LIGHTNING PROTECTION SPARK GAP

Description

[0001] The present invention relates to a lightning protection spark gap with diverging electrodes according to the preamble of claim 1, as known from AU 45775 96 A.

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

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

[0004] DE 10 2005 015 401 A1 discloses a lightning protection spark gap with two diverging electrodes and a spark gap acting between the electrodes, a housing as well as a sliding aid for the arc effective at the electrode base and means for magnetically blowing the arc, wherein the mobility of the arc is increased immediately after its ignition by a combination of measures to intensify the arc-induced intrinsic magnetic field and a staggered gas circulation of the encapsulated arrester.

[0005] Generally, different conductive pure materials are used to form the diverging electrodes, e.g. stainless steel or copper.

[0006] The use of conductive materials with layered structures and varying conductivities is known for the guide rails in switchgear. Relatively thin guide rails and a targeted layered structure utilizing different electrical conductivities increase the current density in the guide rails, particularly in the area of ​​the arc base.

[0007] This creates an increase in the forces exerted on the arc by the intrinsic magnetic field, which can result in greater mobility and a faster entry of the arc into the extinguishing devices.

[0008] This effect is also achieved in homogeneous materials by partially reducing the thickness of the guide rails. This is also utilized in lightning protection spark gaps with tungsten-copper electrodes, as known, for example, from DE 44 35 968 A1.

[0009] In high-performance spark gaps, the thickness of the electrodes or the depth of the incisions cannot be reduced arbitrarily due to the high pulse current load and the associated electromagnetic forces.

[0010] Particularly at the incisions, which create an inhomogeneity in the structure, the arc base can "stuck," leading to an undesirable thermal overload in this case. Therefore, this design variant of the electrodes does not achieve the desired effect.

[0011] However, a disadvantage of using layered electrodes, especially in spark gaps, is that the buoyancy forces increase quadratically with the current height, resulting in very high current forces acting on the arc during pulsed currents.

[0012] In compact devices, this would result in the arc entering the arc chamber too quickly, and the high power output of the arc would destroy the surroundings, so that the amplification of the current forces through the layering of the guide rails would have a rather negative effect under impulse loads.

[0013] In summary, the operating phases of such spark gaps can be summarized as follows.

[0014] During the pulsed current phase, it is important to ensure that the power output in the arc remains as low as possible. Due to the impressed current of the pulsed process, this can only be achieved by minimizing the arc voltage. A minimal arc voltage is primarily achieved by minimizing the arc length in the ignition zone.

[0015] The arc should remain in this ignition zone during the pulse current phase. If the arc were to enter the arc-quenching lamp during the pulse phase, thermal overload or destruction of the spark gap would occur.

[0016] During the follow current phase, the follow current supplied from the low-voltage network must be limited and switched off. This can be achieved by using the highest possible arc voltage, which acts as a counter-voltage to the network voltage.

[0017] In order to achieve the highest possible arc voltage, the arc should therefore run into the arc quenching chamber as quickly as possible after the end of the pulse current phase. Disclosure of the invention

[0018] The present invention provides a lightning protection spark gap according to claim 1.

[0019] Preferred further training courses are the subject of the respective sub-claims. Advantages of the invention

[0020] The core of the invention is the use of at least one of the diverging electrodes with a layer structure of different conductive layers, wherein the conductive layers consist of materials with different electrical conductivity (preferably a factor > 4 or > 10) and the conductive layer with higher electrical conductivity is provided at least in the running area of ​​one of the diverging electrodes.

[0021] The present invention makes it possible to increase the propagation speed of the arc at diverging electrodes when operating with follow current and to reduce the forces acting on the arc under high pulse current loads, thereby creating a "lingering" effect in the ignition zone. This "lingering" effect is accompanied by a low arc voltage (small arc column) and low power consumption and pressure generation. This protects the materials used and the entire assembly.

[0022] According to a preferred embodiment, in the running area of ​​the first and second electrodes, the conductive layer made of conductive material is applied to the base material at least partially.

[0023] According to a further preferred embodiment, in the ignition area of ​​one of the first and second electrodes, the conductive layer made of conductive material is applied to the base material at least partially.

[0024] According to a further preferred embodiment, in the ignition area of ​​the first and second electrodes, the conductive layer made of conductive material is applied to the base material at least partially.

[0025] According to a further preferred embodiment, the first electrode has a first electrical connection area with a first terminal connected thereto, and the second electrode has a second electrical connection area with a second terminal connected thereto.

[0026] According to a further preferred embodiment, the conductive layer of conductive material is applied to the base material, at least partially, on the corresponding inner surface of the first and / or second connection area. This improves heat dissipation for the pulse current.

[0027] According to a further preferred embodiment, the base material is at least partially exposed in the ignition area of ​​the first and / or second electrode.

[0028] According to a further preferred embodiment, on the first outer surface, the conductive layer of the conductive material is applied over the entire surface of the base material, and on the first inner surface, the base material is completely exposed. On the second inner surface, the conductive layer of the conductive material is applied over the entire surface of the base material, and on the second outer surface, the base material is completely exposed. In this way, the intrinsic magnetic field of the arc at the first electrode can be influenced such that the propagation speed of the arc is also increased there.

[0029] According to another preferred embodiment, the first electrode is designed as a long-horn electrode and the second electrode as a hook electrode. This allows the operating behavior to be influenced as desired by the contours of the electrodes.

[0030] According to a further preferred embodiment, the second electrical conductivity is higher than the first electrical conductivity by a factor greater than or equal to 4, in particular by a factor greater than or equal to 10.

[0031] According to another preferred embodiment, the base material is stainless steel and / or the conductive layer is copper or silver. Brief description of the drawings

[0032] They show: Fig. 1 a schematic cross-sectional view to illustrate an exemplary lightning protection spark gap according to a first embodiment of the present invention; Fig. 2 a schematic cross-sectional view to illustrate another exemplary lightning protection spark gap; Fig. 3 a schematic cross-sectional view to illustrate another exemplary lightning protection spark gap; Fig. 4 a schematic cross-sectional view to illustrate another exemplary lightning protection spark gap; Fig. 5 a schematic cross-sectional view to illustrate a lightning protection spark gap according to a first embodiment of the present invention; Fig. 6a),b) a schematic partial top view of the first or second electrode to illustrate another exemplary lightning protection spark gap; Fig. 7a),b) a schematic partial top view of the first or second electrode to illustrate another exemplary lightning protection spark gap.second electrode to illustrate further exemplary lightning protection spark gaps; and Fig. 8 a partial schematic cross-sectional view to illustrate a lightning protection spark gap according to a second embodiment of the present invention.

[0033] In the figures, identical or functionally equivalent elements are provided with the same reference symbols. Description of the exemplary implementations

[0034] Fig. 1 shows a schematic cross-sectional view to illustrate an example of a lightning protection spark gap.

[0035] The lightning protection spark gap according to Fig. 1 The lightning protection spark gap has a first electrode 3a, which has a first outer surface Aa and a first inner surface Ia. Furthermore, the lightning protection spark gap has a second electrode 3b, which has a second outer surface Ab and a second inner surface Ib. The first electrode 3a and the second electrode 3b diverge from each other.

[0036] The first and second electrodes 3a, 3b are formed from a base material which exhibits a first electrical conductivity. In the present example, the base material is stainless steel and has an electrical conductivity between 1.4 MS / m and 9 MS / m, preferably 1.4 MS / m.

[0037] Between the first inner surface Ia of the first electrode 3a and the second inner surface of the second electrode 3b, an ignition zone Z and an adjoining arc path L are formed. In the ignition zone Z, the first electrode 3a and the second electrode 3b are closely spaced, whereas the distance in the arc path L widens continuously.

[0038] In the event of a lightning strike, the lightning energy is essentially converted by an impulse current in the ignition area Z, whereas in the running area L a mains follow current arc driven by a mains follow current propagates towards an arc quenching chamber 4, the arc quenching chamber 4 being laterally surrounded by arc guide plates 5a, 5b.

[0039] In the running area L of the first and second electrodes 3a, 3b, a conductive layer 6a, 6b made of a conductive material with a second electrical conductivity is applied over the entire surface of the base material. In this example, this conductive material is copper, which has an electrical conductivity of 56 MS / m, so that the electrical conductivity of the applied conductive material is approximately 6 times greater than the conductivity of the base material.

[0040] For connection to an electrical system, for example an electrical system with a first and second busbar of a supply network, the first electrode 3a has a first electrical connection area A1 with a first terminal 1a connected thereto, and the second electrode 3b has a second electrical connection area A2 with a second terminal 1b connected thereto.

[0041] In the event of a lightning strike, where the high impulse current flows in the ignition zone Z, the mobility of the arc base point is reduced by the stainless steel base material in the ignition zone of the first and second electrodes 3a, 3b. The coating with the conductive material copper increases the mobility of the arc in the propagation zone L, allowing the follow current arc to quickly enter the arc quenching chamber 4.

[0042] This significantly reduces the time required to extinguish the arc.

[0043] Fig. 2 shows a schematic cross-sectional view to illustrate another exemplary lightning protection spark gap.

[0044] In the example according to Fig. 2 In contrast to the example described above, according to Fig. 1 The layer of conductive copper is also provided across the entire ignition area Z of the first electrode 3a and transitions continuously into the running area L. In contrast, the base material steel is exposed in the ignition area Z of the second electrode 3b.

[0045] This design allows for an increase in energy conversion in the ignition zone Z. However, the thickness of the electrically conductive copper layer 6a should be adjusted so that, at impulse currents of a certain magnitude (energy, charge), where the arc should not enter the arc quenching chamber 4, the conductive copper layer is adiabatically overloaded and at least partially destroyed. This reduces the current density so significantly due to its distribution in a geometrically much thicker layer that known measures for preventing impulse arcs are sufficient, while still allowing for the utilization of accelerated movement during a follow current.

[0046] For example, a copper layer 200 µm thick on a stainless steel layer 1.5 mm thick will be destroyed within approximately 400 µs under a load of 25 kA.

[0047] By appropriately varying the thickness of the conductive layer 6a made of copper, the load can be adjusted to different values ​​of impulse currents.

[0048] In normal pulse currents, the partial coating of the ignition area Z with the conductive layer of copper also contributes to further improved heat dissipation.

[0049] Otherwise, the example corresponds to Fig. 2 according to the example Fig. 1 .

[0050] Fig. 3 shows a schematic cross-sectional view to illustrate another exemplary lightning protection spark gap.

[0051] For example according to Fig. 3 is in contrast to, for example, according to Fig. 2 The conductive layer 6a made of copper is also applied to the inside Ia of the first electrode 3a in the first connection area A1 and is in thermal contact with the first terminal 1a.

[0052] Furthermore, the conductive layer of copper 6b on the inside Ib of the second electrode 3b is also applied in the second connection area A2 and is in thermal contact with the second terminal 1b.

[0053] As in the example according to Fig. 2 is also the case in the example according to Fig. 3 The base material steel is exposed in the ignition area of ​​the second electrode 3b.

[0054] Such copper coating of the first and second connection areas A1, A2 enables significantly improved heat dissipation in the event of a lightning strike, which helps to protect a typically surrounding polymer housing.

[0055] Fig. 4 shows a schematic cross-sectional view to illustrate another exemplary lightning protection spark gap.

[0056] The example according to Fig. 4 differs from the example according to Fig. 3 by the fact that the conductive layer made of copper 6a is only provided in a partial area of ​​the ignition area Z of the first electrode 3a and the conductive layer 6b made of copper is also provided in a corresponding partial area of ​​the ignition area Z of the second electrode 3b.

[0057] As already mentioned in connection with the example according to Fig. 2 As mentioned, by using a suitable thickness of the conductive copper layer, it can be achieved that the conductive copper layer is adiabatically overloaded and partially destroyed at excessively high impulse currents, so that the impulse current remains in the ignition range.

[0058] Fig. 5 Figure 1 shows a schematic cross-sectional view to illustrate a lightning protection spark gap according to a first embodiment of the present invention.

[0059] In the first embodiment, the conductive layer 6a made of copper is applied over the entire surface of the base material on the first outer surface Aa, while on the first inner surface Ia the base material stainless steel is fully exposed.

[0060] On the second inner side Ib, the conductive layer 6b is made of copper on the base material.

[0061] Stainless steel is applied over the entire surface, whereas on the second outer surface Ab the base material stainless steel is exposed over the entire surface.

[0062] In the first embodiment, the coating of the outer surface Aa of the first electrode 6a, in addition to improved heat dissipation, increases the forces exerted by the intrinsic magnetic field on the arc at the second electrode 3a, thereby also achieving greater mobility and faster entry of the arc into the arc quenching chamber 4.

[0063] In the first embodiment, in contrast to the previous examples, the second terminal 1b' is anchored on the outside Ab of the second electrode 3b, so that the inside Ib of the second electrode 3b can be completely covered with the conductive material 6b made of copper.

[0064] Fig. 6a ),b) show a schematic partial top view of the first or second electrode to illustrate further exemplary lightning protection spark gaps.

[0065] In the example according to Fig. 6a ) is at least in the running area L of one of the first and second electrodes 3a, 3b the conductive layer 6a, 6b made of the conductive material copper on the base material stainless steel is applied at least partially over the entire surface.

[0066] Reference symbol K denotes a virtual dividing line between the running area L and the ignition area Z.

[0067] In the ignition area Z of one of the first and second electrodes 3a, 3b, the conductive layer 6a, 6b made of the conductive material copper is applied to the base material stainless steel, at least in some areas, over the entire surface.

[0068] A full-surface area 61 of the conductive layer 6a, 6b in the running area L and a full-surface area 62 of the conductive layer 6a, 6b in the ignition area Z are separated by an area 60 in which the base material is fully exposed.

[0069] In the example according to Fig. 6b ) at least in the running area L of one of the first and second electrodes 3a, 3b the conductive layer 6a, 6b made of the conductive material copper on the base material stainless steel is applied at least in some areas in a longitudinal strip shape with a width less than the width of the inside Ia, Ib.

[0070] In the ignition area Z of one of the first and second electrodes 3a, 3b, the conductive layer 6a, 6b made of the conductive material copper is applied to the base material stainless steel at least in some areas in a longitudinal strip shape with a width smaller than the width of the inside Ia, Ib.

[0071] A longitudinal strip-shaped area 61' of the conductive layer 6a, 6b in the running area L and a longitudinal strip-shaped area 62' of the conductive layer 6a, 6b in the ignition area Z are separated by an area 60 in which the base material is completely exposed.

[0072] Fig. 7a ),b) show a schematic partial top view of the first or second electrode to illustrate further exemplary lightning protection spark gaps.

[0073] In the example according to Fig. 7a ) at least in the running area L of one of the first and second diverging electrodes 3a, 3b the conductive layer 6a, 6b made of the conductive material copper is applied to the base material stainless steel in a longitudinal strip shape with a width smaller than the width of the inside Ia, Ib.

[0074] In the ignition area Z of one of the first and second electrodes 3a, 3b, the conductive layer 6a made of the conductive material copper is applied to the base material stainless steel in a longitudinal strip shape with a width smaller than the width of the inner side Ia, Ib.

[0075] A longitudinal strip-shaped area 61" of the conductive layer 6a, 6b in the running area L and a longitudinal strip-shaped area 62" of the conductive layer 6a, 6b are connected to each other in the ignition area Z.

[0076] In the example according to Fig. 7b ) at least in the running area L of one of the first and second electrodes 3a, 3b the conductive layer 6a, 6b made of the conductive material copper is applied to the base material stainless steel in a longitudinal strip shape with a width smaller than the width of the inside Ia, Ib.

[0077] Fig. 8 is a partial schematic cross-sectional view to illustrate a lightning protection spark gap according to a second embodiment of the present invention.

[0078] In the second embodiment, the first electrode 3a is designed as a long horn electrode and the second electrode 3b as a hook electrode, i.e. the diverging electrodes 3a, 3b run asymmetrically.

[0079] As in the example according to Fig. 5 The conductive layer 6a made of copper is applied over the entire surface of the base material on the first outer surface Aa, while on the first inner surface Ia the base material stainless steel is fully exposed.

[0080] On the second inner side Ib, the conductive layer 6b made of copper is applied over the entire surface of the base material stainless steel, whereas on the second outer side Ab the base material stainless steel is exposed over the entire surface.

[0081] In the second embodiment, the functional separation between the pulse current phase and the mains follow current phase is influenced not only by the material combination but also by the electrode contours.

[0082] The first electrode 3a, designed as a long-horn electrode, has a continuous contour with a substantially constant radius of curvature of up to 90° and no flow inhomogeneities. This allows for the generation of laminar flow along the first electrode 3a without turbulence. The active inner surface Ia of the first electrode 3a is made of stainless steel 6a and has a low thermal conductivity of approximately 20 W / (m·K).

[0083] As a result, the base of the arc moves very slowly or abruptly on the first electrode 6a during the pulse current phase, since it remains fixed in the melting crater.

[0084] In the subsequent follow-current phase, the laminar flow is used to move the arc base towards the arc quenching chamber 4. This requires a certain pressure build-up, which is only achieved after a time delay following the attainment of the maximum pulse current value.

[0085] The second electrode 3b, designed as a hook electrode, has a discontinuous contour with a higher radius of curvature in the same direction as the first electrode 3a, designed as a long horn electrode, starting from the ignition area Z, and then, after a turning point, a radius of curvature in the opposite direction to that of the first electrode 3a, designed as a long horn electrode.

[0086] Of particular importance is the flow shadow after the maximum curvature of the second electrode 3b. Copper 6b, which has a high thermal conductivity of approximately 380 W / (m·K), is used as the material on the active inner surface Ib. As a result, no melt crater forms there that would cause the arc to stall.

[0087] The high mobility of the arc base point on the inner surface Ib of the second electrode 3b could cause the arc to move too quickly from the ignition zone Z towards the arc quenching chamber 4. However, with appropriate dimensioning, the aforementioned flow shadow causes the arc base point to remain in the ignition zone Z for several hundred microseconds up to one microsecond, and only then, and thus after the pulse current has decayed, does the rapid movement towards the arc quenching chamber 4 begin.

[0088] By using a corresponding layer thickness of the conductive layer 6b made of copper on the second electrode 3b, which is designed as a hook electrode, it can also be achieved in this embodiment that the conductive layer 6b made of copper is adiabatically overloaded and partially destroyed in the event of excessively high impulse currents, so that the impulse current remains in the ignition range.

[0089] For example, a 0.2 mm thick conductive layer 6b made of copper, which has been applied, for example, by electroplating, coating or plating, melts at 25 kA for 10 / 350 µs. Although the present invention has been fully described above with reference to preferred embodiments, it is not limited thereto, but can be modified in many ways.

[0090] The present invention is not limited to the material combination of steel / copper. It has been found that any material combination can be used for the diverging electrodes to achieve the effects according to the invention.

Claims

1. Lightning protection spark gap comprising: 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 and the second electrode (3a, 3b) diverging from one another; the first and the second electrode (3a, 3b) being formed from a conductive base material having a first electrical conductivity; an ignition region (Z) and an adjacent arcing region (L) for an arc being formed between the first inner face (Ia) of the first electrode (3a) and the second inner face (Ib) of the second electrode (3b); a conductive layer (6a, 6b) of a conductive material having a second electrical conductivity being applied to the base material at least in regions at least in the arcing region (L) of one of the first and the second electrode (3a, 3b); and the second electrical conductivity being higher than the first electrical conductivity; characterised in that the conductive layer (6a, 6b) of the conductive material is applied to the base material at least in regions on the associated outer face (Aa, Ab) of the other of the first and the second electrode (3a, 3b).

2. Lightning protection spark gap according to claim 1, wherein the conductive layer (6a, 6b) of the conductive material is applied to the base material at least in regions in the arcing region (L) of the first and the second electrode (3a, 3b).

3. Lightning protection spark gap according to either claim 1 or claim 2, wherein the conductive layer (6a, 6b) of the conductive material is applied to the base material at least in regions in the ignition region (Z) of one of the first and the second electrode (3a, 3b).

4. Lightning protection spark gap according to claim 3, wherein the conductive layer (6a, 6b) of the conductive material is applied to the base material at least in regions in the ignition region (Z) of the first and the second electrode (3a, 3b).

5. Lightning protection spark gap according to any of the preceding claims, wherein the first electrode (3a) has a first electrical connection region (A1) having an associated first terminal (1a), and the second electrode (3b) has a second electrical connection region (A2) having an associated second terminal (1b; 1b').

6. Lightning protection spark gap according to claim 5, wherein the conductive layer (6a, 6b) of the conductive material is applied to the base material at least in regions on the associated inner face (Ia, Ib) of the first and / or the second connection region (A1, A2).

7. Lightning protection spark gap according to either claim 3 or claim 4, wherein the base material is exposed at least in regions in the ignition region (Z) of the first and / or the second electrode (3a, 3b).

8. Lightning protection spark gap according to claim 1, wherein the conductive layer (6a) of the conductive material is applied to the base material over the whole area on the first outer face (Aa), and the base material is exposed over the whole area on the first inner face (Ia), and wherein the conductive layer (6b) of the conductive material is applied to the base material over the whole area on the second inner face (Ib), and the base material is exposed over the whole area on the second outer face (Ab).

9. Lightning protection spark gap according to any of the preceding claims, wherein the first electrode (3a) is formed as a long horn electrode and the second electrode (3b) is formed as a hook electrode.

10. Lightning protection spark gap according to any of the preceding claims, wherein the second electrical conductivity is higher than the first electrical conductivity by a factor greater than or equal to 4, in particular by a factor greater than or equal to 10.

11. Lightning protection spark gap according to any of the preceding claims, wherein the base material is high-grade steel and / or the conductive layer (6a, 6b) is copper or silver.