JP2591068B2 - Surge arrester - Google Patents

Description

Description: BACKGROUND OF THE INVENTION A. Field of the Invention The present invention relates to a lightning arrester using a zinc oxide element, and more particularly to a lightning arrester in which an element group is integrally supported.

B SUMMARY OF THE INVENTION The present invention provides a lightning arrester provided with electrodes at both ends of an element group in which zinc oxide elements are stacked, and sprayed electrodes on both end faces of each element. Adhering the sprayed electrode and the electrode at the end of the element group with a conductive adhesive as necessary to integrate the element group, stabilizing the characteristics of the lightning arrester and simplifying and miniaturizing the structure It is.

C Prior Art A surge arrester using a zinc oxide element is constructed by stacking and storing a plurality of elements made of a zinc oxide element inside an insulator tube and closing both ends of the insulator tube, each of which is adapted to the rated voltage of the surge arrester. It is formed in a disk shape so that it can be set to any length, it is stacked in the axial direction inside the insulator tube, electrodes are provided at both ends, the electrodes at both ends are pressed and housed via insulating rods, and In general, when a short circuit occurs, a release means for releasing generated gas is provided at at least one end of the insulator tube.

Hereinafter, a conventional lightning arrester will be described in detail with reference to FIGS. 5, 6, and 7. FIG.

FIG. 5 is a front view of the porcelain pipe cut longitudinally, and FIG. 6 is a Y view of FIG.
FIG. 7 is a partially enlarged view of a portion C in FIG. 5, and FIG. 7 is an enlarged view of a portion of FIG. 5. In these figures, reference numeral 1 denotes an insulator, and a plurality of elements 2a are provided in the insulator 1 in the axial direction. Stacked and stored. On both end surfaces of the element 2a, metal electrodes 2b sprayed with, for example, aluminum, copper, or the like are provided in order to maintain electrical characteristics when the elements 2a are stacked. A support plate made of an insulating material is provided at one end of the element group 2 via the upper electrode 3 and at the other end via the lower electrode 4.
5a and 5b are provided in contact with the inner wall of the insulator tube 1 at a plurality of places. The support plates 5a and 5b are formed in a substantially triangular shape as shown in FIG. 6, and each of the support plates 5a and 5b has a mounting hole through which the insulating rod 6 passes. In order to absorb a variation in the diameter dimension generated in the manufacturing process of the element 2a on the outer periphery, the element group 2 is separated from the element group 2 by an equal distance with some allowance.
The insulating rod 6 for supporting the shaft in the axial direction of the insulator tube 1
And so on.

On the side of the support plate 5a, a spring 8 which presses the inside of the insulator tube 1 in the axial direction between the upper electrode 3 protruding through the support plate 5a and the end of the insulator tube 1 is elastically inserted. On the side,
A tubular distance 9 is provided between the lower electrode 4 protruding through the support plate 5b and the end of the insulator tube 1 to ensure a predetermined distance in the axial direction inside the insulator tube 1.

Openings at both ends of the porcelain tube 1 are provided with pressure relief plates for releasing gas generated from the element group 2 in the event of a short circuit, thereby sealing the inside of the porcelain tube 1.

D Problems to be Solved by the Invention In such a conventional lightning arrester, insulating rods 6 equidistantly arranged in the vicinity of the outer circumference of the element group 2 are attached through support plates 5a, 5b provided at both ends of the element group 2. With the configuration, the number of parts for supporting the element group 2 is increased, so that the structure is complicated, so that there is a problem that a large number of processing and assembling steps are required, and a processing and assembling error is apt to occur.

Further, since a distance for attaching the insulating rod 6 is required between the outer periphery of the element group 2 and the inner wall of the insulator tube 1,
It was difficult to make the insulator tube 1 smaller by bringing the inner wall of the insulator tube 1 closer to the outer periphery of the element group 2.

Further, between the element group 2 and the insulating rod 6, the element 2a
The element 2a is not constrained in the radial direction of the insulator tube 1 because there is a gap in consideration of the variation in the manufacturing error of the device 2a. However, there is a problem that the individual pieces are shifted in the radial direction of the insulator tube 1 individually.

For this reason, when the element 2a is displaced, the metal electrode 2b sprayed on both end faces of the element 2a is worn by the friction between the elements 2a, the surface of the electrode 2b is worn, and the fine powder of the electrode 2b material falls, There has been a problem that the electrical characteristics of the device are reduced.

Further, since the elements 2a having the spray electrodes 2b attached to both end surfaces thereof are merely stacked in the axial direction of the porcelain tube 1 and pressed against each other by the spring 8, when the portion C in FIG. 5 is enlarged, as shown in FIG. The surface has irregularities, and the sprayed electrodes 2b are in point contact with each other, so that when an impulse current exceeding 40 KA (approximately 1 to 1.5 KA / Cm ² ) is applied, a minute discharge occurs at the contact area and micro arc is disadvantageously degrade components of these insulating medium when particularly filled porcelain tube 1 inside the SF ₆ gas, or an insulating oil.

Further, since the spray electrode 2b itself is melted by the minute discharge, there is a problem that the electrical characteristics of the element 2a deteriorate.

E Means for Solving the Problems The lightning arrester of the present invention is a lightning arrester having a zinc oxide element stacked inside a porcelain tube, electrodes provided at both ends thereof and housed, and sprayed electrodes formed by metal spraying on both end surfaces of each element. The surface of the sprayed electrode of the element is made to have a roughness of 20 to 120 S, and at least the portions between the sprayed electrodes are bonded to each other with a conductive adhesive to form an integral structure.

F action In the surge arrester of the present invention, the roughness of the sprayed electrode surface of the element is set to 20 to 120S, and the sprayed electrodes are bonded with a conductive adhesive to integrate the element group, so that the adhesive strength is high,
In addition, the structure is simplified, and fine discharge of the contact portion due to the unevenness of the sprayed electrode surface does not occur. Also, there is no displacement due to vibration and impact of transport, so that fine powder on the electrode surface does not occur. It does not cause deterioration of electrical characteristics.

G Embodiment An arrester according to the present invention will be described in detail with reference to an embodiment shown in FIGS. 1, 2 and 3. FIG. In FIGS. 1 to 3, the same parts as those in FIGS. 5 to 7 described above or corresponding parts are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 1 is a front view of a porcelain pipe cut longitudinally, and FIG.
3 is a cross-sectional view taken along an X-ray, and FIG. 3 is a partially enlarged view of the portion A in FIG. 1. In these figures, for example, silver, copper, aluminum, graphite, etc. A conductive adhesive 11 made of a fine powder of a conductive material such as an organic binder or an inorganic binder such as an epoxy resin is applied to bond the sprayed electrodes 2b to each other.

An upper electrode is connected to one end of the integrated element group 12.
A lower electrode 13 is provided on the other end by bonding with the conductive adhesive 11 described above. The support fitting 15 and the lower electrode 14 fitted to the upper electrode 13 are fitted respectively to both ends of the porcelain tube 1 to support and fix the element group 12 in the axial direction of the porcelain tube 1.

Next, various discharge tolerance tests were performed on the lightning arrester based on the embodiment of the present invention described above and the lightning arrester in which the conductive adhesive 11 of the present invention was directly applied between the elements 2a, and the results were shown in Table 1 below. Show.

In Table 1, as shown in FIG. 3, the test device is a sprayed electrode 2b (material is aluminum, thickness = approximately) of the element 2a of the present invention.
100μm, surface roughness = about 50S) Conductive adhesive 11 between
As shown in Fig. 4, the lightning arrester and test device coated with
1 shows a lightning arrester in which a conductive adhesive 11 according to the present invention is applied directly between each other. The thickness of the conductive adhesive 11 is about 15
About 0 μm is applied. The size of the element 2a is 65 mm in outer diameter and 25 mm in thickness in both the test device and the test device.

As test current, wave front length = 8μS, wave tail length = 20μS
10K, and wave front length = 4μS, wave tail length = 10μS, 100K
The two types of current A are supplied.

In Table 1 above, “good” means that when each test current was applied for the number of times of the test, each test current endured without any abnormality.
It shows that there is no abnormality even when a torsional torque of 100 kg · Cm is applied to the element 2a. In addition, a failure indicates a case where the above condition is not satisfied, or a case where adhesion between the elements 2a has been peeled off during energization.

From the results of the various discharge withstand tests shown in Table 1, the test device, which is the lightning arrester of the present invention, has a conductive adhesive directly between the elements 2a.
Compared to the test device which is a lightning arrester coated with 11, it was proved that the test device formed by applying and bonding the conductive adhesive 11 between the sprayed electrodes 2b had better electrical characteristics.

However, when an adhesive is used, the bonding strength is generally closely related to the surface roughness of the bonding surface, and the higher the surface of the bonding surface is, the higher the bonding strength is.

Therefore, also in the case of the test device, both surfaces of the element 2a are blasted in advance to make the surface of the device 2a approximately 20S rough and then the conductive adhesive 11 is applied and bonded. It is considered that the difference in the adhesive strength in the above-mentioned discharge withstand test influenced the smoothness as compared with the roughness of about 50S.

Therefore, it is considered that if the surface roughness of the element 2a is further roughened, the bonding strength will be increased. However, since the element 2a is ceramic, it is very hard, and the roughening of the surface requires considerable equipment and man-hours.

In addition, when the surface of the element 2a is roughened, the distribution of the operation start voltage V ₁ mA is deteriorated, which causes a current concentration at the time of a discharge withstand voltage test and causes a decrease in electric characteristics such as a decrease in discharge withstand voltage. .

Therefore, for the above reasons, there are various problems in roughening the surface of the element 2a.For this reason, the use of the sprayed electrode 2b whose surface roughness can be easily changed by the spraying condition ultimately results in a higher adhesive strength. Become. Then, next, the results of various discharge withstand tests performed by changing the surface roughness of the sprayed electrode 2b of the element 2a are shown in Table 2 below.

In Table 2, as a test device, the test was performed under the same conditions except for the surface roughness of the sprayed electrode 2b of the element 2a as in the discharge withstand test in Table 1 described above.

In Table 2 above, good or bad indicates the same result as in Table 1.

Based on the results of the various discharge withstand tests shown in Table 2, the current value of 8 / 20μS-10KA is 20
It was proved that the surface roughness of the sprayed electrode 2b satisfying this requirement was 20 to 120S.

In Table 2, the surface roughness of the sprayed electrode 2b was 20
When the value was less than S, as described above, the surface of the electrode 2b became smooth, so that the adhesive strength was reduced. And, when the surface roughness exceeds 120S, the surface roughness becomes rough, and as a result, the sprayed electrode 2b must be thickened. This was because a large thermal strain was generated and the adhesive strength of the sprayed electrode 2b itself was reduced.

Here, the conductive adhesive 11 for bonding the sprayed electrodes 2b to each other will be described below.

In most cases, the conductive adhesive 11 contains an organic binder.When the organic binder is supplied with electric current, it rapidly generates heat and evaporates to reduce the adhesive strength. It was confirmed by conducting a test that a certain thickness was required.

The thickness of the conductive adhesive 11 was required to be at least 10 μm or more in dimension B as shown in FIG.

In addition, a test was conducted by changing the conductivity of the conductive adhesive 11, and it was confirmed that there was no practical problem if the conductivity was 0.1 Ω · Cm or less.

H Effect of the Invention The lightning arrester of the present invention has a structure in which the roughness of the sprayed electrode surface of the element is set to 20 to 120S and the sprayed electrodes are bonded to each other with a conductive adhesive to integrate the element group. ,
A conventional support plate provided at both ends of the element group for supporting the element group, and an insulating rod for supporting the element group in the axial direction at a distance equidistant from the outer periphery of the element group on the support plate. A simple structure is not required, and the number of parts is reduced due to the simplification of the structure, so that the number of processing and assembling steps is reduced, and errors in processing and assembling can be extremely reduced.

In addition, the distance between the outer periphery of the element group and the inner wall of the insulator tube is not required as in the conventional case, so the inner wall of the insulator tube is brought closer to the outer periphery of the element group to reduce the diameter of the insulator tube and reduce the shape of the insulator tube. Can be miniaturized.

Therefore, since the distance between the element group and the inner wall of the insulator tube is reduced, the heat radiation characteristic of dissipating the heat generated in the element group to the outside of the insulator tube can be improved.

Furthermore, when the lightning arrester is moved due to the integration of the element group, especially during transportation, the element does not shift in the radial direction of the insulator tube due to vibration, impact, etc. In this case, the friction between the sprayed electrodes of the element does not cause the wear of the electrode surface and the drop of fine powder of the electrode material to cause the deterioration of the electrical characteristics.

In addition, since the conductive adhesive is applied between the spray electrodes of the element, not only the point contact due to the unevenness of the roughness of the spray electrode surface is eliminated, but also the contact by the conductive material in the conductive adhesive is added. However, when an impulse current is applied, the occurrence of arcs due to the micro-discharge at the contact portion between the conventional spraying electrodes is suppressed, especially when the insulator tube is filled with SF ₆ gas or insulating oil. There is no longer any decomposition of the components of the insulating medium.

Further, since the occurrence of arc due to the minute discharge at the contact portion between the sprayed electrodes is suppressed, the sprayed electrodes themselves are not damaged, and therefore, the electric characteristics of the element are not reduced.

Furthermore, in the case of the thermal spray electrode, the particles can be made large when spraying, so that the surface roughness can be increased. Therefore, the adhesive strength of the thermal spray electrode itself is increased, and the electric characteristics (particularly, discharge capability) of the element are improved. be able to.

In addition, when the particles to be sprayed are enlarged, the spraying time can be shortened, and the productivity of the spraying electrode attaching operation can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view showing one embodiment of an arrester of the present invention,
2 is a cross-sectional plan view taken along the line XX of FIG. 1, FIG. 3 is an enlarged view of a portion A of FIG. 1, and FIG. 4 is a partially enlarged view of applying a conductive adhesive directly between the elements. FIG. 5 is a vertical sectional front view of the conventional lightning arrester, FIG. 6 is a cross-sectional plan view taken along the line YY of FIG. 5, and FIG. 7 is an enlarged view of a portion C of FIG. 1 ... insulator tube, 2a ... element, 2b ... sprayed electrode, 11 ... conductive adhesive, 12 ... element group, 13 ... upper electrode, 14 ... lower electrode.

Claims (1)

(57) [Claims] 1. A lightning arrester having a zinc oxide element stacked inside a porcelain tube, electrodes provided at both ends thereof and housed therein, and both ends of each element provided with sprayed electrodes by metal spraying.
A lightning arrester characterized in that the thermal spray electrode surface of the element has a roughness of 20 to 120 S, and at least the thermal spray electrodes are integrated by bonding with a conductive adhesive.