JPH0642404B2 - Lightning arrester - Google Patents

Abstract

PURPOSE:To enhance a discharge characteristic by a method wherein an electrode plate is made larger than a size of an outside diameter of an arrester element, its edge-face shape is formed to be an arc shape or a spherical surface shape and a plane part of a prescribed length from an outer periphery face of the arrester element is formed with reference to a part to an outer periphery of the electrode plate. CONSTITUTION:When an overvoltage of a lightning surge is applied to a lightning arrester 1, this electric current is guided as follows: an upper-part hat-shaped electrode 8 an upper- part conductive piece 13 an upper-part sealing electrode 4 an intermediate electrode 6 a soft conductive foil film 21 an arrester element 3 a lower-part sealing electrode 5 a lower-part conductive piece 13 a lower-part hat-shaped electrode 9. During this process, the arrester element 3 built in a wall tube insulator 2 quickly reduces its resistance value by its characteristic and passes a large electric current caused by the lightning surge. The arrester element 3 immediately restores its resistance value with reference to an operating voltage following the lightning surge and restores its insulation; accordingly, a follow-current discharge is not caused, and a line is restored to a normal state. A plane part 6b at a prescribed distance L from an outer periphery face 3b of the arrester element 3 is formed at a part to an outer periphery of the intermediate electrode 6; accordingly, lines of electric force H continued from the inside to the outside of the arrester element 3 are continued smoothly to a spherical surface part 6a; it is possible to relax that an electric field is concentrated in a part near the plane part 6b. Thereby, it is possible to suppress a sudden rise and a disorder of the line of electric force stretched from the inside to the outside of the lightning element and to make the discharge characteristic good.

Description

Description: [Field of Industrial Application] The present invention suppresses an increase in lightning surge potential of a power transmission line by promptly discharging the lightning surge current to the ground when a lightning surge current flows in the power transmission line due to electric shock. By doing so, the present invention relates to a lightning arrester that prevents power failure due to a flashover ground fault and enables power transmission.

[Prior Art] As a conventional lightning arrester, as shown in FIG.
A lightning arrester element 42 having zinc oxide as a main material is built in 1, and electrode plates 43 are brought into contact with both upper and lower ends thereof, and both electrode plates 43 are elastically pressed by a cap electrode 44. Also,
The outer peripheral end surface of the electrode plate 43 was formed into a spherical shape, and only the spherical portion 43a thereof was projected to the outside from the outer peripheral surface 42a of the lightning arrester 42 (see Japanese Utility Model Laid-Open No. 63-65203). Problem to be Solved by the Invention With this conventional configuration, as shown in FIG. 6, when the lightning arrester element 42 and the electrode plate 43 are in a proper assembled state, the electric field, that is, the distribution density of the lines of electric force H becomes substantially uniform. Absent. However, the conventional lightning arrester has a spherical portion 43 of the electrode plate 43.
Since only a protrudes from the outer peripheral surface of the lightning protection element 42,
If the assembled state is abnormal, the line of electric force H continuing from the inside of the lightning arrester element 42 to the outside suddenly rises in the vicinity of the spherical surface portion 43a, and the electric field is likely to be concentrated on the surface of the element, and the discharge characteristic is deteriorated. was there. In particular, as shown in FIG. 7, for example, the contact between the side surface 42b of the lightning protection element 42 and the end surface 43b of the electrode plate 43 may cause a manufacturing or assembly error, thermal expansion or contraction of the lightning protection element 42, or the both end surfaces 42b, 4b.
When a small interval is formed between 3b, the line of electric force H rises sharply and the concentration of the electric field becomes remarkable.

Further, as shown in FIG. 8, a soft metal plate 45 is usually interposed between the both end surfaces 42b and 43b in order to improve the contact state between them and reduce the electric resistance.
5 due to an assembly error, the outer peripheral surface 42a of the lightning protection element 42
When projecting from the electric field line H near the projecting portion, the electric field tends to concentrate.

The present invention has been made by paying attention to the problems existing in such a conventional technique, and alleviates the concentration of the electric field generated at the outer periphery of the joint between the lightning protection element and the electrode plate, thereby improving the discharge characteristics. The purpose is to provide a lightning arrester that can.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention has a lightning protection element built in an insulating cylinder, and electrode plates are bonded to both end faces of the lightning protection element, An external sealing electrode is fitted and fixed to the end of the body, and further, the electrode plate is made larger than the outer diameter of the lightning protection element, and the end face shape is formed in an arc shape or a spherical shape, and the outer circumference of the electrode plate. In contrast to this, a measure is taken to form a flat surface portion of a predetermined length from the outer peripheral surface of the lightning protection element.

[Operation] In the present invention, since the flat portion having a predetermined length is formed from the outer peripheral surface of the lightning protection element near the outer periphery of the electrode plate, the electric force line continuing from the inside of the lightning protection element to the outside smoothly continues to the spherical surface portion. As a result, the concentration of electric field is alleviated. Even if there is a manufacturing or assembly error in the lightning protection element or electrode plate, a gap may be created between the two, or even if the soft metal plate protrudes from the outer peripheral surface of the lightning protection element, the lines of electric force may change suddenly. Therefore, the concentration of the electric field is alleviated and the discharge characteristics are improved.

[Embodiment] The first embodiment of the lightning arrester of the present invention will be described below.
This will be described with reference to FIGS.

As shown in FIG. 4, inside the porcelain tube 2 having the cap portion 2a that constitutes the arrester 1, the voltage-current characteristic, which is mainly made of zinc oxide (ZnO) and is excellent in the continuous current interruption characteristic, is non-linear. A plurality of lightning protection elements 3 having a columnar shape are housed in series.

Plate-shaped upper and lower sealing electrodes 4 and 5 made of a conductive material such as aluminum, aluminum alloy (duralumin), or copper alloy (phosphor bronze) are bonded and fixed to the inclined surfaces of the upper and lower ends of the porcelain tube 2 by an adhesive. An intermediate electrode 6 as an electrode plate is elastically interposed between the upper surface 3a of the lightning protection element 3 and the lower surface 4a of the sealing electrode 4.

Upper and lower cap-shaped electrodes 8 and 9 as external sealing electrodes made of a conductive material such as aluminum or copper are fitted to both upper and lower ends of the porcelain bushing via packing 10.
The outer peripheral portions of the both cap-shaped electrodes 8 and 9 are fixed by caulking to a concave groove 2b formed on the outer periphery of the porcelain insulator 2. Coil-shaped springs 11 and 12 are interposed between the sealing electrodes 4 and 5 and the cap-shaped electrodes 8 and 9. A conductive piece 13 is attached to the spring 12.

Next, the intermediate electrode 6 will be described with reference to FIG.

In this embodiment, a short cylindrical portion 16b is formed on the outer peripheral edge of a disk-shaped electrode body 16a made of a conductive material such as aluminum or copper having elasticity, and the end edge of the short cylindrical portion 16b is outwardly directed. Bending at a right angle 16
By integrally forming c, the upper cap electrode 16
Is formed.

On the other hand, the lower cap electrode 17 is a disk-shaped electrode body 1 made of a conductive material such as aluminum or copper having elasticity.
A cylindrical portion (see a chain line in FIG. 1) 17b is curvedly formed on the outer peripheral portion of 7a. Then, the cylindrical portion 17b of the lower cap electrode 17 is caulked to the locking flange portion 16c of the upper cap electrode 16, and the upper and lower cap electrodes 16 and 17 are coupled to each other.

Inside the both cap electrodes 16 and 17, a pair of upper and lower disc springs 19 are interposed by a disc-shaped spring receiver 18. The disc springs 19 are electrically connected by a conductive member 20 made of a thin conductive foil having a thickness of, for example, about 0.1 mm.

The outer peripheral portion of the intermediate electrode 6 configured as described above has a spherical portion 6a.
The flat surface portion 6b formed on the spherical surface portion 6a is provided for a predetermined distance L from the outer peripheral surface 3b of the lightning protection element 3 so that the electric field is not concentrated near the boundary between the two.

A soft conductive foil film 21 of copper or aluminum is interposed between the lower surface 17c of the cap electrode 17 and the upper surface 3a of the lightning protection element 3.

Next, the operation of the lightning arrester 1 configured as described above will be described.

When an overvoltage of a lightning surge is applied to the arrester 1, this current is generated by the upper cap electrode 8 → the upper conductive piece 13 → the upper sealing electrode 4 →
The intermediate electrode 6 → the soft conductive foil film 21 → the lightning protection element → the lower sealing electrode 5 → the lower conductive piece 13 → the lower cap-shaped electrode 9 are reached.

At this time, the lightning protection element 3 built in the porcelain bushing 2 quickly reduces the resistance value due to its characteristics and allows a large current due to a lightning surge to pass. Further, the lightning arrester element 3 immediately restores the resistance value and restores the insulation with respect to the operating voltage which continues to the lightning surge, so that the follow current discharge is not formed and the electric line is normally restored.

In this embodiment, since the flat portion 6b having the predetermined distance L from the outer peripheral surface 3b of the lightning protection element 3 is formed near the outer circumference of the intermediate electrode 6, the electric force line H continuing from the inside of the lightning protection element 3 to the outside is spherical. It smoothly continues to the part 6a, and as a result, the flat part 6
The concentration of the electric field near b is relaxed. As shown in FIG. 2, there is a manufacturing or assembling error in the lightning protection element 3 and the intermediate electrode 6, and a gap is generated between the two, or as shown in FIG. Outer peripheral surface 3
Even if it protrudes from b, the line of electric force H does not change abruptly, so that the concentration of the electric field is alleviated and the discharge characteristic is improved.

The present invention is not limited to the configuration of the above-described embodiment. For example, instead of the intermediate electrode 6, a solid integral electrode plate is used, or the end portion of the intermediate electrode 6 is formed in an arc shape. For example, the present invention can be embodied by arbitrarily changing it without departing from the spirit of the present invention.

[Effects of the Invention] As described above, according to the present invention, it is possible to suppress an abrupt rise and disturbance of the lines of electric force extending from the inside to the outside of the lightning arrester and improve the discharge characteristics of the lightning arrester. is there.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of the present invention, FIGS. 2 and 3 are enlarged sectional views showing electric lines of force in an abnormal state of the essential part, and FIG. 4 is a lightning arrester. FIG. 5 is a vertical sectional view showing the whole, and FIG. 5 is a vertical sectional view of a central portion showing a conventional example.
6 to 8 are enlarged sectional views for explaining the operation of the conventional example. 1 ... Lightning arrester, 2 ... Insulator tube, 3 ... Lightning arrester element, 3a ...
Top surface, 3b ... Outer peripheral surface, 6 ... Intermediate electrode, 6a ... Spherical surface portion, 6b ... Flat surface portion, H ... Electric force line.

Claims (1)

[Claims] 1. A lightning protection element is built in an insulating cylinder, electrode plates are joined to both end faces of the lightning protection element, and an external sealing electrode is fitted and fixed to an end of the insulating cylinder. , The electrode plate is larger than the outer diameter of the lightning protection element, and the end face shape is formed into a spherical shape or an arc shape, and a flat portion having a predetermined length from the outer peripheral surface of the lightning protection element with respect to the outer periphery of the electrode plate. A lightning arrester characterized by forming a.