EP4270688A1 - Multiple spark gap arrangement - Google Patents

Abstract

Shown and described is a multiple spark gap (1) for a surge protection device, with several electrodes (2) and insulating elements (3) arranged between the electrodes (2), with two opposite electrodes (2) forming a single spark gap (4, 41) and the individual spark gaps (4, 41) are connected in series, with two electrically conductive contact elements (5, 6), between which the electrodes (2) are arranged, so that the first contact element (5) has the first electrode (21) and the second contact element (6) electrically contacts the last electrode (23) of the multiple spark gap (1), and with a control circuit (7) for controlling the ignition behavior of the multiple spark gap (1), the control circuit (7) having a plurality of control elements (8) which are connected to the individual electrodes (2, 22, 23), apart from the first electrode (21), are connected. The multiple spark gap (1) according to the invention therefore has both a high mains follow current extinguishing capacity and a relatively low protection level, the distance x<sub>1</ sub> between the first electrode (21) and the adjacent second electrode (22), which together form the first individual spark gap (41), is greater than the respective distances x₂ between the other adjacent electrodes (2 , 22, 23), which form the further individual spark gaps (4), and that an ignition aid (9) is provided for igniting the first individual spark gap (41), which has at least one resistive ignition element (10) and a voltage-limiting element (11), wherein the ignition element (10) is connected to the arc combustion chamber (12) of the first individual spark gap (41) and on one side to the first electrode (21) and on the other side via the voltage-limiting element (11) to the second contact element ( 6) is electrically connected.

Description

The invention relates to a multiple spark gap for a surge protection device, with several electrodes and insulating elements arranged between the electrodes, with two opposing electrodes forming a single spark gap and the individual spark gaps being connected in series. For electrical connection, the multiple spark gap has two electrically conductive contact elements, between which the electrodes are arranged, so that the first contact element electrically contacts the first electrode and the second contact element electrically contacts the last electrode of the multiple spark gap.

A variety of surge protection devices are known from the prior art and are used to protect electrical devices or lines from surges that can be caused, for example, by lightning strikes or defects in technical systems. Spark gap arrangements with multiple electrodes have been used for decades in the area of overvoltage protection in electrical devices and systems.

In order to dissipate high overvoltages while at the same time ensuring a high mains follow current extinguishing capacity, multiple spark gaps are often used, which are often referred to as stacked spark gaps due to their structure. Such stacked spark gaps consist of several electrodes and several insulations, which are arranged between the individual electrodes, so that there is insulation between two electrodes, which has an opening in the middle, so that two electrodes form a single spark gap. The electrodes are often designed as circular or rectangular graphite disks, between which corresponding ring-shaped or frame-like insulation is then arranged. The insulation is often designed as thin insulating disks or insulating films made of plastic, for example PTFE.

In order to influence the ignition behavior of a multiple spark gap, it is known from the prior art to provide control circuits that have several passive control elements. This is how it reveals DE 197 42 302 A1 a multiple spark gap, which consists of a plurality of individual spark gaps connected in series, the individual spark gaps, with the exception of the first responding single spark gap in the case of leakage A graduated network of resistors are connected so that the individual spark gaps switch through successively. Each individual spark gap has a resistor connected in parallel and the resistors of all individual spark gaps are connected in series to earth. So that the response voltage of the multiple spark gap does not exceed a maximum value of, for example, 4 kV, the distance between the two electrodes of the first individual spark gap should be chosen to be correspondingly small.

Capacitances, in particular capacitors, are often used as control elements in multiple spark gaps, with one capacitor each contacting an electrode with one connection and all capacitors being electrically conductively connected to one another and to the second connection or the second contact element of the multiple spark gap with their second connection. This results in a capacitive voltage divider that concentrates the applied voltage onto a single spark gap. Once this individual spark gap has ignited, the total voltage, reduced only by the arc voltage of the first individual spark gap, is applied to the next individual spark gap, so that the individual spark gaps switch through successively.

Different variants are known from practice as to how the individual electrodes and the individual insulation can be connected to form a multiple spark gap. Large-area contact plates are often used as contact elements, which form the end faces of the multiple spark gap and are clamped together in the axial direction by screwing over several guide rods, so that the individual electrodes and the individual insulations are clamped in their stacked arrangement between the contact plates. If the guide rods arranged between the contact plates are guided past the individual electrodes on the outside, this means that the required installation space is relatively large.

The DE 10 2011 102 864 A1 discloses a stacked spark gap with several individual spark gaps connected in series, with the individual electrodes each being arranged in an insulating body. The insulating bodies each have a recess for receiving a disk-shaped electrode and a receptacle for a control element, the receptacle for the control element being connected to the recess for the electrode. A control element is connected to the edge via a contact spring connected to the electrode, so that triggering of the individual electrodes of the stack spark gap can be achieved via the control elements.

Compared to single spark gaps, multiple spark gaps have the advantage of improved mains follow current extinguishing capacity. The ability to extinguish the mains follow current increases as the number of individual spark gaps increases. At the same time, however, as the number of individual spark gaps increases, the response voltage of the multiple spark gap also increases. Multiple spark gaps, which are made up of many individual spark gaps, therefore have a high mains follow current extinguishing capacity, but at the same time they also generally have a protection level that is too high for low-voltage applications.

The present invention is therefore based on the object of specifying a multiple spark gap that has both a high mains follow current extinguishing capacity and the lowest possible protection level.

This task is solved with the multiple spark gap described at the beginning with the features of patent claim 1. The distance x ₁ between the first electrode and the adjacent second electrode, which together form the first individual spark gap, is larger than the respective distances x ₂ between the other adjacent electrodes, which form the further individual spark gaps. In addition, an ignition aid for igniting the first individual spark gap is provided, which has at least one resistive ignition element and a voltage-limiting element, the ignition element being connected to the arc combustion chamber of the first individual spark gap and on one side with the first electrode and on the other side via the voltage-limiting element is electrically connected to the second contact element.

The multiple spark gap according to the invention is at least functionally divided into two areas. The first area includes the first individual spark gap and the second area includes the remaining individual spark gaps. The second area thus includes all electrodes except the first electrode, which is electrically conductively connected to the first contact element, while the first area only includes the first two electrodes. The second electrode adjacent to the first electrode, which forms the first individual spark gap with the first electrode, is assigned to both the first area and the second area, since the second electrode is connected to the next electrode also forms another individual spark gap, the second individual spark gap.

The reduction of the respective distances x ₂ between the adjacent electrodes, which form the further individual spark gaps, compared to the distances of conventional individual spark gaps, leads to a reduction in the response voltage in this area. Although this is advantageous in terms of the desired lowest possible protection level of the multiple spark gap, it at the same time leads to an unwanted reduction in the insulation strength in this area, especially during operation if contamination occurs on the respective insulation gaps after the multiple spark gap has been ignited.

In order to ensure that the multiple spark gap according to the invention still has a sufficiently high insulation strength, the distance x ₁ between the first electrode and the adjacent second electrode is chosen to be so large that the first individual spark gap has sufficient insulation strength for the respective system voltage. Since a correspondingly large distance x ₁ between the first electrode and the adjacent second electrode, which together form the first individual spark gap, leads to a response voltage that is significantly above the standard market requirements, the multiple spark gap according to the invention also has an ignition aid for igniting the first individual spark gap on.

The ignition aid consists at least of a resistive ignition element and a voltage-limiting element, for example a varistor. The ignition element is in electrical connection on one side with the first electrode and on the other side via the voltage-limiting element - directly or indirectly - with the second contact element. In addition, the ignition element is spatially connected to the arc combustion chamber of the first individual spark gap, ie the ignition element projects into the arc combustion chamber with one end face or is arranged at the edge of the arc combustion chamber. When an overvoltage occurs that is greater than the response voltage, a current initially flows from the second contact element via the voltage-limiting element and the resistive ignition element to the adjacent first electrode and to the first contact element. The current flow via the ignition element leads to a discharge on the surface of the ignition element, so that in the area adjacent to the ignition element Ignition area within the arc combustion chamber ionized gas is generated, which spreads in the arc combustion chamber. This leads to a reduction in the breakdown voltage of the first individual spark gaps, so that the first individual spark gap between the first electrode and the adjacent second electrode is ignited.

The response voltage of the multiple spark gap according to the invention is therefore determined by the response voltage of the ignition aid and not by the response voltage of the first individual spark gap, so that a sufficiently low response voltage of the multiple spark gap can be achieved despite the increased distance x ₁ of the first individual spark gap. In particular, due to the formation of a plurality of individual spark gaps with the multiple spark gap according to the invention, it is possible to achieve a high mains follow current extinguishing capacity and at the same time a relatively low protection level. When designing the multiple spark gap for a 230/400 V system, a protection level of, for example, 1.5 kV can be achieved.

It was previously stated that the resistive ignition element is electrically connected to the first electrode on one side and, directly or indirectly, to the second contact element on the other side via the voltage-limiting element. This means that the resistive ignition element does not have to be directly and permanently electrically connected to the second contact element via the voltage-limiting element. It is also possible for further electrical components that are part of the ignition aid to be arranged in the series connection of the ignition element and the voltage-limiting element.

According to an advantageous embodiment of the invention, the ignition aid also has a voltage switching element which is arranged in a series connection with the resistive ignition element and the voltage-limiting element. The voltage switching element can be arranged both between the resistive ignition element and the voltage-limiting component and between the voltage-limiting element and the second contact element. The response voltage of the ignition aid is then determined by the response voltage of the voltage switching element, since the ignition circuit only becomes conductive when there is an overvoltage that is greater than the response voltage of the voltage switching element. Another advantage of this ignition aid is that the spark gap present on the multiple spark gap external voltage during the ignition process is already limited by the ignition circuit, i.e. the series connection of voltage switching element, voltage-limiting element and resistive ignition element, until the multiple spark gap has completely ignited. Voltage peaks during ignition are limited by the ignition circuit.

It is also particularly preferred if the voltage switching element, which can be, for example, a gas arrester (GDT), is arranged between the second contact connection and the voltage-limiting element in such a way that it is also electrically connected between the second contact element and the control circuit for control the ignition behavior of the further individual spark gaps is arranged, so that the control circuit is electrically connected to the second contact element only in the case of leakage, when the voltage switching element has responded.

According to one embodiment of the multiple spark gap according to the invention, the control circuit has capacitors as control elements, with one capacitor in each case electrically contacting an electrode of the further individual spark gaps with its first connection and the individual capacitors being electrically connected to one another and to the second contact element with their second connections. Here too, with regard to the connection of the second connections of the control elements or the capacitors, these can be connected both directly and indirectly to the second contact element. An indirect connection can be realized according to the aforementioned advantageous embodiments in that a voltage switching element is arranged between the common reference point of the second connections of the control elements or the capacitors and the second contact element. This has the advantage that the control circuit is only electrically connected to the second contact element in the event of leakage, i.e. only when there is an overvoltage at the multiple spark gap that is greater than the response voltage of the voltage switching element. This leads to an improvement in the insulation properties of the multiple spark gap.

It was previously stated that in order to ensure a sufficiently high insulation strength, the distance x ₁ between the first electrode and the adjacent second electrode is chosen to be so large that the first individual spark gap has sufficient insulation strength for the respective system voltage. When using the multiple spark gap as intended in the power supply of low-voltage networks, the distance x ₁ is preferably at least 0.5 mm, in particular between 1 mm and 2 mm. Such a relatively large distance between the two electrodes of the first single spark gap would normally lead to such a high level of protection that the multiple spark gap would not meet the current requirements for surge arresters. However, due to the ignition aid used according to the invention in the multiple spark gap with at least one resistive ignition element and a voltage-limiting element, the response voltage of the multiple spark gap and thus its protection level can be significantly reduced.

The distances x ₂ between the adjacent electrodes of the further individual spark gaps, on the other hand, are significantly smaller than the distance x ₁ . According to a preferred embodiment, the distances x ₂ are a maximum of 0.2 mm, in particular between 0.05 mm and 0.15 mm. With the preferred dimensioning of the multiple spark gap according to the invention, the distance x ₁ is therefore at least 5 times the distance x ₂ . Even if, in principle, the distances x ₂ between the adjacent electrodes of the further individual spark gaps can differ from one another, it is also advantageous from a manufacturing perspective if the distances x ₂ between the adjacent electrodes of the further individual spark gaps are the same or essentially the same within the scope of usual manufacturing tolerances are.

The multiple spark gap according to the invention thus uses the advantage of multiple spark gaps with a plurality of individual spark gaps, namely their high mains follow current extinguishing capacity, while at the same time the disadvantage of a relatively high protection level, which would otherwise be present with such multiple spark gaps, is eliminated. The individual electrodes of the multiple spark gap are preferably designed as rectangular or round thin disks made of carbon. The thickness of the electrode disks is preferably less than 1 mm, in particular less than 0.75 mm, for example only approximately 0.5 mm to 0.6 mm.

The insulating elements between the individual electrodes of the multiple spark gap can basically consist of individual insulating disks or insulating foils, each of which is designed in the shape of a ring or frame. However, the individual insulating elements are advantageously part of a common insulating and holding arrangement in which both the individual electrodes and the two contact elements are arranged. The insulating and holding arrangement then also ensures the secure mechanical fixation of the individual electrodes of the multiple spark gap.

Alternatively, the individual insulating elements can also each be part of an insulating and holding frame, in which case the individual insulating and holding frames are connected to one another, in particular screwed or locked together. The individual insulating and holding frames can then each have a receiving opening for receiving a control element.

Fig. 1

eine Prinzipdarstellung eines ersten Ausführungsbeispiels einer Mehrfachfunkenstrecke, in Schnittdarstellung und

Fig. 2

eine Prinzipdarstellung eines zweiten Ausführungsbeispiels einer Mehrfachfunkenstrecke, in Schnittdarstellung.

In detail, there are a variety of options for further developing and designing the multiple spark gap according to the invention. Reference is made to both the subordinate patent claims and the following description of two exemplary embodiments in conjunction with the drawing. Show in the drawing

Fig. 1

a schematic representation of a first exemplary embodiment of a multiple spark gap, in a sectional view and

Fig. 2

a schematic representation of a second embodiment of a multiple spark gap, in a sectional view.

The two figures each show a schematic representation of a multiple spark gap 1 according to the invention, which has a plurality of electrodes 2 and insulating elements 3 arranged between the electrodes 2. Two opposing electrodes 2 each form an individual spark gap 4, with the individual individual spark gaps 4 themselves being connected in series. The first electrode 21 shown in the figures above forms, together with the adjacent second electrode 22, a first individual spark gap 41, which differs in its structure from the other individual spark gaps 4. The first electrode 21 is also electrically connected to the first contact element 5, while the second contact element 6 is electrically conductively connected to the last electrode 23 of the multiple spark gap 1. All electrodes 2, 21, 22, 23 of the multiple spark gap 1 are thus arranged between the two contact elements 5, 6.

In both exemplary embodiments of the multiple spark gap 1 shown, a control circuit 7 is also provided for controlling the ignition behavior of the multiple spark gap 1, the control circuit 7 having a plurality of control elements 8 designed as capacitors, which all electrodes 2, 22, 23 except the first electrode 21 are connected. In addition, the multiple spark gap 1 has an ignition aid 9, which serves to ignite the first individual spark gap 41. The ignition aid 9 has a resistive ignition element 10 and the series connection of a voltage-limiting element 11 and a voltage switching element 13. A varistor in particular can be used as the voltage-limiting element 11 and a gas arrester in particular can be used as the voltage switching element 13. The ignition element 10 is connected to the arc combustion chamber 12 of the first individual spark gap 41. In addition, the resistive ignition element 10 is electrically connected to the first electrode 21 on one side and to the second contact element 6 on the other side via the series connection of the voltage-limiting element 11 and voltage switching element 13.

The multiple spark gap 1 according to the invention is divided into two areas, namely a first area which includes the first individual spark gap 41 and a second area which includes the remaining individual spark gaps 4. The first area also includes the ignition aid 9 with the resistive ignition element 10 projecting into the arc combustion chamber 12 of the first individual spark gap 41 and the second area includes the control circuit 7 with the individual control elements 8.

As can be seen from both figures, the distance x ₁ between the first electrode 21 and the adjacent second electrode 22, which together form the first individual spark gap 41, is significantly larger than the respective distance x ₂ between the other adjacent electrodes 2, 22, 23 , which form the further individual spark gaps 4. The distance x ₁ between the first electrode 21 and the adjacent second electrode 22 is preferably between 1 mm and 2 mm, while the distance x ₂ between the other adjacent electrodes 2, 22, 23 of the further individual spark gaps 4 is preferably between 0.05 mm and is 0.15 mm. The distance x ₁ is therefore preferably approximately ten times as large as the distance x ₂ .

Due to the relatively large distance x ₁ between the first electrode 21 and the adjacent second electrode 22, the first single spark gap 41 and thus also the multiple spark gap 1 as a whole have a sufficiently high insulation strength. At the same time, the response voltage in the second area is clear due to the very small distance x ₂ between the adjacent electrodes 2, 22, 23 of the further individual spark gaps 4 reduced. Due to the additionally designed ignition aid 9, the multiple spark gap 1 has a very low protection level while at the same time having a high mains follow current extinguishing capacity.

Both in the exemplary embodiment according to Fig. 1 as well as in the exemplary embodiment according to Fig. 2 the control circuit 7 has 8 capacitors as control elements. In principle, however, other control elements can also be used. The first connection 14 of the individual control elements 8 is electrically connected to an electrode 2, 22, 23, while the second connections 15 of the control elements 8 are electrically connected to one another. These second connections 15 of the control elements 8 are in the exemplary embodiment Fig. 1 directly electrically conductively connected to the second contact element 6.

In the exemplary embodiment according to Fig. 2 On the other hand, the voltage switching element 13 of the ignition aid 9 is connected between the second contact element 6 and the common potential 18 of the second connections 15 of the control elements 8. This resulted in the control circuit 7 or the individual control elements 8 only being electrically connected to the second contact element 6 when the voltage switching element 13 had already responded. The control circuit 7 is therefore only electrically connected to the second contact element 6 in the case of leakage, whereby the insulation properties of the multiple spark gap 1 in the second area are significantly improved.

The ones in the Fig. 1 and 2 The illustrated embodiments of the multiple spark gap 1 therefore differ in the specific arrangement of the ignition aid 9 with respect to the control circuit 7. In the exemplary embodiment according to Fig. 2 the voltage switching element 13 is electrically connected with its first connection 16 to the second contact element 6 and with its second connection 17 to both the voltage-limiting element 11 and to the common potential 18 of the second connections 15 of the control elements 8.

In both exemplary embodiments, the individual insulating elements 3 are part of a common insulating and holding arrangement 19, which also serves to mechanically fix the individual electrodes. In addition, the two contact elements 5, 6 are also accommodated by the insulating and holding arrangement 19, so that a relatively compact multiple spark gap 1 can be realized is. Due to the very small distances x ₂ between the electrodes 2, 22, 23 forming the further individual spark gaps 4, the multiple spark gap 1 can have a plurality of electrodes 2, 22, 23, without thereby changing the dimensions of the multiple spark gap 1 between the two contact elements 5, 6 becomes too big. It is obvious to the expert that the Fig. 1 and 2 The number of electrodes 2 shown is only an example and the multiple spark gap 1 according to the invention is in no way limited to the number of electrodes 2 shown.

Reference symbols

1

Multiple spark gap

2

Electrodes

21

first electrode

22

second electrode

23

last electrode

3

Insulating elements

4

Single spark gap

41

first single spark gap

5

Contact element

6

Contact element

7

Control circuit

8th

Control element

9

Ignition aid

10

Ignition element

11

stress-limiting element

12

Arc combustion chamber

13

Voltage switching element

14

first connection control element

15

second connection control element

16

first connection voltage switching element

17

second connection voltage switching element

18

common potential of the second connections of the control elements

19

Isolation and holding arrangement

x1

Distance electrodes first individual spark gap

x2

Distance electrodes further individual spark gap

Claims (12)

Multiple spark gap (1) for a surge protection device, with several electrodes (2) and insulating elements (3) arranged between the electrodes (2), with two opposite electrodes (2) forming a single spark gap (4, 41) and the individual spark gaps (4, 41) are connected in series, with two electrically conductive contact elements (5, 6), between which the electrodes (2) are arranged, so that the first contact element (5) is the first electrode (21) and the second contact element (6) is the last electrode (23) of the multiple spark gap ( 1) electrically contacted, and with a control circuit (7) for controlling the ignition behavior of the multiple spark gap (1), the control circuit (7) having a plurality of control elements (8) which are connected to the individual electrodes (2, 22, 23), except for the first electrode (21), are connected, characterized, that the distance x ₁ between the first electrode (21) and the adjacent second electrode (22), which together form the first individual spark gap (41), is larger than the respective distances x ₂ between the other adjacent electrodes (2, 22, 23 ), which form the further individual spark gaps (4), and that an ignition aid (9) is provided for igniting the first individual spark gap (41), which has at least one resistive ignition element (10) and a voltage-limiting element (11), wherein the ignition element (10) is connected to the arc combustion chamber (12) of the first individual spark gap (41) and on one side to the first electrode (21) and on the other side via the voltage-limiting element (11) to the second contact element ( 6) is electrically connected. Multiple spark gap (1) according to claim 1, characterized in that the ignition aid (9) has a voltage switching element (13) which is arranged in a series connection with the resistive ignition element (10) and the voltage-limiting element (11). Multiple spark gap (1) according to claim 1 or 2, characterized in that each control element (8) has an electrode (2, 22, 23). further individual spark gaps (4) are electrically contacted with its first connection (14) and that the control elements (8) are electrically connected to one another and to the second contact element (6) with their second connections (15). Multiple spark gap (1) according to claims 2 and 3, characterized in that the voltage switching element (13) with its first connection (16) with the second contact element (6) and with its second connection (17) with both the voltage-limiting element (11) and is also electrically connected to the second connections (15) of the control elements (8). Multiple spark gap (1) according to one of claims 1 to 4, characterized in that the distance x ₁ between the first electrode (21) and the adjacent second electrode (22) of the first individual spark gap (41) is at least 0.5 mm, in particular 1 mm up to 2 mm. Multiple spark gap (1) according to one of claims 1 to 5, characterized in that the distances x ₂ between the adjacent electrodes (2, 22, 23) of the further individual spark gaps (4) are each at most 0.2 mm, preferably 0.05 mm to is 0.15 mm. Multiple spark gap (1) according to one of claims 1 to 6, characterized in that the distances x ₂ between the adjacent electrodes (2, 22, 23) of the further individual spark gaps (4) are essentially the same size. Multiple spark gap (1) according to one of claims 1 to 7, characterized in that the distance x ₁ between the first electrode (21) and the adjacent second electrode (22) of the first single spark gap (41) is at least 5 times, preferably at least that 10 times the distance x ₂ between the adjacent electrodes (2, 22, 23) of the further individual spark gaps (4). Multiple spark gap (1) according to one of claims 1 to 8, characterized in that the individual electrodes (2, 21, 22, 23) are designed as thin disks made of carbon. Multiple spark gap (1) according to one of claims 1 to 9, characterized in that the insulating elements (3) between the individual ones Electrodes (2, 21, 22, 23) are part of a common insulating and holding arrangement (19), in which both the individual electrodes (2, 21, 22, 23) and the two contact elements (5, 6) are arranged. Multiple spark gap (1) according to one of claims 1 to 9, characterized in that the individual insulating elements (3) between the individual electrodes (2, 21, 22, 23) are each part of an individual insulating and holding frame, and that the individual insulating - and holding frames are connected to one another, in particular screwed or locked together. Multiple spark gap (1) according to claim 11, characterized in that the individual insulating and holding frames each have a receiving opening for receiving a control element (8).

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