EP2831967B1 - Surge arrester - Google Patents

Description

The invention relates to a surge arrester having at least one insulation section and an arc combustion chamber formed in series between two electrodes, wherein in the arc combustion chamber at least one electrically conductive disc is arranged, wherein between the electrodes an annular housing is arranged to contact, which surrounds the disc and which consists of in the high-resistance area electrically conductive material.

A surge arrester of this kind is for example from the EP 2 287 984 B1 known. In this solution, granules of graphite grains or balls is provided instead of an electrically conductive disc between the electrodes of the arc combustion chamber. This ensures that the component is very low impedance before the current flow in the event of an overvoltage event. In the case of an overvoltage event, such as a lightning strike, many small spark gaps are ignited between the granules, so that at the corresponding current load due to the Countervoltages of the numerous transitions between the granules a high attenuation of the Netzfolgestromes is achieved, so that the Netzfolgestrom goes out.

The prior art is further on the DE 10 2008 038 486 A1 directed. From this document a similar solution is known. In order to prevent the occurrence of a current flow through the overvoltage protection device when applying the rated voltage, the arc combustion chamber is connected there in series an insulation section, which ensures the insulation resistance of the overvoltage protection device at rated voltage. The insulation section is dimensioned such that it becomes conductive only at the response voltage of the overvoltage protection device. As insulation path, for example, a varistor or a gas-filled arrester can be provided. This document also describes that the insulation gap can also be realized by a highly insulating spark gap.

A surge arrester corresponding to the genus of the present application, is in the DE 10 2010 016 985 A1 described. In the surge arrester described there, the isolation path is formed by a spark gap. To this end, connected in series is an electrical element which consists of two electrodes, between which a plurality of parallel to the plate-shaped electrodes aligned electrically conductive discs are provided, which are pressed together by means of a spring-loaded electrode. This unit is from surrounded an insulating material, which is formed temperature-resistant.

A generic surge arrester is from the US 2,298,114 A known.

Based on this prior art, the present invention seeks to provide a further solution for a surge arrester available, in which a system with only one possible insulation gap, in particular spark gap, and thus a corresponding response is provided, which is a Folgestromlöschvermögen a Has multiple spark gap. The construction effort is to be minimized here and in addition to the existing solutions an enrichment of the state of the art to be achieved.

To solve this problem, it is proposed that the disk is arranged with play between the electrodes that the annular housing is formed of a material ring, which consists of graphite-doped plastic.

An alternative solution is seen in that the disc is arranged with play between the electrodes and that the annular housing is formed of a ring of material which is doped with graphite Ceramic material exists.

Another alternative solution is seen in that the disc is arranged with play between the electrodes and that the annular housing is formed of a material ring, which consists of insulating material and which is coated at least on the inner shell and at its end faces with electrically conductive material, preferably Graphite, so that there is an electrically conductive material layer in the high-resistance range.

According to this embodiment, an annular housing, for example a tube, of conductive material is arranged between the electrodes. This ring-shaped housing, which is conductive in the high-resistance region and makes contact with the electrodes, conducts the potential necessary for the ignition Isolation path. As a result, the amount of the operating voltage depends only on the insulation distance. After ignition of the insulation section due to an overvoltage event, a current first flows through the electrodes and the high-impedance annular housing and generates a voltage there. This voltage is tapped in the interior of the tubular housing by the arranged at a small distance between the electrodes disc or there several times arranged discs. Since the distance between electrodes and disks and possibly also between the individual disks is extremely small, or there is a contact resistance between the disks, and the resistance of the disks is much lower than that of the pipe, since the disks are low-resistance, this results in a Rollover on the discs. As a result, the current is passed through the discs and generates, at their junctions to the electrodes or to the individual discs, if several are arranged, countervoltages by arcs. These reverse voltages result in attenuation of the line follow current. If, depending on the positional orientation of the surge arrester, the current flows directly through the disks, namely if the operating position of the system permits direct contact with the fixed electrodes, countervoltages due to arcing, which develop the described effect, also occur at the junctions of the electrodes or disks ,

The conductive annular housing ensures in particular the contacting of the insulation gap in a vertical position of use of the surge arrester.

If the annular housing is formed of a material ring, which consists of graphite-doped plastic, so can be used as plastic, for example, because of the temperature resistance polyamide, which is doped with graphite or other conductive particles to achieve the desired high-resistance conductivity.

If it is provided that the annular housing is formed of a material ring, which consists of insulating material and which is coated at least on the inner shell and at its end faces with electrically conductive material, preferably graphite, so that there is an electrically conductive material layer in the high-resistance region, so here not the complete annular housing is formed of corresponding conductive material, but only the inner jacket and the end faces are coated with electrically conductive material to establish a conductive connection between the electrodes.

In order to achieve the desired effect, it is also provided in particular that the disc surrounded with radial movement play by the housing.

Here, of course, as well as in claim 1 to 3 several discs can be arranged.

Furthermore, it is provided in a conventional manner that the isolation path is a spark gap.

A further embodiment is characterized in that the surge arrester is connected between N conductor and PE conductor of a power network and only one electrically conductive disk is arranged in the housing.

This arrangement and design represents a special feature in that the surge arrester is provided between the N conductor and the PE conductor.

In the event of a phase fault on the PE conductor, the line following current must also be present here go out, for which the inventive design is necessary and advantageous. In such an embodiment, it is only necessary to arrange a disc in the annular housing between the electrodes. This results in a low overall height of the entire component, which is advantageous in terms of application, since there is only a small amount of space for the installation of such a unit. In a practical case, for example, the installation space can be 17.5 mm.

The performance of such an overvoltage device can be relatively low. In this embodiment, only a power of about 100 amps must be sustained and a corresponding deletion function can be achieved.

An alternative embodiment is characterized in that the surge arrester is connected between a phase conductor and PE conductor of a power network and a plurality of electrically conductive disks are arranged in the housing.

In this case, such an overvoltage protection device is designed as a phase arrester, so that the surge arrester is connected between a phase conductor and the PE conductor.

In this case, it is usually necessary to arrange a plurality of disks in the annular housing in order to obtain sufficient power values, since a phase conductor must preferably withstand kiloampere power.

In all solution forms it is achieved that the response of a single spark gap is achieved while the erase behavior corresponds to a multiple spark gap.

Preferably, it is also provided that the disc or discs consist of graphite.

In the embodiment according to the invention is achieved by the arrangement of one or more loosely superimposed conductive discs in the tubular housing of conductive material, that the conductive in the high-resistance area housing the necessary for ignition potential for insulation route, in particular to the spark gap, directs. The amount of the operating voltage is therefore dependent only on the spark gap. After the ignition of the spark gap, a current first flows through the high-impedance tube and generates a voltage there. This voltage is tapped inside the tube by the closely spaced discs or else through the only disc arranged in the tube. Since the distance between slices and electrodes is small and the resistance of the discs, which are made of graphite, for example, is much lower than the resistance of the annular housing, it will flash over to the discs. The current is passed through the discs and generates at their transitions countervoltages by arcing. These reverse voltages result in attenuation of the line follow current.

Figur 1

die wesentlichen Elemente eines Überspannungsableiters mit einer losen Scheibe aus leitfähigem Material;

Figur 2

eine entsprechende Anordnung mit mehreren aufeinanderliegenden losen Scheiben.

Embodiments of the invention are illustrated in the drawings and described in more detail below. It shows:

FIG. 1

the essential elements of a surge arrester with a loose disc of conductive material;

FIG. 2

a corresponding arrangement with several superimposed loose slices.

The surge arrester 1 has at least one insulation gap, in the exemplary embodiment, a spark gap 2, which consists of a disc 3 made of conductive material, in particular graphite, and a second disc 4 made of graphite, which is also the one electrode of the arc combustion chamber.

Between the discs 3,4, an insulating ring 5 is arranged, for example made of PTFE. To the insulation section 2, the arc combustion chamber 7 formed from the electrodes 4 and 6 is connected, wherein in the arc combustion chamber at least one electrically conductive disc 7, preferably made of graphite, is arranged. Between the electrodes 4,6 an annular housing 8 is arranged, which surrounds the disc 7 and which consists of electrically conductive material in the high-resistance region. The disk 7 is arranged with movement play between the electrodes 4, 6. The annular housing 8 is applied in an electrically conductive manner to the electrodes 4, 6 with its end faces. The disc 7 is surrounded in particular by radial movement of the housing 8. In the FIG. 1 an embodiment is shown, which can be connected, for example, as a surge arrester 1 between the N conductor and PE conductor of a power network and only one electrically conductive disc 7 accommodates in the housing 8. In the embodiment according to FIG. 2 an arrangement is shown in which the surge arrester 1 has a plurality of electrically conductive disks 7 between the electrodes 4,6. Such an arrangement is suitable to be connected between a phase conductor and a PE conductor of a power network.

The annular housing 8 may for example consist of a plastic ring which is doped with graphite and thus is conductive in the high-resistance range. The electrodes 3, 4, 6 and the disks 7 are preferably made of graphite.

The embodiment according to the invention provides a surge arrester system which, with only one isolation path, in particular spark gap 2, has the follow current quenching capability of a multiple spark gap.

The invention is not limited to the embodiment, but in the context of the disclosure often variable.

Claims (8)

1. A surge arrester (1) comprising at least one insulation gap (2) and an arc chamber connected in series thereto and formed between two electrodes (4, 6), in said arc chamber at least one electrically conductive disk (7) being arranged, between the electrodes (4, 6) an annular housing (8) being arranged in a contacting manner, which housing surrounds the disk (7) and which consists of a material being electrically conductive in the high-impedance range, characterized by that the disk (7) is arranged with play for movement between the electrodes (4, 6), and that the annular housing (8) is formed of a material ring consisting of a plastic material doped with graphite.
2. A surge arrester (1) comprising at least one insulation gap (2) and an arc chamber connected in series thereto and formed between two electrodes (4, 6), in said arc chamber at least one electrically conductive disk (7) being arranged, between the electrodes (4, 6) an annular housing (8) being arranged in a contacting manner, which housing surrounds the disk (7) and which consists of a material being electrically conductive in the high-impedance range, characterized by that the disk (7) is arranged with play for movement between the electrodes (4, 6), and that the annular housing (8) is formed of a material ring consisting of a ceramic material doped with graphite.
3. A surge arrester (1) comprising at least one insulation gap (2) and an arc chamber connected in series thereto and formed between two electrodes (4, 6), in said arc chamber at least one electrically conductive disk (7) being arranged, between the electrodes (4, 6) an annular housing (8) being arranged in a contacting manner, which housing surrounds the disk (7) and which consists of a material being electrically conductive in the high-impedance range, characterized by that the disk (7) is arranged with play for movement between the electrodes (4, 6), and that the annular housing (8) is formed of a material ring consisting of an insulating material and being coated at least on its inner surface and on its front faces with an electrically conductive material, preferably graphite, so that a material layer being electrically conductive in the high-impedance range exists.
4. The surge arrester according to one of claims 1 to 3, characterized by that the disk (7) is surrounded by the housing (8) with radial play of movement.
5. The surge arrester according to one of claims 1 to 4, characterized by that the insulation gap (2) is a spark gap.
6. The surge arrester according to one of claims 1 to 5, characterized by that the surge arrester (1) is connected between the N conductor and PE conductor of a power network, and only one electrically conductive disk (7) is arranged in the housing (8).
7. The surge arrester according to one of claims 1 to 6, characterized by that the surge arrester (1) is connected between a phase conductor and the PE conductor of a power network, and several electrically conductive disks (7) are arranged in the housing (8).
8. The surge arrester according to one of claims 1 to 7, characterized by that the disk (7) or the disks (7) consist of graphite.

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