EP0920098A2 - Overvoltage protection element - Google Patents

Abstract

The overvoltage protection element (1) has a housing (5) enclosing a pair of spaced electrodes (2,3) defining a spark path (4). Each electrode has a termination arm (6,7) and a relatively angled spark horn (8,9). The first part of each spark horn extends at right angles to the termination arm, with its outer end curved for providing a curved or angled spark path.

Description

The invention relates to an overvoltage protection element for the derivation of transients Surges, with two electrodes, one effective between the electrodes Air breakdown spark gap and a housing that receives the electrodes, where each electrode has one lead leg and one at an acute angle the associated connecting leg has a spark horn and between the spark horns of the two electrodes, spaced apart from each other the air breakdown spark gap is formed.

Electrical, but in particular electronic measuring, control, regulating and switching circuits, especially telecommunications equipment and systems are sensitive to transients Surges such as those caused by atmospheric discharges, but also due to short circuits and switching operations in energy supply networks may occur. This sensitivity has increased as electronic Components, in particular transistors and thyristors, are used; above all, integrated circuits are increasingly being used to a large extent endangered by transient overvoltages.

In addition to the surge protection element from which the invention is based (cf. the DE - A - 44 02 615), ie one with an air breakdown spark gap, there are overvoltage protection elements with an air flashover spark gap to which a sliding discharge occurs when activated (cf. DE-A-27 18 188, DE-A-29 34 236 and DE-A-31 01 354).

Surge protection elements of the type from which the invention is based, that is to say those with an air breakdown spark gap, now have overvoltage protection elements with an air flashover spark gap the advantage of a higher one Surge current carrying capacity, but the disadvantage of a higher one - and not particularly constant - response voltage.

There are now various surge protection elements with an air breakdown spark gap has been developed in terms of response voltage have been improved (cf. DE - A - 41 41 681, DE - A - 41 41 682 and DE - A - 42 44 051).

An older patent application (cf. DE-A-44 02 615) was based on the task the overvoltage protection element described at the outset in its total Improve surge protection behavior, especially with regard to the Response voltage, the lightning impulse current and line follow current carrying capacity behavior and the line follow current deletion behavior.

The above problem is solved by various teachings, these Teaching can be used alternatively, but above all also cumulatively.

A first lesson after the aforementioned older patent application has and essentially to the content that the spark horns of the electrodes in their to the connecting leg adjacent areas with a through the connecting leg Hole are provided. These holes ensure that at the moment the response of the overvoltage protection element an improved ignition and arc running behavior is given, in particular the arc next to the Drilling through thermal-atmospheric blowing is "set in motion".

A second lesson after the aforementioned older patent application has initially and essentially to the content that between the opposite ends the connecting leg of the two electrodes has a - triggering a sliding discharge - Ignition aid is provided. With the surge protection element designed according to this teaching is as it were in the narrowest part of the air breakdown spark gap, So where there is a response, an auxiliary air arcing spark gap integrated. The integrated auxiliary air arcing spark gap has a relatively constant and above all, lower response voltage than that of the actual surge protection serving air breakdown spark gap. Once addressed at a relatively constant low response voltage, the ignited auxiliary air breakdown spark gap leads to a "sudden" ignition of the air breakdown spark gap with a relatively high current carrying capacity, i.e. high lightning impulse current and grid follow current carrying capacity. So in this embodiment are the advantages an air breakdown spark gap and an air breakdown spark gap realized and their disadvantages eliminated.

A third teaching after the aforementioned older patent application has and essentially to the content that the housing is at least partially made of a plastic exists that does not give off carbon during combustion, or at least is partially lined with such a plastic. Usually the installation of electrodes forming an air breakdown spark gap with spark horns in a relatively small, plastic, which when heated or burned Releases carbon, existing housing is problematic. In particular it happens due to the very hot arc that arises after the response Combustion of the plastic and thus an enormous release of carbon. This leads to the electrodes becoming dirty and no longer having insulation strength is available. In addition, the enormous amount of carbon in the Gas mixture the extinguishing behavior of the electrodes. The disadvantages described above of course do not occur if the housing is at least partially made of one Plastic consists of no carbon when heated or burned emits, or if the housing at least partially with such a plastic is lined.

A fourth teaching after the aforementioned older patent application has and essentially to the content that the side walls of the housing are relatively close to the spark horns of the electrodes are used. One enters through this teaching extraordinarily good atmospheric blowing of the arc. It runs very well quickly to the tips of the spark horns, so it does not get stuck in the ignition area.

Finally, a fifth teaching after the aforementioned older patent application first and for the most part to the content that the spark horns of the electrodes Adjacent housing cover made of electrically conductive material, preferably made of There is copper tungsten, the distance between the Housing cover adjacent ends of the spark horns of the electrodes and the housing cover is chosen so that between the ends adjacent to the housing cover arcing can occur between the spark horns and the housing cover. At this overvoltage protection element, the arc initially migrates out of the Ignition area at the tips of the spark horns. Then form between the tips the spark horns and the housing cover made of electrically conductive material two arcs. The conductor loop that builds up ensures that that the two arcs are driven behind the spark horns. That has to Consequence that two arcs are formed, all of which for an enormously high arc burning voltage with the follow-up current. This in turn means that the Deletion behavior for the network follow-up current has changed significantly, namely one quasi short-circuit proof discharge path has arisen. Because the two arcs behind the spark horns is the sensitive ignition area extremely well protected between the spark horns.

Starting from the prior art described in detail above, the The present invention is based on the object of a surge protection behavior again improved surge protection element specify.

The surge protection element according to the invention is now characterized in that that the air breakdown spark gap bent and / or angled is and that the spark horns are each approximately at right angles to the connecting leg trending straight lower area and one on the straight Have area adjacent arcuate upper area. In the house of Applicant has surprisingly found that due to the previously described formation of the air breakdown spark gap in terms Surge protection element further improved in its surge protection behavior in contrast to one with a simple V or angular shape trained air breakdown spark gap results. When tests are carried out it has been found that the training of the invention Air breakdown spark gap the plasma between the two spark horns is blown out directly and very quickly, so that the invention has a high lightning current carrying capacity and network follow current extinguishing isolating spark gap and thus results in a significantly improved surge protection element. Because of the rapid blow-out it is practical to "seize" the arc in the ignition area not possible anymore.

An overvoltage protection element is already known (see US - A - 3,309,575), which, like the surge protection element according to the invention, is a non-symmetrical one Air breakdown spark gap; the air breakdown spark gap is arched. The surge protection element according to the invention differs from this known surge protection element characterized in that in the overvoltage protection element according to the invention Electrodes each have a special connection leg and the spark horns run at an angle to the associated connecting leg, while in the known surge protection element mentioned above, such Connection legs are not realized, and that in the invention Surge protection element the air breakdown spark gap from a lower Area and an upper area, with the lower area through straight areas of the two spark horns is formed, the lower areas of the two Spark horns therefore run parallel to each other, while in the previously mentioned known surge protector the two the air breakdown spark gap electrodes are continuously curved are.

In particular, there are various options for the surge protection element according to the invention to design and develop.

Basically, it is to at least partially achieve the advantages mentioned above possible to bend the air breakdown spark gap between 10 ° and 180 °. A particularly advantageous surge protection behavior and a very fast one However, movement of the arc to the tips of the spark horns results then when the air breakdown spark gap is bent by about 90 ° and / or is angled. Otherwise, it is advantageous if the lower region of the air breakdown spark gap an angle of about 10 ° to 40 °, preferably of includes about 20 ° to 30 ° and the two areas of the spark horns essentially smoothly merge.

Furthermore, it is particularly useful that the air breakdown spark gap opens directly into a blow-out opening in the housing, so that the resulting exhaust gases can be blown out directly and not in the housing knock down.

In addition, it is particularly advantageous if at least within the housing a quenching plate arrangement having a plurality of quenching plates is provided. The surge protection behavior, in particular the line follow current quenching behavior improving effect of the quenching plate arrangement is based on the fact that the arc is arranged in a series of short, partial arcs is resolved and that the sum of the partial arcs is higher Voltage requirement than the undivided arc, so that after the voltage zero a higher re-ignition voltage is required than with an undivided arc. In addition, touching the Arc or the partial arc with the relatively cold, good heat conducting Extinguishing plates intensive cooling and thus deionization of the arc plasma.

In order to achieve a quick and good arc extinguishing, it is still advantageous if the quenching plate arrangement in or following the air breakdown spark gap is arranged in the region of the blow-out opening. Hereby the arc runs almost directly into the quenching plate arrangement.

To drive the arc even faster into the quenching plate arrangement, it is also appropriate to use extinguishing plates made of ferromagnetic material, preferably made of iron. The creation of the forces that cause the arc in the Extinguishing sheet arrangement drives in, explained when using extinguishing sheets made of ferromagnetic material from the endeavor of the one through which current flows Conductor surrounding magnetic flux, if possible through the magnetic much better to run as air-conducting iron quenching plates; the arc is therefore from a quenching plate arrangement, the quenching plates made of ferromagnetic material exist, attracted.

Are extinguishing plates in the surge protection element according to the invention If iron is used, it is recommended to cover the fire-extinguishing plates with a surface coating made of corrosion-resistant material, preferably of silver or nickel Mistake.

If it has previously been said that the surge protection element according to the invention Has baffle plates, it is preferably around rectangular baffle plates, the baffle plates having a cross section with a length to width ratio of about 4: 1 to about 2: 1, preferably of about 3: 1.

Finally, it lends itself to the exhaust gases that occur during the formation of the arc not only through a blow-out opening, but also through one, the blow-out opening drain the opposite exhaust opening in the housing. Accordingly the larger spark horn is designed so that it creates the resulting exhaust gases on the one hand leads in the direction of the blow-out opening, on the other hand an outflow into Direction of the exhaust opening allows. By creating another opening - The exhaust opening - is the danger that the exhaust gases are inside the housing precipitate and thereby the function of the surge protection element have been significantly reduced.

The measures described in detail above are inventive in themselves Meaning; they can also be implemented with surge protection elements, where the teaching or the teachings of the earlier patent application discussed at the beginning are not realized. Of particular importance is the one described above Measures however in connection with the teaching or the teaching the earlier patent application discussed at the beginning.

Fig. 1

einen Längsschnitt durch eine erste Ausführungsform eines erfindungsgemäßen Überspannungsschutzelementes,

Fig. 2

einen Schnitt durch das Überspannungsschutzelement aus Fig. 1 entlang der Schnittlinie II - II in Fig. 1,

Fig. 3

einen Längsschnitt durch eine weitere Ausführungsform eines erfindungsgemäßen Überspannungsschutzelementes und

Fig. 4

einen Schnitt durch das Überspannungsschutzelement aus Fig. 3 entlang der Schnittlinie IV - IV in Fig. 3.

Further features, advantages and possible uses of the present invention result from further patent claims, which are not mentioned in detail, from the following description of exemplary embodiments with reference to the drawing and the drawing itself Subject of the present invention, regardless of their summary in the claims or their relationship. Show it

Fig. 1

2 shows a longitudinal section through a first embodiment of an overvoltage protection element according to the invention,

Fig. 2

2 shows a section through the overvoltage protection element from FIG. 1 along the section line II-II in FIG. 1,

Fig. 3

a longitudinal section through a further embodiment of an overvoltage protection element according to the invention and

Fig. 4

4 shows a section through the overvoltage protection element from FIG. 3 along the section line IV-IV in FIG. 3.

The overvoltage protection elements 1 shown in FIGS. 1 to 4 are used for derivation of transient overvoltages and for limiting surge currents. In 1 and 2 on the one hand and 3 and 4 on the other are two different Embodiments of overvoltage elements 1 shown. Both embodiments but have essentially the same structure. Each of the surge protectors 1 points to two electrodes 2, 3, one between the electrodes 2, 3 effective air breakdown spark gap 4 and an electrode 2, 3 receiving Housing 5. Each electrode 2, 3 has a connecting leg 6, 7 and a spark horn 8, 9 running at an angle to the connecting leg 6, 7. The mentioned angle between the respective connecting leg 6, 7 and the spark horn 8, 9 refers to the functional area of the spark horn 8, 9. The spark horns 8, 9 of the two electrodes 2, 3 arranged at a distance from one another together the air breakdown spark gap 4. Because the spark horns 8, 9 in the manner explained above at an angle to the connecting legs 6, 7 run, the air breakdown spark gap 4 is angled and preferably tapered.

As can be seen from the individual figures, the two spark horns 8, 9 are in their to the connecting legs 6, 7 adjacent areas each with a preferably provided bore 10, 11 running parallel to the connecting legs 6, 7, those in the exemplary embodiment of the figures shown in the center of the spark horns 8, 9 the electrodes 2, 3 are realized. In the illustrated embodiments, in only one bore 10, 11 is provided for each spark horn 8, 9. However, it is it is also possible to have two holes in a spark horn to provide. The in the spark horns 8, 9 of the electrodes 2, 3 of the overvoltage protection element 1 provided holes 10, 11 ensure that at the moment the response of the overvoltage protection element 1, ie the ignition, the resulting arc next to the holes 10, 11 by a thermal and / or electrical and / or magnetic pressure and / or force "in Ride is set ", that is to say it moves away from its point of origin.

Otherwise, it can be seen from the figures that in the exemplary embodiments shown the spark horns 8, 9 of the electrodes 2, 3 on each side provided with a chamfer 12, 13 and convex on their mutually facing sides are trained. The chamfering of the spark horns 8, 9 of the electrodes 2, 3 prevents that there is material removal at the edges of the spark horns 8, 9. The preferred implemented measure, the spark horns 8, 9 of the electrodes 2, 3 on their Forming sides facing each other in a convex manner leads to the fact that after one Response of the overvoltage protection element 1 arcing preferably occurs centered in the area of the spark horns 8, 9 and centered at the ends or tips of the spark horns 8, 9 runs.

In the two exemplary embodiments of overvoltage protection elements shown in the figures 1 is between the opposite ends of the connecting leg 6, 7 and in the lower area of the two spark horns 8, 9 of the two Electrodes 2, 3 are provided with a starting aid 14 which triggers a sliding discharge. This ignition aid 14 is preferably made of an insulating material which, when the state changes, for example heating, no carbon in detrimental function Provides dimensions, and slightly, preferably 0.1 mm or more, in the air breakdown spark gap formed by the spark horns 6 of the electrodes 2 4 protrudes. In the exemplary embodiment shown, the ignition aid 14 projects up to the center of the bores 10, 11 into the air breakdown spark gap 4. in the remaining is the ignition aid 14, as can be seen from FIGS. 2 and 4, at its Air breakdown spark gap 4 facing side V-shaped. To the V-shaped formation can be a narrow slot extending downward connect that is not shown. This slot in the ignition aid 14 has a positive effect the response voltage.

In the illustrated exemplary embodiments of overvoltage protection elements 1 is now, as it were, in the narrowest part of the measures described above Air breakdown spark gap 4, namely where there is a response or ignition takes place, an auxiliary air arcing spark gap integrated. This integrated Auxiliary air arcing spark gap has a relatively constant and above all less Response voltage as the actual surge protection Air breakdown spark gap 4. Once addressed, at a relatively constant low response voltage, leads the ignited auxiliary air arcing spark gap to a "sudden" ignition of the air breakdown spark gap 4 with a relatively high current carrying capacity.

The housing 5 of the surge protection element 1 according to the invention is made at least partially made of a plastic, which during heating or combustion don’t release carbon. Alternatively, it can be provided that the housing has a liner made of a plastic which, when heated or Combustion does not give off carbon.

It is now essential for the present invention that the air breakdown spark gap 4 is bent and / or angled and that the spark horns 8, 9 each have a straight line running approximately at right angles to the connecting leg 6, 7 lower area and an arcuate adjoining the straight area have upper area. This special design of the air breakdown spark gap on the one hand it is ensured that the between the Spark horns 8, 9 and directly blown out formed plasma on the other hand and as a result of the arc being extinguished quickly, safely and well. All in all results from the formation of the spark gap according to the invention high-lightning current carrying and line follow current extinguishing isolating spark gap.

The air breakdown spark gap 4 is preferably between 10 ° and 180 °, in particular bent and / or angled by about 90 ° and closes the lower one Area of the air breakdown spark gap 4 an angle of approximately 10 ° to 40 °, preferably from about 20 ° to 30 °.

The embodiments shown in the figures are appropriate because between the individual, previously mentioned areas have a smooth transition and there is no unintentional material removal on edges or steps is coming.

The two shown in FIGS. 1 and 2 on the one hand and 3 and 4 on the other Embodiments each have another similarity, namely that the Air breakdown spark gap 4 in a discharge opening located in the housing 5 15 opens into it. So this means that the plasma is directly or immediately together are blown out with the resulting exhaust gases via the blow-out opening 15 can.

In the embodiment shown in FIGS. 3 and 4 is a quenching plate arrangement 16 provided within the housing 5, which has a plurality of quenching plates 17 has. The quenching plate arrangement 16 is connected to the air breakdown spark gap 4 arranged, preferably in the region of the blow-out opening 15, right in front of this. The quenching plates 17, which are preferably rectangular Have cross section, are made of ferromagnetic material, preferably made of iron. For "extinguishing" reasons, it is advisable that the extinguishing plates a cross section with a ratio of length to width of about 4: 1 to 2: 1, preferably about 3: 1. In addition, the quenching plates 17 with a surface coating made of corrosion-resistant metal, preferably silver or made of nickel.

In addition to the quenching plates 17 provided in the discharge opening 15, the Quenching plate arrangement 16 still a top quenching plate 18 or an uppermost Ladder and a lower quenching plate 19 or a lowermost conductor. At the in 3 and 4, the embodiment shown is the top extinguishing plate 18 the same potential as the larger spark horn 8, while the lower quenching plate 19 has the same potential as the smaller spark horn 9. The respective Extinguishing plates 18, 19 are electrically connected to the respective spark horns 8, 9. It should also be provided here that the transition from the larger spark horn 8 on the top extinguishing plate 18 and from the smaller spark horn 9 to the bottom Extinguishing plate 19 is essentially stepless.

In order to get away as quickly and efficiently as possible when the Arc occurring exhaust gases from the housing 5 to realize a precipitation To be avoided in the housing 5 as far as possible, in the case of FIGS. 3 and 4 illustrated embodiment provided that the width of the larger spark horn 8 is at least in the upper area less than the width of the housing 5 and that opposite the blow-out opening 15, an exhaust opening 20 in the housing is provided. It is expedient on both sides between the larger spark horn 8 and the housing 5 each have a slot 21, 22, to which in the outflow direction the exhaust gases connects the exhaust opening 20. Overall, the in 3 and 4 embodiment shown a bilateral exit of the exhaust gases.

In the embodiment shown in FIGS. 1 and 2, the slots 21, 22 not provided. Here, the side walls 23, 24 of the housing 5 to the spark horns 8, 9 are used. This results in an extraordinarily good one Running behavior of the arc; it runs very quickly to the tips of the spark horns 8, 9.

Claims (10)

Surge protection element (1) for dissipating transient overvoltages, with two electrodes (2, 3), an air breakdown spark gap (4) effective between the electrodes (2, 3) and a housing (5 ), each electrode (2, 3) having a connecting leg (6, 7) and a spark horn (8, 9) running at an angle to the associated connecting leg (6, 7) and between the spark horns (8, 9) of the two - The air breakdown spark gap (4) is formed at a distance from one another - electrodes (2, 3), characterized in that the air breakdown spark gap (4) is bent and / or angled and that the spark horns (8 , 9) each have a straight lower region running approximately at right angles to the connecting leg (6, 7) and an arcuate upper region adjoining the straight region. Surge protection element according to claim 1, characterized in that the Air breakdown spark gap (4) between 10 ° and 180 °, in particular by about 90 ° bent and / or angled and / or that the lower region of the air breakdown spark gap (4) an angle of about 10 ° to 40 °, preferably from about 20 ° to 30 °. Surge protection element according to claim 1 or 2, characterized in that the two areas of the spark horns (8, 9) essentially continuously pass over. Surge protection element according to one of Claims 1 to 3, characterized in that that the air breakdown spark gap (4) directly into one in the housing (5) located discharge opening (15) opens. Surge protection element according to one of Claims 1 to 4, characterized in that within the housing (5) at least one quenching plate arrangement (16) with a plurality of quenching plates (17) is provided and that the quenching plate arrangement (16) preferably in the or preferably immediately afterwards is arranged on the air breakdown spark gap (4). Surge protection element according to claim 5, characterized in that the Quenching plate arrangement (16) is arranged in the region of the blow-out opening (15). Surge protection element according to claim 5 or 6, characterized in that the extinguishing plates (17) made of ferromagnetic material, preferably iron consist of and / or with a surface coating of corrosion-resistant metal, preferably made of silver or nickel. Surge protection element according to one of Claims 5 to 7, characterized in that the quenching plates (17) have a rectangular cross section, preferably with a length to width ratio of about 4: 1 to about 2: 1, especially of about 3: 1. Surge protection element according to one of Claims 5 to 8, characterized in that that the top quenching plate (18) at the same potential as that larger spark horn (8) and the lowest quenching plate (19) on the same potential like the smaller spark horn (9). Surge protection element according to one of Claims 1 to 9, characterized in that that the width of the larger spark horn (8) at least in the upper area is smaller than the width of the housing (5) and preferably opposite the exhaust opening (15), an exhaust opening (20) is provided in the housing (5) is and / or that on both sides between the larger spark horn (8) and the side walls (23, 24) of the housing (5) a slot (21, 22) is provided.

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