Lightning-protection spark gap

Abstract

The present invention relates to a lightning-protection spark gap, comprising: - a housing (G); - a first electrode (3a), which has a first outer face (Aa) and a first inner face (Ia); and - a second electrode (3b), which has a second outer face (Ab) and a second inner face (Ib); wherein the first electrode (3a) and the second electrode (3b) diverge from each other; wherein a striking region (Z) and an adjoining propagation region (L) for a spark are formed between the first inner face (Ia) of the first diverging electrode (3a) and the second inner face (Ib) of the second diverging electrode (3b); wherein the housing (G) forms an arc chamber (LK) between the first electrode (3a) and the second electrode (3b), which arc chamber is delimited by a quenching chamber (4); and wherein, in the housing (G), at least one first gas circulation channel (K1) is formed, by means of which a gas flow escaping from the quenching chamber (40) in the event of a lightning strike can be returned to the arc chamber (K) via at least one first cutout (V1; V1'; V1''; V1''') in the propagation region (L) of the first electrode (3a). The first cutout (V1; V1'; V1''; V1''') is asymmetrical with respect to a longitudinal extent of the first cutout (V1; V1'; V1''; V1''') in the propagation direction of the arc; the first cutout (V1; V1'; V1''; V1''') falls in the propagation direction of the arc from a first cross-section (Q1) of the first electrode (3a) to a minimum cross-section (QM) of the first electrode (3a) over a first distance (l1; l1'; l1''; l1''') and rises from the minimum cross-section (QM) of the first electrode (3a) to a second cross-section (Q2) of the first electrode (3a) over a second distance (l2; l2'; l2''; l2'''). The first distance (l1; l1'; l1''; l1''') is shorter than the second distance (l2; l2'; l2''; l2''').

Description

[0001] The present invention relates to a lightning protection spark gap with mutually diverging electrodes according to the preamble of claim 1, as known from DE 10 2005 015 401 A1.

[0002] Although applicable to any lightning protection spark gaps with mutually diverging electrodes, the present invention and the problem underlying it are explained with regard to lightning protection spark gaps with mutually diverging electrodes which have an arcing chamber with a plurality of arcing plates. State of the art

[0003] DE 10 2011 051 738 A1 discloses a lightning protection spark gap with diverging electrodes. The distance between the opposing electrode surfaces is kept narrow in the ignition zone and widens in the running zone. The pulse current load is therefore essentially limited to the ignition zone, while the line follow currents flow along the diverging electrodes in the running zone, and the line follow current arc is split and extinguished in an arcing chamber.

[0004] The generic document DE 10 2005 015 401 A1 discloses a lightning protection spark gap with two mutually diverging electrodes and a spark gap acting between the electrodes, a housing, a sliding aid for the arc acting at the electrode base, and means for magnetically blowing the arc. The mobility of the arc is increased immediately after its ignition by a combination of measures for amplifying the arc-induced inherent magnetic field and staggered gas circulation in the encapsulated arrester. In particular, the electrodes have rectangular recesses for gas circulation.

[0005] With such lightning protection spark gaps, care must be taken to keep the power dissipation in the arc as low as possible during the pulse current phase. Due to the impressed current of the pulse process, this can only be achieved by keeping the arc voltage as low as possible. The lowest possible arc voltage can be achieved, in particular, by keeping the arc length in the ignition zone as short as possible.

[0006] The arc should remain in this ignition range during the pulse current phase. If the arc were to enter the arc quenching lamp during the pulse current phase, this would place extreme stress on the spark gap.

[0007] During the mains follow current phase, the mains follow current supplied from the low-voltage grid must be limited and switched off. This can be achieved by using the highest possible arc voltage, which acts as a countervoltage to the mains voltage.

[0008] In order to achieve the highest possible arc voltage, the arc should run into the arc extinguishing chamber as quickly as possible after the end of the pulse current phase.

[0009] In particular, at the recesses, which in the state of the art represent an inhomogeneity of the structure, the arc root point may "perish" and thus lead to an undesirable thermal overload.

[0010] Fig. 5a )-d) are schematic views to explain a lightning protection spark gap known from DE 10 2005 015 401 B4.

[0011] The known lightning protection spark gap comprises a first electrode 3a, which has a first outer side Aa and a first inner side 1a. Furthermore, the lightning protection spark gap comprises a second electrode 3b, which has a second outer side Ab and a second inner side 1b. The first and second electrodes 3a, 3b are arranged in a housing G, the trough-shaped underside of which is shown. The housing cover is not shown.

[0012] The first and second electrodes 3a, 3b are formed of a conductive material. In the present example, the material is stainless steel or copper, or an alloy thereof. The first and second electrodes 3a, 3b diverge from each other.

[0013] Between the first inner side 1a of the first electrode 3a and the second inner side of the second electrode 3b, an ignition zone Z and an adjoining arc travel zone L are formed. In the ignition zone Z, the first electrode 3a and the second electrode 3b are closely spaced, whereas the distance continuously widens in the travel zone L. When the housing cover (not shown) is in place, an arc chamber LK is formed between the first and second electrodes 3a, 3b.

[0014] At the end of the travel area L, the arc chamber LK contains an arc quenching chamber 4, which has a plurality of parallel quenching plates 40, to which gas outlet channels 45 are connected. The arc quenching chamber is laterally surrounded by the end regions 5a, 5b of the first and second electrodes 3a, 3b.

[0015] A first gas circulation channel K1 is formed between the housing G and the outer side Aa of the first electrode 3a, and a second gas circulation channel K2 is formed between the housing G and the outer side Ab of the second electrode 3b.

[0016] The first electrode 3a is connected to a first electrical connection contact 1a via a connection area 6a, and the second electrode 3a is connected to a second electrical connection contact 1b via a connection area 6b. The first and second electrical connection contacts 1a, 1b are led outward through the wall of the housing, so that an electrical connection can be established with an electrical network to be protected from lightning strikes.

[0017] On the outer side Aa of the first electrode, a ferromagnetic concentrator F1 is additionally provided opposite the running area L.

[0018] In the running area L adjacent to the ignition area Z, the first electrode 3a has symmetrically opposite first recesses V01, and in the running area L adjacent to the ignition area Z, the second electrode 3a has symmetrically opposite second recesses V02. The first recesses V01 form a fluidic connection between the first gas circulation channel K1 and the arc chamber LK, and the second recesses V02 form a fluidic connection between the second gas circulation channel K2 and the arc chamber LK.

[0019] During a lightning strike, the lightning energy is converted in a first phase essentially by a pulse current in the ignition area Z, whereas in a second phase in the running area L a line follow current arc driven by a line follow current propagates towards the arc extinguishing chamber 4.

[0020] The gas flow resulting from the arc formation is guided via the gas outlet channels 45 into the first and second gas circulation channels K1, K2 and is at least partially returned via the first and second recesses V1, V2 into the arc chamber LK to support the arc movement.

[0021] The state of the art, as described in Fig. 5c ) and d), the recesses V01, V02 are formed in a rectangular trough shape symmetrically with respect to their longitudinal extent in the direction of travel of the arc and have right-angled corners E and E'.

[0022] This type of recesses V01, V02 produces good results for smaller arcs, but larger arcs often get stuck on the second edge KA of the recesses V01, V02. Disclosure of the invention

[0023] The present invention provides a lightning protection spark gap according to claim 1.

[0024] Preferred further training is the subject of the respective subclaims. Advantages of the invention

[0025] The core of the present invention is an asymmetrical shape of the recesses of the electrode or electrodes in the direction of travel of the arc, wherein a drop from a first cross section to a minimum cross section occurs over a significantly shorter distance than a subsequent increase from the minimum cross section to a second cross section, which preferably corresponds to the first cross section.

[0026] The present invention thus makes it possible to increase the speed of the arc on the electrodes during the mains follow current and to prevent the arc from getting stuck in the recesses.

[0027] According to a preferred embodiment, the first electrode has two first recesses arranged symmetrically opposite one another. This increases the efficiency of gas circulation.

[0028] According to a further preferred embodiment, at least one second gas circulation channel is formed in the housing, via which a gas flow escaping from the quenching chamber during a lightning strike can be recirculated into the arc chamber via at least one second recess in the travel region of the second electrode; wherein the second recess is formed asymmetrically with respect to a longitudinal extent of the second recess in the travel direction of the arc; wherein the second recess decreases in the travel direction of the arc from a first cross-section of the second electrode to a minimum cross-section of the second electrode over the first path and increases from the minimum cross-section of the second electrode to a second cross-section of the first electrode over a second path; and wherein the first path is shorter than the second path. The efficiency of the gas circulation can thus be further increased.

[0029] According to a further preferred embodiment, the second electrode also has two second recesses which are arranged symmetrically opposite one another.

[0030] According to a further preferred embodiment, the first cross section and the second cross section are the same.

[0031] According to a further preferred embodiment, the second path is at least twice as long as the first path. This allows for a particularly uniform discharge of the arc from the recess(es).

[0032] According to a further preferred embodiment, the first distance is zero.

[0033] According to a further preferred embodiment, the first path and / or the second path runs over at least one round-arch-like section.

[0034] According to a further preferred embodiment, the first path and / or the second path runs over at least one linear section.

[0035] According to a further preferred embodiment, the quenching chamber has a plurality of parallel arranged quenching plates, to which gas outlet channels are connected, which open into the first and second gas circulation channels, respectively. Short description of the drawings

[0036] They show: Fig. 1a)-d) schematic views for explaining a lightning protection spark gap according to a first embodiment of the present invention, namely Fig. 1a ) as a perspective representation, Fig. 1b ) as an enlarged section of the first electrode, Fig. 1c ) as a plan view of the inside of the first electrode and Fig. 1d ) as a detail enlargement of the contour of a recess of the first electrode; Fig. 2a), b) schematic views to explain a lightning protection spark gap according to a second embodiment of the present invention, namely Fig. 2a ) as a plan view of the inside of the first electrode and Fig. 2b ) as a detail enlargement of the contour of a recess of the first electrode; Fig. 3a), b) schematic views to explain a lightning protection spark gap according to a third embodiment of the present invention, namely Fig. 3a ) as a plan view of the inside of the first electrode and Fig. 3b ) as a detail enlargement of the contour of a recess of the first electrode; Fig. 4a), b) schematic views to explain a lightning protection spark gap according to a fourth embodiment of the present invention, namely Fig. 4a ) as a plan view of the inside of the first electrode and Fig. 4b ) as an enlarged detail of the contour of a recess of the first electrode; and Fig. 5a)-d) schematic views to explain a lightning protection spark gap known from DE 10 2005 015 401 B4.

[0037] In the figures, identical or functionally identical elements are provided with the same reference numerals. Description of the embodiments

[0038] Fig. 1a )-d) show schematic views for explaining a lightning protection spark gap according to a first embodiment of the present invention, namely Fig. 1a ) as a perspective representation, Fig. 1b ) as an enlarged section of the first electrode, Fig. 1c ) as a plan view of the inside of the first electrode and Fig. 1d ) as an enlarged detail of the contour of a recess of the first electrode.

[0039] The lightning protection spark gap according to the first embodiment comprises a first electrode 3a, which has a first outer side Aa and a first inner side 1a. Furthermore, the lightning protection spark gap comprises a second electrode 3b, which has a second outer side Ab and a second inner side 1b. The first and second electrodes 3a, 3b are arranged in a housing G, the trough-shaped underside of which is shown. The housing cover is not shown.

[0040] The first and second electrodes 3a, 3b are formed of a conductive material. In the present example, the material is stainless steel or copper, or an alloy thereof. The first and second electrodes 3a, 3b diverge from each other.

[0041] Between the first inner side 1a of the first electrode 3a and the second inner side of the second electrode 3b, an ignition zone Z and an adjoining arc travel zone L are formed. In the ignition zone Z, the first electrode 3a and the second electrode 3b are closely spaced, whereas the distance continuously widens in the travel zone L. When the housing cover (not shown) is in place, an arc chamber LK is formed between the first and second electrodes 3a, 3b.

[0042] At the end of the travel area L, the arc chamber LK contains an arc quenching chamber 4, which has a plurality of parallel arc quenching plates 40, to which gas outlet channels 45 are located. The arc quenching chamber is laterally surrounded by the end regions 5a, 5b of the first and second electrodes 3a, 3b.

[0043] A first gas circulation channel K1 is formed between the housing G and the outer side Aa of the first electrode 3a, and a second gas circulation channel K2 is formed between the housing G and the outer side Ab of the second electrode 3b.

[0044] The first electrode 3a is connected to a first electrical connection contact 1a via a connection area 6a, and the second electrode 3a is connected to a second electrical connection contact 1b via a connection area 6b. The first and second electrical connection contacts 1a, 1b extend outward through the wall of the housing, allowing for electrical connection to an electrical network to be protected from lightning strikes. The first and second electrodes 3a, 3b have pins Za, Zb, via which they are anchored in corresponding anchoring holes in the housing G.

[0045] On the outer side Aa of the first electrode, a ferromagnetic concentrator F1 is additionally provided opposite the running area L.

[0046] In the running area L adjacent to the ignition area Z, the first electrode 3a has symmetrically opposite first recesses V1, and in the running area L adjacent to the ignition area Z, the second electrode 3a has symmetrically opposite second recesses V2. The first recesses V1 form a fluidic connection between the first gas circulation channel K1 and the arc chamber LK, and the second recesses V2 form a fluidic connection between the second gas circulation channel K2 and the arc chamber LK.

[0047] During a lightning strike, the lightning energy is converted in a first phase essentially by a pulse current in the ignition area Z, whereas in a second phase in the running area L a line follow current arc driven by a line follow current propagates towards the arc extinguishing chamber 4.

[0048] The gas flow resulting from the arc formation is guided via the gas outlet channels 45 into the first and second gas circulation channels K1, K2 and is at least partially returned via the first and second recesses V1, V2 into the arc chamber LK to support the arc movement.

[0049] The special design of the first and second recesses V1, V2 provided on both sides opposite each other on the first and second electrodes 3a, 3b, as shown in particular in Fig. 1c) und 1d ), promotes the running behavior of the arc in the area of ​​the recesses V1, V2 and can effectively prevent the arc from lingering or getting stuck in the area of ​​the recesses V1, V2.

[0050] In the first embodiment, the recesses V1, V2, shown here at the recess V1, extend asymmetrically with respect to the longitudinal extent of the recesses V1, V2 in the direction of arc travel. In particular, the cross-section of the first electrode 3a narrows from a first cross-section Q1 to a minimum cross-section QM in the form of a round-arch section R1 and then continuously increases again in a linear section L1 to the cross-section Q2, which here corresponds to the cross-section Q1.

[0051] A path length 11 of the round-arch section R1 is considerably shorter than a path length 12 of the linear section L1.

[0052] Fig. 2a ), b) are schematic views for explaining a lightning protection spark gap according to a second embodiment of the present invention, namely Fig. 2a ) as a plan view of the inside of the first electrode and Fig. 2b ) as an enlarged detail of the contour of a recess of the first electrode.

[0053] The special design of the first and second recesses V1', V2' provided on both sides opposite each other on the first and second electrodes 3a, 3b, as shown in particular in Fig. 2a) und 2b ), also promotes the running behavior of the arc in the area of ​​the recesses V1', V2' and can effectively prevent the arc from lingering or getting stuck in the area of ​​the recesses V1', V2'.

[0054] The recesses V1', V2', shown here at the recess V1', also extend asymmetrically in the second embodiment with respect to the longitudinal extent of the recesses V1', V2' in the direction of arc travel. In particular, the cross-section of the first electrode 3a narrows from a first cross-section Q1 to a minimum cross-section QM in the form of a first linear section L1 and then increases continuously again in a second linear section L2' to the cross-section Q2, which here corresponds to the cross-section Q1.

[0055] A path length l1' of the first linear section L1' is substantially shorter than a path length l2' of the second linear section L2'.

[0056] Otherwise, the second embodiment is designed like the first embodiment described above.

[0057] Fig. 3a ), b) are schematic views for explaining a lightning protection spark gap according to a third embodiment of the present invention, namely Fig. 3a ) as a plan view of the inside of the first electrode and Fig. 3b ) as an enlarged detail of the contour of a recess of the first electrode.

[0058] The special design of the first and second recesses V1", V2", provided on both sides opposite each other on the first and second electrodes 3a, 3b, as shown in particular in Fig. 3a) und 3b ), similarly promotes the running behavior of the arc in the area of ​​the recesses V1", V2" and can effectively prevent the arc from lingering or getting stuck in the area of ​​the recesses V1", V2".

[0059] The recesses V1", V2", shown here at the recess V1", run asymmetrically in the third embodiment with respect to the longitudinal extent of the recesses V1", V2" in the direction of travel of the arc. In particular, the cross section of the first electrode 3a narrows from a first cross section Q1 to a minimum cross section QM in the form of a rectangular step L1" and then increases continuously in a linear section L2" over a distance l2" up to the cross section Q2, which here corresponds to the cross section Q1. The first distance l1" is practically zero in this embodiment.

[0060] Otherwise, the third embodiment is designed like the first embodiment described above.

[0061] Fig. 4a ), b) are schematic views for explaining a lightning protection spark gap according to a fourth embodiment of the present invention, namely Fig. 4a ) as a plan view of the inside of the first electrode and Fig. 4b ) as an enlarged detail of the contour of a recess of the first electrode.

[0062] The special design of the first and second recesses V1‴, V2‴ provided on both sides opposite each other on the first and second electrodes 3a, 3b, as shown in particular in Fig. 4a) und 4b ), promotes the running behavior of the arc in the area of ​​the recesses V1‴, V2‴ and can also effectively prevent the arc from lingering or getting stuck in the area of ​​the recesses V1‴, V2‴.

[0063] In the fourth embodiment, the recesses V1‴, V2‴, shown here at the recess V1, extend asymmetrically with respect to the longitudinal extent of the recesses V1‴, V2‴ in the direction of arc travel. In particular, the cross-section of the first electrode 3a narrows from a first cross-section Q1 to a minimum cross-section QM in the form of a first linear section L1‴ and then increases continuously again in a second linear section L2‴ to the cross-section Q2, which here corresponds to the cross-section Q1.

[0064] A path length l1‴ of the first linear section L1‴ is substantially shorter than a path length l2‴ of the second linear section L1‴.

[0065] Compared to the previously described embodiments, in the fourth embodiment the total path length l1‴ + l2‴ of the recesses V1‴, V3‴ is shorter.

[0066] Otherwise, the fourth embodiment is designed like the first embodiment described above.

[0067] Although the present invention has been fully described above using preferred embodiments, it is not limited thereto but can be modified in many ways.

[0068] In particular, the present invention is not limited to the specific recess geometries shown. Nor is the invention limited to the described electrode geometry, but is in principle applicable to any electrode geometry, provided that they fall within the scope of the patent claims.

[0069] Although in the described embodiments asymmetrical recesses are provided on both electrodes in a mirror-symmetrical manner on both sides, the invention is not limited thereto, and an asymmetrical recess can also be provided only on one side of one or both electrodes or on both sides of only one of the two electrodes.

Claims

1. Lightning protection spark gap comprising: a housing (G); a first electrode (3a), which has a first outer face (Aa) and a first inner face (Ia), and a second electrode (3b), which has a second outer face (Ab) and a second inner face (Ib), the first electrode (3a) and the second electrode (3b) diverging from one another; an ignition region (Z) and an adjacent arcing region (L) for an arc being formed between the first inner face (Ia) of the first diverging electrode (3a) and the second inner face (Ib) of the second diverging electrode (3b); the housing (G) forming an arc chamber (LK), which is arranged between the first and the second electrode (3a, 3b) and which is delimited by a extinguishing chamber (4); and at least a first gas circulation duct (K1), by way of which a gas flow leaving the extinguishing chamber (4) in the event of a lightning strike can be passed back into the arc chamber (LK) via at least one first recess (V1; V1'; V1"; V1"') in the arcing region (L) of the first electrode (3a), being formed in the housing (G); characterised in that the first recess (V1; V1'; V1"; V1‴) is formed asymmetrically in terms of a longitudinal extension of the first recess (V1; V1'; V1"; V1‴) in the arcing direction of the arc; and the first recess (V1; V1'; V1"; V1‴) decreases from a first cross section (Q1) of the first electrode (3a) to a minimum cross section (QM) of the first electrode (3a) over a first distance (l1; l1'; l1"; l1‴) and increases from the minimum cross section (QM) of the first electrode (3a) to a second cross section (Q2) of the first electrode (3a) over a second distance (12; 12'; l2"; l2‴) in the arcing direction of the arc; and the first distance (11; 11'; l1"; l1‴) is shorter than the second distance (12; 12'; l2"; l2‴).

2. Lightning protection spark gap according to claim 1, wherein the first electrode (3a) has two first recesses (V1; V1'; V1"; V1‴) which are arranged symmetrically opposite one another.

3. Lightning protection spark gap according to either claim 1 or claim 2, wherein at least one second gas circulation duct (K2), by way of which a gas flow leaving the extinguishing chamber (4) in the event of a lightning strike can be passed back into the arc chamber (LK) via at least one second recess (V2; V2'; V2"; V2‴) in the arcing region (L) of the second electrode (3b), is formed in the housing (G); the second recess (V2; V2'; V2"; V2‴) is formed asymmetrically in terms of a longitudinal extension of the second recess (V2; V2'; V2"; V2‴) in the arcing direction of the arc; and the second recess (V2; V2'; V2"; V2‴) decreases from a first cross section (Q1) of the second electrode (3b) to a minimum cross section (QM) of the second electrode (3b) over the first distance (11; 11'; l1"; l1‴) and increases from the minimum cross section (QM) of the second electrode (3b) to a second cross section (Q2) of the first electrode (3a) over a second distance (12; 12'; 12"; l2‴); and the first distance (11; 11'; 11"; l1‴) is shorter than the second distance (12; 12'; 12"; l2‴).

4. Lightning protection spark gap according to claim 3, wherein the second electrode (3b) has two second recesses (V2; V2'; V2"; V2‴) which are arranged symmetrically opposite one another.

5. Lightning protection spark gap according to any of the preceding claims, wherein the first cross section (Q1) and the second cross section (Q2) are equal.

6. Lightning protection spark gap according to any of the preceding claims, wherein the second distance (12; 12'; 12"; l2‴) is at least twice as long as the first distance (11; 11'; l1"; l1‴).

7. Lightning protection spark gap according to claim 1, wherein the first distance (11; 11'; l1"; l1‴) is zero.

8. Lightning protection spark gap according to claim 1, wherein the first distance (11; 11'; l1"; l1‴) and / or the second distance (12; 12'; l2"; l2‴) extend over at least one circle-arc-like portion (R1).

9. Lightning protection spark gap according to claim 1, wherein the first distance (11; 11'; l1"; l1‴) and / or the second distance (12; 12'; l2"; l2‴) extend over at least one linear portion (L1; L1', L2'; L1", L2"; L1‴, L2‴).

10. Lightning protection spark gap according to any of the preceding claims, wherein the extinguishing chamber (4) has a plurality of mutually parallel extinguishing plates (40), to which gas outlet ducts (45) are connected which open into the first and second gas circulation ducts (K1; K2) respectively.

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