EP1542323B1 - Overvoltage protection device, based on spark gaps, comprising at least two main electrodes arranged in an enclosed housing - Google Patents

Description

The invention relates to a spark arrestor overvoltage protection device, comprising at least two main electrodes located in a pressure-tight housing and at least one auxiliary starting electrode, wherein a functional subassembly for reducing the response voltage of the spark gap is housed in the housing volume, which is in communication with one of the main electrodes and the auxiliary ignition electrode. The trend in the development of electrical and electronic systems is towards greater compactness and smaller external dimensions. At the same time, however, the sensitivity to inner and outer overvoltages of such systems is increasing. In addition, there is the desire and the need for a trouble-free operation of electrical and electronic devices, resulting in new requirements for the surge protection technology.
So are surge arresters with reduced operating voltage z. B. from the DE 199 52 004 A1 or the DE 198 03 636 A1 known. In order to make the systems even more compact, in recent years there has been an increasing tendency to arrange lightning current arresters for coarse protection and surge arresters for fine protection without the previously customary decoupling via cable runs or by specially dimensioned inductors directly next to each other.
So that the less powerful fine protection element is not necessarily overloaded in such a compact arrangement, there are special requirements for the lightning arrester and the coarse protection element.

To realize this task, it was known to use separate and externally coupled to the lightning arrester on spark gap basis, sometimes quite complex ignition aids. According to DE 199 52 004 A1 Under certain conditions, these ignition aids also assume functions or partial functions of the fine protection.

In general, the starting aids for high-performance surge arresters are designed for use in low-voltage networks between L and N or else N and PE as active ignition aids. These ignition aids generate a high ignition voltage with the aid of a pulse transformer, through which one of the partial sections is covered in a typical three-electrode spark gap arrangement.
The disadvantage of such a solution is on the one hand the sometimes considerable space requirement of the ignition aid, which usually consists of a plurality of components, and on the other hand, the resulting interference factors.

The space requirement of this ignition device limits the design possibilities for the main functional element, namely the actual spark gap, given the relatively small dimensions of the surge arresters. This limitation not only concerns the volume generally available, but also the need for the necessary additional contacting of a third electrode.

Compared to a simple spark gap without ignition aid is currently a variety of additional sources of interference.
In the spark gap itself, not only the function of a separation distance must be guaranteed, but the function of two or even three separation distances between the three-electrode arrangement. If damage occurs to one of these separation sections, there is a risk of the arrester failing. This can lead to damage within the spark gap, but also the ignition aid itself. This can quickly lead to destruction of the entire arrester and endangering adjacent elements, in particular when the ignition aid is overloaded. The same is not only for damage within the spark gap, but also in case of disturbances such as vibrations, vibrations, burn-off, poor installation and so on, damage or corrosion of the contacts of the ignition device with the main terminals and the connectors to the spark gap quite possible.
Bad or aged contact points can lead to sparking outside the spark gap and ultimately to outer spark gap.

Although there are certainly ways to protect the ignition aids from overloading at least partially, but such measures, such as in the DE 199 14 313 A1 shown, only further, costly effort and space requirements.

However, with all the difficulties discussed above, a priming aid for desired low levels of protection is indispensable. The general reduction of the distance of the main electrodes, as was the case with older devices of the prior art, is not expedient in modern arresters, as in the usual geometric conditions, the required distances are not feasible or this means a significant deterioration of the achievable surge currents ,

In the generic DE 101 57 817 A1 an arrangement for a spark gap is presented, in which a conventional active ignition aid is integrated with a pulse transformer in a chamber-shaped housing enclosed by the electrodes.

However, this arrangement has the disadvantage that an active ignition aid is necessary, whereby the space requirement and the susceptibility increase. This safe operation of active ignition aids is disturbed, inter alia, by changing the response values and the insulation value of the individual separation sections. As these phenomena increase with the number and magnitude of loads, this can lead to thermal overload or even failure of the ignition aid. The risk of thermal overload increases in the above-mentioned arrangement additionally by the lack of cooling or by the heating due to the power consumption in the spark gap and thus the ignition device under load.

The design of the electrodes according to DE 101 57 817 A1 would also be relatively large, so on the one hand the ignition aid can be added and on the other hand, the ignition aid is protected from the influence of temperature of the thermally heavily loaded electrodes. Furthermore, there is the need for frictional connection to produce reproducible distances of the partial spark gaps between the electrodes, whereby the ignition aid is not only thermally but also loaded by mechanical forces.
Also occur strong dynamic loads between the electrodes in response to the spark gap. Further restrictions arise in this arrangement when used in a spark gap for network applications. In contrast to the spark gap, network spark gaps must master and resolve secondary currents in the kA range, which not only causes further and in particular longer-acting thermal loads, but also corresponding consequential current-quenching or even consequential current-limiting measures have to be implemented. In particular, with regard to the possibilities of limiting the reticule current in conventional dimensions of the surge arresters for grid application, which are generally smaller than separating spark gaps, leads an arrangement as in DE 101 57 817 A1 to extreme limitations in choosing a suitable method of limiting current.

In the DE 195 10 181 A1 is an ignition aid from a first spark gap, which serves to ignite a flashover, and a second spark gap, which is the first connected in parallel and the deletion of the secondary stream, presented. Furthermore, reference is made to the integration of a passive, simple ignition aid in a spark gap. In the illustrated spark gaps, the first spark gap is used to set the response voltage and the resulting spark of the pre-ionization of the second, longer and more current-carrying spark gap. Due to the pre-ionization and the voltage drop across the impedance connected in series with the spark gap, the second spark gap is ignited. The second spark gap has, in contrast to the first spark gap, a high surge current carrying capacity and a good follow current extinguishing capability.
A disadvantage of this solution, however, that the first spark gap the thermal stresses due to the arc and the impurities is exposed as a result of the stresses. The maintenance of low and almost constant threshold voltages is made difficult or impossible. Although in a spatially separated arrangement of the first and second spark gap, it is possible to ensure compliance with a low response value, it is disadvantageous, however, that the preionization of the second spark gap must be dispensed with in order to reduce the response voltage. As a result, the voltage drop across the impedance must be increased until reaching the undiminished response voltage of the second spark gap. If lower response values of the entire spark gap are to be achieved, the choice and performance of the second spark gap will diminish DE 195 10 181 C1 limited.

According to the stack spark gap for medium and high voltage applications after US 3,223,874 individual spark gaps have an ignition aid for preionization. This arrangement can be carried out at least partially encapsulated. However, such a type of spark gaps is only designed for low surge current loads of 8/20 μs and can not withstand the pressures and force effects of significant lightning surge currents. The extinguishing capability for follow-on currents which is partially present in such an arrangement results for the most part from the series connection of a multiplicity of partial spark gaps, each with a starting aid. However, such an expense is not justified for low-voltage arrangements.
The ignition aid is connected directly to the respective main electrodes of the spark gap. It has no third auxiliary electrode and there is no direct discharge directly between the main electrodes. The type of preionization is based there on partial discharges, which spread over both sides of the surface of an existing insulation part. One possibility for a spark discharge, as is commonly used in modern low-voltage arresters, does not exist because the auxiliary electrodes of the ignition aid are located on opposite sides of the insulator. This form of ignition aid is sufficient at high potential differences of several kV for rapid ignition. However, if the response voltage is <1 kV, such an embodiment of a starting aid is not efficient. Moreover, the entire Zündhilfe is defenseless the effect of the arc exposed, which can lead both to disruption in their function as well as to complete destruction.

There are known versions with auxiliary spark gaps, in which a spark discharge is possible. In such arrangements, the discharge from the auxiliary spark gap, in which the current flow is limited by various measures, is transferred to the main electrodes. In such solutions, however, the auxiliary spark gap would have to be equipped with a suitable ignition aid regardless of the delay time to ignite the main spark gap to even a response voltage of z. B. <1kV to keep reliable.

The WO 03/021735 A1 shows a simplified ignition aid for surge arrester, which may be located at least partially inside the spark gap. This ignition aid is based on a series connection of a voltage switching element and a so-called ignition element. The response voltage of the arrester is advantageously determined by the voltage-switching element. The main spark gap is ignited by the fact that after ignition of the voltage-switching element, a current flows through the ignition element, whereby a voltage is built up over the main spark gap. As a result of poor electrical contact between the ignition element and a main electrode it should then come to sparking. The spark travels along the firing element and extends until the main spark gap rolls over. This solution has functionally significant disadvantages. The crucial component for safe operation is the so-called ignition element. This is located according to the operation directly in the combustion chamber of the arc. It is thus exposed not only to the ignition of an electrical load, but during the entire discharge process. Likewise, there is a burden on possible subsequent streams. This results in all known materials to considerable Abschmelzungen. This affects in particular metals, but also polymers. Due to the strong dynamic loads, ceramics tend to crack rapidly or change their surface or total resistance as a result of metallic or other conductive deposits. However, this is the beginning to a large extent the sparking, the electrical load of the ignition element and the beginning, but also determines the speed of arc migration along the ignition element.
In addition, the ignition element in this solution during the entire arc duration, consisting of pulse and follow current, due to the direct parallel arrangement to the main electrodes and thus the entire arc voltage with a current flow, whereby the electrical and thermal stress of the ignition element and u. U. also the voltage-switching element is large. Another requirement for the basic function according to WO 03/021735 A1 is the necessary sparking between standing in electrically conductive contact parts, namely the local electrode and the ignition element. It should be obvious that in the embodiment described there, the contact point of load to load even with a spring contact always changed due to melting phenomena or unavoidable contamination. A reproducible spark at such a contact point is thus very difficult to adjust. The aforementioned limitations lead to a very complicated geometry and material selection. Furthermore, the dynamic and thermal stresses caused by the arc and the secondary current can quickly lead to malfunction or defect.
The inserted spring for making contact and tracking of the ignition element may possibly track in case of burning or demolition of the tip of the ignition element. However, the spring can avoid neither a complete break of the ignition element after changes in the contact point due to the formation of melt on the electrode or on the ignition element or the deposits of impurities in the contact area. Of course, the spring must also be protected from burn-off products and the thermal and dynamic stresses caused by the arc.
With a small or even delayed sparking, however, increases the Zündverzugszeit the main spark gap. On the one hand, this can significantly increase the electrical load on the voltage-switching element and also of the ignition element; on the other hand, the voltage across the ignition element and thus over the entire spark gap increases sharply. This also endangers the elements to be protected and the desired low residual voltage values of the lightning arrester.

Another disadvantage of the cited solution is that the distance of the main electrodes is directly connected to the length of the ignition element. In particular, for network spark gaps, however, a relatively large main electrode spacing is often advantageous. However, as the distance between the main electrodes increases, so does the response voltage between the electrodes. That is, at higher distances, a greater preionization between the main electrodes must be made, so that it can lead to the rollover at the desired low voltages. Likewise, the distance at which the spark must travel from the bad pad lengthens until it reaches the other major electrode. This also restricts, as already mentioned, the choice of the usual means for the sequence current deletion or limitation.

The spark gap arrangement after DE 199 52 004 A1 can be operated with both an active and a highly simplified passive ignition aid. These ignition aids are all outside the spark gap.
Moreover, the Zündhilfen consist of a variety of components, which should take over the task of fine protection. However, this requires relatively large and powerful components, whereby integration into the spark gap is difficult. However, the task of fine protection also requires a relatively high power consumption and an additional thermal load.
In the passive ignition aid, which advantageously consists of only a few components, although the space requirement would reduce, but the problem of power conversion remains in the realization of fine protection. The disadvantage is in the DE 199 52 004 A1 Furthermore, that the response of the overall arrangement by the geometric design of the spark gap is determined. In this case, the response voltage of the shorter separation path thus defines the response voltage of the entire arrester. The Ansprechspannungen achievable in this way, however, are not resistant to aging and strongly dependent on the load condition of the spark gap.

The integration of a PTC element in the spark gap is problematic. Such PTC elements heat up due to their operation by up to several 100 K. However, such heating places very high demands on the load capacity of the insulation elements. In addition, such application of a PTC element is made more difficult by the fact that, in order to ensure the functioning of the spark gap, it has to be cooled relatively quickly after loading. However, such a cooling would be hampered by encapsulation.
From the foregoing, it is therefore an object of the invention to provide a spark arrester overvoltage protection device, in particular for low-voltage applications comprising at least two located in a pressure-tight housing main electrodes and at least one auxiliary ignition, which avoids possible sources of interference between ignition aid and spark gap and the principle in all known method for subsequent current deletion, follow current limiting or even the avoidance of subsequent currents in spark gaps can be used. The solution to be specified should therefore allow universal applications, regardless of the specific electrode geometry.
The object of the invention is achieved with a surge protection device on spark gap basis according to the combination of features according to claim 1, wherein the dependent claims represent at least expedient refinements and developments.
According to the basic idea of the invention, a simplified starting aid is assumed which consists of at least one voltage-switching element, an impedance and an isolating distance. The simplified ignition aid is integrated between two main electrodes and completely in the pressure-resistant housing of the overvoltage protection device, ie in the spark gap itself and is part of this. Occurs on such an arrangement, an overvoltage that exceeds the sum of the operating voltages of the switching element and the separation distance of the series circuit, so the ignition aid, whereby a current through the voltage switching element, the impedance and the associated separation distance from the first main electrode to the second main electrode flows. By the arc, which bridges this aforementioned separation distance are immediately at Response of the priming charge carriers placed in the spark gap, which causes an immediate ionization of the separation distance between the two main electrodes, whereby the dielectric strength of this separation distance is reduced and it due to the current increasing voltage drop across the impedance it finally to exceed the now reduced withstand voltage of the separation path between the two main electrodes and thus comes to the ignition of the spark gap.

By integrating into the pressure-resistant housing of the spark gap, but outside the combustion chamber of the arc, all external connection problems of the ignition device are eliminated at the spark gap.
The flameproof enclosure is designed for the control of pressures up to several 10 bar as a result of the strains of the spark gap during lightning and line flow.
In case of a possible overload of the ignition aid, the damage potential is thus essentially limited by the flameproof enclosure of the spark gap. This also eliminates additional protective measures of the ignition itself, such. B. fuses or the like. A possibly desired evaluation of the state of the arrester is also greatly facilitated, since only the overall function, measurable at the outer terminals of the spark gap, and not individual components, connections and components must be monitored.

According to the invention, the Zündhilfs function module for selectively reducing the operating voltage of the spark gap from a fully integrated into the pressure-tight housing, located outside the arc combustion chamber series connection of a voltage-switching element, an impedance and a separation path is formed, wherein the separation distance by the distance of the auxiliary ignition electrode nearest main electrode is defined.

The voltage switching element may for example be a gas arrester. It is also possible to form the voltage-switching element as a suppressor diode, thyristor, varistor and / or as a defined erosion-resistant air or sliding spark gap.

The auxiliary ignition electrode can itself be designed impedance-related and have a complex resistance.

Preferably, the auxiliary ignition electrode extends partially into the arc combustion chamber or is located in this.
The auxiliary ignition electrode may be made of a conductive plastic or a plastic with conductive additives, such as. B. conductive fibers.

The impedance in turn consists of a material with a nonlinear or linear resistance profile.

Likewise, however, the impedance can also consist of a conductive plastic or a conductive ceramic.

Also, an embodiment of the impedance as a discrete component, for. B. resistance, varistor or capacitance lying within the meaning of the invention.

The auxiliary ignition electrode is insulated from the main electrode, wherein the response voltages of each of the main electrodes resulting sub-sections are chosen differently.

The response voltage e _{1 of} the first main electrode to the auxiliary ignition electrode is much larger than the response voltage of the further separation distance e ₂ selected.

To reduce the response voltage of the separation distance e ₂ this is designed as a thin, erosion-resistant insulating film, as erosion-resistant paint coating or other thin insulating layer.
In a further preferred embodiment, the overvoltage protection device has means for flowing the arc with hard gas.

For producing the hard gas, hard-gas-releasing material surrounds at least portions of the arc-combustion chamber, wherein the hard-gas-emitting material additionally has conductive properties to the potential of one of Main electrodes should be brought to the separation distance of the auxiliary ignition electrode.

In the hard gas embodiment, a pressure equalization port prevents accumulation of an undesirable increase in pressure over time.

The pressure equalization port may be formed by the housing or by electrode materials which are at least partially gas permeable.
For this purpose, portions of the housing may consist of a porous polymer material, porous ceramic or correspondingly porous metal.

In a further embodiment, the overvoltage protection device can have residual voltage limiting means.

In particular, it is possible here to carry out the conductive, hard-gas-emitting material, which is electrically connected to one of the main electrodes, in a defined geometry and with defined electrical properties, so that the targeted influencing of the course and the height of the residual voltage can be realized.

Preferably, the resistance of the hard gas-emitting material to the impedance of the series connection of the functional element is lower.

The conductive, hard gas-emitting material carries during the load with surge current as well as with subsequent currents part of each flowing total current, so that increases the reliability of the device according to the invention and its long-term stability.

The proportion of current which is taken over by the conductive, hard-gas-emitting material is virtually adjustable by the ratio of the resistance of this material to the resistance value of the arc.

Preferably, the average value of the resistance of the conductive, hard gas-emitting material is chosen to be greater than the average, mean resistance value of the arc.

In order to protect against thermal and / or mechanical stresses, in one embodiment of the invention, the voltage-switching element and / or the discrete impedance can be integrated into one of the main electrodes. For this purpose, one of the main electrodes have an externally accessible cavity, whereby also, if necessary, an interchangeability of the voltage-switching element is ensured.

The voltage-switching element is inserted in a single-pole insulated manner in the cavity, wherein the cavity has an internal thread for receiving a conductive screw contacting the inserted voltage-switching element.

In a further embodiment of the invention, the end of the auxiliary ignition electrode reaching the arc combustion chamber lies essentially at the same level as the end of the main electrode which reaches into the combustion chamber and is associated with the first separation zone.

Also, the Zündhilfselektrode laterally offset and / or relative to the arc main combustion chamber set back to protect this can be arranged.

Via a supplementary voltage-switching element, which is located outside the pressure-tight enclosure, an adjustment or adjustment of the operating voltage of the overvoltage protection device can take place.

In principle, the presented overvoltage protection device can also be implemented as a combination of a triggerable partial spark gap high response voltage and at least one downstream partial spark gap low response voltage.

In this embodiment, the partial spark gaps may include means for internal potential control.
The partial spark gaps are mechanically fixed and connected via spacers.
The spacers may consist of a conductive, field-controlling material.

In one embodiment of the invention, the spacers and the electrodes of the partial spark gaps may have a sheath, wherein the sheath comprises a shield which is electrically connected on one side for targeted potential distortion or is designed as such itself.

The distance of the electrodes which form the partial spark gap with auxiliary ignition electrode is preferably chosen to be greater than the spacing of the electrodes which define the respectively following partial spark gaps.

The spacer can be performed for the non-triggerable by the auxiliary ignition partial spark gap as an integral component in terms of manufacturing rationalization and easier installation.

To avoid an electrical flashover outside of the arc combustion chamber additional insulating sections or insulating materials, preferably provided in the outer region of the electrodes of the partial spark gap or arranged there.

The spacers have on their side remote from the arc combustion chamber on an insulation coating or insulation sheath, which is a complementary measure to avoid unwanted flashovers.

It is possible to replace the first, triggerable partial spark gap by a gas discharge tube, which determines the response voltage of the overall arrangement, without departing from the basic idea of the invention.

In principle, the spark gap according to the invention can be embodied as a horn spark gap or else as a stack spark gap.

The invention will be explained below with reference to exemplary embodiments and with the aid of figures.

Fig. 1

eine Prinzip-Schnittdarstellung durch eine in einer gekapselten Funkenstrecke befindlichen Zündhilfe;

Fig. 2

eine Ausführungsform ähnlich Fig. 1, jedoch mit zusätzlichem hartgasabgebenden Material, welches den Lichtbogen-Brennraum umgibt;

Fig. 3

eine weitere Ausführungsform der Überspannungsschutzeinrichtung ähnlich wie in Fig. 2 dargestellt, jedoch mit variierter Heranführung des Potentials der Hauptelektrode an die Zündhilfselektrode;

Fig. 4

eine Darstellung einer Überspannungsschutzeinrichtung mit einem spannungsschaltenden Element, integriert in eine der Hauptelektroden;

Fig. 5

eine Ausführungsform mit spezieller höhenmäßiger Zuordnung einer der Hauptelektroden zur Zündhilfselektrode;

Fig. 6

eine weitere Ausführungsform der Zuordnung von Zündhilfselektrode und benachbarter Hauptelektrode;

Fig. 7

eine Darstellung mit einem spannungsschaltenden Element außerhalb der druckfesten Kapselung der Funkenstrecke;

Fig. 8

eine Funkenstrecke, umfassend mehrere Teilfunkenstrecken;

Fig. 9

eine Darstellung ähnlich Fig. 8, jedoch mit einem gemeinsamen Distanzhalter für die nicht triggerbaren Teilfunkenstrecken und

Fig. 10

eine Darstellung einer Funkenstrecke ähnlich den Fig. 8 und 9, jedoch mit zusätzlichen Maßnahmen zur Isolation zum Zweck des Vermeidens von unerwünschten äußeren Durchschlägen.

Hereby show:

Fig. 1

a schematic cross-sectional view through a located in an encapsulated spark gap ignition aid;

Fig. 2

an embodiment similar Fig. 1 but with additional hard gas emitting material surrounding the arc combustion chamber;

Fig. 3

a further embodiment of the overvoltage protection device similar to in Fig. 2 illustrated, but with varied approach of the potential of the main electrode to the auxiliary ignition electrode;

Fig. 4

an illustration of an overvoltage protection device with a voltage-switching element integrated in one of the main electrodes;

Fig. 5

an embodiment with special elevational assignment of one of the main electrodes to the auxiliary ignition electrode;

Fig. 6

a further embodiment of the assignment of Zündhilfselektrode and adjacent main electrode;

Fig. 7

a representation with a voltage-switching element outside the flameproof enclosure of the spark gap;

Fig. 8

a spark gap comprising a plurality of partial spark gaps;

Fig. 9

a representation similar Fig. 8 , but with a common spacer for the non-triggerable partial spark gaps and

Fig. 10

a representation of a spark gap similar to the Fig. 8 and 9 but with additional insulation measures for the purpose of avoiding unwanted external breakdowns.

The passive ignition aid 100 accordingly Fig. 1 is integrated into the flameproof enclosure 5 of the spark gap, which has two main electrodes 1 and 2. These main electrodes 1 and 2 are kept isolated in an example of metallic encapsulation 5 with respect to this.

The ignition aid 100 consists of a voltage-switching element 4, preferably a gas arrester, but also suppressor diodes, thyristors, varistors, defined erosion-resistant separation sections or a combination of these elements are suitable. Furthermore, the starting aid 100 has an impedance-dependent auxiliary starting electrode 3. There is also the possibility that a discrete impedance 3a exists as a separate element.

As impedance 3a, elements or materials such as plastics or ceramics with linear, but also with non-linear resistances or characteristic curves are suitable. When using a discrete impedance 3a, this z. B. as a resistor, as a varistor, as a capacitor or even made of materials with corresponding characteristics of such devices.

The auxiliary ignition electrode or ignition electrode 3 is insulated from the two main electrodes 1 and 2. The response voltages of the resulting partial spark gaps e ₁ and e ₂ , however, are designed differently.

The response voltage of the distance e ₁ , ie the main electrode 1 to the auxiliary ignition electrode 3 is much larger than the response voltage of the distance e ₂ , formed by the distance of the main electrode 2 to the auxiliary ignition electrode. 3

The response voltage of the distance e ₁ is at least equal, but generally higher than the response voltage of the voltage-switching element 4 of the ignition aid 100th
On the other hand, the response voltage of the distance e ₂ is at most equal but generally lower than the response voltage of the voltage-switching element 4 of the ignition aid 100.

In this way, it is ensured that the response voltage of the entire arrester is essentially determined by the response voltage of the voltage-switching element 4 and thus can be selected independently of the usual geometric conditions of the main spark gap. Advantageously, all functionally relevant parts for the response are not exposed to the direct action of arcing. Only one end of the Zündhilfselektrode 3, which preferably own impedance, z. B. can be performed as a conductive plastic is located partially in the arc combustion chamber and is isolated from the two main electrodes 1, 2 executed.

If the auxiliary ignition electrode 3 is not made of an impedance-sensitive material, but of a low-resistance material, for. As copper, or the like is carried out, as already mentioned, a separate impedance 3a is used, which is then located completely outside the direct arc action.

The unavoidable burning of all parts in the arc combustion chamber can damage the auxiliary starting electrode 3 only partially. Since the arc erosion takes place on all sides in the entire combustion chamber of the spark gap, all the combustion chamber delimiting parts, including the auxiliary ignition electrode 3, are gradually burned off with their adjacent insulation parts.
This ensures that the geometric proportions of all components remain largely the same after each load.
As a result of uneven burning or as a result of contamination, however, damage to or bridging of the short insulation gap e ₂ may also occur in this geometry. In particular, in almost all active external ignition aids this would virtually for short circuit of the pulse transformer and thus lead to failure or overloading of the ignition aid. However, this is not the case with the design proposed here according to the exemplary embodiment. The resulting impurities as well as the usually only partial contact bridges, which are formed by melting phenomena and due to the design of the components are only slightly, have a relatively high resistance and are eliminated by a low current flow.

The electrical parameters of the components integrated in the spark gap are predetermined on the one hand by the geometric dimensions. On the other hand, the power conversion is also limited in favor of a simple construction of the contact points and also the thermal load of the insulation stretches. The performance of the ignition aid in the present embodiment is limited to small impulse powers.

In the description of the general functional description Fig. 1 is shown a basic, simplified geometry of a possible spark gap arrangement. In this arrangement, which relates only to the ignition range, no measures to follow current limit are included for simplicity.

The main electrodes 1 and 2 are manufactured in known manner from erosion-resistant, electrically conductive materials such as metals, metallic alloys, sintered metals, graphite, ceramics or composite ceramics.

With regard to the auxiliary starting electrode 3, it should also be noted that, as stated, these are themselves either made of a material having a high impedance, e.g. Resistance material, electrically conductive plastic, plastic with filler or is connected to a separate impedance 3a in the form of a resistor.

In the plastic material of the auxiliary ignition electrode can not only soot or graphite elements or to set desired impedance properties Metal or carbon fibers contained, but it is possible to introduce micro varistors or nanotubes.

The main electrode 1 is connected to the voltage switching element 4, which is a gas discharge tube, a gas discharge tube with Microgap; a spark gap, an isolating path, a suppressor diode, a varistor or a combination of the aforementioned elements may be connected to the impedance 3a or the auxiliary starting electrode 3 within the outer pressure-resistant encapsulation 5 of the spark gap.

As stated, the three electrodes form two parting lines e ₁ and e ₂ , wherein e _{2 has} a significantly lower response voltage than the separation distance e ₁ .
The response voltage of the subsection e ₂ is equal to or less than the response voltage of the voltage switching element 4. Since the Gleichansprechspannung the entire arrester should be equal to or less than 1 kV, there are special requirements for the execution of the separation distance e _2nd
This separation distance e ₂ can z. B. by thin films of erosion-resistant materials or by temperature-resistant coatings, but also by means of special erosion-resistant paints can be realized.

After the voltage-switching element 4 and the separation path e ₂ respond, a spark is produced between the auxiliary starting electrode 3 and the main electrode 2. The current flows from the main electrode 1 via the impedance 3a, the auxiliary starting electrode 3 and the spark to the main electrode 2. This spark brings charge carriers into the interior of the spark gap, whereby the dielectric strength of the separation distance e ₁ is reduced very quickly.
Between the main electrode 1 and the auxiliary starting electrode 3 according to Fig. 1 There is a voltage difference, which is essentially determined by the magnitude of the current in the ignition circuit and the impedance 3a. This voltage difference exceeds the reduced by the charge carrier input withstand voltage of the isolating distance e _1, so these lights, takes over the current and relieves the ignition circuit. The partial arcs over the separation lines e ₁ and e ₂ connect and the spark gap ignites between the main electrodes 1 and 2.

Fig. 2 shows a spark gap for grid applications, in particular between L and N. This spark gap is able to produce higher arc voltages. These are realized in the present case by flowing the arc with hard gas.

To Hartgasbeströmung a hard gas-emitting substance 10, z. B. POM, polytetrafluoroethylene polymer-based or mineral-based, z. As CaCO ₃ or BaCO ₃ used.

The effect can also be exploited by electrically conductive additives, such as metal fibers, carbon black, carbon fibers, microvaristors, nanotubes, metal particles, semiconductor particles or even per se conductive polymers, the potential of the main electrode 2 to lead to the separation distance of the auxiliary ignition electrode 3.
By this measure, the response voltage of the separation sections e ₁ and e _{2 is} not changed; however, the effective arc length between the main electrodes 1 and 2 is increased.

The spark occurs between the auxiliary ignition electrode 3 and the conductive hard gas-emitting material 10 and can then extend very quickly to the main electrode 2 already or only after the rollover of the separation distance e ₁ .
As a result, on the one hand, the arc length is increased and on the other hand, the arc cooled by the hard gas and flowed.

Both measures increase the arc voltage, as known, a current limit can be achieved in Netzfolgeströmen. The generation of hard gas and the flow of the arc results in a pressure increase which can be dissipated through the pressure compensation opening 11. This prevents that in the pressure-tight sealed volume a gradual increase in pressure occurs over the generated gas, whereby the bursting strength of the spark gap could possibly be exceeded after repeated loads.

For pressure equalization, structurally existing channels of small cross-section can be used. It is also possible, even porous, permeable to gases or certain types of gas housing materials such. As porous polymers, metals or ceramics, alternatively to use constructive channels.
The operating voltage of the spark gap is from a pressure increase z. B. when using gas discharge arresters as a voltage-switching element 4 is not affected.

With reference to the illustration after Fig. 3 can be introduced in a similar manner, the potential of the main electrode 1 to the auxiliary ignition electrode 3.

As already explained, the distance between the two main electrodes can be extended without influencing the response voltage by using appropriately conductive materials 10. The size of the conductive, hard gas-emitting part 10 is preferably chosen to be larger than the dimensions of the separation distance e ₁ .

As is known, the residual voltage of a surge arrester, which occurs only after the arrester has responded and thus when the current flows through the arrester, loads downstream equipment. This is particularly important in the new generation of surge arresters, as these, as already explained, without additional decoupling to protect the downstream devices at a low overall protection level.

The amount of residual stress in the spark gap arrangement according to Fig. 1 and 2 can be classified into three areas. A first time range begins, as it were, after the voltage-switching element has responded and the separation gap e ₂ flashes. A current flows over it voltage switching element 4, the impedance 3 and the electrically conductive part 3 ( Fig. 2 ).
The impedance of all these elements determines the voltage drop across the arrester. If the, reduced by the pre-ionization strength of the distance e _{1 is} exceeded, there is a flashover between the main electrode 1 and the part 10. This results in a discharge of the ignition circuit and it reduces the residual voltage by the voltage drop across the ignition circuit. Now, the residual stress is determined essentially by the part 10. With progressing ionization between the two main electrodes 1 and 2 and the migration of the arc along the part 10, the flashover occurs between the main electrodes 1 and 2. At this time, the residual voltage is determined by the arc between the main electrodes. Of course, the first arc flash over the part 10 and then only the rollover of the separation distance e _1st This is inventively avoidable by a corresponding geometric design. In this way it is prevented that the load of the ignition circuit increases.

Since the process requires a certain amount of time until the flashover between the two main electrodes, the residual voltage increases during this period as a function of the currently effective impedance and the pulse current. At high voltage gradients or surge currents, the residual voltage may therefore assume too high values, whereby a hazard or even an overload of the downstream elements may occur.

According to the invention, the task of an effective residual voltage limiting is additionally transmitted to the conductive, hard-gas-emitting part 10. For this purpose, a certain dimensioning of the resistance of the part 10 is required according to the embodiment.
A targeted influence on the course and the height of the residual stress can be done by the rest in addition to the electrical design of the part 10 by the geometric. Is the resistance of member 10 chosen to be relatively high impedance relative to the impedance 3a, the residual stress increases even after the breakdown of the separation distance s ₁ to pass. So it would be particular In the case of large dimensions (length) of the part 10 (greater ignition delay time) there is the risk of an excessively high residual voltage at high pulse currents.
Is the resistance of the part 10 on the other hand chosen 3a low compared to the impedance, the rise in the residual voltage can be reduced after the roll of the separating section e _1, whereby the risk of excessive residual stress is significantly reduced.

The effective effective resistance of the part 10 can be influenced by the material, the geometry of the part and the respective contact surface of the part 10 on the electrode 2. Equally effective, however, is the design of the transition region between the part 10 and the auxiliary ignition electrode 10 and the positioning of the main electrode 1. If the Zündhilfselektrode 3 z. B. is executed with a larger inner diameter than the part 10, it is compared to the part as quasi reset, there is a virtually larger contact surface on the part 10 for the spark between the main electrode 1 and the part 10 itself, resulting in a lower effective resistance of Part 10 sets.
If the auxiliary ignition electrode is practically present in the arc combustion chamber, the resistance increases. It can also be carried out in the direction of the axes analogous measures of geometric design.

It should also be borne in mind when influencing the residual stress that the material of the part 10 undergoes a corresponding electrical and thermal load by taking over a significant proportion of current of up to several kA in the case of pulsed current loading and must be designed accordingly. However, a thermal preload of the part 10 during the ignition phase is also to be seen positively, since in particular POM materials accelerate the release of hard gas at a higher temperature. This leads to an overall better extinguishing behavior with possible subsequent streams, which of course also partially flow over the material of the part 10 and this load electrically and thermally.

The height of the resistance of the part 10, for example, as a hollow cylinder with an Au ßendurchmesser of 18 mm, an inner diameter of 4 mm at a Height of 5 mm can practically be varied between several hundred kΩ and values up to approx. 1 Ω without any negative effects regarding the extinguishing capacity of the spark gap and the material selection. The maximum limitation of the residual voltage results, as explained, at lowest resistance values.

• Z_{Teil 10} > Mittelwert des Widerstands des Lichtbogens bei Impuls- und Folgeströmen
• Mittelwert des Widerstands des Lichtbogens bei Impulsströmen < Z_{Teil 10} < Mittelwert des Widerstands des Folgestrom-Lichtbogens
• Z_{Teil 10} < Mittelwert des Widerstands des Lichtbogens bei Impuls- und Folgeströmen.

However, any reduction is not possible, because from certain values, the overall properties of the spark gap do not change favorably. In principle, three dimensioning ranges for the mean value of the resistance of the conductive, gas-emitting part 10 can be recorded:

• Z _{Part 10} > Average value of the resistance of the arc during pulse and subsequent currents
• Mean value of the arc resistance at pulse currents <Z _{part 10} <mean value of the resistance of the follow current arc
• Z _{Part 10} <Average value of the resistance of the arc during pulse and sequence currents.

The resistance of the part 10 of a spark gap according to Fig. 2 or 3 attains a special significance not only in the residual stress, but also in its effect on the subsequent current quenching. The part 10 is in the described arrangements basically parallel to the arc or at least to portions of the arc. This applies to all loads in which the spark gap between the main electrode 1 and 2 is ignited. The part 10 always takes over a portion of the total current both during the load with surge currents as well as the load with subsequent currents. The amount of this portion is dependent on the height of the resistance of the part 10 and the quasi-resistance of the arc.

As is known, the current-voltage characteristic of an arc is not linear, but depends on numerous factors, including the composition of the gas, pressure, temperature and so on. These variables are determined in a real spark gap, inter alia, by the geometry, the materials used and the electrical load. Because of all these sizes Even with fixed spark gap geometry vary greatly due to aging, the exact arc curve can only be predicted insufficient. However, considering the follow current arc at AC voltage, it is also known that the resistance of the arc at the time of ignition and at the time of extinction is in part significantly increased. In this time range, therefore, the parallel resistance of the part 10 takes on a correspondingly higher proportion of current or even the total current at low values <10 Ω. As a result, charge carriers are naturally removed from the arc, as a result of which the ionization decreases greatly. This leads to premature extinction of the arc. Part 10 leads here the follow current up to the current zero crossing.

The low resistance value of the part 10 may also serve to avoid a line follow current arc. The mains voltage is relatively low in relation to the driving voltage of the pulse current and also dependent on the phase position. Among other things, this leads in practice to the fact that the pulsed current arc often does not pass directly into the follow-up current arc, but this can ignite due to the reduced dielectric strength of the switching path due to the pulse load. However, due to its electrical conductivity, the parallel resistance of the part 10 virtually reduces the voltage load on the switching path, as a result of which the ignition of the line follow current arc can be prevented. In such a case, the follow-on current can for one thing be completely prevented or, on the other hand, only a limited follow-on current flows through the part 10 until the current zero crossing. In this mode of action, the extinguishing and firing tips of the arc are avoided. This effect is a positive side effect, with the rest still no risk of damage to the part 10 is independent of the selected conductive material.

However, the resistance of the part 10 corresponds approximately to the resistance of the follow-current arc, is to be expected with a strong current load of the part 10 over the entire arc phase. Therefore, only those materials are used that can not be damaged by a sustained current and temperature effect. For spark gaps, where a very effective follow current limiting is to be achieved, ie where the height of the arc voltage, which reaches the mains voltage after one millisecond at the latest, the arc resistance has a value of substantially 0.5 to 1 Ω in the case of a follow-up current. If this value is exceeded by the part 10, this leads on the one hand to a heavy load on the part 10, but on the other hand, the arc can be deleted faster or it is an ignition preventable.

When choosing a very low resistance value of the part 10 is to be considered that the follower current load decreases, and that both the separation distance e ₁ and the voltage-switching element 4 must master the occurring secondary currents and also the burn-off multiple times.
A lowering of the resistance of the part 10 at spark gaps in accordance with z. B. Fig. 2 under the generally much lower resistance of the arc (about <1/10) in the case of pulse currents, a desired strong follow current limitation hampers disproportionately. The strong difference between the resistance of the arc at momentum currents and at subsequent currents results in arrangements according to Fig. 2 among other things from the delayed delivery of hard gas from the part 10 used for this purpose.

A safe operation and a hardly limited choice of material for the part 10 is given in particular when the average resistance of the part 10 is generally higher than the average resistance of the arc.
For special spark gap arrangements, however, interpretations may be useful in which by lowering the average value of the resistance of the part 10 below the mean value of the resistance of the follow-current arc, an arc should be largely avoided in the follow-on current. However, such an arrangement requires due to the high electrical and thermal loads of a particular selection of materials and design of the part 10. Conceivable here are conductive ceramics, composite materials, varistor material or the use of PTC material.

The Fig. 4 to 7 show further design variants of the integrated ignition aid in combination with a spark gap with follow current extinction according to the hard gas principle.

According to Fig. 4 the voltage switching element 4 is integrated directly into a recess of the main electrode 1 for protection against, in particular, thermal and mechanical loads. This recess can, for. B. in the form of a bore in the power supply of the main electrode. This hole can have an internal thread. By screwing in a conductive screw, the voltage-switching element 4 located in the cavity can then be securely mechanically fastened and contacted.

Although not shown in the drawing, it is also possible to include a separate impedance 3a in a corresponding recess in the main electrode 1, so that this element is better protected against static and dynamic mechanical stresses during manufacture and during operation.

It should be noted that one side of the voltage-switching element 4 is insulated from the main electrode 1 and there is an insulated conductive connection or connection to the auxiliary starting electrode 3.

According to Fig. 5 the Zündhilfselektrode 3 is introduced into the arc-combustion chamber quasi at the same height with the reaching to the arc-combustion end of the main electrode 1.
This causes after the ignition of the main spark gap very quickly extinguishing the current in the ignition circuit, since this is practically no longer exposed to a potential difference. The Zündhilfselektrode 3 is thus protected from direct arcing Fußabbrand.

Fig. 6 shows a representation in which the auxiliary ignition electrode 3 is arranged laterally offset from the arc combustion chamber, which also sets a special protected embodiment of the electrode 3.

According to the illustration according to Fig. 7 it is possible to arrange a, even complementary, voltage-switching element 4 outside the flameproof enclosure 5 of the spark gap.

This makes it possible to freely select the response voltage of the arrester regardless of the spark gap even after installation in the application environment or to adapt it to the application environment and the conditions of use.

In principle, the illustrated ignition aid described in the exemplary embodiment can also be applied to other extinguishing principles or electrode arrangements. Known sequence current extinguishing method for low-voltage arrester in addition to the variants explained is z. As the use of horn-shaped electrodes for arc extension, often in combination with arc-free arrangements, or even the generation of high pressures to increase the arc field strength. Likewise, a series circuit of multiple spark gaps for multiplying the electrode drop voltage is conceivable.

The use of arrangements with horn-shaped electrodes requires no further explanation, since both a basic solution accordingly Fig. 1 , but also arrangements with a prolonged by electrically conductive materials electrode spacing, z. B. accordingly Fig. 2 , Can be provided in a symmetrical or asymmetrical arrangement in a known manner with horn-like spark gaps. The forming follow-current arcs can be known to be supplied after the extension of the horns to a variety of extinguishing systems.

However, the realization of an effective follow current limiting is also possible by a strong pressure build-up inside the spark gap. Here is, for example, on the DE 196 04 947 C1 directed. Although this is also realized in the production of hard gas, it can also be found as an individual measure. The same is z. B. in spark gaps of advantage, in which the cost, which is necessary in terms of flow and cooling of the gas released, is to be limited, or even at spark gaps, where the lowest possible aging is of interest.

Arrangements according to the DE 196 04 947 C1 are basically feasible with a starting aid according to the invention. Hartgasabgebende substances can partially or completely replaced by electrically conductive substances with linear, but also with non-linear characteristics. This can z. B. pressure-resistant conductive ceramics, fiber ceramics or composite materials with conductive components or else, for example, materials with varistor characteristic or a PTC characteristic. The pressure build-up is due to the limited internal volume z. B. realized in a cylinder. In a partial use of hard gas z. B. a sandwich solution can be used.
However, it is also possible to use a porous basic structure, eg. B. of conductive ceramic with gas-emitting substances, eg. B. POM to fill.

Variants with active triggering for the introduction of charge carriers in one or more partial spark gaps for use in low-voltage systems show the Fig. 8 to 10 ,

According to Fig. 8 the ignition aid explained above can also be used in an embodiment with a plurality of partial spark gaps and does not restrict the use of the generally known methods for controlling the potential of the partial spark gaps.

However, it should be noted that arresters with a series connection of partial spark gaps usually also have externally connected means for potential control. This can be impedances, capacitances, linear and non-linear resistances, their combinations or also additional external spark gaps, which are likewise used for potential control.
Regardless of which type of discrete elements is also used for potential control, these elements and their contact points to the individual partial spark gaps is a risk factor, as a result of very high pulse steepnesses or poor or aged contact making it to partial or complete external arcing and thus to Destruction of the arrester can come. So if it is safe to ignite an arrester of the type mentioned with a starting aid and a response value <1 kV, not only the actual ignition aid, but also the potential control must be performed safer than usual.

This can be realized according to the embodiment in that instead of a potential control with external and discrete elements anyway necessary components are modified so that a sufficient, internal potential control is possible.

For this purpose, individual electrode of the partial spark gaps 20 are separated by spacers 21. The material of this spacer 21 can be made of conductive or field controlling material up to the distance or distances, which is provided with a starting aid.
Alternatively or additionally, an outer casing of the actual spark gaps can be connected to an isolated, unilaterally connected screen for potential distortion 22.

The partial spark gap with the ignition aid from the parts 3, 3a and 4 is designed so that, despite possibly occurring contamination, in particular by the burning of the ignition electrode, is able to control the burden of the recurring mains voltage alone after the response of the spark gap ,
For this purpose, the distance of the electrodes 22 and 23 of the triggerable via the ignition aid partial spark gap is increased compared to the distance of the other partial spark gaps. In addition, for better control of the recurrent voltage for the material of the main electrodes of the triggerable partial spark gaps, a material with high instantaneous solidification can be selected. The material of the remaining sections, on the other hand, should have a low erosion and a high electrode drop voltage.

The spacers 21 may consist of electrically conductive polymers or ceramics. Their resistance characteristic can be linear, but also non-linear.

In a potential-controlling embodiment, the material of the spacer 21 in addition to certain dielectric properties, whereby a capacitive control is possible, in addition also be provided with micro varistors, resulting in a better potential-controlling effect especially at high slopes. Alternatively, the individual can be electrically conductive contact holder also on one side or on both sides with a thin insulation layer or a defined poor contact to be provided or executed. Although this requires a minimum operating voltage of z. B. some 10 V, but promotes the faster escape of the arc from the material and the sparking ionization of the partial spark gap and thus the ignition of the entire spark gap.
Of course, the described measures for potential control can also be used to reduce the response voltage of the partial spark gaps 20 by known from the field of gas discharge arresters measures such. B. the use of special gases or activation measures are supported.

According to Fig. 9 the individual spacers 21 of the non-triggerable partial spark gaps can be replaced by a common spacer. With an electrically conductive design of the spacers 21, care must be taken that the conductive material is not overloaded by the flowing partial flow. This can be influenced on the one hand by the material selection and on the other hand also by the geometric design in the sense of the thickness and the contact surface.

Fig. 10 shows a design variant in which jointly or alternatively applicable measures are used to further reduce the likelihood of unwanted outer rollover.
For this purpose, additional insulation measures are carried out in the outer region of the electrodes. The electrodes of the partial spark gaps may be provided with insulating material 25 in the outer region. The inner diameter of the isolated area is to be selected larger than the inner diameter of the spacers 21. The spacers 21 may further also be surrounded on the outer circumference with a ring of insulating material 26.

Is with an arrangement according to the Fig. 8 to 10 a limitation of the subsequent currents to values of a few hundred amperes or less realized, the use of a powerful gas discharge is also possible instead of the triggerable partial spark gaps, which then determines the response voltage of the overall arrangement.

Claims (43)

1. Overvoltage protection device, based on spark gaps, for low-voltage applications, comprising at least two main electrodes (1; 2) located in a pressure-tight housing (5) and at least one auxiliary ignition electrode (3), wherein, in the housing volume, a functional assembly for reducing the spark gap response voltage is accommodated which is connected to one of the main electrodes (1; 2) and the auxiliary ignition electrode (3),
   wherein the functional assembly for reducing the spark gap response voltage consists of a series connection of a voltage switching element (4), an impedance (3) and an isolating distance (e₂), which series connection is fully integrated into the pressure-tight housing (5) and is located outside the arc combustion chamber and connected to the first main electrode (1), wherein the isolating distance (e₂) is formed by the distance from the auxiliary ignition electrode (3) to the closest second main electrode (2), and the response voltage of the isolating distance (e₂) is equal or less than the response voltage of the voltage switching element (4), so that, in the event of overvoltage occurring which exceeds the sum of the response voltages of the switching element (4) and the isolating distance (e₂), a current will flow from the first of the main electrodes (1) via the impedance (3a) to the second main electrode (2), with the consequence that the arc bridging the isolating distance (e₂) will provide charge carriers for the immediate ionization of the separating distance between the main electrodes (1; 2), whereby the dielectric strength of said separating distance is reduced and, due to the voltage drop at the impedance (3a) increasing with the current, the reduced dielectric strength of the isolating distance is exceeded, whereby the desired igniting of the spark gap takes place.
2. Overvoltage protection device according to claim 1,
   characterized in that
   the voltage switching element is a gas discharge tube.
3. Overvoltage protection device according to claim 1,
   characterized in that
   the voltage switching element is a suppressor diode, a thyristor, a varistor and/or an air or sliding spark gap of a defined arc erosion resistance.
4. Overvoltage protection device according to any one of claims 1 to 3,
   characterized in that
   the auxiliary ignition electrode itself is implemented to be subject to impedance and has a complex resistance.
5. Overvoltage protection device according to any one of the preceding claims,
   characterized in that
   the auxiliary ignition electrode is in part located within or extends into the arc combustion chamber.
6. Overvoltage protection device according to claim 4,
   characterized in that
   the auxiliary ignition electrode is made of a conductive plastic material.
7. Overvoltage protection device according to any one of claims 1 to 3,
   characterized in that
   the impedance is made of a material having a non-linear or linear resistance curve.
8. Overvoltage protection device according to claim 7,
   characterized in that
   the impedance is made of a conductive plastic material or conductive ceramics.
9. Overvoltage protection device according to claim 7,
   characterized in that
   the impedance is realized discretely as a resistor, varistor or capacitance.
10. Overvoltage protection device according to any one of the preceding claims,
    characterized in that
    the auxiliary ignition electrode is insulated with respect to the main electrodes, wherein the response voltages of the respectively resulting partial distances to the main electrodes are selected to be different.
11. Overvoltage protection device according to claim 10,
    characterized in that
    the response voltage of the first main electrode to the auxiliary ignition electrode is by far larger than the response voltage of the isolating distance (e₂).
12. Overvoltage protection device according to any one of the preceding claims,
    characterized in that,
    for reducing the response voltage of the isolating distance (e₂), the isolating distance (e₂) is formed as a thin, arc erosion-resistant insulating film, arc erosion-resistant lacquer coating or any other thin insulating layer.
13. Overvoltage protection device according to any one of the preceding claims,
    characterized in that
    the overvoltage protection device comprises means for flowing hard gas to the arc.
14. Overvoltage protection device according to claim 12,
    characterized in that,
    for generating the hard gas, a hard gas emitting material surrounds at least portions of the arc combustion chamber, the hard gas emitting material having in addition conductive properties so as to guide the potential of one of the main electrodes close to the isolating distance of the auxiliary ignition electrode.
15. Overvoltage protection device according to claim 13 or 14,
    characterized in that
    at least one pressure compensation opening is provided for preventing a pressure increase accumulating over time.
16. Overvoltage protection device according to claim 15,
    characterized in that
    the pressure compensation opening is formed by housing or electrode materials which are gas-permeable.
17. Overvoltage protection device according to claim 16,
    characterized in that
    at least portions of the housing are made of a porous polymer material, ceramics and/or metal.
18. Overvoltage protection device according to any one of the preceding claims,
    characterized in that
    the overvoltage protection device comprises means for residual voltage limitation.
19. Overvoltage protection device according to claim 18 and claim 14,
    characterized in that
    the conductive, hard gas emitting material, which is electrically connected to one of the main electrodes, has a defined geometry and defined electrical properties for the purpose of influencing the curve and level of the residual voltage.
20. Overvoltage protection device according to claim 19,
    characterized in that
    the resistance of the hard gas emitting material with respect to the impedance of the series connection is low.
21. Overvoltage protection device according to any one of claims 15 to 20,
    characterized in that,
    during the exposure to both surge and follow currents, the conductive, hard gas emitting material carries a part of the respectively flowing total current.
22. Overvoltage protection device according to claim 21,
    characterized in that
    the current proportion conducted by the conductive, hard gas emitting material is adjustable via the relation of the resistance of said material to the resistance value of the arc.
23. Overvoltage protection device according to claim 22,
    characterized in that
    the mean value of the resistance of the conductive, hard gas emitting material is higher than the average, mean resistance value of the arc.
24. Overvoltage protection device according to any one of the preceding claims,
    characterized in that
    the voltage switching element and/or the impedance is/are integrated into one of the main electrodes for protecting against thermal or mechanical loads.
25. Overvoltage protection device according to claim 24,
    characterized in that
    one of the main electrodes comprises a cavity.
26. Overvoltage protection device according to claim 25,
    characterized in that
    the voltage switching element is inserted into the cavity, in particular in a single-pole insulated manner.
27. Overvoltage protection device according to claim 26,
    characterized in that
    the cavity comprises an internal thread for receiving a screw contacting the inserted voltage switching element.
28. Overvoltage protection device according to any one of the preceding claims,
    characterized in that
    the end of the auxiliary ignition electrode extending to the arc combustion chamber is substantially at the same level as the end of that main electrode, which extends into the combustion chamber, that is associated to the first isolating distance (e₂).
29. Overvoltage protection device according to any one of the preceding claims,
    characterized in that
    the auxiliary ignition electrode is arranged to be laterally offset and/or to be reset relative to the arc main combustion chamber.
30. Overvoltage protection device according to any one of the preceding claims,
    characterized in that
    a supplementary voltage switching element for the subsequent setting and/or adjusting of the response voltage is located outside the pressure-tight encapsulation.
31. Overvoltage protection device according to any one of the preceding claims,
    characterized by
    a combination of a triggerable partial spark gap of a high response voltage and at least one partial spark gap of a low response voltage that is arranged downstream.
32. Overvoltage protection device according to claim 31,
    characterized in that
    several non-triggerable partial spark gaps comprise means for internal potential control.
33. Overvoltage protection device according to claim 32,
    characterized in that
    the partial spark gaps are mechanically fixed via spacers.
34. Overvoltage protection device according to claim 33,
    characterized in that
    the spacers are made of a conductive, field-controlling material.
35. Overvoltage protection device according to claim 33 or 34,
    characterized in that
    the spacers and the electrodes of the partial spark gap comprise a sheathing.
36. Overvoltage protection device according to claim 35,
    characterized in that
    the sheathing includes or is formed as shield electrically connected on one side for targeted potential distortion.
37. Overvoltage protection device according to any one of claims 31 to 36,
    characterized in that
    the distance of the electrodes forming the partial spark gap comprising the auxiliary ignition electrode is selected to be greater than the distance of the electrodes of the respectively following partial spark gaps.
38. Overvoltage protection device according to any one of claims 31 to 37,
    characterized in that
    the spacer is realized as an integral component for partial spark gaps that are not triggerable by the auxiliary ignition electrode.
39. Overvoltage protection device according to any one of claims 31 to 38,
    characterized in that,
    for preventing an electric flashover outside the arc combustion chamber, additional insulating sections or insulating materials are provided or arranged preferentially in the outer area of the partial spark gaps.
40. Overvoltage protection device according to any one of claims 31 to 39,
    characterized in that
    the spacers comprise an insulating coating or cladding on their sides distant from the arc combustion chamber.
41. Overvoltage protection device according to any one of claims 31 to 40,
    characterized in that
    the first, triggerable partial spark gap is replaced by a gas discharge tube which determines the response voltage of the entire arrangement.
42. Overvoltage protection device according to claim 1,
    characterized by a horn spark gap.
43. Overvoltage protection device according to claim 1,
    characterized by a stacked spark gap.

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