DE102018131537B4 - Spark gap arrangement for a multi-stacked spark gap - Google Patents

Abstract

Spark gap arrangement (10; 10'; 10''), having a multiple spark gap (20) with a plurality of series-connected individual spark gaps in a stack arrangement, each individual spark gap being formed by two electrodes (21; 22) which are formed by at least one insulating material element ( 23) are separated from one another, and the stack arrangement of individual spark gaps is clamped resiliently in the stacking direction between two opposing holding elements (30; 31), the holding elements (30; 31) being connected to a frame structure which acts as an abutment for both holding elements (30; 31 ) acts, and the holding elements (30; 31) are metallically and directly electrically insulated from one another, characterized in that the frame structure is formed by two insulating plates (40; 41) between which the multiple spark gap (20) is arranged, and each Holding element (30; 31) is connected to the two insulating plates (40; 41).

Description

The invention is based on a spark gap arrangement having a multiple spark gap with a plurality of individual spark gaps connected in series in a stack arrangement according to the preamble of claim 1.

In the area of overvoltage protection for electrical devices or systems, overvoltage protection elements are used that respond to a specific overvoltage, which would otherwise lead to disruptions and/or damage in an electrical circuit in the event of an overvoltage event. Surge arresters based on spark gaps, for example, can be used as such overvoltage protection elements. Spark gaps have proven their worth, particularly for diverting so-called transient overvoltages with very high amplitudes. As soon as a spark gap has ignited, a conductive connection is established across the arc gap of the spark gap, through which the high-voltage pulse is then dissipated.

In particular, spark gaps are used that minimize the mains follow current or are even operated without mains follow current. The mains follow current is the part of a current flow that flows through a spark gap after dissipating an overvoltage event from the power supply network. Such a mains follow current can last up to a few milliseconds and have the intensity of a short-circuit current. Therefore, mains follow currents represent a load for the entire electrical installation that must be prevented.

In order to operate a spark gap without a mains follow current, multiple spark gaps in which several individual spark gaps are connected in series have proven particularly advantageous. These multiple spark gaps are also known as multi-arc spark gaps (MAFS), which are based on the principle of arc multiplication. In order to form a multiple spark gap, in certain embodiments a plurality of disc-shaped electrodes are joined together to form a stack, these electrode discs being made of carbon or graphite, for example. A thin foil or disk made of an insulating material is placed between the individual electrodes. This results in a number of individual spark gaps between the electrodes, which can be ignited via an appropriately designed voltage controller.

The multi-arc spark gap technology has the advantage of a very constant, current-independent arc voltage, which can be very well adapted to the operating voltage conditions via the number of electrode disks. With suitable dimensioning, mains follow currents can be almost completely ruled out. Significant advantages result in particular with regard to use in AC networks.

If one typically chooses electrodes made of graphite, there are further advantages. The property of graphite to sublimate when heated allows the formation of very small gaps between the electrodes. The resulting very short arcs in connection with a relatively large surface area and the relatively high thermal mass of such graphite stack spark gaps ensure robust behavior in the event of impulse dissipation.

Therefore, the technology of multiple spark gaps can be used to realize very compact structures with high energy efficiency. Compact devices of this type can be used in overvoltage protection devices that can be mounted on a top-hat rail, but can also be installed directly on printed circuit boards in any electrical devices. However, the high degree of compactness in connection with the integration into electrical devices, in which increased ambient temperatures prevail, requires a particularly temperature-resistant mechanical structure. Such a structure must in particular ensure that a stacked spark gap is always sufficiently compressed in the event of temperature fluctuations. Furthermore, the stack spark gap should not be destroyed in the event of strong heating, as occurs in the case of leakage.

For this purpose, typically metallic housing constructions are used, which have a high temperature resistance. However, due to the increased insulation distances, these require a large installation space and are usually associated with relatively high costs.

From the disclosure document DE 10 2013 113 614 A1 a multi-pole spark gap for lightning protection is known, in which in each case a spark gap is arranged in a chamber in an insulating material housing. The disclosure document DE 10 2011 102 941 A1 discloses a stacked spark gap having a mechanically biased isolation element to interrupt the main current path of the spark gap in the event of a fault or overload. From the disclosure document DE 10 2016 101 633 A1 an arrangement for diverting surge voltages with a plurality of gas-filled surge arresters is known.

Also disclosed, for example, the generic patent DE 12 56 306 B a spark gap consisting of a stacked arrangement with a sequence of disc-shaped electrodes and insulating rings, which each have a radial overhang to the graphite electrodes and are designed like a frame for the electrodes. The stacked arrangement is clamped between two press plates, for example, and arranged in a tubular insulating material housing.

The invention is based on the object of providing a spark gap arrangement with a further developed holding structure for a multiple spark gap.

This object is achieved by a spark gap arrangement having the features of claim 1. Advantageous developments of the spark gap arrangement result from the dependent claims 2-14.

The spark gap arrangement according to the invention has a multiple spark gap with a plurality of individual spark gaps connected in series, which are located in a stack arrangement. The multiple spark gap is based on the principle of arc multiplication and is also known as a stacked spark gap or multi-arc spark gap. In this case, a single spark gap is formed by two electrodes, which are separated from one another by at least one insulating material element and are thus kept at a distance. A number of n+1 electrodes thus forms n individual spark gaps. Preferably the electrodes are graphite electrodes, i.e. graphite discs. The electrodes can be ring-shaped or disc-shaped. Thin disks or foils made of a known insulating material such as vulcanized fiber can be used as insulating material elements. The electrodes are held, for example, in a recess in a frame, with the insulating material elements being arranged between the frames and fixed by them. The frames of the electrodes then also consist of an insulating material such as vulcanized fiber. The insulating material elements are ring-shaped, so that the required distance for a single spark gap is formed between two electrodes, which leads through an opening in an insulating material element.

According to the invention, the stacked arrangement of individual spark gaps is clamped resiliently in the stacking direction between two opposite metallic holding elements. The holding elements are connected to a frame structure which acts as an abutment for both holding elements. Furthermore, the holding elements are directly electrically insulated from one another, which is preferably effected by an electrically insulating frame structure. The frame structure itself can in turn be connected to other components of an overvoltage device. In this context, “directly electrically insulated from one another” in the context of the present invention means that there is no direct electrical connection between the two holding elements. However, the frame structure can create an indirect connection between the two holding elements via an ignition device and its electrical components.

According to the invention, the holding elements compress the stack spark gap, this compression being ensured in the direction of the stack even in the event of temperature fluctuations. The clamping between the two holding elements is designed to be resilient for this purpose, so that it can compensate for changes in length during operation of the multiple spark gap. Tolerance compensation can also be achieved in the production of the spark gap arrangement.

The frame structure is preferably simple in construction. According to the invention, the frame structure is formed by two frame parts, between which the multiple spark gap is arranged, and each holding element is connected to both frame parts. If the holding elements extend plane-parallel to the electrodes of the multiple spark gap and absorb the compressive forces of the stack arrangement, the frame parts run at an angle of approximately 90° to the holding elements and, as abutments, absorb the resulting tensile forces from the holding elements.

In particular, these frame parts are formed by two insulating plates which are spaced apart plane-parallel and accommodate the multiple spark gap between them. Printed circuit boards represent a particularly simple form of frame parts, and the combination of stamped and bent parts and a printed circuit board structure results in a particularly advantageous and cost-effective structure.

In one embodiment of the invention, the frame structure is formed from an electrically insulating fiber composite material. In particular, it is an electrically insulating, flame retardant and flame retardant fiber composite material. It is therefore an insulating structure. The fiber composite material is preferably a material that is also used for the production of printed circuit board substrates, i.e. printed circuit board material. In particular, it is therefore a material of class FR4. For example, a composite material made of epoxy resin and a glass fiber fabric is used here. However, other circuit board materials such as laminated paper, which is formed from paper and a resin, can also be used.

Due to its material properties, such a frame structure can be arranged at a short distance from the multiple spark gap. Therefore, a spark gap arrangement can be provided overall that has a high temperature resistance in a small installation space. Since printed circuit board material is an inexpensive material, this also has a positive effect on the production costs for the spark gap arrangement.

This is particularly the case when the holding elements are also designed to save space and be as simple as possible. They extend essentially plane-parallel to the electrodes of the multiple spark gap. Their structure is designed in such a way that they compensate for thermal and mechanical movements and tolerances in the multiple spark gap. In the simplest form, these are elastically yielding metal sheets between which the multiple spark gap is clamped. In a preferred embodiment of the invention, however, it is provided that at least one holding element is formed by a metal stamped and bent part. Stamped and bent parts are not expensive to produce, but with an appropriate design and connection to the frame structure they can meet the requirements mentioned with regard to the compensation of thermal and mechanical movements and tolerances in the multiple spark gap. For example, a stamped and bent part has at least one fold, bend, tab and/or protuberance for this purpose, through which a prestressing force V acts on the multiple spark gap in the stacking direction. This preferably applies to both holding elements.

The connection between the holding elements and the frame structure can be formed in different ways. It is designed to be permanent or soluble. In particular, one embodiment of the invention provides that at least one retaining element is connected to the frame structure by a temperature-sensitive connection that releases when a specific temperature is reached. In this way, a thermal point of separation is formed, which becomes detached when the multiple spark gap and thus at least one holding element exceed a maximum temperature.

Provision is preferably made here for the holding element to be connected to the frame structure in such a way that releasing the thermosensitive connection releases a movement of the entire holding element in the direction away from the multiple spark gap. For safety reasons, this can be used to detect a multiple spark gap that has heated up too much and/or to switch it to a safe state. For example, the spark gap arrangement according to the invention can have detection means for this purpose, which are designed to detect a movement of the entire holding element in the direction away from the multiple spark gap. The holding element moves away from the stack arrangement, as a result of which there is no longer sufficient compression of the stack arrangement. This information from the detection means can be used in different ways. For example, the detection means can report via a communication means that the multiple spark gap is in a critical state.

In another embodiment, it is provided that measures to further secure the multiple spark gap are initiated as an alternative or in addition. For example, the spark gap arrangement has an arc shield and means for introducing this arc shield between the multiple spark gap and a holding element, the movement of which was detected by the detection means. The arc shield can be moved into the cleared area between the multiple spark gap and the support member for arc quenching that may be required and to achieve good insulation.

In order to ensure a sufficiently large separation path, additional means can be provided in order to move a holding element away from the multiple spark gap after its thermosensitive connection has been released. This is preferably a separating means which is designed to support a separating of the holding element from the frame structure in this case. For example, such separating means are designed to apply a force F to at least one holding element, this force F acting in a direction opposite to a biasing force V through the holding element in the direction of the multiple spark gap. Due to its clamping, the holding element thus exerts a prestressing force or compressive force on one side of the stacked arrangement of the multiple spark gap. The force F opposes this direction. If the clamping of the holding element is released, it is therefore pushed away from the multiple spark gap by the force F.

The force F for such a separation of the holding element can be generated in particular by a spring mechanism and is then a spring force. Furthermore, such a force F can act on the holding element at different points. A force F preferably acts at each connection point between the holding element and the frame structure in order to loosen as many connection points as possible.

The holding elements can be held on the frame structure in different ways. In one embodiment of the invention, at least one holding element is held in a force-receiving recess in the frame structure. This is done in particular by a soldered or press-fit connection. When using a thermosensitive connection such as a soldered connection, in particular at least one recess has a longitudinal extent in the stacking direction of the multiple spark gap that is greater than the extent of the holding element held therein in the stacking direction. This longitudinal extent is preferably many times greater than the extent of the holding element held therein in the stacking direction. The recess is then at least twice as wide as the holding element in this direction. During the manufacture of the spark gap arrangement, the holding element can therefore initially move in the stacking direction, as in a slot.

The soldering is then carried out under prestress in the direction of the multiple spark gap, so that after the soldering point has solidified, the desired permanent prestress for tolerance compensation is achieved. The retaining element is then held in the recess by a thermosensitive connection under pretension in the direction of the multiple spark gap, this thermosensitive connection optionally being designed in such a way that it releases when a specific temperature is reached. A soldered connection thus has the advantage that it can also be used as a detachable thermosensitive connection at the same time.

Means for controlling and triggering the multiple spark gap and/or means for monitoring the overvoltage protection through the multiple spark gap and/or communication means for signaling and/or remote transmission of status data of the multiple spark gap are particularly advantageously arranged on the frame structure. The status data includes, in particular, the condition of the means of separation. Furthermore, means for electrical decoupling, isolation, disconnection of the overvoltage protection from the electrical network can be arranged on the printed circuit boards.

If printed circuit boards are used as the frame structure, these additional components can advantageously be attached to the printed circuit boards, connected to the multiple spark gap and also connected to one another. In the case of means for controlling and triggering the multiple spark gap, the required electrical potentials are transferred, for example, to the connection points of the holding elements with the printed circuit boards. Typically this is done at the soldering points. The electrodes of the multiple spark gap can also be connected directly to electrical structures formed on the frame structure via a respective contact.

Overall, a compact spark gap structure for contacting, stabilization and electrical connection of overload devices can be provided between circuit board material, which is easy to manufacture. This applies in particular to multiple spark gaps with graphite electrodes.

Further advantages, special features and expedient developments of the invention result from the subclaims and the following description of preferred exemplary embodiments with reference to the illustrations.

• 1 eine schematische Darstellung einer ersten Ausführungsform einer erfindungsgemäßen Funkenstreckenanordnung;
• 2 eine schematische Darstellung einer zweiten Ausführungsform einer erfindungsgemäßen Funkenstreckenanordnung;
• 3 eine Aufsicht auf eine Funkenstreckenanordnung gemäß 2;
• 4 eine schematische Darstellung einer dritten Ausführungsform einer erfindungsgemäßen Funkenstreckenanordnung mit Abtrennmitteln; und
• 5 eine Funkenstreckenanordnung gemäß 5 mit ausgelösten Abtrennmitteln.

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• 1 a schematic representation of a first embodiment of a spark gap arrangement according to the invention;
• 2 a schematic representation of a second embodiment of a spark gap arrangement according to the invention;
• 3 a top view of a spark gap arrangement according to FIG 2 ;
• 4 a schematic representation of a third embodiment of a spark gap arrangement according to the invention with separation means; and
• 5 a spark gap arrangement according to FIG 5 with triggered release agents.

1 shows a schematic representation of a spark gap arrangement 10 according to the invention in a first embodiment. It comprises a multiple spark gap (multi-arc spark gap, MAFS) 20, which is held by two frame parts 40, 41 and two holding elements 30, 31. The multiple spark gap 20 is essentially formed by a plurality of disc-shaped electrodes 21, 22 which are each spaced apart from one another by thin insulating material elements 23. The insulating material elements 23 are in the form of disks or foils with a central opening and are fixed between two electrodes 21, 22, so that a single spark gap is formed in each case in the gap 24 between two electrodes. The insulating material elements 23 cause the required distance between two electrodes 21, 22 to form a combustion chamber 24 through the central recess. Several such individual spark gaps are arranged in series and form a spark gap stack.

Overall, the multiple spark gap 20 is integrated as an overvoltage arrester in an electrical system (not shown). at 1 it is therefore only a schematic Representation of the essential functional components of a multiple spark gap in order to explain their mounting. The specific design of the multiple spark gap is therefore only to be understood as an example and it can be designed in any suitable way. This also applies in particular to the number, dimensions, shape and arrangement of elements in the multiple spark gap.

The multiple spark gap 20 is clamped between two metallic holding elements 30 and 31 in the stacking direction. These holding elements 30, 31 are preferably designed as stamped and bent parts and are provided with a structure that compensates for thermal and mechanical movements and tolerances of the multiple spark gap 20. For this purpose, the holding elements each have a protuberance or indentation 32 , 33 in the direction of the multiple spark gap 20 . Furthermore, the two holding elements 30, 31 are directly electrically insulated from one another, i.e. there is no direct electrical connection between the two holding elements 30, 31.

For this purpose, the two holding elements 30, 31 are connected to two frame parts in the form of insulating plates 40, 41. The insulating plates 40, 41 consist of an electrically insulating fiber composite material, in particular an electrically insulating, flame-retardant and flame-retardant fiber composite material. They are referred to below as printed circuit boards, since it is preferably a material that is also used to manufacture printed circuit boards. It is preferably a material of class FR4.

The printed circuit boards 40, 41 run essentially plane-parallel to one another, and the multiple spark gap 20 is arranged between the printed circuit boards 40, 41. The structure is designed in such a way that the two printed circuit boards 40, 41 act as abutments for the two holding elements 30, 31. The holding elements 30, 31 are arranged essentially plane-parallel to the electrodes 21, 22 of the multiple spark gap 20 and the printed circuit boards 40, 41 run at an angle of approximately 90° to the holding elements 30, 31. The two holding elements 30, 31 take through their clamping compressive forces from the multiple spark gap 20, and the printed circuit boards 40, 41 take the resulting tensile forces as an abutment. A prestressing force V acts on the stack arrangement of the multiple spark gap 20 from both ends.

Opposite ends of the holding members 30,31 are held in force-receiving recesses 42,43,44 and 45 in the circuit boards 40,41. These recesses can as in the embodiment of 1 be designed as through openings through which the holding elements 30, 31 protrude completely. However, they can also be designed as a kind of blind hole into which one end of the holding element is inserted. In the embodiment of 1 the holding elements 30, 31 are pressed into the recesses 42, 43, 44, 45.

A control and/or trigger unit 50 for controlling the multiple spark gap 20 is also shown in dashed lines on the printed circuit board 40 . This can be designed in a suitable way, as is already known in the case of control and/or trigger units on printed circuit boards. Furthermore, the electrodes 21, 22 are each directly connected via a contact 60 to electrical structures on the printed circuit board 41 (not shown). Potentials required for controlling the multiple spark gap 20 are transferred to the holding elements 30, 31, for example. This is preferably done via a soldering point between the holding element and the printed circuit board.

2 shows a second embodiment of a spark gap arrangement 10', in which the holding elements 30, 31 are connected to the printed circuit boards 40, 41 via soldered connections. The recesses 42, 43, 44, 45 therefore have a greater extent in the stacking direction than the holding elements accommodated therein. The structure of the spark gap assembly 10 'differs from the embodiment of FIG 1 only in this type of connection between the holding elements 30, 31 and the circuit boards 40, 41, so that the description of the essential structure of the spark gap arrangement applies analogously.

The two holding elements 30, 31 in the force-receiving recesses 42, 43, 44, 45 are also the supervision of 3 refer to. These recesses 42, 43, 44, 45 are designed as elongated holes in the stacking direction, in which the holding elements 30, 3' can initially move in the stacking direction during manufacture of the spark gap arrangement 10'. The holding elements 30, 31 are then soldered under prestress in the stacking direction, so that the desired permanent prestressing forces V act after the soldering points have solidified.

These soldered connections are thermosensitive connections that detach at a certain maximum temperature. This type of soldering of the metallic holding elements 30, 31 in the recesses 42, 43, 44, 45 can therefore be used to form a thermal separation point in each case. This thermal separation point triggers when the electrode stack and thus the holding elements 30, 31 exceed a maximum temperature. At least one retaining element 30, 31 can thus separate from the multiple spark gap 20, as a result of which the biasing forces V are no longer effective.

In order to make the separating path as long as possible in such a case, supporting separating means can be provided. 4 shows schematically a further embodiment of a spark gap arrangement 10", which has separating means for separating a holding element 31 in the event of impermissible heating of the multiple spark gap 20. In this case, at least the holding element 31 is again held in the recesses 43 and 45 via soldered connections, which is shown as a dotted structure The release agents are in 4 shown only schematically and may be shaped in any suitable manner. Essentially, they have means for generating a force F on the holding element 31, which is opposed to the pretensioning force V.

If the soldered connections in the recesses 43 and 45 come loose due to impermissible heating, the holding element 31 is pushed away from the multiple spark gap 20 by the force F. This state is in the 5 shown and the direction of movement of the holding element 31 shown with a white arrow. A movement transmission element 80 is connected to the holding element 31, which reports this movement to a signal unit 81 by means of pressure. This signal unit 81 in turn is connected to a communication means 82, which can display the separation and/or report it to another location. In this way, the status of the spark gap arrangement can be monitored.

This structure is again only to be understood as an example in order to explain the mode of operation of the separation. The separating means 70, 71, the movement transmission element 80, the signal unit 81 and the communication means 82 can be designed in any suitable way. The same applies to an arc shield 90, which is optionally moved between the holding element 31 and the multiple spark gap 20 after separation.

Reference List

10, 10', 10''

spark gap arrangement

20

Multiple spark gap, MAFS

21, 22

electrode

23

insulating element

24

gap, combustion chamber

30, 31

Retaining element, stamped and bent part

32, 33

protuberance

40, 41

Frame part, insulating plate, circuit board

42, 43, 44, 45

recess

50

Control and/or trigger unit

60

Contact

70, 71

release agent

80

motion transmission element

81

signal unit

82

means of communication

90

Arc Shield, Arc Shield

Claims (14)

Spark gap arrangement (10; 10';10''), having a multiple spark gap (20) with a plurality of series-connected individual spark gaps in a stack arrangement, each individual spark gap being formed by two electrodes (21; 22) which are formed by at least one insulating material element ( 23) are separated from one another, and the stack arrangement of individual spark gaps is clamped resiliently in the stacking direction between two opposing holding elements (30; 31), the holding elements (30; 31) being connected to a frame structure which acts as an abutment for both holding elements (30; 31 ) acts, and the holding elements (30; 31) are metallically and directly electrically insulated from one another, characterized in that the frame structure is formed by two insulating plates (40; 41), between which the multiple spark gap (20) is arranged, and each Holding element (30; 31) is connected to the two insulating plates (40; 41). spark gap arrangement claim 1 , wherein the frame structure is formed from an electrically insulating, flame retardant and flame retardant fiber composite material. spark gap arrangement claim 1 or 2 , wherein at least one holding element (30; 31) is formed by a metallic stamped and bent part which extends essentially plane-parallel to the electrodes (21; 22) of the multiple spark gap (20). spark gap arrangement claim 3 , wherein the holding element (30; 31) has at least one fold, bend, tab and/or protuberance, through which a prestressing force V acts on the multiple spark gap (20) in the stacking direction. Spark gap arrangement according to one of Claims 1 until 4 , wherein at least one holding element (30; 31) by a temperature-sensitive connection connected to the frame structure, which detaches when a certain temperature is reached. spark gap arrangement claim 5 , wherein the retaining element (30; 31) is connected to the frame structure such that releasing the thermosensitive connection releases movement of the entire retaining element (30; 31) in a direction away from the multiple spark gap (20). spark gap arrangement claim 6 , wherein it has detection means (80; 81) which are designed to detect a movement of the entire holding element (30; 31) in a direction away from the multiple spark gap (20). spark gap arrangement claim 7 comprising an arc shield (90) and means for introducing said arc shield (90) between said multiple spark gap (20) and a support member (30;31) whose movement has been detected by said detection means (80;81). Spark gap arrangement according to one of Claims 5 until 8th , wherein separating means (70; 71) are provided for applying a force F to at least one holding element (30; 31) which acts in a direction corresponding to a biasing force V through the holding element (30; 31) towards the multiple spark gap (20) is opposite. Spark gap arrangement according to one of Claims 1 until 9 wherein at least one holding element (30; 31) is held in a force-receiving recess (42; 43; 44; 45) in the frame structure. spark gap arrangement claim 10 , wherein the holding element (30; 31) is held in the recess (42; 43; 44; 45) by a soldered or press-fit connection. spark gap arrangement claim 10 or 11 , wherein at least one recess (42; 43; 44; 45) has a longitudinal extension in the stacking direction of the multiple spark gap (20) which is many times larger than the extension of the holding element (30; 31) held therein in the stacking direction, and this Holding element (30; 31) is held in the recess (42; 43; 44; 45) by a thermosensitive connection under prestress in the direction of the multiple spark gap (20), which releases when a certain temperature is reached. Spark gap arrangement according to one of Claims 1 until 12 , wherein on the frame structure means (50) for controlling and triggering the multiple spark gap (20) and/or means for monitoring the overvoltage protection through the multiple spark gap (20) and/or communication means (82) for signaling and/or long-distance transmission of Status data of the multiple spark gap (20) are arranged. Spark gap arrangement according to one of Claims 1 until 13 , wherein the electrodes (21;22) of the multiple spark gap (20) are connected directly to electrical structures formed on the frame structure via a respective contact (60).

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