EP2916401B1 - Spark gap - Google Patents

Description

The invention relates to a spark gap for surge arresters or as part of a surge arrester having at least three spaced apart from each other by a gap electrodes which form a spark gap, and in each case between two adjacent electrodes arranged annular insulator elements.

Such spark gaps are known in the art and have proven themselves to dissipate high lightning currents. During the discharge process of a current generated by a lightning strike, an arc is formed between the spark gaps. This arc derives the lightning current occurring. The arc forms a gaseous plasma in which the particles are at least partially ionized.

The resulting released charge carriers have the consequence that the plasma gas, which thereby arises, is electrically conductive.

The fact that the resulting plasma and the arc form abruptly during the Ableitvorganges, it comes directly to an extreme pressure increase within the spark gap. As a result, an undesirable Nachaußendringen of the plasma in the application during the discharge is possible. This can lead to a voltage flashover of electrical parts outside the spark gap, thereby possibly damaging them.

In particular, at very high lightning currents, there is the danger that the resulting plasma is pressed by the high pressure between the electrode and insulator element or between two electrodes, thereby penetrating the insulator element to the outside and there can lead to an outside flashover or more external flashovers ,

From the DE 298 10 937 U1 is a spark gap according to the preamble of the current claim 1 known. From the D2 it is known to provide expansion spaces in a spark gap with a plurality of electrodes, which are in open communication with an arc combustion chamber.

Due to the input mentioned prior art, the present invention seeks to provide a spark gap of the type mentioned, in which the leakage of plasma during the discharge of lightning currents is prevented, which is inexpensive and easy to produce and has only small dimensions ,

To solve this problem, the invention proposes that one between a first electrode and a Third electrode arranged second electrode encloses at least one cavity, which via at least one channel with the gap between the first electrode and second electrode and / or via at least one channel with the gap between the second electrode and the third electrode is in open communication.

By arranging such a cavity, which is in open communication with channels with the respectively adjacent gap, the plasma gas produced during the discharge process of lightning currents within the spark gap can escape from the gap formed between two electrodes into the cavity. In this case, the escape of plasma from the spark gap is prevented in the outer environment and the guided into the cavity plasma in the cavity both relaxed and cooled. As a result, a spark gap is provided in a cost-effective and simple manner, in which an escape of plasma gas in the vicinity of the spark gap, which arises during the discharge of lightning currents, is effectively prevented. Thus, the damage is prevented by located within the environment of the spark gap devices or parts by the leakage of plasma. The plasma produced during the lightning current thus remains completely within the closed system, namely within the cavity of the second electrode and / or within the gap or gaps formed between the first and second electrodes or between the second and third electrodes. In particular, it can be provided in particular that the first, the second and the third electrode consist of disks of approximately circular shape.

The formation of electrodes with a circular shape is known per se and has proven particularly useful.

Furthermore, it can be particularly preferred that the second electrode consists of two disks lying one on top of the other, wherein a recess is formed in one disk and forms the cavity with the other disk.

The formation of such a cavity by the juxtaposition of two disks, one of which has a recess, represents a cost effective and easy to manufacture solution.

In addition, it can be particularly preferably provided that both disks, which together form the second electrode, each have a recess, which together form the cavity in the case of disks lying on one another.

In this way, a particularly large cavity for receiving the resulting during the discharge of currents, in particular lightning currents plasma is created. In addition, this solution is inexpensive and easy to produce.

In a conventional manner may be particularly preferably provided that the electrodes consist of graphite discs.

In addition, it can be particularly preferably provided that a plurality of channels, preferably evenly distributed over the cavity bounding surfaces of the second electrode are provided which connect the cavity with the columns.

The arrangement of several channels ensures that the plasma produced during the discharge process by lightning currents is led into the cavity without thereby penetrating the spark gap to the outside and leaving there.

In particular, it may be particularly preferred that four channels are provided evenly distributed, which connect the cavity with the gap between the first and second electrode and four channels are evenly distributed, which connect the cavity with the gap between the second and third electrodes.

The arrangement of four channels, which are arranged evenly distributed, allows a particularly efficient discharge of the plasma ejection out of the gap between the first and second electrodes into the cavity. In addition, discharge from the cavity into the second gap between the second and third electrodes can take place, whereby a further pressure equalization and optionally a further cooling is possible.

In addition, it may be particularly preferred that the channels have a diameter of at least one millimeter.

It can also be particularly preferred that the channels have a diameter of two millimeters.

The design of the channels with a diameter of 2 mm has proven to be particularly effective in practice.

Furthermore, it can be particularly preferred that the insulator elements consist of one or more annular disks of heat-resistant insulating material, in particular PTFE, which are arranged between the edges of the electrode plates surrounding the gap.

The formation of the annular discs of a heat-resistant insulating material such as PTFE is known per se and has proven extremely useful in practice.

Finally, it can be particularly preferably provided that the first and the third electrode each have near its peripheral edge an annular recess open to the gap, into which the channels open.

This annular recess is partially covered by a region of the respective disc of heat-resistant insulating material. These annular recesses are suitable for receiving during the discharge of lightning currents arising or deposited within the gap dusts during the discharge process.

An embodiment of the invention is shown in the figure and described in more detail below.

Figur 1

eine erfindungsgemäße Funkenstrecke im Querschnitt gesehen.

It shows:

FIG. 1

a spark gap according to the invention seen in cross section.

In the figure, an NPE spark gap 1 for surge arresters is shown. The spark gap 1 may also be part of a surge arrester and connected to other parts. In the exemplary embodiment, the spark gap 1 consists of three electrodes 4, 5, 6 which are spaced apart from one another by a gap 2 or 3. The electrodes 4, 5, 6 together with the gaps 2, 3 form a spark gap 1 Electrodes 4, 5 and 5, 6 annular insulator elements 7 are arranged.

The one electrode 4 is connected, for example, to a phase conductor or a neutral conductor, while the other electrode 6 for example, connected to a ground terminal at ground potential.

According to the invention, the second electrode 5 arranged between the first electrode 4 and the third electrode 6 encloses a cavity 8. In the exemplary embodiment, this cavity 8 has four channels 9 with the gap 2 between the first electrode 4 and the second electrode 5 and four channels 10 the gap 3 between the second electrode 5 and the third electrode 6 in open connection.

In alternative embodiments, fewer or more than four channels 9 and / or fewer or more than four channels 10 may be provided. During the Ableitvorganges lightning currents in a spark gap according to the invention 1 formed by the arc gaseous plasma, which arises in the gap 2 between the electrodes 4 and 5, penetrate into the space enclosed by the second electrode 5 cavity 8 through the channels 9 and relax there and cooling down. Thus, an unwanted escape of the plasma, for example, laterally outwardly by destruction of the insulator elements, effectively prevented. In addition, the plasma loses its electrical conductivity by cooling.

In addition, the plasma can escape from the cavity 8 into the gap 3 and continue to cool there and optionally relax.

The electrodes 4, 5, 6 consist in the embodiment of discs with a circular shape. Alternatively, the electrodes 4, 5, 6 may also consist of a shape deviating from the circular shape.

In the exemplary embodiment, both disks, which form the second electrode 5, each have a recess. These discs lie with their recesses on each other so that they together form the cavity 8. Alternatively, a recess may also be formed in only one disk, which is covered by the other disk, so that a cavity 8 is formed.

In a manner known per se, the electrodes 4, 5, 6 consist of graphite disks.

The channels 9, 10 have in the embodiment a diameter of 2 mm. Alternatively, the channels 9, 10 may also have a diameter of at least 1 mm.

The annular insulator elements 7 are formed in the embodiment of annular discs made of PTFE. The disks made of PTFE are arranged between the edges of the electrodes 4, 5 or 5, 6 surrounding the gap 2, 3.

In particular, for receiving dust formed within the respective gap 2 or 3 is at the first electrode 4 and at the second electrode 6 each near its peripheral edge an open to the gap 2 or 3, annular recess 11 is formed. In the exemplary embodiment, the channels 9, 10 partially open into the recess 11.

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

All disclosed in the description and / or drawing single and combination features are considered essential to the invention.

LIST OF REFERENCE NUMBERS

1

radio link

2

gap

3

gap

4

first electrode

5

second electrode

6

third electrode

7

Insulator element

8th

cavity

9

channel

10

channel

11

recess

Claims (11)

1. A spark gap (1) for a surge arrester or as part of a surge arrester comprising at least three electrodes (4, 5, 6) spaced from each other by one gap (2, 3) each, thus forming a spark gap (1), and annular insulator elements (7) respectively disposed between two adjacent electrodes (4, 5; 5, 6), characterized by that a second electrode (5) disposed between a first electrode (4) and a third electrode (6) encloses at least one cavity (8) that is in open communication via at least one channel (9) with the gap (2) between first electrode (4) and second electrode (5) and/or via at least one channel (10) with the gap (3) between second electrode (5) and third electrode (6).
2. The spark gap (1) of claim 1, characterized by that the first, the second, and the third electrodes (4, 5, 6) consist of disks with an approximately circular shape.
3. The spark gap (1) of claim 2, characterized by that the second electrode (5) consists of two disks arranged on top of each other, in one disk a recess being provided that, together with the other disk, forms the cavity (8).
4. The spark gap (1) of claim 3, characterized by that both disks forming the second electrode (5) have one recess each that commonly form, with disks arranged on top of each other, the cavity (8).
5. The spark gap (1) of any one of claims 1 to 4, characterized by that the electrodes (4, 5, 6) consist of graphite disks.
6. The spark gap (1) of any one of claims 1 to 5, characterized by that a plurality of channels (9, 10) are provided, preferably evenly distributed over the surfaces limiting the cavity (8) of the second electrode (5), said channels connecting the cavity (8) to the gaps.
7. The spark gap (1) of any one of claims 1 to 6, characterized by that four evenly distributed channels (9) are provided that connect the cavity (8) to the gap (2) between first and second electrodes (4 or 5, respectively), and four evenly distributed channels (10) are provided that connect the cavity (8) to the gap (3) between second and third electrodes (5 or 6, respectively).
8. The spark gap (1) of any one of claims 1 to 7, characterized by that the channels (9, 10) have a diameter of at least one millimeter.
9. The spark gap (1) of any one of claims 1 to 8, characterized by that the channels (9, 10) have a diameter of two millimeters.
10. The spark gap (1) of any one of claims 1 to 9, characterized by that the insulator elements (7) consist of one or more annular disks of a heat-resistant insulating material, in particular PTFE, that are disposed between the edges of the electrode plates surrounding the gap.
11. The spark gap (1) of any one of claims 1 to 10, characterized by that the first and the third electrodes (4 or 6, respectively) comprise near their peripheral edges an annular recess (11) open toward the gap (2 or 3, respectively), in which the channels (9, 10) terminate.

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