EP3834260B1 - Arrangement for firing spark gaps - Google Patents

Description

The invention relates to an arrangement for igniting spark gaps with a trigger electrode located on or in one of the main electrodes and insulated from this main electrode, the trigger electrode being electrically connectable to the further main electrode via at least one voltage-switching or voltage-monitoring element and between the main electrode and the further main electrode there is an air gap, wherein the trigger electrode forms a sandwich structure with an insulation layer and a layer made of a material with lower conductivity than the material of one of the main electrodes, the insulation layer is designed as a thin film or lacquer layer and the layer made of the material with lower conductivity with one of the main electrodes is in contact or rests on it, according to the preamble of claim 1.

Spark gaps can be differentiated in terms of their behavior as breakdown or sliding spark gaps. Such spark gaps can be triggered, but can also be carried out untriggered. In triggered spark gaps, there is at least one trigger electrode in addition to the main electrodes. Ignition with triggered spark gaps occurs either through the use of an ignition transformer, which results in a high response voltage of the correspondingly well-insulated trigger electrode or, alternatively, through a special arrangement of the trigger electrode in relation to the main electrode without an ignition transformer.

Triggered spark gaps generally have a controllable response behavior.

With the flameproof coupled spark gap arrangement for dissipating harmful interference caused by overvoltages DE 200 20 771 U1 A trigger voltage can be applied directly via a conductive housing present there to form a partial spark gap in the discharge space. About the Partial spark gap, the main spark gap between the main electrodes is ignited. Furthermore, an ignition transformer is used there, which is part of the trigger device.

However, ignition transformers require a considerable amount of installation space. In addition, the magnitude of the ignition voltage generated on the secondary side in the ignition transformer depends on the current change di/dT on the primary side. If such a current pulse does not have sufficient steepness, the voltage occurring on the secondary side is not sufficient to reliably ignite the spark gap.

If the trigger electrode is connected to one of the main electrodes, an ignition transformer can be omitted. With such solutions, during the ignition process, a sliding discharge is triggered between one of the main electrodes and the trigger electrode, which after a certain time reaches the other main electrode and triggers the ignition process.

Such a solution is, for example, in DE 101 46 728 B4 disclosed.

Such trigger electrodes have permanent electrical contact with one of the two main electrodes. This means that there is no galvanic separation of the main potentials. For this reason, a voltage-switching element, for example in the form of a gas arrester, must be connected to the trigger circuit.

From the DE 10 2011 102 937 A1 An arrangement for igniting spark gaps is previously known, which has a trigger electrode located on or in one of the main electrodes and insulated from these main electrodes and with which the response behavior can be specified over a large range.

In this regard, the generic solution has a trigger electrode which forms a sandwich structure with an insulating layer and a layer made of a material with lower conductivity than the material of one of the main electrodes. The insulation layer is preferably designed as a thin film or lacquer layer. The layer of the material is lesser Conductivity is in contact with or rests on one of the main electrodes.

The layer dielectric of the sandwich structure appears as a series connection of a first partial capacitance with the dielectric of the insulation section and a second partial capacity with the material of lower conductivity as the dielectric, the partial capacitances being chosen to be very low.

The material M of the sandwich structure has a conductivity that is many times worse than the material of one of the main electrodes. The ignition arc is extended over the thickness of the layer made of material M.

The thin insulation section between the trigger electrode and the layer of poorly conductive material can preferably be implemented using circuit boards. The trigger electrode then corresponds to the applied conductor track and the insulation layer to the lacquer layer above it, with a front section remaining free of lacquer layer.

The previously known solution DE 10 2011 102 937 A1 , the disclosure content of which is declared to be the subject of the present application, creates a plasma jet or plasma beam in the base area of an arrangement preferably designed as a horn spark gap. This beam results in a strong and rapid targeted movement of ionized gases and charge carriers. This transport is used to significantly accelerate the ignition of the main path between the main electrodes, which can reduce the load on the trigger electrode and the sandwich structure and reduce the residual voltage of the spark gap.

The plasma jet effect explained above is characterized by the expression of a preferred direction of the ionized gas flow. According to the prior art, measures can be taken which, on the one hand, influence the formation of the jet, but also the direction, so that the effect of a rapid ignition of the main path arises. To overcome the air gap between the main electrodes, the proposed beam with its very effective ionization of air distances particularly suitable, which in turn ensures effective operation of the preferred horn spark gap. The electrode arrangement as well as the insulation layer and the layer made of the material with lower conductivity result in a preferred alignment of otherwise only stochastic plasma jets. In particular, the material with lower conductivity can be suitable for releasing gas, which enables further targeted generation of the plasma jet.

The solution after DE 10 2011 102 937 A1 Compared to classic, uninsulated current triggering methods, it offers the advantage of a very quick ignition of the main spark gap, which means that all other components of the spark gap arrangement are subject to a lower energy load and can therefore be designed in a miniaturized manner.

However, the disadvantage is the fact that even the smallest, relatively low-energy pulses from overvoltage events are sufficient to ignite the entire spark gap. This results in possible adverse aging of the corresponding surge arrester arrangement.

The DE 10 2014 102 065 A1 discloses an ignition element for use in a surge protection element having at least two electrodes and a spark gap formed between the two electrodes, the ignition element having at least one insulating layer. The insulating layer has at least two conductive, low-current-carrying areas, each of which extends between the top and bottom of the insulating layer, so that there are at least two conductive connections between the top and the bottom.

The DE 10 2004 006 988 A1 discloses an overvoltage protection device with a trigger electrode, an impedance being arranged in series with the trigger electrode in the trigger path.

From the foregoing, it is therefore the object of the invention to provide a further developed arrangement for igniting spark gaps using a trigger electrode, in which case the basic principle of plasma jet ignition should be used in order to utilize the advantages provided thereby, but on the other hand also to ensure them is that none Premature aging of appropriately equipped surge arresters with such spark gaps results in the fact that when the energy content of overvoltage events is low, the actual overload area between the main electrodes, in particular the main electrodes of a horn spark gap, is prevented from being activated.

The object of the invention is solved with an arrangement according to the combination of features according to claim 1, the subclaims representing at least practical refinements and further developments.

Accordingly, an arrangement for igniting spark gaps with a trigger electrode located on or in one of the main electrodes and insulated from this main electrode is assumed.

The trigger electrode can be electrically connected to the further main electrode via at least one voltage-switching or voltage-surging element.

There is an air gap between the main electrode and the other main electrode.

The trigger electrode forms a sandwich structure with an insulation layer and a layer made of a material with lower conductivity than the material of one of the main electrodes.

The insulation layer is preferably designed as a thin film or lacquer layer. The layer made of the material of lower conductivity is in contact with one of the main electrodes or rests on it.

According to the invention, the arrangement is now developed in such a way that an energetic limit or an energetic threshold value can be determined, with energetically weak overvoltage events being derived below the specified limit or threshold value without the spark gap between the main electrodes responding. If the limit or threshold value is exceeded, the corresponding triggered discharge process takes place by igniting the main spark gap.

The basic idea of the invention is to only use those that can be spatially and structurally integrated into the spark gap itself for determining the limit or threshold value and the means to be provided for this purpose. Additional external wiring where necessary housing bushings and other structural measures must be explicitly excluded.

Accordingly, according to the invention, the insulation layer of the sandwich structure is interrupted outside the ignition area in order to dissipate energetically weak overvoltage events without responding to the spark gap formed between the main electrodes. Alternatively or additionally, an electrical component that influences the response behavior is integrated into the spark gap between the trigger electrode and the main electrode.

By interrupting the insulation layer, an electrical connection is formed between the trigger electrode and the layer of lower conductivity, whereby the dissipable energy content of the overvoltage event can be determined by the limited conductivity or the resistance of the layer of lower conductivity. This in turn allows the aforementioned limit or threshold value to be set.

In one embodiment, the aforementioned electrical component is an integrable, miniaturized resistor.

Overvoltage events with the smallest energy content, for example burst pulses, generally no longer lead to the ignition of the overall spark gap, since the low or minimal pulse energy is dissipated in the layer of lower conductivity.

If the energy content of the overvoltage or overvoltage event is higher, the overall spark gap ignites with a delay. If the energy of the pulse exceeds a predetermined level, such a high voltage drops across the layer of lower conductivity that the auxiliary ignition spark gap ignites and thus the main spark gap can be ignited. The amount of delay can be determined by the structural design and material sizes or material properties can be influenced. The auxiliary ignition spark gap is ignited by a flashover of the insulation gap in the ignition area.

With all the overvoltages with larger energy contents, for example with direct or indirect lightning pulses, the main spark gap ignites at a comparable speed, as is known from the prior art.

In a preferred embodiment, the trigger electrode is formed by a conductor track of a film circuit board and the insulation layer is formed by an insulating cover, in particular a lacquer layer on the conductor track.

The insulating cover is exposed for the interruption, so that the exposed section of the conductor track can be brought into contact with the layer of lower conductivity.

The layer of lower conductivity can preferably consist of a conductive plastic material or be formed from a material with a carbon fiber content.

The invention will be explained in more detail below using an exemplary embodiment and with the help of figures.

Fig. 1

ein Ersatzschaltbild mit der prinzipiellen Anordnung von Hauptelektroden einer Funkenstrecke sowie einer Sandwichstruktur, umfassend eine Triggerelektrode mit einer Isolationsschicht sowie einer Schicht aus einem Material geringerer Leitfähigkeit als das Material einer der Hauptelektroden und Parallelschaltung eines elektrischen Bauelementes in Form eines Widerstandes zwischen Triggerelektrode und zugehöriger Hauptelektrode sowie

Fig. 2

eine Darstellung ähnlich nach Fig. 1, jedoch mit angedeuteter Unterbrechung der Isolationsschicht, so dass die Triggerelektrode außerhalb des Zündbereiches in Kontakt zur Schicht mit dem Material geringerer Leitfähigkeit gelangt, um bei geringen Energiegehalten eines Überspannungsereignisses ein unmittelbares Ableiten ohne Ansprechen der Gesamt-Funkenstrecke zu erreichen.

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Fig. 1

an equivalent circuit diagram with the basic arrangement of main electrodes of a spark gap and a sandwich structure, comprising a trigger electrode with an insulating layer and a layer made of a material of lower conductivity than the material of one of the main electrodes and parallel connection of an electrical component in the form of a resistor between the trigger electrode and the associated main electrode and

Fig. 2

a representation similar to Fig. 1 , but with an indicated interruption of the insulation layer, so that the trigger electrode outside the ignition area comes into contact with the layer with the material of lower conductivity in order to achieve immediate discharge without the overall spark gap responding when the energy content of an overvoltage event is low.

The representation according to the Figures 1 and 2 comprises an electrically conductive trigger electrode T, which is covered by an insulation layer I in the direction of the main electrode H2.

The insulation layer I is followed by a layer made of a material M with lower conductivity.

The layer made of material M lies on the surface of the main electrode H2.

External elements can be connected between trigger electrode T and the main electrode H1 via a connection A. The means provided there can include, for example, gas arresters, varistors, diodes or similar electrical components.

The spark gap formed by the main electrodes H1 and H2 can be designed as a horn spark gap and is electrically connected between the paths L and N/PEN.

The configuration shown corresponds in principle to the arrangement for plasma jet generation DE 10 2011 102 937 A1 and the explanations there about the structural design. In this respect, reference is made to the relevant explanations in the DE 10 2011 102 937 A1 referred to, which embody the knowledge of the relevant expert here.

According to the invention Fig. 1 An electrical component R which influences the response behavior is connected between the trigger electrode T and the main electrode H2. The value of the resistance R determines the response behavior and thus an energetic limit based on the ignition process of the corresponding spark gap.

If the energy content of corresponding overvoltage events is low, the voltage drop resulting across the resistor R is not sufficient to enable ignition in the ignition area of the arrangement. The arrangement of the resistor R makes it possible to dissipate low-energy overvoltage events immediately without the main spark gap responding and thereby aging unnecessarily.

According to the representation Fig. 2 A fully integrated solution is shown instead of connecting the resistor R in parallel.

In this regard, the thin insulation layer I is interrupted outside the ignition and flashover area, so that a conductive connection of the trigger electrode T with the material of lower conductivity M takes place. Due to the resistance value of the material M, this creates the possibility of diverting overvoltage events via the path of the trigger electrode, the material of lower conductivity M and the main electrode H2, without the main spark gap between the further main electrode H1 and the main electrode H2 responding.

In such a case, the energy content of the overvoltage is so low that only a very small current flows and the voltage dropped in the poorly conductive material M is not sufficient to flash over the insulation layer I. This means that the flashover area does not respond and the overvoltage is diverted solely through the energy image area.

However, if the current increases very sharply due to an overvoltage event, so that the voltage falling in the material M flashes over the insulation layer I and generates an ignition spark, the entire spark gap is ignited.

In this embodiment variant of the invention, the layer made of the material M not only has the task of extending the ignition arc by extending the direct flashover distance from the trigger electrode T to the main electrode H2, but rather the resistance value of the poorly conductive material is increased by contacting the trigger electrode with the Layer M used to divert weak overvoltage events. This design allows for any separate electrical or electronic Components for controlling the response behavior, especially in the case of very weak overvoltage events, are completely dispensed with.

Claims (7)

1. Arrangement for igniting spark gaps using a trigger electrode (T) that is located on or in one of the main electrodes (H2) and is insulated from this main electrode (H2), wherein the trigger electrode (T) is electrically connected to the further main electrode (H1) via at least one voltage-switching or voltage-monitoring element (A) and an air gap exists between the trigger electrode (T) and the further main electrode (H1), wherein the trigger electrode (T) forms a sandwich structure with an insulation layer (I) and a layer of a material (M) having lower conductivity than the material of one of the main electrodes (H1, H2), the insulation layer (I) is designed as a thin film or lacquer layer and the layer of the material (M) having lower conductivity is in contact with the main electrode (H2) or rests on it,
   characterised in that
   for dissipation of energetically weak overvoltage events without response of the spark gap that is formed between the main electrodes (H1; H2), the insulation layer (I) of the sandwich structure outside the ignition region is interrupted by an interruption (U) and/or an electrical component that influences the response behaviour is connected between the trigger electrode (T) and the main electrode (H2).
2. Arrangement according to claim 1,
   characterised in that
   an electrical connection between the trigger electrode (T) and the layer of the material (M) having low conductivity is formed by the interruption (U) of the insulation layer (I), wherein the limited conductivity or the resistance of the layer of the material (M) having low conductivity determines the dissipative energy content of the overvoltage event.
3. Arrangement according to claim 1,
   characterised in that
   the electrical component is a resistor (R).
4. Arrangement according to one of the preceding claims,
   characterised in that
   in the case of a low energy content of the overvoltage event, a current flows to the main electrode (H2) through the electrical component and/or the layer of the material (M) having low conductivity, wherein the extent of the voltage drop at the electrical component (R) and/or at the layer of the material (M) having low conductivity determines whether the overvoltage is directly dissipated or whether the voltage drop leads to a flashover of the insulation gap (I) in the ignition region or flashover region (Z) and thus to the ignition of the spark gap between the main electrodes (H1 and H2).
5. Arrangement according to one of the preceding claims,
   characterised in that
   the trigger electrode (T) is formed by a conductor track of a film circuit board and the insulation layer (I) is formed by an insulating cover, in particular a lacquer layer, on the conductor track, wherein the insulating cover is exposed for the interruption (U), and the exposed region is connected to the layer of the material (M) having low conductivity.
6. Arrangement according to one of the preceding claims,
   characterised in that
   the layer of the material (M) having low conductivity is embodied from a conductive synthetic material.
7. Arrangement according to one of claims 1 to 5,
   characterised in that
   the layer of the material (M) of low conductivity is embodied from a material having a carbon fibre proportion.

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