EP1911134A1

EP1911134A1 - Spark-discharge gap

Info

Publication number: EP1911134A1
Application number: EP06761836A
Authority: EP
Inventors: Jürgen Boy; Winfried VÖLKNER
Original assignee: Epcos AG
Current assignee: TDK Electronics AG
Priority date: 2005-08-02
Filing date: 2006-08-02
Publication date: 2008-04-16
Anticipated expiration: 2026-08-02
Also published as: WO2007014556A1; US20080218082A1; DE102005036265A1; JP4928549B2; JP2009503795A; EP1911134B1; US8169145B2; CN101233659A; CN101233659B

Abstract

A spark-discharge gap (1; 21; 50) having a cavity (3; 23; 43), which is surrounded by two connecting electrodes (7a, 7b; 27a, 27b; 47a 47b) and an electrical insulator (2; 22; 42) arranged in between, and having a pin electrode (4; 24; 44) which projects into a tubular electrode (5; 25; 45) is disclosed. In one form, recesses (11; 41) in the connecting electrodes are provided on the side next to the cavity (3; 43), and a guide for the connecting electrodes is provided on the inner wall of the insulator. In another form, stiffening electrodes (12a, 12b; 27c, 27d) are provided which are respectively connected to one of the connecting electrodes. Both forms can be combined.

Description

description

radio link

The invention relates to a spark gap, in particular for the protection of supply lines or AC networks against lightning.

Spark gaps as protective elements against overvoltages are known per se. Thus, WO 2004/017479 A1 describes a hybrid overvoltage protection element in which a varistor and a surge arrester are connected in parallel.

Especially in devices of network protection, there is a need to improve the properties of such elements, in particular with regard to the current carrying capacity and the quenching behavior. Basically suitable for use at high currents and voltages are air gaps with triggering device, which are complex, expensive and bulky.

The invention has for its object to provide an improved spark gap, especially in a compact design, which is suitable for high current loads.

The invention solves the problem with the features of the independent claims. Embodiments of the invention are characterized in dependent claims.

In a first embodiment of the invention, a spark gap with a cavity is proposed, which is comprised of two terminal electrodes and an electrical insulator arranged therebetween. The spark gap points a projecting into a tube electrode pin electrode and cavity-side indentations or bulges of the terminal electrodes and a guide of the terminal electrodes on the inner wall of the insulator.

This embodiment has an extremely compact construction of the spark gap with excellent overall properties. The terminal electrodes terminate the insulator at the end and together with the latter form the cavity. From the respective edge-side transition region of the connection electrodes to the insulator, bulges of the connection electrodes extend into the cavity.

In the production of this very compact spark gap, it is thereby possible for the electrodes carrying the spark discharge to be adapted very precisely to these and their bulges, both with regard to the materials used and with regard to their connection to the terminal electrodes. In addition, it ^is' possible to get as external connections of the radio link provided terminal studs within the bulges to the terminal electrodes to be connected to an even more compact construction and a further optimized material adjustment.

The bulges of the terminal electrodes or the beads in the bulges also allow a precise and secure guidance of the terminal electrodes on the inner wall of the insulator. The connection electrodes and the insulator can therefore be adjusted very precisely to each other even in a miniaturized spark gap during assembly. It is even possible to connect the Ansσhlusselektroden self-aligned with each other with the insulator. In a second embodiment of the invention, a spark gap is provided with a cavity which is comprised of two terminal electrodes and an electrical insulator arranged therebetween. The spark gap has a stylus projecting into a tube electrode and stiffening electrodes, which are each connected to one of the terminal electrodes.

This embodiment has an extremely compact construction of the spark gap with excellent overall properties. Thus, the ^'terminal electrodes are prepared, for example thin and made of a highly conductive material. Preferably, the terminal electrodes have a low heat capacity. The material combination of pin or tube electrode, connection electrode, stiffening electrode and possibly externally connected connection pin enables optimization of the spark gap with regard to its compactness as well as electrical, thermal and mechanical properties.

The shapes of the terminal electrodes and the stiffening electrodes are preferably matched to each other. As a result, both a stable outer electrode and a good heat dissipation in the discharge case is possible.

Even if the spark gap through the terminal electrodes alone should not have the necessary stability, the stiffening electrodes ensure the stability and integrity of the spark gap, especially if the stiffening electrodes are made of a harder material than the terminal electrodes. The individually and in their entirety optimized elements of the claimed embodiments of the spark gap affect on the one hand in a compact design and on the other hand in particular on improved thermal and electrical properties. Thus, the current carrying capacity and the dynamic ignition conditions of the spark gap are improved.

The pin electrode as the first electrode and the tube electrode as the second electrode are arranged in the cavity of the insulator. The first and second electrodes protrude into each other and are spatially separated. The second electrode lies between the insulator and the first electrode and is spatially separated from both. This results in a simple realized nested arrangement.

The pin electrode is considered to be any type of electrode which has a pen-like or rod-like appearance according to its external appearance. This includes pipes with at least one frontal flange. Likewise, a tube electrode has a closed or partially interrupted tube shape. In the following, the terms first electrode and ^■ pin electrode and second electrode and tube electrode are used synonymously.

Due to the nested arrangement, the pin electrode preferably engages the tube electrode such that the inner wall of the insulator surrounding the electrodes, which is preferably tubular, is partially shaded by the pin electrode by the tube electrode.

A shading of the insulator of the pin-shaped electrode by means of the tubular electrode allows the ignition of the spark gap advantageously compliance the structural integrity of the insulator and optionally applied thereon ignition aids, such as graphite, and the stability of the insulating property of the insulator.

The interior of the spark gap is preferably filled with gas, in particular a gas mixture containing noble gas. On the one hand, this positively supports the extinguishing behavior of the spark gap and, on the other hand, ensures uniformized dynamic ignition conditions during repeated ignition of the spark gap.

According to another embodiment of the spark gap, the ends of one or both electrodes are chamfered in the discharge space. It is preferred that the ends have rounded or smoothed outer surfaces, so that local electric Feldüberhöhungen be avoided.

It is also advantageous if at least one of the electrodes has an activation mass. With the activation mass, a higher AC load capacity of the spark gap can be ensured. This is particularly possible if the activation mass is arranged on the free end of the pin electrode and / or on the bottom of the pipe electrode.

The preferably mounted on each end side of the insulator each a connection electrode allows electrical connection of the spark gap to the outside. In this case, in each case one connection electrode is connected to the pin or tube electrode. The contacting of the electrodes is carried out so that each electrode is on the one hand exactly positioned and on the other hand the occurring currents can be safely dissipated. To form the preferably hermetically, ie gas-tight sealed to the outside interior of the spark gap, the terminal electrodes can completely cover the end faces of the insulator.

Particularly advantageous are the two embodiments of the invention combine.

The individually and in their entirety optimized elements of the claimed embodiments of the spark gap affect on the one hand in a compact design and on the other ^' in particular on improved thermal and electrical properties. Thus, the current carrying capacity and the dynamic ignition conditions of the spark gap are improved.

The invention will be described below with reference to

Embodiments and the figures of the drawings explained in more detail.

Showing:

FIG. 1 shows a section through a first spark gap according to the invention,

2 shows a section through a ^'second radio link according to the invention,

3 shows a section through a third spark gap according to the invention, FIG.

4 shows a section through a fourth invention ^'spark gap and Figure 5 is a three-dimensional view of a spark gap according to Figure 1 with end-side connecting bolt.

FIG. 1 shows a spark gap, in particular as a high-current spark gap, which contains a tubular insulator 2, in particular made of ceramic. At the front, the spark gap has connection electrodes 7a and 7b. The terminal electrodes have cavity-side bulges, which are cup-shaped as in the embodiment of Figure 1. They are used alone or, ^'as shown in Figure 1, in conjunction with reinforcement electrodes 12a, 12b, among other things for electrical connection to the protected network.

In the interior of the housing formed by the insulator and the terminal electrodes of the spark gap is a filled with gas, preferably a gas mixture with inert gas, sealed outward cavity 3. In the cavity, a first electrode 4 and a second electrode 5 are arranged, each attached to one of the terminal electrodes 7a and 7b and are electrically connected thereto. The first electrode 4, shown as a partial section, is preferably pin-shaped. and the second electrode 5 is preferably tubular. The spark gap preferably has a height and a diameter of between 25 mm to 35 mm, in particular 30 mm.

The arrangement of the pin and tube electrodes is chosen so that the pin electrode 4 protrudes partially with its free end into the tube electrode 5 or inserted. As a result, the tube electrode 5 partially overlaps the pin electrode 4 and shadows the pin electrode in this area from the inner wall of the insulator. This arrangement forms a nested geometry.

The pin electrode and the tube electrode are preferably concentrically positioned in their nested region so that there is a space 8 between the peripheral surface of the pin electrode and the inner surface of the tube electrode. The space 8 serves as a primary electrical discharge space, with secondary discharges also taking place in other spaces between the first and second electrodes 4 and 5.

The pin and the tube electrode each have free ends lying in the cavity. The other end of Stiftbzw. Tube electrode is firmly connected to a connection electrode 7a and 7b, in particular by means of a hypereutectic brazing.

The edges 4a and 5a preferably of all ends of the electrodes are chamfered or rounded off, thus avoiding excesses of the electric fields at these edges. As a result, a more uniform current discharge in the cavity 3, in particular in the discharge space 8, is achieved. Thus be. locally highly concentrated electromagnetic fields and thus the formation of accompanying temperature peaks avoided. In particular, the current load for the pin and the tube electrode is reduced. Non-chamfered electrodes, on the other hand, can cause impermissibly high current densities at the edges of the electrodes, which can lead to unwanted melting of the electrodes.

The preferred materials of the pin electrode and the tube electrode are copper, iron or a tungsten-copper mixture or at least portions of these materials. The Electrodes may also contain different materials relative to each other, such as a tungsten-copper stud electrode and a copper rod electrode. In this case, the expensive tungsten copper has the lowest burnup at surge current loads, so that this material is also preferred for both electrodes. Electrodes of iron or copper show a higher burnup, but are cheaper and therefore also advantageous.

Depending on the requirements, the interleaved construction of the first and second electrodes 4 and 5 allows materials which are unsuitable for a reliable ceramic-metal compound per se, such as iron or tungsten-copper, to be used in the discharge region.

A suitable ceramic for the insulator 2 is aluminum oxide (Al ₂ O ₃ ). The insulator is dimensioned with a wall thickness of 4 mm to 6 mm, but preferably with a wall thickness of 5 mm, ^• to safely master the enormous pressure wave during a surge discharge in the interior of the spark gap, without the insulator bursting or cracking.

On the inner wall 2a of the insulator ignition aids 9, for example, one or more graphite-containing ignition marks are applied, which ensure above all the good dynamic ignition behavior (eg ignition at <1500 V with a rise time of 5 kV / μsec). Furthermore, such stable characteristic values, such as, for example, ignition voltage and insulation resistance, are ensured. Due to the shading effect of the pipe electrode, the ignition strips are effectively protected against burning. An optimal ceramic-metal connection between the insulator 2 and the terminal electrode 7a or 7b is given if the thermal expansion coefficients of the two materials are the same or similar. In an alumina insulator, the keratnik metal compound is preferably made by a FeNi alloy or copper. In a composite electrode according to the embodiment, the pin and the tube electrode are made of current-resistant materials and fixed to the connection electrode, for example, welded or brazed. Therefore, the terminal electrode contains a material that can be connected well with the material of the pin and tube electrode as well as with that of the insulator. Composite electrodes each comprising first and second electrodes, connection electrode and, as in the exemplary embodiment of FIG. 1, stiffening electrode with. their respective optimized materials and shapes contribute significantly to a mechanical and electrical optimization of the spark gap.

Preferably, the pin electrode and / or the tube electrode are provided with an activation mass in order to reliably control a high alternating current load. In this case, according to Figure 1, an activation mass is arranged on the free end of the pin electrode. It is also possible to apply an activating mass between the walls of the tube electrode 5 to the inside of the connecting electrode 7b connected to the tube electrode, that is to say to the bottom of the tube electrode. The activation compound is preferably a silicate coating, which is applied in recesses at the free end 4a of the inner pin electrode, for example in the form of a wafer pattern. The connection electrodes 7a and 7b are particularly preferably made of copper. They have at the periphery a plurality, preferably six beads 11. These lead the terminal electrodes within the ceramic tube 2 precisely and safely, without the terminal electrodes must be completely against the entire ceramic inner wall. Each connection electrode is connected either to the pin or the tube electrode mechanically and electrically, for example by means of a hypereutectic brazing. It is also possible to use the cup shape itself of the terminal electrodes, ie without beads, for guiding in the insulator.

The connection electrodes are made of copper and can in principle be so thick that they correspond to the resulting pressure and thermal loads. Comparatively thin connection electrodes are possible by providing additional stiffening electrodes 12a and 12b according to FIG. 1, which in particular contain an iron-nickel alloy. The additional stiffening electrodes 12a, 12b are brazed to the associated terminal electrodes 7a, 7b quasi in sandwich construction and form composite electrodes. The stiffening electrodes may for example be about 1 mm thick.

The stiffening electrodes preferably have a form complementary to the terminal electrodes, so that they also have indentations and are adapted to the shape of the terminal electrodes. The stiffening is provided at thin connection electrodes to prevent bursting of the spark gap or a pressing of the terminal electrodes' during a rush current discharge. However, for low surge current requirements of less than 50 kA, the stiffening electrodes 12a, 12b may be omitted if the _. Connection electrodes are amplified accordingly, for example, to 1 mm, see also Figure 4. It is preferable to choose as the electrode material copper or copper-plated before assembly FeNi alloy. During the execution, the reliability of the gas-tight ceramic-metal connection must be maintained.

The interior 3 of the spark gap 'is filled with a gas mixture, which preferably contains an argon content of about 35 to 95%, a hydrogen content of 5 to 20% and a neon content of up to 40%. This achieves a dynamic ignition voltage and a safe extinguishing behavior. With this gas mixture can be set at a distance of 2 mm between the pin and the Rohrelektrod'e or the width of the discharge chamber 8, a static ignition voltage of about 600 V safely. ,

Discharge through the spark gap typically proceeds as follows. The electricity flows from the

Stiffening electrode 12a and the terminal electrode 7a to the pin electrode 4, via the spark discharge of the discharge space 8 to the tube electrode 5 and the terminal electrode 7b. It leaves the spark gap at the stiffening electrode 12b to be further derived there, for example by means of an external line. In the discharge space 8, the surge current discharge takes place, above all, in a radial manner, the insulator 2 being largely shielded from the pin electrode by means of the tube electrode.

A current flow in the reverse direction is also possible, with current flowing through the electrodes 12b, 7b into the tube electrode 5 flows, from there via the discharge space 8 to the pin electrode 4 and finally to the electrodes 7a and 12a. ^■

FIG. 2 shows a further embodiment of a spark gap 21 according to the invention. In the cavity 23 formed by the insulator 22 and the terminal electrodes 27a, 27b, a pin electrode 24 and a tube electrode 25 extend, which are nested and define the main discharge space 28. On the free end of the pin electrode 24, an activation mass 26 is attached, for example in a waffle-like surface structure. The inner wall of the insulator carries applied Zündstriche 29. Sandwich-like stiffening electrodes 27c and 27d are fixedly connected to the terminal electrodes 27a and 27b, for example by soldering. With regard to the selection of materials and the selection of gases, reference is made to the remarks on FIG. 1 in order to avoid repetition. The embodiment results in an extremely compact design with excellent electrical, thermal and mechanical properties. ^''

The embodiment according to Figure 2 differs from the structure of Figure 1 on the one hand by an even lower overall height. On the other hand, the terminal and stiffening electrodes are flat and have no cavity-side protrusions. Overall, the structure with a height of 10 mm is extremely compact, the diameter of, for example, 30 mm corresponds to that of Figure 1. This construction is suitable for electrically switching several, in particular 3 or 4, spark gaps. On a 230 V mains without current-limiting components, such as resistors or varistors, it is possible to strike lightning the streaming stream will be deleted directly. A lowered ignition voltage of about 200 V is ensured with a gas mixture of neon-argon-hydrogen (Ne / Ar / H ~) in a ratio of 89/1/10 and an electrode gap 8 of 1 mm.

Figure 3 shows an embodiment of the invention with a spark gap 30, in which, as in Figure 1, the two solution forms of the invention are combined. In the cavity 33 formed by the insulator 32 and the terminal electrodes 37a, 37b, a pin electrode 34 and a tube electrode 35 which are nested and define the main discharge space 38 extend. On the free end of the pin electrode 34, an activation mass 36 is applied, for example in a waffle-like surface structure. The _. Inner wall of the insulator carries applied ignition strips 39, which are largely shadowed by the tube electrode 35 from the pin electrode 34.

The terminal electrodes 37a, 37b on the end faces of the cylindrical insulator 32 have on the outer edge of the cavity 33 annular bulges 31. Each bulge causes the guide of the corresponding terminal electrode relative to the insulator. Alternatively, the bulges can also be designed so that a series of beads in the bulges of the terminal electrodes takes the lead. The tubular electrode 35 is welded or with the bulge of the terminal electrode 37b soldered, ^'while the pin electrode 34 is welded or in the central region of the connection electrode 37a is soldered to this.

Sandwich-like are with the terminal electrodes 37a and 37b Stiffening electrodes 40a and 40b firmly connected, eg welded or soldered. Possibly. Provided connection bolts are preferably arranged in the bulges of the stiffening electrodes 40a, 40b. With regard to the materials and the selection of the gases, reference is made to the statements on FIG. 1 in order to avoid repetition.

The embodiment achieves a very compact design of the spark gap with optimized properties. This allows the electrode materials to be tailored to specific requirements and to prefabricate the complete electrodes. Due to the annular indentation or the beads a self-aligned or easy-to-adjust mounting is possible. Further advantages result in the same way as in the corresponding features of the other figures ^' .

Figure 4 shows a second solution form of the task. The spark gap 50 has a cavity 43 formed by the insulator 42 and the terminal electrodes 47a, 47b. In the cavity 43 a pin electrode 44 and a tubular electrode 45, the interengaging protrude or are nested ^"and define the discharge space -48. At the free end of the pin electrode 44 extend is an activation mass 46 mounted, for example in a waffle-like surface structure. On the At the bottom of the tube electrode 45 there is an activating mass 19. The inner wall of the insulator bears applied igniter bars 29.

The terminal electrodes 47a and 47b have annular projections 41. Each projection causes the corresponding terminal electrode to be guided relative to the insulator 42. Alternatively, the projections can also be designed in such a way that - 1.6 -

that a series of beads in the bulges of the terminal electrodes takes the lead. The tube electrode 45 is welded or soldered to the bulge of the terminal electrode 47b, while the pin electrode 44 is welded or soldered thereto in the central area of the terminal electrode 47a.

With regard to the selection of the electrode materials and the selection of the gases, reference is made to the remarks on FIG. 1 in order to avoid repetition. In contrast, the material thickness of the terminal electrodes is larger and selected so that the pressures and temperatures occurring during a discharge are reliably controlled. The embodiment leads to an extremely compact design with excellent electrical, thermal and mechanical properties. The functionality of the spark gap corresponds to that of the spark gap shown in FIG. The embodiments of the invention according to Figure 2 and Figure 4 form the two essential solutions of the invention.

The spark gap according to FIG. 5 is shown in a three-dimensional view. It corresponds in terms of their construction to a spark gap according to Figure 1 and has additional connection bolts 13a, 13b. These can either be connected directly to the connection electrodes 7a, 7b or to the stiffening electrodes 12a, 12b, preferably in their respective indentations. The connection can be carried out by soldering or welding.

The spark gaps described are preferably used for deriving direct lightning currents. They can also be used as a device or separating spark gap for the corrosion protection of gas, water and oil lines. Furthermore they can be used as arresters for network protection in home installations.

The spark gaps according to the invention have a very compact design of eg 30 mm diameter and 30 mm height or less. They have AC carrying capacities of, for example, 300 amps for a period of 0.2 seconds and can dissipate lightning currents of up to 200 kiloamps. They are suitable for the load with surge current waves of the normalized curve of 8/20 (rise time 8 μsec and back half-life 20 μsec) and 10/350. Also, they respond quickly, such as at a voltage of less than 1500 volts with a; Slope of about 5 kV / μsec before and after current loads. The static ignition voltage is for example between 600 and 900 volts. The spark gaps have a good quenching behavior at an alternating voltage of 255 volts, with reticule currents in the range of about 100 amps after the first half cycle can be safely deleted.

LIST OF REFERENCE NUMBERS

1, 21, 30, 50 spark gap

2, 22, 32, 42 insulator

3, 23, 33, 43 cavity

4, 24, 34, 44 pin electrode / first electrode 4a, 44a chamfered end of the pin electrode

5, 25, 35, 45 tube electrode / second electrode 5a chamfered end of the tube electrode

6, 19, 26, 36, 46 Aktivieruήgsmasse 7a, 27a, 37a, 47a first terminal electrode 7b, 27b, 37b, 47b second terminal electrode

8, 28, 3-8, 48 discharge space

9, 2, 39, 49 Ignition marks 10 Indentation of a stiffening electrode

11 bead of a connection electrode

12a, 27c, 40a ^• first stiffening electrode

12b, 27d, 40b second stiffening electrode

13a, 13b connecting bolt

14 gas

Claims

claims

A spark gap (1; - 50) having a cavity (3; 43) which is comprised of two connection electrodes (7a, 7b; 47a 47b) and an electrical insulator (2; 5, 45) with indentations (11, 41) of the connection electrodes on the side of the cavity (3, 43) and with a guide of the connection electrodes on the inner wall of the insulator.

2. spark gap according to claim 1, wherein the guide by means of beads (11) takes place in the terminal electrodes.

3.Funkenstrecke according to claim 1 or 2, wherein on the ^■ terminal electrodes (7a, 7b) connecting pins (13) are mounted.

A spark gap (1; 21) having a cavity (3; 23) which is surrounded by two connection electrodes (7a, 7b; 27a, 27b) and an electrical insulator (2; 5, 25) protruding pin electrode (4, 24) and with

Stiffening electrodes (12a, 12b; 27c, 27d) each connected to one of the terminal electrodes. ^•

5. spark gap according to one of the preceding claims, wherein the insulator is cylindrical and on each end side of the insulator (2) has a connection electrode (7a, 7b) is arranged.

6. spark gap according to one of the preceding claims, wherein the pin electrode (4) with a first Connection electrode (7a) and the tube electrode (5) with a second connection electrode (7b) is connected.

7. spark gap according to one of the preceding claims, wherein the inner surface (2a) of the insulator (2) ignition aids (9).

8. spark gap according to one of the preceding claims, wherein the cavity (3) is hermetically sealed to the outside.

9. spark gap according to claim 8, wherein the

Terminal electrodes (7a, 7b) close the insulator (2) gas-tight.

10.Funkenstrecke according to any one of the preceding claims, wherein the cavity (3) with gas (14) is filled.

11. A spark gap according to claim 10, wherein the gas contains at least one of the following components: between 35 and 95% argon, between 5 to 15% hydrogen and between 0 to 40% neon.

12. Spark gap according to one of the preceding claims, wherein the tube electrode (5) and the insulator (2) are spaced from each other.

13. Spark gap according to one of the preceding claims, wherein the pin and the tube electrode (4, 5) each in the cavity (3) lying ends (4a, 5a), which are chamfered.

14. spark gap according to one of the preceding claims, wherein at the pin electrode (4) and / or at the Pipe electrode (5) an activation mass (6) is applied