EP1774630B1 - Automatically-triggering surge arrester arrangement and use of such a surge arrester arrangement - Google Patents

Abstract

The invention relates to an automatically quenching surge arrester arrangement with a surge arrester, which, on exceeding a given first voltage, transforms from a non-conducting into a conducting state and returns to the non-conducting state only when a much smaller second voltage is dropped below and with a switch mechanism reacting to current flow through the surge arrester, interrupting the current flow through the surge arrester and then automatically returning to the rest condition thereof. A simple, robust and compact assembly suitable for HF applications for such a surge arrester arrangement is achieved, whereby the switch mechanism reacts reversibly to the heat generated in the surge arrester by the current flow.

Description

TECHNICAL AREA

The present invention relates to an automatically extinguishing surge arrester arrangement according to the preamble of claim 1 and to the use of such a surge arrester arrangement.

STATE OF THE ART

In electrical and electronic circuits or on electrical lines connected to exposed devices such as radio aerials, Lightning strikes or other short-term phenomena can cause dangerous voltage surges, which can lead to permanent damage to the electrical equipment or to a total failure. To make harmless such spikes are installed for a long time at appropriate points of the device to be protected surge of different construction and operation, which are not conductive under normal circumstances, however, switch on the occurrence of dangerous surges and compensate for the existing potential differences.

One possible type of surge arresters are voltage-dependent resistors, such as metal-oxide varistors (MOVs), which are connected between two conductors, between which dangerous voltage peaks can occur. At normal operating voltages, the resistance of the varistors is large, so that only a small leakage current flows between the two conductors. At high voltage peaks, the resistance of the varistors decreases drastically, so that the desired compensation current can flow. Problems arise in the varistors, however, if in them due to internal changes even under normal conditions greatly increased leakage currents flow, which can burden the circuit to be protected and can lead to changes in their operation. It has therefore already been proposed, in series with a varistor to switch a thermally activatable switching device which interrupts the current through the varistor in the event of strong leakage-induced heating of the varistor and substitutes a spark gap as additional overvoltage protection in the disconnected connection ( US-A-4,288,833 ). The thermally activatable switching device is realized by an elastic switching arm, which is soldered under mechanical prestressing with one end to the varistor and which establishes an electrical connection to the varistor. If the varistor heats up excessively due to excessive leakage currents, the solder of the solder joint melts and the electrical switching arm releases from the varistor due to its bias voltage and interrupts the current flow through the varistor. With the lifting of the switching arm, a spark gap is effective, between the varistor and the lifted arm or specifically for it provided conductor tips is formed. A disadvantage of this surge arrester arrangement is the irreversible change in the arrangement when the switching device responds. In the same way irreversible is the switching operation of the provided with an external short-circuit device surge arrester from the document DE-A1-197 31 312 , In the event of excessive heating of the surge arrester, two insulating spacers melt, so that a short-circuit bar under elastic prestressing short-circuits the two or three connection contacts of the surge arrester and thus can take over the current flow through the surge arrester.

The FR-A-2 848 353 discloses a protection circuit in which an electrically conductive connection between an input and output is interruptible by a switching mechanism. This switching mechanism has a bimetallic element that responds to a temperature rise when an overvoltage pulse occurs. The bimetallic element releases in one embodiment, a pawl and releases a spring-loaded opener. In another embodiment, the bimetallic element itself is the opener and releases when opening an insulating element which falls by gravity between the bimetallic element and a mating contact and both permanently separated from each other. In the first case, the bimetallic element returns to its original position after a drop in temperature, but the contact remains open until it is closed again from the outside by an intervention. In the second case, the bimetallic element can not return to its initial position, since it is prevented by the insulating element.

Another type of surge arresters are the gas capsule arresters, which in the event of overvoltage ignite a gas discharge in a sealed gas-filled capsule with two or three electrodes. The problem with these arresters, that a once ignited gas discharge at a comparatively low burning voltage is maintained. If, for example, a supply voltage for remote electronics which is greater than or equal to the burning voltage or a high HF power is applied to the gas capsule discharger installed in a circuit or line, the gas discharge continues to burn after the occurrence of a sparking overvoltage peak and overloads the circuit . Management. Additional irreversible switching devices have also been proposed for the gas capsule arresters which react to excess heat generated in the arrester and then permanently interrupt the current supply to the arrester ( US-A-4,051,546 ) or short-circuit the arrester permanently with a bypass ( US-A-3,755,715 or US-A-4,132,915 ). The thermally activated switching devices can be integrated into the surge arrester (see the aforementioned publications), but they can also be formed separately and thermally coupled from the outside to the surge arrester ( US-A-4,275,432 ). Thermally activated, irreversible short-circuit devices are also known in the context of coaxial cable capsule arresters ( US-A-5,724,220 , Figs. 24 and 25).

A reversible switching device for interrupting the discharge current through a gas capsule diverter is known from US-A-4,068,277 known. Here, a separate, equipped with a bimetallic element, thermally-working contactor is provided, the heating element is connected in series with the arrester. If the once ignited discharge remains in the arrester for a certain time, the contactor responds and interrupts the current through the arrester and the one line. If the contactor has sufficiently cooled down again after a longer period of, for example, 20-30 s, it automatically switches on the current through the arrester and the one line, so that the initial state is restored. The disadvantage of this solution is that because of the separate contactor a compact and space-saving arrangement is not possible. Furthermore, the interruption in a line is unsuitable for applications in which a supply current for other circuit parts is routed via the lines.

Special requirements are made of surge arrester arrangements, which are integrated into a coaxial conductor arrangement for high frequencies and therefore not only have to be suitable for the highest frequencies, but at the same time also compact in construction, reliable, low maintenance and robust.

Examples of Koaxialleiteranordnungen with integrated surge arrester arrangement, but without additional switching device are from the CH-A5-660 261 or the EP-A1-0 855 756 or the EP-A1-0 938166 the applicant known. In order to be able to safely reset the gas capsule arrester in the non-conductive state in such surge arrester arrangements in the event of a fault, even when applying a DC voltage or a high-frequency signal, is in the non-conductive state WO-A1-2004 / 032276 The applicant has proposed an additional switching arrangement comprising an inductance, an electromagnetically actuated breaker switch and a diode. This switching arrangement acts together with a series circuit of two similar Gaskapselableitern. Structure and operation of the arrangement can be found in the cited document.

The from the WO-A1-2004 / 032276 Known switching arrangement protects the Gaskapselableiter reliably against a continuous load and turns on after deleting the gas discharge in the Gaskapselableitern automatically again. It has proven itself in practice and can be integrated into the Koaxialleiteranordnungen when the Koaxialleiteranordnungen be designed from the outset for constructive.

However, there is an urgent desire to have an automatically extinguishing surge arrester, which is mainly broadband used, simple and inexpensive to produce, but also in existing coaxial conductor arrangements with integrated surge arrester, as described in the CH-A5-660 261 can be retrofitted without having to make structural changes to the coaxial conductor arrangement itself.

PRESENTATION OF THE INVENTION

It is therefore an object of the invention to provide a self-extinguishing, broadband and cost-effective surge arrester, which is simple and robust, has high reliability, extremely space-saving can be realized and can be retrofitted in existing coaxial applications without structural changes.

The object is achieved by the surge arrester arrangement of claim 1. The essence of the invention is to provide a switching mechanism which reversibly responds to the heat generated in the surge arrester by the current flow at current flow through the surge arrester and interrupts the current flow through the surge arrester and then automatically returns to its original state.

The switching mechanism comprises switching means and also thermally coupled to the surge arrester actuating means for actuating the switching means, which actuating means - unlike the melting solder joints of the prior art - reversibly respond to the heat generated in the surge arrester by the current flow. Due to the direct thermal coupling of the actuating means to the surge arrester both can be structurally combined, so that a very compact arrangement is created. The response of the actuating means to the heat generated in the surge arrester ensures that the interruption occurs with a certain delay and only when the arrester is actually under continuous load. If after the interruption of the current flow through the surge arrester, the heating of the arrester dies down again, the actuating means automatically return to their initial state, so that after a certain delay time, the surge arrester arrangement is ready for use again.

The actuating means comprise expansion means which convert the heat generated in the surge arrester by the current flow by means of thermal expansion in a switching movement. The thermal expansion is a particularly simple, effective, reliable and reproducible mechanism for generating a switching movement, by means of which then the flow of current through the trap can be interrupted. Cools the Surge arrester then follows again, on the expansion, a contraction, which leads back to the initial state.

It is particularly advantageous in terms of simplicity and robustness that the expansion means comprise an expansion body made of a solid material whose thermal expansion in a first axis is utilized as a switching movement. As a result, a linear switching movement is available, which can be particularly easily combined with appropriate switching means. In particular, the thermal expansion of the expansion body in the first axis can be enhanced by a suitable shaping of the expansion body or by an anisotropic material behavior of the expansion body. An example of a suitable shaping is an angled shape in the manner of a (acting in the reverse direction) toggle lever.

The expansion body is made of a heat-resistant rubber-elastic material, in particular a silicone rubber or a fluoroelastomer, wherein the expansion body is surrounded by a limiting the radial expansion and the axial expansion reinforcing limiting element. The limiting body limits the thermal expansion radially with respect to the first axis and, due to the "quasi-hydrostatic" behavior of the expansion body, causes a significant increase in the extent in the direction of the first axis.

If according to a development of the expansion body has the shape of an axial axis to the first disc, and as a limiting element a hollow cylindrical, coaxial, electrically and thermally insulating insulator sleeve, in particular made of polytetrafluoroethylene, is provided, an unwanted outflow of heat flowing into the expansion body heat through the side Limitation be prevented.

In principle, the current flow through the surge arrester can be interrupted by opening a series-connected or by closing a parallel switch. Particularly simple and compact, the surge arrester arrangement is under construction when the switching means comprise a switch which is connected in series with the surge arrester and closed in the initial state, and which is opened when the actuating means respond to the heat generated in the surge arrester by the current flow. It is within the scope of the invention, however, also conceivable that the switching means comprise a switch which is connected in parallel to the surge arrester and opened in the initial state, and which is closed when the actuating means respond to the heat generated in the surge arrester by the current flow.

Preferably, the switch comprises two metallic contact elements, which are pressed against each other by a spring element and against the pressure of the spring element are separable, wherein one of the contact elements connected to the surge arrester arrangement, in particular soldered, and wherein the actuating means or expansion means between the two contact elements are. The contact elements are surface-finished to avoid burnup, especially coated with silver.

Very simple and particularly suitable for use in coaxial RF cables the surge arrester arrangement, when the surge arrester, the metallic contact elements, the spring element and the actuating means or expansion means are arranged axially to a first axis in a common housing one behind the other, when the housing is electrically conductive and serving as a lead to the surge arrester, and when contact springs are provided to make contact with the housing.

The metallic contact elements, the spring element and the actuating means or expansion means can be arranged on one side of the surge arrester.

However, it is also possible to arrange the metallic contact elements and the actuating means or expansion means on one side of the surge arrester and the spring element on the other side of the surge arrester.

The housing may be formed as a one-sided open, screw-housing. But it is also conceivable that the housing is designed as a housing open on one side, and that are provided on the open side of the housing pins for inserting the surge arrester arrangement in a printed circuit.

Preferably, the surge arrester is designed as a gas capsule collector and has a cylindrical shape with arranged on the end faces electrical connections.

According to the invention, a surge arrester arrangement, in which the surge arrester, the metallic contact elements, the spring element and the actuating means or expansion means are arranged coaxially to a first axis in a common housing one behind the other, in which the housing is electrically conductive and serves as a supply line to the surge arrester, and in which contact springs are provided for making contact with the housing, inserted in a coaxial conductor arrangement.

In particular, the coaxial conductor arrangement comprises an inner conductor extending in a second axis and an outer conductor coaxially surrounding the inner conductor, the surge arrester arrangement having the first axis perpendicular to the second axis being fastened to the coaxial conductor arrangement, in particular screwed, the housing is electrically connected to the outer conductor conductively connected, and a second lead to the surge arrester is electrically connected to the inner conductor.

Further embodiments emerge from the dependent claims.

BRIEF EXPLANATION OF THE FIGURES

Fig. 1

einen Längsschnitt durch eine Koaxialleiteranordnung mit einer eingeschraubten Überspannungsableiteranordnung gemäss einem bevorzugten Ausführungsbeispiel der Erfindung;

Fig. 2

den Aufbau der mit einer Gaskapsel bestückten Überspannungsableiteranordnung aus Fig. 1;

Fig. 3

eine für den Einbau in eine gedruckte Schaltung geeignete Überspannungsableiteranordnung gemäss einem anderen Ausführungsbeispiel der Erfindung;

Fig. 4

ein zu Fig. 3 vergleichbares Ausführungsbeispiel mit axialen Anschlussdrähten für eine "fliegende" Verdrahtung;und

Fig. 5

den Querschnitt durch einen Expansionskörper, der aufgrund seiner Formgebung als Kniehebel in einer Achse eine verstärkte thermische Ausdehnungsbewegung ausführt.

The invention will be explained in more detail with reference to embodiments in conjunction with the drawings. Show it

Fig. 1

a longitudinal section through a Koaxialleiteranordnung with a screwed surge arrester according to a preferred embodiment of the invention;

Fig. 2

the structure of equipped with a gas capsule surge arrester arrangement Fig. 1 ;

Fig. 3

a suitable for installation in a printed circuit surge arrester according to another embodiment of the invention;

Fig. 4

one too Fig. 3 comparable embodiment with axial connection wires for a "flying"wiring;

Fig. 5

the cross section through an expansion body, which performs due to its shape as a toggle in one axis, an increased thermal expansion movement.

WAYS FOR CARRYING OUT THE INVENTION

In Fig. 1 is a longitudinal section of a coaxial conductor arrangement reproduced with a screwed surge arrester according to a preferred embodiment of the invention. The coaxial conductor arrangement 10 Fig. 1 is similar in construction and external dimensions with known gas capsule lightning protection devices, as offered by the Applicant on the market and as they are mainly used in mobile base stations application. Such gas capsule lightning protection devices usually have an impedance of 50 Ω, can be used for frequencies up to several GHz and can be loaded with individual current pulses up to 30 kA and multiple current pulses up to 20 kA. Typical external dimensions are axial lengths of around 100 mm and external diameters of around 30 mm. With the invention, such gas capsule lightning protection devices can be retrofitted with a self-extinguishing switching device without significant changes must be made.

The coaxial conductor arrangement 10 comprises a metallic outer conductor 11 (made of surface-finished brass or the like) with graduated inner diameter and a central conductor consisting of several inner conductor sections 12,. The inner conductor 12, .., 15 is arranged by means of insulating disc-shaped holders 16, 17 coaxial in the outer conductor 11 and fixed. The end-side inner conductor sections 14 and 15 are designed as slotted sockets and part of screwed connectors. For screwing serve on the outer conductor 11 mounted external thread 18, 19. In a central portion of the coaxial conductor assembly 10 of the outer conductor 11 and its inner diameter is increased. In this section, an inner conductor section 13 with a reduced outer diameter is simultaneously provided. Perpendicular to the axis 35 of the coaxial conductor arrangement 10 is on one side (in Fig. 1 Above) in the outer conductor or the housing 11, a threaded hole 23 is introduced into which a surge arrester assembly 20 is screwed according to the invention.

The surge arrester arrangement 20 contains a known (cylindrical) surge arrester 22 in the form of a two-pole gas capsule arrester or gas discharge arrester, which lies with its cylinder axis in the axis 34 of the surge arrester arrangement 20. Such gas discharge arresters, such as those offered by the company Epcos, have response voltages of 70 V up to several kV and in the ignited state, a arc-burning voltage of 10-30 V. In the ignited state, the internal resistance drops to values <1 Ω, while he in the locked (cleared) state> 1 GΩ. The capacity is only a few pF, which is particularly favorable for HF applications. The outer dimensions (length x outer diameter) are in the order of 6 mm x 8 mm.

The surge arrester 22 is releasably held in the surge arrester assembly 20. It has two frontal contact surfaces, which are in communication with the internal gas discharge path and are isolated from each other by the intermediate ceramic housing. The surge arrester 22 is seated with the lower free end in an insulating cup 21. With the lower contact surface, it bears against an electrically conductive connecting piece 24, which establishes contact with the inner conductor section 13 through an opening in the bottom of the insulating cup 21.

The surge arrester arrangement 20 from Fig. 1 is in itself in an enlarged view in Fig. 2 played. It comprises a downwardly open housing 25, which holds the surge arrester or gas capsule drain 22 (capsule holder housing). The housing 25 is externally provided with key surfaces and has a screw thread 32 with which it into the threaded hole 23 in the outer conductor 11 (FIG. Fig. 1 ) can be screwed. The housing 25 is initially also open to the other side, so that the accommodated in the housing functional elements 22 and 26, .., 31 can be introduced into the interior of the housing. For (permanent) closure of the upper opening then serves a bolt 33rd

Along the axis 34 of the surge arrester assembly 20 are in the housing 25 - from bottom to top - in succession the surge 28, a center contact 30, an expansion body 29, a contact disc 27 with edge-mounted on the upper periphery and upwardly mounted contact springs 28 and a spring element 26 in Formed a spring washer. The center contact 30 has a circular disk-shaped base plate 40, to which a cylindrical contact pin 39 is formed with a reduced diameter at the top. The outer diameter of the base plate 40 is slightly larger than the outer diameter of the surge arrester 22. The center contact 30 is for example made of brass and is surface-improved to improve the contact properties and especially to avoid erosion, especially coated with silver.

The expansion body 29 has the shape of a circular disk and is preferably made of a heat-resistant rubber-elastic material, in particular a silicone rubber or a fluoroelastomer. He has in the center a coaxial bore 38, which is matched in diameter to the contact pin 39 of the center contact 30. In the assembled state ( Fig. 2 ) extends the center contact 30 with the contact pin 39 through the bore 38 of the expansion body 29 just so far through that at operating temperature, the end face of the contact pin 39 connects flush to the top of the expansion body 29 and at the same time with the bottom of the expansion body 29 arranged contact plate 27 a makes electrical contact.

The circular contact disc 27 is also made of surface-refined, in particular silver-plated, brass. The distributed at the upper edge of the contact disc 27 distributed over the circumference, extending in the axial direction and slightly outwardly bent contact springs 28 make a sliding contact with the inner wall of the housing 25 ago. The housing 25 simultaneously serves as a supply line to the surge arrester 22. To short-circuit the center contact 30 and the contact disk 27 via the housing 25 To prevent the center contact 30 is outside surrounded by a coaxial insulator sleeve 31, which also encloses the expansion body 29 and the lower part of the contact disc 27. The insulator sleeve 31 is formed as a hollow cylinder and consists of an electrically and thermally insulating, heat-resistant material, preferably made of polytetrafluoroethylene. The insulator sleeve 31 engages with an outer projection 41 behind an undercut in the housing 25. At an undercut 42 in the insulator sleeve 31, in turn, the center contact 30 is supported with the base plate 40 from. Thus, the surge arrester 22, which is soldered to the upper contact surface with the base plate 40 of the Mittenkotakts, held in the housing 25.

Between the top of the contact disc 27 and the housing 25 and the bolt 34, a spring element 26 is arranged that is formed in the example shown as a spring washer, but also other forms (disc spring, coil spring or the like.) Can assume. The spring element 26 and the axial dimensions of the individual components of the surge arrester assembly 20 are designed so that the contact pin 39 and the contact plate 27 in the normal state (at operating temperature) are pressed against each other with a spring bias against each other.

The function of the surge arrester arrangement 20 is as follows: In the normal state, when the surge arrester 22 is not ignited and the arrangement is substantially at operating temperature, the switching contact formed by the center contact 30 and the contact disk 27 remains closed. Thus, the surge arrester 22 is connected at its one end to the inner conductor section 13 and at its other end via the elements 30, 27, 28 and the housing 25 to the outer conductor 11 electrically conductive. If the coaxial conductor arrangement 10 is then acted upon by a flash or otherwise with a short-term voltage pulse which exceeds the ignition voltage of the surge arrester 22, the surge arrester 22 ignites and largely compensates for the potential difference. If the voltage drops the decay of the voltage pulse immediately below the burning voltage of the surge arrester 22, this is cleared and the initial state is restored. A significant heating of the surge arrester 22 and thus of the expansion body 29 does not take place.

Remains, however, even after the decay of the voltage pulse above the voltage lying voltage at the surge arrester 22 pending, this is still traversed by a current that generates heat due to the internal resistance of the arrester and leads to a heating of the surge arrester 22. The heat generated in the surge arrester 22 flows axially across the base plate 40 and radially over the contact pin 39 of the center contact 30 in the expansion body 29, heats it and causes thermal expansion, with a rapid radial outflow of heat into the housing 25 through the thermally insulating insulator sleeve 31 is prevented. The thermal expansion of the expansion body 29 takes place almost exclusively in the axial direction, because the expansion body 29 is bounded in the radial direction by the insulator sleeve 31 and the pressure resulting from the restriction due to the "quasi-hydrostatic" material properties of the expansion body 29 in the axial direction is effective , In this way, an axial expansion of the expansion body 29 can be achieved, which is more than a factor of 3 greater than the isotropic expansion, and thus represents a significant reinforcing effect. Due to the axial thermal expansion of the expansion body 29 between the two contacts 30 and 27 are - when a sufficiently high temperature of, for example, 100 ° C or more has been reached - the two contacts against the pressure of the spring element 26 separated from each other. With the separation of the contacts 30 and 27, the current flow through the surge arrester 22 and thus also the heat generation is interrupted (self-extinction). As soon as enough heat has flowed out of the expansion body 29 again after the interruption and the expansion body 29 has cooled and contracted again, the switch formed by the center contact 30 and the contact disk 27 closes again and returns to the initial state.

It goes without saying that the switching operation described works better the higher the coefficient of thermal expansion of the material used for the expansion body 29. At the same time, however, the material should also be thermally stable up to temperatures of> 200 ° C. and have sufficient aging resistance. Finally, it should also have advantageous dielectric properties for use in the coaxial line arrangement. The dielectric properties of the expansion body 29 play a role especially if in a coaxial lightning protection device, which is equipped with a surge arrester without self-extinguishing switching device, subsequently such a switching device to be installed, as is advantageously possible in the inventive surge arrester arrangement.

With a Koaxialleitungsanordnung and a surge arrester according to Fig. 1 Various measurements have been carried out in the laboratory using gas capsule arresters of the type described above with ignition voltages of 230 V and 90 V, respectively. For pulses of 4 kV / 2 kA (according to IEC 61000-4-5), capsule firing times of the order of 10 s to 20 s and reactivation times of the order of 1-2 min were found.

However, the surge arrester arrangement according to the invention can not only be used in conjunction with a coaxial line arrangement of the type described in US Pat Fig. 1 can be used with advantage shown, but can also be used wherever gas capsule arresters are used as surge protection. So it is common, for example, gas capsule drains, which are equipped with connecting wires or solder pins (see the DE-A1-197 31 312 ), to be soldered into printed circuits. A comparable, according to the invention modified surge arrester arrangement is in Fig. 3 played. The surge arrester arrangement 46 of the Fig. 3 includes a surge arrester 22 in gas capsule form, which is housed in a housing 43 open on one side. The series-connected switching device settles again from the soldered to the capsule 22 center contact 30, the disc-shaped expansion body 29 and a contact plate 36 which are isolated from the housing 43 by a Isolationshütse 31 '. The switching device is arranged here below the surge arrester 22, while the contact disk 27 is located with the contact springs 28 above the surge arrester 22. The surge arrester 22 is connected on one side (bottom) via central connection means 45 and the switches 30, 36. On the other side (top), the connection is made via the outer connection means 44, the housing 43 and the contact disk 27 with the contact springs 28. With the connection means 44, 45, the surge arrester arrangement 46 can preferably be connected in a printed circuit.

It is within the scope of the invention but also conceivable in a surge arrester arrangement in Fig. 3 shown instead of the arranged on one side connecting means 44, 45 on both sides axial (or even radial) connecting wires 37 to provide, as shown in Fig. 4 is shown. The surge arrester arrangement 46 can thus be wired "on-the-fly", ie installed in any circuit.

Further, it is conceivable within the scope of the invention to use an expansion body instead of the above-described flat circular disc-shaped expansion body 29, which carries out an increased thermal expansion movement due to an anisotropic material behavior or due to a special shaping. An example of an expansion body with special shaping is in Fig. 5 shown. The expansion body 48 of the Fig. 5 uses the mechanical principle of the toggle lever, in which it is formed either as a conically shaped disc or in the middle kinked strip. The expansion body 48 is supported by the outer edge on an abutment 47. At an in Fig. 5 Due to the special shape given by the double arrows indicated thermal expansion it comes to a reverse toggle effect, ie one reinforced thermal expansion movement in the axis 34 (arrow), which can be advantageously used as a switching movement.

LIST OF REFERENCE NUMBERS

10

Koaxialleitungsanordnung

11

Outer conductor (housing)

12, .., 15

Inner conductor section

16.17

bracket

18.19

external thread

20.46

arrester

21

Insulated

22

Surge arrester (gas capsule)

23

threaded hole

24

connector

25

Housing (capsule holder housing)

26

Spring element (spring washer)

27

contact disc

28

contact spring

29.48

expansion body

30

center contact

31.31 '

insulator sleeve

32

screw thread

33

bolt

34

Axis (expansion body)

35

Axis (coaxial conductor arrangement)

36

contact plate

37

Lead wire

38

drilling

39

Contact pin

40

baseplate

41

head Start

42

undercut

43

casing

44.45

connection means

47

abutment

Claims (17)

1. An automatically quenching surge arrester arrangement (20, 46) having a surge arrester (22), which changes from a non-conductive state to a conductive state when a predetermined first voltage is exceeded and returns to the non-conductive state only when a very much lower second voltage is undershot, and having a switching mechanism (26, ..., 31, 31'), which responds when a current flows through the surge arrester (22) and interrupts the current flow through the surge arrester (22), and then automatically returns to its initial state again, characterized in that the switching mechanism (26, ..., 31) responds reversibly to the heat which is produced by the current flow in the surge arrester (22), that the switching mechanism (26, ..., 31, 31') has switching means (26, 27, 30 and 26, 30, 36), as well as operating means (29, 31, 31', 48) which are thermally coupled to the surge arrester (22) for operation of the switching means (26, 27, 30 and 26, 30, 36), with the operating means (29, 31, 31', 48) responding reversibly to the heat which is produced by the current flow in the surge arrester (22), that the operating means (29, 31, 31') have expansion means (29, 48) which convert the heat produced by the current flow in the surge arrester (22) to a switching movement, by means of thermal expansion, that the expansion means have an expansion body (29, 48) composed of a solid material, whose thermal expansion on a first axis (34) is used as a switching movement, and that the expansion body (29) is composed of heat-resistant rubber-elastic material, in particular a silicone rubber or a fluoroelastomer, and in that the expansion body (29) is surrounded by a limiting element (31, 31'), which limits the radial expansion, and thus amplifies the axial expansion.
2. The surge arrester arrangement as claimed in claim 1, characterized in that the expansion body (29) is in the form of a circular disk which is axial with respect to the first axis (34), and a hollow-cylindrical, co-axial, electrically and thermally insulating insulator sleeve (31, 31'), in particular composed of polytetrafluoroethylene, is provided as the limiting element.
3. The surge arrester arrangement as claimed in claim 2, characterized in that the switching means have a switch (27, 30 or 30, 36), which is connected in series with the surge arrester (22) and is closed in the initial state, and which is opened when the operating means (29, 31, 31') respond to the heat which is produced by the current flow in the surge arrester (22).
4. The surge arrester arrangement as claimed in one of claims 1 to 3, characterized in that the switching means have a switch which is connected in parallel with the surge arrester (22) and is open in the initial state, and which is closed when the operating means respond to the heat which is produced by the current flow in the surge arrester (22).
5. The surge arrester arrangement as claimed in claim 3, characterized in that the switch has two metallic contact elements (27, 30 and 30, 36), which are pressed against one another by a spring element (26) and can be separated from one another against the pressure of the spring element (26), in that one of the contact elements (30) is connected, in particular soldered, to the surge arrester arrangement (22), and in that the operating means (29, 31, 31') and/or the expansion means (29) are/is arranged between the two contact elements (27, 30 and 30, 36).
6. The surge arrester arrangement as claimed in claim 5, characterized in that the contact elements (27, 30 and 30, 36) are surface-treated, in particular being coated with silver.
7. The surge arrester arrangement as claimed in claim 5 or 6, characterized in that the surge arrester (22), the metallic contact elements (27, 30 and 30, 36), the spring element (26) and the operating means (29, 31, 31') and/or the expansion means (29) are arranged one behind the other axially with respect to a first axis (34) in a common housing (25, 43), in that the housing (25, 43) is electrically conductive and is used as a supply line to the surge arrester (22), and in that contact springs (28) are provided in order to produce the contact with the housing (25, 43).
8. The surge arrester arrangement as claimed in claim 7, characterized in that the metallic contact elements (27, 30 and 30, 36), the spring element (26) and the operating means (29, 31, 31') and/or the expansion means (29) are arranged on one side of the surge arrester (22).
9. The surge arrester arrangement as claimed in claim 7 or 8, characterized in that the housing (25, 25') is in the form of a housing which is open on one side and can be screwed in.
10. The surge arrester arrangement as claimed in claim 7, characterized in that the metallic contact elements (27, 30 and 30, 36) and the operating means (29, 31, 31') and/or the expansion means (29) are arranged on one side of the surge arrester (22), and the spring element (26) is arranged on the other side of the surge arrester (22).
11. The surge arrester arrangement as claimed in claim 7 or 10, characterized in that connecting means (37, 44, 45) for connection of the surge arrester arrangement (46) in a circuit, in particular a printed circuit, are provided on the housing (43).
12. The surge arrester arrangement as claimed in one of claims 5 to 11, characterized in that the spring element (26) is a spring washer.
13. The surge arrester arrangement as claimed in one of claims 1 to 12, characterized in that the surge arrester (22) is a gas capsule arrester and has a cylindrical shape with electrical connections arranged on the end faces.
14. The surge arrester arrangement as claimed in claim 1, characterized in that the thermal expansion of the expansion body (48) on the first axis (34) is amplified by suitable shaping of the expansion body.
15. The surge arrester arrangement as claimed in claim 1, characterized in that the thermal expansion of the expansion body on the first axis (34) is amplified by the expansion body material having an anisotropic behavior.
16. Use of a surge arrester arrangement (20) as claimed in one of claims 1 to 10 in a coaxial conductor arrangement (10).
17. The use as claimed in claim 16, characterized in that the coaxial conductor arrangement (10) has an inner conductor (12, ..., 15) which runs on a second axis (35) and an outer conductor (11) which coaxially surrounds the inner conductor (12, ..., 15), in that the surge arrester arrangement (20) is mounted with the first axis (34) at right angles to the second axis (34) on the coaxial conductor arrangement (10), in particular by being screwed on, in that the housing (25) is electrically conductively connected to the outer conductor (11), and in that a second supply line (24) to the surge arrester (22) is electrically conductively connected to the inner conductor (12, ..., 15)

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