EP2057724B1 - Encapsulated, pressure-tight surge arrestor capable of conducting lightning currents and having a capacity for quenching system follow currents - Google Patents

Abstract

The invention relates to an encapsulated, pressure-tight surge arrestor which is capable of conducting lightning currents and has a capacity for quenching system follow currents, comprising two main electrodes, which lie opposite one another, spaced apart and insulated, wherein at least one spacer disc or one spacer body is arranged in the space between the main electrodes so as to form a large number of discharge sections at least in the case of pulse-like surge current loads, wherein the spacer disc or the spacer body has a plurality of parallel channels, concentric annular gaps and/or thread-like grooves and, in the case of a conductive or semiconducting embodiment, is insulated from one of the main electrodes.

Description

The invention relates to an encapsulated, pressure-resistant designed lightning current carrying surge arrester with Netzfolgestromlöschvermögen, comprising two spaced apart isolated opposite main electrodes, according to claim 1.

To increase the surge current resistance of surge arresters, it is from the DE 101 64 025 B4 previously known to use quasi parallel arresters. The parallel spark gap has a separate pressure equalization chamber and separate vents. Of both spark gaps, only the heat sink is shared.

At the horn spark gap after DE 102 31 431 A1 the discharge space is divided into a plurality of parallel chambers, which are connected transversely to the running direction with openings for pressure equalization. The local chambers serve for the ignition of parallel arcs and the uniform pressure load with powerful pulses.

The prior art includes extending the separation distance between main electrodes of a spark gap by conducting or semiconducting materials. The aim of extending the main separation line is to improve the subsequent current extinguishing capacity by increasing the arc voltage. Reference is made to this on the DE 197 17 802 or the DE 196 19 223 ,

The extension of the arc is no longer sufficient for the desired small sizes of the spark gap. Therefore, in the described prior art, an additional increase in the arc voltage, for example, by confining the arc and by radial flow with a gas.

A disadvantage of these prior art arrangements, however, is that the arc channel for pulse currents and subsequent currents is identical. This means that an independent dimensioning for the completely different current loads is not possible.
The channels for the discharge must on the one hand be as small as possible in order to achieve a high arc voltage at subsequent currents. On the other hand, the channels should have the largest possible cross-section in order to limit the arc voltage and thus the power consumption in pulse discharges. This is necessary, on the one hand, for reasons of reducing the load on the spark gap and, on the other hand, in order to ensure the lowest possible protection level and sufficient coordination capability with other overvoltage protection devices or terminals of modern arrester modules.

In addition, extremely high mechanical requirements are placed on the materials used, which limit the minimum cross section of the discharge channel, especially in the case of pulse loads.

These problems lead to a significant additional design and correspondingly greater expense in the production of spark gaps.

In summary, it can be concluded from the prior art that the design of spark gaps for the opposite requirements in the case of impulse loads at the following current load inevitably leads to a compromise and thus not to ideal solutions for the corresponding load cases.

Due to the increasingly pronounced follow current limiting of network spark gaps of the aforementioned type, arc burning voltages in the area of the driving mains voltage are required. Since an independent influence of the arc voltages in pulses and reticule currents is limited, this leads on the one hand to the fact that the design of the spark gaps is strongly based on the requirements of the sequence current load, and on the other hand to the fact that under pulse loads, so with impressed currents in the kA range, arc voltages, which can be several times the voltage at Netzfolgestrom.

These high voltages not only affect the level of protection and the coordination, but lead to a significant load on the spark gap. This applies in addition to the dynamic mechanical load and the power sales. The increased power conversion leads to a considerable burnup of the materials used and causes a per se to be avoided wear of the spark gap.

In order to reduce the arc voltage at pulse load of spark gaps, for example, attempts were made to cause a so-called nozzle clogging between the discharge area and the pressure compensation range at pulse currents or generate a back pressure in the pressure compensation range at pulse loads (see DE 101 64 025 B4 ).

Although the aforementioned methods cause a reduction of the arc voltage at impulse load, whereby the protection level and the coordination ability can be secured to other devices, but internally the pressure load of the spark gap is greatly increased.

From the DE 2 204 988 A1 a gas discharge arrester for protection against surges in devices of telecommunications is already known. In the gas-filled vessel of the arrester, a spark discharge is formed between the electrodes, wherein in the intermediate electrode space, a bush attached to one of the electrodes is provided. The socket has at least one channel which is designed so that the spark discharge passes between the electrodes through this channel. By this measure, the extinguishing voltage of the unloader is to be increased and its dimensions and mass are reduced. However, such a previously known gas discharge arrester has no lightning current carrying capacity and is only lower for pulses Amperage and low energy content specified. A lightning current-carrying spark gap is therefore not available.

From the foregoing, it is therefore an object of the invention to provide an encapsulated, pressure resistant executed lightning current carrying surge with Netzfolgestromlöschvermögen, comprising two spaced apart opposing main electrodes, which provides opportunities for independent influence of the arc voltages in impulse discharge and Netzfolgeströmen in a simple and cost-effective manner, in addition, the mechanical Loads of the individual components of the spark gap, in particular reduced by impulse loads.

According to the invention, this is achieved by providing a plurality of separate parallel discharge channels within one or more conductive or semiconductive spacers between the main electrodes of the spark gaps.

It thus takes place by the design measures a separation of functions between pulsed discharges and loads by power frequency follow currents within a spark gap. In particular, in the case of pulsed loads, a division of the arc into a plurality of parallel discharge channels within the spark gap is made, whereby a strong pressure relief, a limitation of the arc voltage at impulse load and a reduction of wear are possible.

In the case of power-frequency follow-on currents, on the other hand, the discharge preferably takes place only in a discharge channel, wherein the choice of the geometry and the material of this channel, the arc voltage can be influenced independently of the load at pulsed discharges.

The discharge at pulsed currents with rise times in the range of a few microseconds has directly after the emergence, ie the ignition of the spark gaps, often a positive current-voltage characteristic.

This characteristic allows a division of the discharge channel into parallel channels. The mentioned characteristic results u. a. from the high voltage requirement and the mechanisms for the provision of charge carriers.

When air gaps under normal pressure changes after the start of the discharge, the characteristic of the arc quite quickly, so that in general sets after a few microseconds, the usual negative current-voltage curve of an arc discharge.

In order to achieve effective relief of an air gap by parallel channels, according to the invention at the beginning of the discharge, the rapid division into the largest possible number of parallel channels supported and the positive current-voltage characteristic over a longer period obtained or enforced.

This division is supported by the introduction of conductive or semiconducting materials with parallel channels in the form of spacers or spacers between the main electrodes. In one embodiment, the spacers may also consist of an insulating or non-conductive material.

In addition to the potential control and the specification of the discharge paths causes the material used by its electrical conductivity and a lowering of the residual voltage to the rollover of the total distances. This results in a low residual stress and good coordination even with long separation distances between the main electrodes.

The material and the geometry of the channels within the spacer or spacers or spacers is chosen so that at least in pulsed discharges with currents in the kA range, a discharge with positive current-voltage characteristic is generated even in air over a longer period of time.

This is achieved by extracting and / or blowing out of each arc so much energy that its voltage requirement rises sharply. This forced characteristic of the discharge is the physical prerequisite that with geometrically parallel channels also an effective division of the discharge takes place over a longer period of time.

In the otherwise usual in air negative current-voltage characteristic would be no longer division of the discharge and thus no meaningful relief of the spark gap or reduction of the arc voltage possible even with geometrically existing parallel channels.

In order to force a positive characteristic of the arc in air at atmospheric pressure, the arc within the spark gap is at least Partially converted from a so-called Freibrennenden arc in a wall-stabilized arc. In the process, the arc is deprived of a great deal of energy, as a result of which its voltage requirement increases with increasing current intensity.

The described effect lasts until the impressed current drops so low that the constriction and the cooling within a channel are no longer sufficient.

The partial arc travels or jumps from the positive range of the current-voltage characteristic in the negative region and forcibly extinguished. If the current continues to drop, this process is repeated for further partial arcs until only one discharge channel remains. The magnitude of the current sufficient for a positive current-voltage characteristic is in addition to the environmental conditions such as pressure, gas, electrode material, the cooling effect of the channel, i. geometry, material, heat capacity, gas output and surface area.

In addition to influencing the pulse discharge, the above measures also allow the discharge to be influenced in the case of subsequent currents. If a very strong cooling of the arc is achieved, a division of secondary currents in the kA range is also possible here.

The object of the invention is achieved by resorting to the above explanations with the combination of features of claim 1, wherein the dependent claims represent expedient refinements and developments.

Thus, in order to form a plurality of discharge paths, at least one spacer disk or a spacer body made of a conductive or semiconductive material is arranged in the space between the main electrodes, at least for pulsed impulse current loads, the spacer disc or the spacer body having a plurality of parallel channels, concentric annular gaps and / or thread-like grooves and is isolated from one of the main electrodes.

The spacer or spacer is spaced from both main electrodes and may be formed in electrical communication with one of the main electrodes by means of a support member.

The support member may rest against the entire surface of the corresponding spacer or the spacer body and also have channels, annular gaps and / or grooves whose position coincides with those in the spacer or the spacer body to form continuous discharge paths.

In one embodiment, an insulating part with channels, annular gaps and / or grooves, which fills the space between the main electrode and spacer or spacer body, can be arranged on the surface of the spacer or of the spacer which is opposite the supporting part, wherein the channels, annular gaps and / or grooves of the aligned stack assembly. In this embodiment, a spark gap, in which the separation distance is not realized as an air gap spark gap, but as a sliding spark gap.

A further embodiment is carried by a plurality of spacers, which are provided with each other and spaced apart from the main electrodes, wherein the channels, gaps and / or grooves of adjacent spacers offset from each other.

Here, the spacers can be electrically connected in series and performed isolated from both electrodes.

In the embodiment of a plurality of spaced spacers, it is possible to insert insulated in one of the main electrodes a Zündelektrode or to arrange.

Between each pair of the set of spaced shims, means for ionization and / or potential control may be provided.

To increase the mechanical load carrying capacity, an arrangement of support elements can take place between the spacers, or the spacers themselves can have integral support elements.

The aforementioned spacers or spacers may in addition to their conductive or semiconductive properties also consist of a gas-emitting material or have such a material.

In one embodiment of the invention, the spacer or the spacer body is spaced from both main electrodes, wherein one of the main electrodes of a conductive or semiconductive, a series impedance forming plate is covered and the spacer or the spacer body is by means of a support member with the plate in electrical connection.

In addition, it is possible to form one or more gaps between the supporting part and the plate, wherein the main electrode has projections for fixing the supporting part. Here, the vertical discharge from the main electrode is combined by the spacer with a horizontal gap discharge between the plate and the support member. The dimension of the gap is here at values below substantially 0.1 mm. The discharge in the gap can be used on the one hand to further influence the arc voltage and it On the other hand, a cost-effective reduction of the erosion-resistant material of the respective main electrode can take place.

In the embodiment of a spacer, which may be designed as a cylindrical body in a cylindrical surge arrester arrangement, circumferential annular gaps are provided, wherein the spacer body on one of the main electrodes or rests. In this case, channels or bores are located in this main electrode which are in register with the annular gap outlet openings in the spacer body.

The channels or holes in the main electrode may then pass into a vent gap or be in communication with such a vent gap.

In summary, the invention provides a lightning current-carrying, encapsulated and pressure-resistant surge arrester for use in the low-voltage network with at least two electrodes, wherein at least one electrically conductive or semiconductive spacer in the form of a disk or a spacer body with a plurality of parallel discharge channels is located between the main electrodes. The spacer forces a division of the discharge into a plurality of separate and parallel channels, at least in the case of pulsed impulse current loads.

It is within the meaning of the invention to also design the surge arrester pressure-tight in the sense of a gas arrester.

According to the invention, the division of the pulse current into a plurality of channels already occurs at values starting at approximately 1 kA, in which case pulses of 8/20 μs are assumed. The number of channels or through holes is in the range of 5 to 1000, with assumed through holes the diameter is in the range between 0.1 mm and 2 mm. The thickness of the spacers and thus the channel length is in the range of 2 mm to 20 mm.

The invention will be explained below with reference to an embodiment and with the aid of figures.

Fig. 1

eine erste Ausführungsform des Überspannungsableiters mit einer von beiden Hauptelektroden beabstandeten Distanzscheibe;

Fig. 2

eine nicht zum Erfindungsgenstand gehörende Ausführungsform eines Überspannungsableiters mit zwei Distanzscheiben, die jeweils an oder in der Nähe der Hauptelektroden befindlich sind;

Fig. 3

eine Ausführungsform des Überspannungsableiters mit Gleitfunkenstrecken;

Fig. 4

eine Ausführungsform des Überspannungsableiters mit einer Vielzahl von jeweils beabstandeten Distanzscheiben;

Fig. 5

eine nicht zum Erfindungsgenstand gehörende Ausführungsform eines Überspannungsableiters mit Distanzkörper, der in seinem Inneren Ringspalte aufweist, die sich über die gesamte Höhe des Distanzkörpers erstrecken;

Fig. 6

eine Draufsicht auf die Oberfläche verschiedener Distanzscheiben, die erkennen lässt, welche unterschiedlichen Formen die Kanäle bzw. deren Querschnitte aufweisen können;

Fig. 7

ein Ausführungsbeispiel eines Überspannungsableiters mit einer Reihenimpedanz bezogen auf eine der Hauptelektroden;

Fig. 8

eine Ausführungsform ähnlich derjenigen nach Fig. 7, jedoch mit zusätzlichem Ringspalt im Bereich einer der Hauptelektroden;

Fig. 9

Varianten des Distanzkörpers gemäß der Prinzipdarstellung nach Fig. 5;

Fig. 10

verschiedene Darstellungen in Schnitt-, Drauf- und Teilschnittansicht eines zylindrischen Distanzkörpers mit mäanderförmigem Ringspaltkanal, wobei Innenteil des Zylinders und Außenmantel aus verschiedenen Materialien unterschiedlicher Leitfähigkeit bestehen können und wobei die resultierende Kanallänge bei gleichbleibender Zylinderhöhe über die Steigung der Kanäle einstellbar ist, und

Fig. 11

eine weitere Darstellung eines zylinderförmigen Distanzkörpers, wobei im inneren Zylinderteil gewindeähnliche Nuten eingebracht sind. Hier kann über die Steigung der parallelen Nuten eine Einstellung der Kanallänge bei ansonsten konstanter Zylinderhöhe analog zu Fig. 10 erfolgen.

Hereby show:

Fig. 1

a first embodiment of the surge arrester with a distance from both main electrodes spacer;

Fig. 2

a not belonging to the subject invention embodiment of a surge arrester with two spacers, which are located respectively at or in the vicinity of the main electrodes;

Fig. 3

an embodiment of the surge arrester with Gleitfunkenstrecken;

Fig. 4

an embodiment of the surge arrester with a plurality of spaced spacers;

Fig. 5

a not belonging to the subject invention embodiment of a surge arrester with a spacer body having annular gaps in its interior, which extend over the entire height of the spacer body;

Fig. 6

a plan view of the surface of various spacers, which can recognize what different shapes the channels or their cross-sections may have;

Fig. 7

an embodiment of a surge arrester with a series impedance with respect to one of the main electrodes;

Fig. 8

an embodiment similar to that after Fig. 7 but with additional ring gap in the area of one of the main electrodes;

Fig. 9

Variants of the spacer according to the schematic diagram according to Fig. 5 ;

Fig. 10

various representations in sectional, top and partial sectional view of a cylindrical spacer with meandering annular gap channel, wherein the inner part of the cylinder and outer shell may consist of different materials of different conductivity and wherein the resulting channel length is adjustable with the same cylinder height over the pitch of the channels, and

Fig. 11

a further illustration of a cylindrical spacer, wherein in the inner cylinder part thread-like grooves are introduced. Here, an adjustment of the channel length with an otherwise constant cylinder height analogous to the slope of the parallel grooves Fig. 10 respectively.

According to the figurative representations, it is assumed that an encapsulated, pressure-resistant, lightning current-carrying surge arrester with reticule current extinguishing capability, comprising two main electrodes 1 and 2 which are spaced apart from each other in an insulated manner.

The main electrodes 1 and 2 are received by an insulating body 5, which in turn is surrounded by a metallic, pressure-resistant housing 6.

Between the main electrodes 1 and 2 is a spacer or a spacer body 3 made of a conductive or semiconductive material with a linear or preferably non-linear characteristic, which has a plurality of openings or channels 31 of small cross-section.

The spacer 3 is at least opposite to one of the main electrodes, according to Fig. 1 the main electrode 1, isolated.

According to Fig. 1 there is a common separation distance L1 between the main electrode and the spacer 3.

The spacer 3 is connected via a conductive or semiconducting material 4 (support member) to the main electrode 2.

The spacer 3 and the support member 4 can also be realized by a single part.

Furthermore, a common cavity 8 is located between the spacer 3 and the main electrode 2, which is particularly advantageous in the generation of additional gases.

This room then also serves as a collection room of the gas.

A vent 7 small cross section for pressure equalization after the load is also provided.

As an alternative to this, individual channels 31 can be led to the main electrode 2, in which case the venting takes place in the region of the electrode. Likewise, a connection of the individual discharge channels or a separate vent is conceivable.

Furthermore, the semiconductive or conductive spacer 3 allows for spark gaps without ignition aid an electric pre-discharge with sparking.

Upon reaching the operating voltage of the separation path L1 sparking occurs between the main electrode 1 and the spacer 3. Thereafter, often slide several pre-discharges along the channels 31 to the main electrode 2 and there is a flashover between the main electrodes 1; 2. The formation of a discharge in multiple channels can be influenced by the residual voltage drop across the spacer 3 and the support member 4.

The in Fig. 1 shown cavity 8 between the main electrode 1 and the spacer 3 allows in addition to the distribution of the charge carriers of Zündfunkens on several channels and an exchange of charge carriers between the individual channels 31 after ignition of the main line. This promotes with appropriate characteristics of the arc additionally a fast and uniform ignition of other, parallel channels.

Should ignite only one channel despite the measures described above, on the one hand forced due to the high voltage requirement at the beginning of the discharge and the other due to the constriction and cooling of the arc, a positive U / I characteristic of the arc at sufficiently high currents even in air.

The above allows the formation of parallel arcs whose number increases with the current of the impressed current. As a result, a distribution of the pulse current to numerous parallel discharge channels within a spark gap in air is possible. Important in particular for long-lasting discharges here is that the positive characteristic of the arc is maintained even at relatively small pulse currents.

An even with long-lasting pulse discharges stable arc distribution allows independent dimensioning of the channel geometries in Netzfolgeströmen.

The previous dimensioning of simple channel geometries in spark gap arresters made in the prior art was not independent of the type of load. Although a discharge channel with a large diameter or cross section allowed high impulse loads, it only led to a low following current limitation. In order to achieve a sufficiently high sequence current limitation at a desired pulse load capacity, the discharge channel has usually been lengthened. However, this leads to a high power conversion and high voltages at pulse loads.

The achieved stable division of the impulse discharge now makes it possible to dimension the individual discharge channels exclusively according to the requirements of the subsequent current. The height of the desired pulse load capacity is adjustable via the material, the number of parallel channels taking into account the dimension of the spark gap.

When choosing the channel geometry (see Fig. 6 ), the basic functions of the surge arrester are taken into account. This includes a limitation of the residual voltage level and duration to the response of the spark gap in order to ensure a corresponding coordination of the arrester.
These values are also determined by the material of the spacer or spacer 3 and the length of the rollover travel. The spacer made of conductive or semiconducting material has a positive effect on the control of the residual voltage until the main section is overturned, as well as on the division of the discharge, especially in the case of air gaps.

At high channel lengths, the rollover time may be delayed too much. For applications where this is critical, the spacer or the spacer is divided into several, connected in series sections. This already leads to an improvement due to the greater inhomogeneity. In addition, auxiliary spark gaps can be introduced between the individual spacers, which cause ionization.

The above-described variant of the division of the spacer or the spacer 3 also offers the possibility to deliberately delay the formation of a continuous discharge channel, for example by an offset arrangement of the through channels (see Fig. 4 ).

At high subsequent currents in the kA range, which can occur, for example, at increased mains voltages, it is also possible to divide them into parallel arcs, thus reducing the load on individual discharge channels.

When dimensioning the channels with very small and / or long channels can also be dispensed with an additional gas delivery, as is otherwise customary. Thus, the resulting pressures within the spark gap and the resulting wear can be reduced.

According to Fig. 2 an embodiment not belonging to the subject invention is shown, in which both main electrodes 1 and 2 are provided with a spacer 3.

In the figurative representation, the respective main electrodes 1 and 2 touch the respective spacers 3, but this is not absolutely necessary.

The cavity 8 is located here between the two spacers. 3

In this cavity 8, which simultaneously forms the main separation path of the main electrodes 1 and 2, a third, ignition electrode 9 is integrated by way of example, which serves for the external ignition of the spark gap.

Fig. 3 shows a spark gap, in which the separation distance is not designed as a Luftdurchschlagsfunkenstrecke, but as a sliding spark gap.

For this purpose, the insulating material 10 in each case above a channel 31 of the spacer 3 has an opening which allows a sliding overlap between the main electrode 1 and the spacer 3.

The spacer 3 is electrically conductively connected in this embodiment with the main electrode 2 via the support member 4.

The support member 4 can also be used as a metal part with high conductivity or, as in the embodiment according to Fig. 1 be designed as a part with low electrical conductivity or semiconducting.

The support member 4 has below the channels 31 of the spacer 3 also channels 31, which allow a direct passage from the spacer 3 to the cavity 8.

An emerging arc is thus extended from the main electrode 1 to the main electrode 2.

The venting of the cavity 8 takes place here again via one or more channels 7 small cross-section.

The channels 31 in the elements 3, 4 and 10 are exemplified as holes.

Fig. 4 illustrates an arrangement with a series connection of a plurality of electrically conductive or semiconducting spacers 3 between the main electrodes 1 and 2.

The main electrode 1 is provided here with a centrally executed third ignition electrode 11, which is separated from the main electrode 1 by the part 12 high impedance.

The main electrode 1 is separated from the closest spacer part 3a by an insulating part 5a and the distance L1.

The channels 31 of the superimposed and spaced spacers 3 are offset from each other.

Between the spacers 3 may be devices for additional ionization of the gap. These devices can accelerate the flashover between the main electrodes 1 and 2.

Between the spacers 3a and 3b are on the insulating part 13, two conductive or semiconductive layers 14, which are separated by a minimum distance with increased resistance or an insulating path. This track is designed to overturn even at low voltages. The associated sparking ionizes the gap between the spacers 3a and 3b.

Between the spacers 3b and 3c, an insulation gap or a stretch of increased resistance 16 is arranged between two electrically conductive or semiconducting parts 15. This has the same already described function of the ionization of the space between the spacers 3b and 3c.

Between the spacers 3c and 3d, there is an electrically conductive or semiconducting material 4, which tends to a rapid slip-over when subjected to stress. Furthermore, there is a connection between the part 4 and the main electrode 2.

At small distances of the discs 3, the part 4 can also be made isolated. Here it must be ensured that the response voltage of the total spark gap is not significantly increased.

According to Fig. 4 the venting of the arrangement is again via a channel small cross-section. 7

If the material of the spacers 3 chosen so that an additional gas discharge takes place, or should very high loads are controlled, a vent may already be provided in the spaces between the spacers 3. This can be done laterally within, through or between parts 5 and 6.

These respective venting channels can run separately or merged. The execution of the or the venting channels from the housing can also be done on the front side or the cylinder wall.

For mechanical stabilization, it is possible to supplement the spacers 3 by supporting elements between the discs. These support elements but can also be integral components of the spacers 3 or be executed from a separate part with divergent material properties, eg isolated. If such support elements realized, these can be equipped with suitable means for ionization of the interstices.

Fig. 5 shows a not belonging to the subject inventions variant in which the discharge is not in continuous holes through a spacer, but between circumferential annular gaps 17 of a spacer body 3 takes place. The individual annular gaps 17 are each vented in separate channels 18 in or through the main electrode 2. The spacer body 3 can according to the variants of the Fig. 9 to 11 will be realized.

Fig. 6 shows various plan views of the spacers 3. Here is the variety of design variants recognizable. The corresponding channels 31 can be designed, for example, slot-shaped or as bores. Also, the center-oriented column 33 or concentric annular gaps 32 are conceivable. It is crucial that the discharge channel is strongly concentrated at least in the x or y direction. This constriction and the material then essentially determine the achievable electric field strength of the arc. The required arc voltage can be set over the length of the channel (z-direction). The individual discharge channels 32 (annular gaps) can be interconnected (34) for ionization and pressure equalization.

In the embodiment according to Fig. 7 who are essentially after those Fig. 1 corresponds, the second main electrode 2 is covered by a plate-shaped part 19.

The material of this plate 19 is electrically conductive or semiconducting, preferably with a non-linear characteristic, and represents a series impedance for the arc.

The plate 19 can also be used to create an additional voltage drop.

Advantageously, the plate 19 is made of a material which, in particular with momentum loading, tends to have no concentrated base-point behavior of the arc. This reduces the burnup of the main electrode 2 and then allows the use of cheaper materials there. Suitable materials for the plate 19 are e.g. those materials which have a high melting point, composites with high melting point components, or materials which do not permanently permit a concentrated arc root, such as e.g. most electrically conductive polymers.

As an alternative to electrically conductive materials, high-resistance or insulating materials with a certain porosity are also possible, which then allow the discharge in the form of a diffuse discharge through the porous layer.

Fig. 8 shows an embodiment similar to that after Fig. 7 with a covered main electrode 2, in which the material of the plate 20 of the plate 19 according to Fig. 7 may correspond, but alternatively also consists of a dense high-resistance or insulation material.

In this embodiment, the main electrode 2 additionally has vertical extensions 2a, by way of example.

Between the support member 4 and the plate 20 is a circumferential gap 200 or there are several parallel sections of column provided.

The material of the support member 4 can be selected to be electrically conductive or semiconducting.

At short distances to the spacer 3, an insulating embodiment of the support member 4 is possible. It is crucial that only one separation line L1 or the distance extension 2a to the spacer 3, the response dominated by a non-triggered spark gap. Alternatively, a vertical layering of the extensions 4 made of different materials is conceivable.

The vertical discharge from the main electrode 1 through the spacer 3 is combined by the plate 20 with a horizontal gap discharge between the plate 20 and the support member 4. The dimension of the gap is here at values below 0.1 mm.

The discharge in the gap 200 can on the one hand be used to further influence the arc voltage and on the other hand, a cost-effective reduction of the erosion-resistant electrode material can be made. In addition, a mechanical separation of functions of the quasi-assembled main electrode 2 is possible.

The combination with a gap discharge is not limited to the illustrated embodiment. Alternatively, a horizontal (radial) gap discharge can be replaced by a vertical (axial) gap discharge. Furthermore, a combination of vertical and horizontal discharge is possible, with the necessary diversion of the discharge leading to a further increase in the voltage drop.

Fig. 9 shows another variant of in Fig. 5 illustrated embodiment of a spacer, as a cylinder in the interior of the spark gap.

Variants 1 and 2 are characterized by a lower cylinder part 301 and an upper cylinder part 302.

According to variant 1, the lower cylinder 301 has a circular groove 303 between the two annular slots 304. The annular slots or annular grooves 304 have a different diameter for gas deflection.

Also conceivable are one or more connecting grooves 306 according to variant 2.

Between the two cylinders 301 and 302 can also, as in the Fig. 4 shown in principle, ignition aids are located.

In the embodiment of a cylindrical spacer 3 after Fig. 10 a meandering channel 307 is provided. The meander structure runs here in the axial direction.

The inner part 308 of the cylinder may be made of a different material than the outer part 309. Here, materials of different conductivity can be selected.
The resulting channel length 307 can be adjusted with the same cylinder height over the slope, ie the meander course.

The cylinder for the spacer after Fig. 11 again has an outer part 309 and an inner part 308.

In the inner part 308 thread-like extending grooves 35 are present, which extend from the top to the bottom of the spacer body 3. About the slope of the substantially parallel grooves 35 an adjustment of the channel length is given at a constant cylinder height.

Claims (16)

1. Encapsulated, pressure-tight surge arrester which is capable of carrying lightning currents and has the capacity to quench mains follow currents, comprising two main electrodes (1; 2) which lie opposite one another, spaced apart and insulated, wherein at least one spacer disc or one spacer body (3) made of a non-conducting, non-conducting but gas-emitting, conductive or semi-conductive material is arranged in the space between the main electrodes (1; 2) so as to form a plurality of discharge gaps at least in the case of pulsed surge current loads, wherein the spacer disc or the spacer body (3) has a plurality of parallel channels (31), concentric annular gaps (32) and/or thread-like grooves (35) and, in the case of a conductive or semi-conductive embodiment, is insulated from the main electrodes (1; 2), wherein further the spacer disc or the spacer body (3) is spaced apart from both main electrodes (1; 2).
2. Surge arrester according to claim 1,
   characterized in that
   in the case of a conductive or semi-conductive embodiment the spacer disc or the spacer body (3) is electrically connected to one of the main electrodes (2) by means of a carrier part (4).
3. Surge arrester according to claim 2,
   characterized in that
   the carrier part (4) lies against the entire surface of the spacer disc or the spacer body (3) and also has channels, annular gaps and/or grooves whose position corresponds to those in the spacer disc or the spacer body (3) so as to form continuous discharge gaps.
4. Surge arrester according to claim 3,
   characterized in that
   an insulating part (10) with channels, annular gaps and/or grooves is arranged on the surface of the spacer disc or the spacer body (3) opposite the carrier part (4), which fills in the space between the main electrode (1) and the spacer disc or the spacer body (3), wherein the channels, annular gaps and/or grooves of this stacked arrangement are in alignment.
5. Surge arrester according to claim 1,
   characterized in that
   a plurality of spacer discs (3a to 3d) are provided, which are spaced apart from one another and from the main electrodes (1; 2), wherein the channels, gaps and/or grooves of adjacent (3a; 3b) spacer discs run offset with respect to one other.
6. Surge arrester according to claim 5,
   characterized in that
   the spacer discs are electrically connected in series and are insulated from both main electrodes (1; 2).
7. Surge arrester according to claim 5 or 6,
   characterized in that
   an ignition electrode (11) is arranged in one of the main electrodes (1).
8. Surge arrester according to one of claims 5 to 7,
   characterized in that
   ionization means and/or means for the control of potential are respectively provided between a pair of spacer discs.
9. Surge arrester according to one of claims 5 to 8,
   characterized in that
   support elements are arranged between the spacer discs (3a to 3d).
10. Surge arrester according to one of the preceding claims,
    characterized in that
    the spacer discs or spacer bodies (3) are made of a gas-emitting material or contain such materials.
11. Surge arrester according to claim 1,
    characterized in that
    the spacer disc or the spacer body (3) is arranged to be spaced apart from both main electrodes (1; 2), wherein one of the main electrodes (2) is covered by a conductive or semi-conductive plate (19) forming a serial impedance and the spacer disc or the spacer body (3) is electrically connected to the plate (19) by a carrier part (4).
12. Surge arrester according to claim 11,
    characterized in that
    a gap (200) is formed between the carrier part (4) and the plate (19; 20), wherein the main electrode (2) has prolongations (2a) for fixing the carrier part (4).
13. Surge arrester according to claim 1,
    characterized in that
    a spacer body (3) comprises circumferential annular gaps (17), wherein the spacer body (3) lies on one of the main electrodes (2) and channels or bores (18) are provided in this main electrode (2), which are in register with the annular gap outlet openings in the spacer body (3).
14. Surge arrester according to claim 13,
    characterized in that
    the channels or bores (18) extend into a vent gap (7) or are connected to it.
15. Surge arrester according to one of claims 1 to 13,
    characterized by a pressure-tight embodiment.
16. Surge arrester according to one of claims 1 to 13,
    characterized by provided small-diameter vent channels (7).

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