore, at the time of heat destruction of the latter, if the inside is in a high pressure state, the phenomenon of explosion scattering occurs as in the former case.

Therefore, in general, a lightning arrester employs a pressure release means for releasing the increased internal pressure into the atmosphere and lowering it in order to prevent explosion and scattering.

Various proposals have been made for this pressure releasing means, but the following means are known.

(1) A ZnO element is housed in a pressure-resistant insulating cylinder made of a material such as reinforced plastic (FRP) having excellent mechanical strength, heat resistance, and pressure resistance, and thin pressure-release plates are provided on the upper and lower sides of the ZnO element. A means of breaking internal pressure and releasing internal pressure to the outside.

(2) Further, as disclosed in Japanese Patent Laid-Open No. 62-139301, pressure release holes are provided in a withstand voltage insulating cylinder for accommodating a ZnO element, and between the withstand voltage insulating tube and the ZnO element. When a high temperature and high pressure arc is generated inside the lightning arrester by providing a rubber mold on the outer periphery of the pressure resistant insulation tube, the coating near the pressure release hole of the pressure insulation insulation tube and a part of the rubber mold are softened or melted and destroyed. A means to forcibly form an arc pressure release path that leads to the outside by being scattered by high-pressure gas.

(3) Further, as disclosed in Japanese Patent Application Laid-Open No. 2-203501, a heat-resistant insulating cylinder for accommodating the ZnO element is formed of an elastic insulating material, and a plurality of axial slits are formed on the cylindrical surface. -Shaped pressure release hole is provided, the outer periphery of this heat-resistant insulating cylinder is covered with a heat-shrinkable tube, and the gas pressure generated inside is directly acted on the heat-shrinkable tube through the pressure release hole to locally destroy it. It is known that a pressure relief path is formed by means of which the gas is released into the atmosphere to lower the internal pressure and prevent the lightning arrester from exploding and scattering.

[0009]

In the means described in the above (1), since the pressure release plates must be installed above and below the insulating cylinder for accommodating the ZnO element, the total length of the arrester becomes longer, Since it is necessary to coordinate the insulation with the existing arc horn of the insulator series like the power transmission arrester, there is a restriction on the external gap length of the power transmission arrester itself, and it is not suitable when the shorter overall length is desirable.

Further, in both the means described in (2) and (3) above, since pressure release holes are provided in the pressure-resistant or heat-resistant insulating cylinder for accommodating the ZnO element to release pressure, there is no need for a pressure release plate. Although the total length of the arrester is shortened, however, it requires machining to provide a pressure relief hole, and since it has a pressure relief hole, it absorbs moisture through the rubber jacket, so this rubber material is transparent. It is necessary to use a material with a high coefficient of moisture, but it is not suitable for selecting a material with a high coefficient of moisture permeability such as silicone rubber.

Further, if there is a space such as a pressure release hole, there is a problem that the absorbed moisture condenses in the space and affects the characteristics of the arrester.

In view of the above points, it is an object of the present invention to provide a lightning arrester that does not have a pressure release plate or a pressure release hole, has a short overall length, and does not cause dew condensation.

[0013]

Means for Solving the Problems In the present invention, the means for solving the above problems is one or a plurality of ZnO.
The elements are stacked, electrodes having circumferential grooves are arranged above and below the elements to press the ZnO element and the electrodes under pressure, and the upper and lower electrodes are fixed by a plurality of arc-shaped insulating bars. The insulating bar and the outer peripheral side of the upper and lower electrodes are covered with a rubber outer cover, and the upper and lower electrodes are covered with caps.
A circumferential groove portion of the electrode is roll-formed from the outside of the cap to integrally seal the electrode, the rubber outer cover and the cap in an airtight manner.

Zn of one or both of the upper and lower electrodes
A desiccant-accommodating hole is provided on the surface side facing the O element, and the desiccant is accommodated in the accommodating hole to absorb the moisture absorbed from the rubber casing and maintain the characteristics of the arrester for a long period of time.
A plurality of fitting grooves cut in the axial direction from the inner end surface side are provided on the outer sides of both the upper and lower electrodes, and arc-shaped insulating bars are fitted into the fitting grooves and fixed by fixing means. As another embodiment of the fixing means for fixing the insulating bar to the electrode in order to reduce the efficiency and weight of the assembling work, a circumferential groove is formed in the protrusion between the insulating bar and the fitting groove of the electrode. It is proposed that the fixing ring be fitted into and be roll-formed and fixed.

As described above, since the pressure-resistant or heat-resistant insulating cylinder for accommodating the ZnO element is not used, and the ZnO element is accommodated by simply providing a plurality of arc-shaped insulating bars, the weight of the entire lightning arrestor becomes extremely small, and , This arc-shaped insulation bar
It can be used in place of the O element assembly jig, the number of assembly steps can be reduced, and the desiccant can be stored in the electrode, so even if moisture is absorbed through the rubber outer cover, the moisture is absorbed and water droplets are condensed. There is nothing to do. Therefore, the lightning arrester can be maintained for a long period of time without impairing its characteristics.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In the lightning arrester of the present invention, the upper and lower pressure relief devices are removed so that the gas pressure is released from the side face to shorten the overall length of the lightning arrester and further accommodate the ZnO element. The feature is that the weight of the entire arrester is reduced by using an insulating bar instead of using an insulating cylinder, and the number of assembling steps can be reduced.

Embodiments will be described below with reference to the drawings. 1A and 1B are explanatory views of an embodiment of the present invention. FIG. 1A is a vertical front view, and FIG. 1B is a sectional view taken along the line AA of FIG. FIG. 2 is a perspective view of the electrodes. In these figures, 1 and 2 are upper and lower electrodes, which have substantially the same structure. This structure will be described in detail with respect to the lower electrode 2 shown in FIG. That is, the electrode 2 is provided with a ring-shaped groove 2a in a part of the outer circumference.
The electrodes 1 and 2 are axially cut from the inner end surface for fitting a desiccant storage hole 2b for storing a desiccant in the center of the end surfaces (inner end surfaces) facing each other and an arc-shaped insulating bar 3 described later. A plurality of (3 in the example in the figure) fitting grooves 2c, a projection 2d between the fitting grooves 2c, a communication groove 2e that is cut on the inner end surface of the projection 2d and communicates outside from the desiccant accommodating hole 2b, and an insulation Bar 3
Has a screw hole 2f for fixing. Although the lower electrode 2 has been described above, the upper electrode 1 has the same structure.

The bottom surface of the fitting groove 2c has an arc shape.
The radius of the arc is formed to be substantially equal to the radius of the ZnO element, and the arc of the arc-shaped insulating bar 3 fitted in the fitting groove 2c is aligned with the arc of the fitting groove 2c.

Reference numeral 4 denotes a sintered body containing zinc oxide as a main component (hereinafter, referred to as ZnO element) as a characteristic element of the arrester, and one or more stacked bodies are used according to the rated voltage of the arrester. Reference numeral 5 is a pressure contact spring, which is the Zn arrayed between the electrodes 1 and 2.
A pressure contact force is applied between the O elements and between the ZnO element and the electrodes.

6 and 6'are desiccant receiving holes 1b and 2
The lid 6b also serves as a spring receiver. Reference numeral 7 denotes a spring bearing, and the pressure contact spring 5 is mounted between the lids 6 and 7 which also serve as the spring bearing.

The pressure contact spring 5 is not limited to the leaf spring as shown in the figure, but may be a coil spring.

8 and 9 are caps, 10 and 11
Is the upper and lower terminals provided on this cap,
Reference numeral 12 denotes a desiccant contained in the desiccant accommodating hole 2b, 14 denotes a rubber jacket, and 15 denotes a space between arc-shaped insulating bars.

The arc-shaped insulating bar 3 includes upper and lower electrodes 1 and 2.
It is fitted in the fitting groove 2c of No. 2 and is fixed by a screw 13 (or a pin) or the like.

Next, the assembly procedure will be described. The assembly procedure is not uniform, but one of them will be explained.

First, the arc-shaped insulating bar 3 having a predesigned length is fitted into the fitting groove 2c of the lower electrode 2 and the screw 13 is screwed into the screw hole 2f of the electrode 2 so that the electrode 2 is fitted. Install.

Next, the desiccant 12 is accommodated in the desiccant accommodating hole 2b of the electrode 2 (may be accommodated in advance), and the lid 6'is surrounded by a plurality of arc-shaped insulating bars 3. , The required number of Z
The upper electrode 1 accommodating the nO element 4, the spring receiver 7, the pressure contact spring 5, the lid 6, and the desiccant 12 is stacked in this order, and the upper end portion of the arc-shaped insulating bar 3 is fitted into the fitting groove 1c of the upper electrode 1. Then, the arc-shaped insulating bar 3 is fixed to the electrode 1 with the screw 13 while the press-contact spring 5 is compressed.

Next, the outer side surfaces of the upper and lower electrodes 1 and 2 are left, and the entire side surfaces are covered with a rubber jacket 14 to form the upper and lower electrodes 1.
And 2 are covered with caps 8 and 9, respectively, and the ring-shaped groove 2a provided in each electrode is compression-molded with a roll,
The lightning arrester is completed by pressure-bonding in the groove and air-tightly sealing it with the roll forming part 16 in which the electrode, the rubber outer cover and the cap are integrated. As a result of this assembly, the space 15 between the arc-shaped insulating bars 3 shown in FIG.
The moisture desiccated in the lightning arrester is absorbed by the desiccant 12 accommodated in the desiccant accommodating hole 2b.

In the above embodiment, the connecting means such as a screw or a pin is used for fixing the upper and lower electrodes 1 and 2 and the arc-shaped insulating bar 3, but FIG. The means for fixing with a ring for use is shown.

This fixing means, as shown in FIG.
The lower electrode 1 and 2 (FIG. 4 shows only the lower electrode 2 but the upper electrode 1 has the same structure), the protrusion 2d and the arc-shaped insulating bar, the fixing ring insertion grooves 20 and 21 (FIG. 4). ) Is cut, the fixing ring 22 is fitted into the grooves 20 and 21, and compression molding is performed by a roll.
Is fixed to the electrode 2 (1).

Since the present invention is constructed in this manner, when a high temperature, high pressure arc is generated inside the lightning arrestor and the internal pressure rises, the rubber outer cover is partially torn by the high pressure gas, and from the rift. The internal pressure is released and the explosion and scattering of the container is prevented.

At this time, the upper and lower electrodes 1 and 2 and the arc-shaped insulating bar 3 must be fixed (joined) with each other until the side surface of the rubber jacket is torn by the internal pressure. However, this bonding strength is sufficiently maintained by the arc-shaped insulating bar 3, the electrode 1 (2) and their fixing means.

Further, although the electrode and the rubber outer cover have an airtight structure in which they are integrated with each other through a cap, the rubber outer cover absorbs moisture when used for a long time even if it has a high moisture permeability coefficient. However, it is possible that moisture condenses in the space.

However, in the case of the present invention, the electrode is provided with a desiccant accommodation hole, and the desiccant accommodation hole is suitable for the moisture permeation amount of 30 years or more with respect to the moisture permeation from the rubber jacket. Since it contains the water, the problem due to the condensation of water droplets is solved.

[0034]

Since the present invention is configured as described above, it has the following effects.

(1) The total length can be shortened by removing the upper and lower pressure release devices and discharging gas from the side surface.

(2) Since it is not necessary to use an insulating cylinder having a high cost, the cost can be reduced.

(3) Complete airtightness can be maintained by roll-forming the electrode and the rubber jacket with the cap interposed therebetween.

(4) Since the insulating cylinder is not used, the weight can be reduced to about 1/3 of the conventional weight.

(5) When assembling the arrester, the arc-shaped insulating bar can be used as a jig for assembling the ZnO element.
Assembly man-hours are reduced.

(6) It can be applied to any arrester for power distribution, power generation and transformation, power transmission lines, equipment protection, etc.

[Brief description of drawings]

FIG. 1 is an explanatory view of the present invention, (A) a vertical sectional front view, and (B) A.
-A sectional arrow view.

FIG. 2 is a perspective view of an electrode according to the embodiment of the present invention.

FIG. 3 is an explanatory view of the fixing means of the present invention.

FIG. 4 is a perspective view of an essential part of the arc-shaped insulating bar used in FIG.

[Explanation of symbols]

 1, 2 ... Electrode 3 ... Arc-shaped insulating bar 4 ... ZnO element 5 ... Pressing spring 6,6 '... Lid 7 ... Spring receiver 8,9 ... Cap 10, 11 ... Terminal 12 ... Desiccant 13 ... Screw 14 ... Outside rubber Numeral 15 ... Space 16 ... Roll forming part 20, 21 ... Fixing ring insertion groove 22 ... Fixing ring

Claims (4)

[Claims] 1. A stack of one or a plurality of ZnO elements, and an electrode having a circumferential groove above and below the ZnO element is arranged so that the ZnO elements and the electrodes are pressure-contacted with each other, and the upper and lower electrodes. A plurality of arc-shaped insulating bars are fixed between the insulating bars, and the insulating bars and the outer peripheral sides of the upper and lower electrodes are covered with a rubber jacket. Further, the upper and lower electrodes are covered with a cap, and the electrodes are applied from the outside of the cap. A lightning arrester, characterized in that the electrode, the rubber cover, and the cap are integrally formed to be hermetically sealed by roll-forming the circumferential groove portion of the. 2. The lightning arrester according to claim 1, wherein a desiccant storage hole is provided on the inner end surface side of one or both of the upper and lower electrodes, and the desiccant is stored in the desiccant storage hole. 3. A plurality of fitting grooves formed in the axial direction from the inner end face side are provided outside the upper and lower electrodes, and arc-shaped insulating bars are fitted into the fitting grooves and fixed by fixing means. The lightning arrester according to claim 1 or 2, wherein 4. The fixing means for fixing the insulating bar to the electrode comprises:
3. A groove in the circumferential direction is formed on the protrusion between the insulating bar and the fitting groove of the electrode, and a fixing ring is fitted into the groove and roll-molded to fix it. Or the lightning arrester described in 3.