HK1179747A - Overvoltage protection element - Google Patents

Description

Overvoltage protection element

The invention relates to an overvoltage protection element having a housing, a terminal for electrically connecting the overvoltage protection element to a current or signal line to be protected, two varistors arranged inside the housing and electrically connected in parallel, an intermediate electrode arranged at least partially between the varistors, wherein the housing has two housing halves made of metal and electrically connected to one another, wherein the intermediate electrode is insulated from the housing halves and is electrically connected with its mutually opposite sides in each case to a first connection region of the varistor, wherein the two varistors and the intermediate electrode are arranged in a sandwich-like manner between the two housing halves.

Electrical circuits and devices usually operate without interference at a voltage specific to them, the nominal voltage. But not when overpressure occurs. All voltages above the upper limit of the rated voltage error are overvoltages. Overvoltage includes, in particular, transient overvoltage, which occurs as a result of atmospheric discharges, but can also occur as a result of switching actions or short circuits on the supply network and is input into the electrical circuit in a dc, inductive or capacitive manner. Overvoltage protection elements have been developed and are known for many years in order to protect electrical or electronic circuits, in particular the electronic measuring, control, regulating and switching circuits, which are used for protecting them from transient overvoltages.

Due to aging and the occasional occurrence of overvoltage (TOV) in the secondary region, particularly for overvoltage protection elements with varistors as arresters, the leakage current of the varistor increases undesirably at the operating voltage. Therefore, overvoltage protection components with varistors as arresters nowadays often have thermal disconnection devices with which the varistors which can no longer function properly are electrically disconnected from the current line to be monitored. In the case of known overvoltage protection elements, the state of the varistor is monitored on the basis of the principle of a temperature switch, wherein, in the event of overheating of the varistor, for example due to the occurrence of a leakage current, the defined soldered connection between the varistor and the disconnection device is broken, which results in the varistor being electrically disconnected.

Such an overvoltage protection element is known, for example, from DE 69503743T 2. The known overvoltage protection element has two varistors arranged parallel to one another, the thermal disconnection device of which is additionally also connected to an optical status display, so that the status of the overvoltage protection element can be directly detected on site by means of the optical status display. The overvoltage protection element has a first slide arranged in the housing as an optical state display, which is activated by a separating tongue forming a separating mechanism and in this case interacts with a second slide which can be moved as a function of the position of the first slide relative to the observation window.

However, the known overvoltage protection devices or overvoltage protection elements have the disadvantage that each open contact can be electrically arcing at operating voltages of more than 30 volts and high current loads. When the soldered connection is broken, an arc can thus occur between the varistor and the disconnection device, which can lead to damage to the components arranged within the overvoltage protection element or to damage to the overvoltage protection element as a whole, in particular to the plastic housing surrounding the varistor. Since such overvoltage protection elements or overvoltage protection devices are often arranged in a plurality adjacent to one another and to other electronic devices, the adjacent overvoltage protection devices or other electronic devices can also be damaged or destroyed as a result of the occurrence of an arc inside the housing.

DE 60112410T 2 discloses an overvoltage protection device with a varistor disk (disk) arranged in a metal housing, which varistor disk is pressed against the bottom of a pot-shaped housing by means of a rod-shaped electrode. The housing is closed with a cap which is either screwed into the pot-shaped housing or is fixed by means of an elastic ring or clip which engages in a groove in the side wall of the housing. Here, an opening is provided in the top cover, through which opening the shaft of the electrode protrudes from the housing to the electrical connection of the electrode. In this case, a second terminal for electrically connecting the overvoltage protection device to the current or signal line to be protected is formed on the housing. In order to electrically insulate the electrode from the housing, an insulating ring is provided which is arranged inside the housing and likewise has an opening for the electrode rod.

According to a further embodiment, an overvoltage protection device known from DE 60112410T 2 has two varistor disks which are each pressed against an intermediate wall of a cylindrical housing by means of a plug-shaped electrode. For connecting the housing, housing electrode lugs are formed on the housing. Although the housing is made of aluminum, which prevents the housing from being damaged when an arc occurs at the varistor, the electrical contacting of the varistor and its arrangement in the housing and the arrangement and design of the electrodes make the known overvoltage protection device rather complicated to construct and install.

DE 102007030653 a1 discloses an overvoltage protection element of the type mentioned at the outset, which also has a metal housing consisting of two housing halves. The overvoltage protection elements disclosed in both DE 102007030653 a1 and DE 60112410T 2 have the problem that the varistor disks arranged inside the housing, in particular their thickness, have tolerances, so that both overvoltage protection elements incorporate spring elements in the housing in order to ensure reliable contact with the varistor connection region.

According to a preferred embodiment of the overvoltage protection element known from DE 102007030653 a1, two elastic contact elements are each arranged between the housing half shells and the associated first connection region of the varistor. Although the electrical connection between the two housing halves and the two varistors can thus be achieved by a purely mechanical connection, so that no soldering or soldering process is required for the installation of the overvoltage protection element, the reliable and permanent function of the overvoltage protection element is sometimes impaired because different contact forces occur due to the different actual thicknesses of the two varistors. Furthermore, the use of elastic contact elements has the disadvantage that the resistance of the electrical connection to the varistor is increased by the resistance of the elastic contact element, which in turn also increases the possible level of protection. In addition, the contact area of the varistor with the housing half-shell is reduced, which further increases the resistance of the electrical connection.

The invention is therefore based on the object of improving an overvoltage protection element of the generic type in such a way that the lowest possible protection level is achieved. Furthermore, the overvoltage protection element should preferably be particularly durable and have a long service life, and be as simple and inexpensive as possible to construct and install.

The object is achieved with the overvoltage protection component described in the introduction by the following measures: one housing half is designed as a cover with a cover section and a retracted engagement section, wherein in the connected state of the two housing halves the engagement section is inserted into a corresponding receiving space formed by the other housing half and the cover section covers the receiving space. The two housing halves are designed and can be connected to one another in such a way that, in the connected state, a clear gap exists between the two housing halves, wherein the width of the clear gap varies as a function of the thickness of the two varistors. The maximum width of the seam is always smaller than the corresponding distance of the engagement section of the second housing half designed as a cover.

Since according to the invention a clear gap is formed between the two housing halves, it is possible in a simple manner to compensate for differences between different thicknesses of the varistor used, the gap width being varied as a function of the thickness difference. The different varistors have different thicknesses as a result of the manufacturing process, and no additional elements, such as the elastic contact elements used in the prior art, are required to compensate for the tolerances of these varistors, based on the construction principle with the development of slits. The intermediate electrode is arranged between the two varistors and contacts the first connection regions of the two varistors, preferably the two housing halves are screwed together, i.e. the cover is screwed to the first housing half designed as a housing shell, whereby the required contact pressure between the parallel connected varistors and the intermediate electrode is achieved.

The intermediate electrode of the overvoltage protection element according to the invention preferably has a planar section whose dimensions are substantially equal to the dimensions of the varistor, in particular to the dimensions of the first varistor connecting region, so that the connecting regions of both varistors can make planar contact with the side of the intermediate electrode. This allows a very low impedance electrical connection to the varistor, so that a low protection level can also be achieved.

According to a further advantageous embodiment, the intermediate electrode is formed from two metal parts arranged parallel to one another and electrically connected to one another, the two metal parts being spaced apart from one another at least in the region between the two varistors. A spring element is preferably arranged in the intermediate space between the two metal parts, which are pressed away from each other in this region by the spring element, so that their sides facing away from each other each press against the first connection region of the varistor.

This design of the intermediate electrode makes it possible to selectively arrange varistors with different thicknesses in the housing of the overvoltage protection element. Since the rated voltage is proportional to the thickness of the varistor, different varistors with different rated voltages can be selectively accommodated and contacted in the housing of the overvoltage protection element without additional measures or changes having to be made on the housing. The intermediate electrode is preferably formed by two identical bent plates, which are mounted at 180 ° relative to one another. In this way, the two metal parts of the intermediate electrode can be brought directly against one another in the region outside the varistor, while they are separated from one another in the region between the two varistors by bending.

The two housing halves of the overvoltage protection element described in the introduction do not form a clear gap, for which, in principle, a further teaching of the invention can also be realized, according to which at least one temperature-dependent short-circuit switch is arranged inside the housing, so that at least one varistor is short-circuited when a predetermined limit temperature T1 is reached as a result of overheating of this varistor. In this case, it is possible in principle either to short-circuit the two varistors together or only the varistors which have become hot when a predetermined limit temperature is reached as a result of the varistors overheating, so that the two varistors short-circuit independently of one another.

As already mentioned in the introduction, the varistor exhibits a reduction in the insulation properties at the end of its life due to ageing and frequent pulse loading, as a result of which power losses occur in the varistor, which leads to heating of the varistor. In this case, the temperature of the varistor may rise sharply, thereby creating a burning risk. In order to prevent the varistor from heating up so sharply, according to a further teaching of the invention, at least one temperature-dependent short-circuit switch is provided, by means of which, however, only the varistor or varistors are short-circuited and are not electrically separated from the current line to be monitored, as is customary in the prior art.

According to a first basic embodiment of the overvoltage protection element according to the invention, the two housing halves are each electrically connected to a second connection region of the varistor. The two varistors connected in parallel are thus contacted on the one hand by the intermediate electrode arranged between them and on the other hand by the two housing halves, wherein the housing can be connected to a reference potential, and the intermediate electrode is connected directly or indirectly to a first terminal of the overvoltage protection element for connecting at least one active conductor of the current or signal line to be protected.

According to this embodiment, preferably only one temperature-dependent short-circuit switch is provided, which has a short-circuit bar, an insulating holding element mechanically connected to the short-circuit bar, at least one spring element and a metal holding part. In the normal state of the varistor, i.e. when the varistor is not overheated, the short-circuit bar is arranged spaced apart from the intermediate electrode, although the spring force of the spring element acts on the holding element toward the intermediate electrode. In this case, the holding element is supported by means of a spacer element which projects through an opening in the intermediate electrode on a metal holding part which is connected to the intermediate electrode by means of a soldered connection, thereby holding the holding element in this (first) position.

If the varistor generates heat, this also leads to heating of the intermediate electrode, which at a predetermined temperature, for example 140 °, causes the soldered connection to fuse or break, so that the short-circuit bar or the holding element can no longer be held in the first position by the metal holder. The spring force of the spring element then causes the holding element, and thus also the short-circuit bar, to pass into a second position, in which the short-circuit bar contacts both the intermediate electrode and the housing, so that the varistor is short-circuited by the short-circuit bar.

In accordance with a preferred embodiment, the short-circuit bar is substantially U-shaped, so that it has a U-shaped back and two U-shaped legs. In the event of a short circuit, the U-shaped back contacts the intermediate electrode and the two U-shaped legs contact the housing. For this purpose, corresponding contact sections are formed on the housing, which are contacted by the U-shaped legs in the event of a short circuit.

According to a second basic embodiment of the overvoltage protection element according to the invention, the intermediate electrode is connected to a first terminal for connecting at least one active conductor of a current or signal line to be protected, and a metal connection is provided between the two housing halves and the facing second connection regions of the two varistors, wherein the metal connections are insulated from the housing halves by insulating elements. According to this embodiment, two varistors connected in parallel are thus contacted on the one hand by the intermediate electrode arranged between them and on the other hand by metal connections, respectively, wherein these metal connections are connected directly or indirectly to the housing. However, the two varistors are not, as in the first embodiment described above, directly connected in a planar manner to the two housing halves, but rather are preferably also connected in a planar manner to each metal connection.

In this embodiment, a short-circuit switch is preferably associated with each of the two varistors, wherein each short-circuit switch has a flexible conductor section, an actuating pin and an elastic element. In this case, a first end of the flexible conductor section is electrically connected to the contact section on the associated metal connection, and a second end of the flexible conductor section is connected to an end of the associated actuating pin. In the normal state of the varistor assigned to the short-circuit switch, the second end of the flexible conductor section is arranged at a distance from the contact section formed on the intermediate electrode, wherein the spring force of the spring element acting on the contact section of the spring element facing the intermediate electrode acts on the actuating pin. In the normal state, a heat-sensitive element acts counter to the spring force of the spring element, with which the actuating pin is held in its first position against the spring force of the spring element.

If the varistor generates heat, this leads to softening of the heat-sensitive element at a predetermined temperature, so that the second end of the flexible conductor section is transferred by the spring force of the spring element acting on the actuating pin into a second position in which the second end of the flexible conductor section contacts the contact section of the intermediate electrode. The varistor is then short-circuited by the flexible conductor section, since the intermediate electrode connected to the first connection region of the varistor is electrically conductively connected by the flexible conductor section and a metal connection which is connected to the second connection region of the varistor.

According to this embodiment, the actuating pins each preferably pass through a hole in the associated contact section of the metal connection, and the spring elements are each arranged between the first end of the actuating pin and the contact section of the metal connection. In the normal state of the varistor, the spring element is compressed against its spring force, wherein a thermally sensitive pin is provided in each of the actuating pins, which is located on the side of the contact section of the metal connection opposite the spring element and bears against it, whereby the actuating pin is held in its first position. If the varistor develops heat, this can also lead to heat generation of the metal connection contacting the varistor and thus also of the contact section of the metal connection. This causes the heat-sensitive pin to also heat up, thereby losing its strength from the predetermined temperature, so that the pin can no longer overcome the spring force of the spring element to hold the actuating pin in the first position.

According to a preferred variant of this embodiment, each of the two varistors is associated with a spare fuse, in particular a fuse (schmelzschecherung), wherein the terminals of the spare fuses are each electrically conductively connected to an associated metal connection. The second terminal of the emergency fuse is connected directly or indirectly to the housing of the overvoltage protection element.

The provision of the spare fuse in the housing of the overvoltage protection element eliminates the need for an additional separate spare fuse. This embodiment also has the following advantages: only the overloaded varistor is short-circuited and subsequently, in the event of a short-circuit current, is disconnected from the current or signal line to be monitored and thus from the supply voltage by means of the backup fuse, so that despite the loss of the protective function of the overvoltage protection element, a basic protection is ensured as the second varistor continues to be active.

Fuses commonly used as spare fuses withstand a pulse current only under certain conditions in accordance with a unique fuse integration. In the embodiment described above, two short-circuit switches and two redundant fuses are provided, so that the pulse current associated with the overvoltage is distributed to the two fuses, so that a lower fuse rating can be determined. Furthermore, a smaller short-circuit current is generated in the event of a short circuit and the current flow time is shorter, thereby reducing voltage interruption due to the short-circuit current. Therefore, the heavy load of the equipment fuse is reduced, the quality of the power grid is improved, and the equipment availability is integrally improved.

Instead of using a spare fuse and a thermal short-circuit switch, it is also possible to use (only) a fuse with a fuse, which is then arranged and constructed such that it assumes both the function of the spare fuse and the function of the thermal short-circuit switch. For this purpose, the fuse, which is electrically conductively connected to the varistor, is designed in such a way that it is triggered both when a predetermined limit temperature is reached as a result of overheating of the varistor and when a short circuit occurs, so that the associated varistor is electrically disconnected from the circuit.

The fuse preferably has a fuse made of a low-melting material, for example zinc, so that, unlike conventional fuses, the fuse is triggered not only when a short-circuit current occurs, but also when it heats up sharply, in particular the fuse is destroyed by the short-circuit current or the heating. The switching arc occurring inside the fuse is extinguished by means of suitable arc extinguishing aids, for example sand.

According to a further teaching of the present invention, the overvoltage protection component described in the introduction has a further arrester, in particular a gas-filled overvoltage arrester, which is arranged between the connection of the overvoltage protection component and the parallel circuit of the two varistors. According to this teaching of the invention, not only two varistors connected in parallel, but also an additional arrester, preferably a gas-filled overvoltage arrester, is therefore provided within the housing of the overvoltage protection element, wherein the additional arrester is arranged in series with the parallel circuit of the two varistors.

In a first basic embodiment of the overvoltage protection element, the two housing halves are each electrically connected to a second connection region of the varistor, according to which a first connection of a further arrester is electrically conductively connected to a first connection of the overvoltage protection element for connecting at least one active conductor of the current or signal line to be protected, and a second connection of the further arrester is electrically conductively connected to the intermediate electrode. Thus, according to this embodiment, the first connection of the overvoltage protection element is electrically conductively connected to the first connection of the further arrester, to which the active conductor of the current or signal line to be protected can be connected, and the second connection of the further arrester is electrically conductively connected to the intermediate electrode, the mutually opposite sides of the intermediate electrode being electrically connected in each case to the first connection regions of the two varistors, and the second connection regions of the two varistors being electrically conductively connected in each case to a housing half, wherein the housing can be connected to the reference potential via the second connection.

The arrangement of a further arrester, in particular a gas-filled arrester, between the terminal of the overvoltage protection element for the active conductor and the intermediate electrode has the advantage that the individual ignition voltage of the further arrester must first be exceeded before an overvoltage occurs at the varistor. This results in the varistor being loaded only when an overvoltage seriously endangers the installation or the current or signal line to be protected. Thus, a small voltage spike below the ignition voltage of the other arrester does not result in the varistor being loaded, which makes ageing and damage of the varistor relatively slow. In addition, the provision of a further arrester has the advantage that the overvoltage protection element has an overvoltage protection function even in the event of a short circuit of one varistor or of both varistors.

In a second basic embodiment of the overvoltage protection element, the intermediate electrode is connected to a first terminal for connecting at least one active conductor of the current or signal line to be protected, and metal connections are provided between the two housing halves and the associated second connection regions of the two varistors, wherein the metal connections are insulated from the housing halves by means of insulating elements, respectively. Thus, according to this embodiment, the first connection of the overvoltage protection element to the active conductor is connected to the intermediate electrode, the mutually opposite sides of the intermediate electrode are electrically connected to the first connection regions of the two varistors, respectively, the second connection regions of the two varistors are connected to two metal connections, respectively, which are connected directly or indirectly to the second connection of the further arrester, respectively, the first connection of the further arrester being connected to the housing of the overvoltage protection element, wherein the housing can also be connected to the reference potential via the second connection.

As mentioned above, the second connection of the other arrester is connected directly or indirectly to the two metal connections. If the second connection of the further arrester is connected directly to the two metal connections, a permanently electrically conductive connection is produced between the second connection and the two metal connections. However, according to a preferred embodiment of this embodiment, a backup fuse, in particular a fuse, is provided between the second connection of the further arrester and the two metal connecting parts, so that the second connection of the further arrester is connected (only) indirectly to the two metal connecting parts. The metal connecting parts each have a contact section which is electrically conductively connected to a first connection of the associated spare fuse, while the second connections of the two spare fuses are electrically conductively connected to a second connection of the other arrester.

In principle, both the second teaching and the third teaching of the invention can be implemented on the overvoltage protection element described in the introduction independently of one another and independently of the first teaching of the invention. However, all three teachings of the invention are preferably implemented in common on the overvoltage protection element, so that not only the housing has a slot, but also at least one temperature-dependent short-circuit switch and a further arrester are arranged inside the housing.

As already described, the metal housing can be connected to a reference potential via the second connection. In this case, according to one embodiment, the housing has a fastening region, by means of which the housing can be connected to a mounting plate as a reference potential, whereby the second connection can be realized in terms of construction. Alternatively or additionally, the housing, in particular the first housing half, has a safety terminal as a second terminal, by means of which the safety terminal can be (additionally) electrically connected to the housing.

According to a preferred embodiment, the first connection of the overvoltage protection element for connecting at least one active conductor of the current or signal line to be protected can be formed by a high-current terminal opening, which is preferably arranged on an end face, in particular on the top side, of the first housing half. The use of high-current terminal ports makes it possible to mount one or more connecting lines in a contact-proof manner, wherein a Potential (Potential) is introduced into the housing in an insulated manner and can carry a high current. The use of additional insulating molded parts inside the housing can further increase the air and electrical clearance in this area.

Instead of using a high-current terminal, in particular in the second embodiment of the overvoltage protection element according to the invention, the connecting electrode, which is preferably integrally connected to the intermediate electrode, can project through the insulating housing through-opening into the housing interior.

In a final preferred embodiment of the overvoltage protection element according to the invention, an optical display, preferably also a remotely transmittable display, is formed or arranged on the housing for displaying the state of the varistor. The display means preferably has a circuit board, on which a plurality of LEDs are located. In addition, the display mechanism has a plurality of heat shields in thermal contact with the intermediate electrodes. If the temperature of the intermediate electrode reaches a predetermined first limit temperature, the first heat protection element is triggered, which results in the preferably green LED, which indicates a no-fault state, being extinguished. At the same time, the second LED, preferably red, starts to emit light, thereby indicating a fault condition. The second heat shield, which is preferably provided as a remotely transferable functional display, can be called up by a pluggable circuit board connector. A third heating prevention piece can be further arranged, the trigger temperature of the third heating prevention piece is matched with the on state of the short-circuit switch, and therefore the on state of the short-circuit switch or the reaching state of the switch temperature of the short-circuit switch can be remotely transmitted.

In particular, a large number of solutions are available for designing and improving the overvoltage protection element according to the invention. Reference is hereby made both to the claims dependent on claim 1 and to the following description of preferred embodiments in conjunction with the accompanying drawings. In the drawings:

fig. 1 shows a first exemplary embodiment of an overvoltage protection element according to the invention, with its cover removed;

fig. 2 is an exploded view of the overvoltage protection component according to fig. 1;

fig. 3 is a sectional view of an overvoltage protection element with a short-circuit strip (Kurzschlussb ü gel) in the normal state of the varistor and in the event of a short circuit;

fig. 4 is a sectional view of a variant of the overvoltage protection device according to fig. 1;

fig. 5 shows a second embodiment of the overvoltage protection element according to the invention, with its cover removed;

fig. 6 is an exploded view of the overvoltage protection component according to fig. 5; and

fig. 7 is a sectional view of a part of the overvoltage protection device according to fig. 1.

These figures show two basic embodiments of the overvoltage protection element 1, of which a first embodiment is shown in particular in fig. 1, 2 and 3 and a second embodiment is shown in fig. 5 and 6. Unlike the embodiment shown, not all components shown in the housing have to be implemented on the overvoltage protection component 1 according to the invention. Furthermore, the individual features shown in this embodiment can also be implemented in other embodiments. The features shown in particular in fig. 4 and 7 can also be implemented both in the first embodiment and in the second embodiment.

The overvoltage protection element 1 shown in these figures has a housing with terminals 2, 3 for electrically connecting the overvoltage protection element 1 to the current or signal line to be protected. Two varistors 4, 5 electrically connected in parallel are arranged inside the housing, which varistors each have a circular base surface, wherein the diameters of the two varistors 4, 5-apart from deviations due to errors-are equal. Between the two varistors 4, 5, an intermediate electrode 6 is arranged, which is insulated with respect to the two housing halves 7, 8 forming the housing. The mutually opposite sides of the intermediate electrode 6 are each electrically conductively connected to a first connection region 9 of the two varistors 4, 5, wherein, as shown in particular in fig. 2 and 6, the two varistors 4, 5 and the intermediate electrode 6 are arranged in a sandwich-like manner between the two housing halves 7, 8.

As can be seen in particular from fig. 2 and 3, the two housing halves 7, 8 are designed differently, wherein the second housing half 8 is designed as a cover with a cover section 10 and a retracted engagement section 11. In the connected state of the two housing halves 7, 8 (see fig. 3), the engagement section 11 of the cover 8 is inserted into the corresponding receiving space 12 formed by the first housing half 7, while the receiving space 12 is covered by the cover section 10. It can also be seen from fig. 3 that, in the connected state of the two housing halves 7, 8, a display gap (sichtfuse) 13 is also present between the two housing halves 7, 8. Here, the width B of the developing slit 13 varies depending on the thickness of the two varistors 4, 5. The two housing halves 7, 8 are designed in such a way that-in any case when using the permissible varistors 4, 5-the maximum width B of the display slot 13 is always smaller than the corresponding distance, i.e. the width B of the engagement section 11.

Due to the formation of the slits 13, manufacturing-related thickness errors of the varistors 4, 5 can be compensated in a simple manner without additional elements for error compensation. The two housing halves 7, 8 can simply be screwed together, whereby the required contact pressure between the two housing halves 7, 8 and the varistor 4, 5 or between the varistor 4, 5 and the intermediate electrode 6 is achieved.

The intermediate electrode 6 has a planar section 14, the size or diameter of which is substantially equal to the diameter of the varistors 4, 5, so that the first connection regions 9 of the varistors provided with the metallization, which are opposite the two sides of the intermediate electrode 6, are contacted planarly by the intermediate electrode 6. In the embodiment according to fig. 1 and 2, the second connecting section 15 of the varistor 4, 5 is directly contacted by the two housing halves 7, 8, so that the two connecting regions 9, 15 of the two varistors 4, 5 are in planar contact, as a result of which a low-impedance connection of the varistors 4, 5 is achieved. The planar connection of the two varistors 4, 5 to the two housing halves 7, 8 also results in an optimum dissipation of heat from the varistors 4, 5 to the housing, which has a positive effect on the efficacy and the lifetime of the varistors 4, 5.

Fig. 4 shows a variant of the overvoltage protection element 1 according to fig. 1 to 3, whereby the intermediate electrode 6 is formed from two metal parts 6a, 6b arranged parallel to one another and electrically connected to one another. In the region between the two varistors 4, 5, the two metal parts 6a, 6b are spaced apart from one another, wherein an elastic element 17, preferably a wave spring (Wellenfeder), is arranged in the intermediate chamber 16 thus formed. The two metal parts 6a, 6b are pushed away from each other by means of the spring element 17, so that the sides of the two metal parts 6a, 6b facing away from each other press against the first connection region 9 of the varistors 4, 5, respectively, and thus contact the two varistors 4, 5. In the region arranged outside the two varistors 4, 5, the two metal parts 6a, 6b are, in turn, directly connected to one another in a planar manner, wherein the two metal parts 6a, 6b are fixed in this region by means of a fixing nut 18. The two metal parts 6a, 6b are configured and bent or bent identically and are mounted with a relative rotation of only 180 °, as a result of which the two metal parts 6a, 6b can be produced particularly easily.

In the exemplary embodiment of the overvoltage protection element 1 according to the invention shown in the drawing, at least one temperature-dependent short-circuit switch is arranged inside the housing, so that when a predetermined limit temperature T1 is reached as a result of excessive heating, at least one varistor 4, 5 is short-circuited, or both varistors 4, 5 are short-circuited (embodiment 1), or only the heated varistor 4, 5 is short-circuited (embodiment 2). This prevents the varistor 4, 5 from becoming excessively hot and creating a risk of burning, which could lead not only to damage of the varistor 4, 5 but also to damage of other components and sometimes to damage of adjacent equipment or even to endangerment of personnel.

In the first embodiment according to fig. 1 to 3, only one short-circuit switch is provided inside the housing, which short-circuit switch has a short-circuit bar 19, an insulating holding element 20 mechanically connected to the short-circuit bar 19, two spring elements 21 and a metal holding section 22. In the normal state of the varistor 4, 5 shown in fig. 3a, the short-circuit strip 19 is arranged adjacent to the intermediate electrode 6, although the spring element 21 is compressed against its spring force and exerts a spring force on the holding element 20 towards the intermediate electrode 6. That is to say, the holding element 20 is supported with a spacer element 24 through an opening 23 in the intermediate electrode 6 on a metal holder 22 which is connected to the underside of the intermediate electrode 6 by means of a soldered connection, whereby the short-circuit strip 19 is held in a first position spaced apart from the intermediate electrode 6 in the normal state of the varistor 4, 5.

If the varistor 4, 5 becomes excessively hot, this also leads to heating of the intermediate electrode 6, whereby the soldered connection between the intermediate electrode 6 and the metal holder 22 is broken from a certain temperature, for example 140 ℃. The metal holder 22 or the soldered connection can thus no longer exert a reaction force of the elastic force. The metal holder 22 is thus pressed by the spacer element 24 of the holding element 20-downwards-away from the intermediate electrode 6 by the elastic force of the elastic element 21, and the short-circuit strip 19 held by the holding element 20 is pressed against the intermediate electrode 6. In this second position of the holding element 20, the shorting bar 19 contacts both the intermediate electrode 6 and the first housing half 7, so that the varistors 4, 5 are short-circuited by the shorting bar 19 (fig. 3 b). Since the metal holding portion 22 is held on the two guide pins provided on the holding member 20 along the locking point, the metal holding portion 22 is prevented from falling down even after the brazing connection is disconnected.

In the normal state of the varistor 4, 5, the short-circuit bar 19 is arranged without mechanical load in the housing, i.e. is received by the holding element 20. Since the short-circuit strip 19 for breaking the soldered connection between the intermediate electrode 6 and the metal holder 22 does not have to be designed elastically, the cross section of the short-circuit strip 19 and its electrical conductance (leitter) can optimally meet the electrical requirements of the overvoltage protection element 1 in the event of a short circuit. Since the elastic element 21 is only pressed by the cover 8 during installation, the individual components can be installed in the first housing half 7 in a simple and cost-effective manner, since all components can be installed without mechanical stress; thus, no additional fixing part is required.

As can be seen from fig. 3, the short-circuit strip 19 has a U-shaped back 25 and two U-shaped legs 26 which rest against corresponding contact sections 27 of the housing halves 7 in the event of a short circuit. Adjacent to the contact section 27, contact ribs 28 are formed on the housing half 7, which contact ribs are also contacted by the U-shaped legs 26 of the short-circuit bars 19 in the event of a short circuit. For this purpose, the ends of the U-shaped legs 26 each have a bent-back end section 29, which in the event of a short circuit always rests against the contact rib 28.

The U-shaped design of the short-circuit bars 19 and the structure of the bent-back end sections 29 of the U-shaped legs 26 advantageously utilize the dynamic electrodynamic forces (Stromkraft) in the event of a short circuit to improve the contact behavior. In the event of a short circuit, a current flows in opposite directions in the U-shaped leg 26 and the bent-back end section 29 which are at an angle α to one another, which leads to the U-shaped leg 26 and the bent-back end section 29 being bent away from one another by electromotive force, i.e. the angle α increases. This results in an increased contact force between the short-circuit strip 19 and the housing part 7, both on the contact section 27 and on the contact rib 28. Furthermore, the short-circuit current flowing through the short-circuit bar 19 causes an electrodynamic force which also increases the angle β between the U-shaped back 25 and the two U-shaped legs 26, and thus also the contact pressure between the U-shaped legs 26 and the contact section 27. Always, a smooth current transmission between the shorting bar 19 and the housing half 7 is achieved by the preferred design of the shorting bar 19 and the housing half 7.

In the second embodiment according to fig. 5 and 6, a short-circuit switch is associated with each of the two varistors 4, 5. According to this embodiment, the intermediate electrode 6 is connected to a connecting electrode 30, which passes through the housing passage 31 in an insulated manner into the housing interior. The intermediate electrode 6 can be connected to the active conductor by means of the connecting electrode 30. The second connection regions 15 of both varistors 4, 5 are contacted by metal connections 32 which are arranged on the side of the varistors 4, 5 facing away from the intermediate electrode 6. Between the housing halves 7, 8 and the metal connections 32, in each case an insulating element 33 is arranged, which may consist, for example, of a silicon film or insulating paper, so that the two metal connections 32 are insulated from the housing halves 7, 8.

The two short-circuit switches each have a flexible conductor section 34, an actuating pin 35 and an elastic element 36. Here, a first end 37 of the flexible conductor section 34 is connected to a contact section 38 of the metal connection 32, and a second end 39 of the flexible conductor section 34 is connected to an end 40 of the actuating pin 35. In the normal state of the associated varistor 4, 5 (see fig. 5), the second end 39 of the flexible conductor section 34 is arranged spaced apart from the contact section 41 of the intermediate electrode 6. Here, the spring element 36 is arranged between a contact section 38 of the metal connection 32 and a disk-shaped end 40 of the actuating pin 35 and surrounds a section of the actuating pin 35, wherein the spring element 36 is compressed against its spring force. The operating pin 35 is held in this first position against the spring force of the spring element 36 by means of a heat-sensitive element 42 in the form of a pin.

If the varistor 4, 5 becomes hot, this also causes the associated metal connection 32 and the contact section 38 to become hot, and thus also the heat-sensitive element 42 to become hot until it loses its strength when a certain limit temperature is reached, so that it can no longer exert a counter force to the spring force of the spring element 36. The actuating pin 35 is then pressed downward by means of the spring element 36 — in the illustration according to fig. 3 — so that the second end 39 of the flexible conductor section 34 is transferred into a second position, in which the second end 39 contacts the contact section 41 of the intermediate electrode 6, so that the varistors 4, 5 are short-circuited by the flexible conductor section 34. In this case, the actuating pin 35 passes through a hole formed in the contact section 38 of the metal connection 32. As material for the heat-sensitive pin 42, plastic or metal can be used, which changes its strength at a predetermined temperature, so that the intended short-circuit of the overheated varistor 4, 5 occurs, in particular, the intermediate electrode 6 is electrically conductively connected to the metal connection 32 via the flexible conductor section 34.

In the embodiment of the overvoltage protection element 1 shown in fig. 5 and 6, a backup fuse (Vorsicherung)43 is also associated with each of the two varistors 4, 5. In this case, the respective contact sections 44 of the metal connections 32 each contact a first terminal 45 of the associated auxiliary fuse 43.

In addition, in both the embodiment of the overvoltage protection element 1 shown in fig. 1 and 2 and the embodiment shown in fig. 5 and 6, a gas-filled surge arrester 46 is provided as a further arrester (Ableiter) in the housing in addition to the two varistors 4, 5. The gas-filled surge arrester 46 is arranged here in series with the two varistors 4, 5 connected in parallel. The parallel-connected varistors 4, 5 are connected in series with a gas-filled surge arrester 46, so that the overvoltage protection element 1 has an overvoltage protection function even in the event of a short circuit of one or both of the varistors 4, 5. If an overvoltage occurs after short-circuiting of the varistors 4, 5, this can lead to the gas-filled overvoltage arrester 46 burning, so that the device or apparatus to be protected with the overvoltage protection element 1 is not damaged by the overvoltage.

In the exemplary embodiment according to fig. 1 and 2, a first connection 47 of the gas-filled surge arrester 46 is electrically conductively connected to the first connection 2 of the overvoltage protection element 1, which is used for connecting active conductors, while a second connection 48 is electrically conductively connected to the intermediate electrode 6. In this case, in the region of the gas-filled surge arrester 46, an additional insulation 49 is provided inside the housing, which additionally insulates at least the further surge arrester 46 and the connection region of the first connection 47 of this surge arrester 46 to the first connection 2 of the overvoltage protection element 1 from the housing. This increases the air and electrical gap, so that the gas-filled surge arrester 46 can be installed in a reduced installation space.

In the exemplary embodiment according to fig. 5 and 6, the first connection 47 of the gas-filled surge arrester 46 is connected to the housing, specifically to the housing half 7, and the second connection 48 is connected to the two metal connections 32 via the two back-up fuses 43. In order to be able to electrically connect the two emergency fuses 43 in parallel to the second connection 48 of the gas-filled surge arrester 46, a contact metal part 51 is provided between the second connection 48 of the gas-filled surge arrester 46 and the second connection 50 of the emergency fuse 43.

In a variant of the design according to fig. 5 and 6, which is not shown here, the two thermal short-circuit switches and the two emergency fuses 43 are each replaced by a fuse (Sicherung) with a fuse (Schmelzleiter). The two fuses are then each connected on the one hand to the varistor 4, 5 via the metal connection 32 and on the other hand to the gas-filled surge arrester 46 via the contact metal part 51. The heat of the varistor is thus transferred to these fuses, so that the fuse, which is made of a low-melting material, is thermally destroyed. In the event of a short circuit, the fuse is destroyed by the short-circuit current which now flows, so that in both cases the associated varistor is electrically disconnected from the circuit.

In order to be able to connect the metal housing to a reference Potential (PE), the housing half 7 according to fig. 1 and 2 has a fastening region 52 as the second terminal 3, with which the housing half 7 can be fastened to the mounting plate. On the bottom side of the fastening region 52, recesses 53 are formed in the housing half 7, with which possibly present support rails can be mounted. The housing can then be firmly fixed by means of screws inserted into the fixing grooves 54, wherein the electrical connection of the housing halves 7 to the mounting plate takes place simultaneously. Additionally, a safety terminal connector 55 is formed on the side of the housing half 7 as the second connector 3, by means of which a safety terminal (Schutzleiter) can be electrically connected to the housing. The safety terminal 55 has a receptacle 56 for this purpose, into which a screw can be inserted in a rotationally fixed manner and pressed against the side wall of the housing half 7 in order to attach a ring-shaped cable terminal sleeve (Ringkabelschuh) connected to the safety terminal. In the exemplary embodiment according to fig. 5 and 6, a corresponding fastening region, preferably also a safety terminal, can be formed as the second terminal 3.

In the exemplary embodiment according to fig. 1 and 2, a high-current terminal port 57, through which the potential of the active conductor is conducted into the interior of the housing in an insulated and current-carrying manner, is fastened as the first terminal 2 on the top side of the housing half 7. The insulating portion 58 additionally increases the air and electrical clearance in this region while acting as a torque support when connecting the conductors. The two terminals of the high-current terminal port 57 are electrically connected to the first terminal 47 of the gas-filled surge arrester 46 via a connecting angle (Anschlusswinkel) 59. The connections of the high current lead port 57 may thus be wired in a parallel circuit.

As can also be seen from fig. 1 and 2, a two-component inner housing is formed inside the housing, which encloses at least the varistor 4, 5, the section 14 of the intermediate electrode 6 and the short-circuit switch, and which is formed by a first housing part 60 connected to the first housing half 7 and a second housing part 61 connected to the cover 8. In order to achieve a complete sealing of the inner housing, a sealing cord (Dichtschnur)62 is laid in a groove in the first housing part 60, and an insulating bushing 63 is placed over the intermediate electrode 6, through which bushing the intermediate electrode 6 is inserted into the inner housing and is thereby insulated from the housing.

Fig. 7 shows an embodiment of a display device for displaying the status of the varistors 4, 5, which enables both an optical display on the housing and a remotely transmittable status display. The display device has a circuit board 64 which is connected to the base of a plug 65 which projects from the housing. The local optical display device is operated with auxiliary power by means of the plug 65. On the circuit board 64, there are a green LED 66 that emits light in a normal state and a red LED 67 that does not emit light in a normal state. Furthermore, a plurality of heat shields 68 are provided, which are connected to the printed circuit board 64 on the one hand and are in good thermal contact with the intermediate electrode 6 via heat shield holders 69 fixed to the intermediate electrode 6 on the other hand.

If the temperature of the intermediate electrode 6 reaches the predetermined first limit temperature, the first heat-proof member 68 is turned off, which results in the green LED 66 showing the no-fault state being turned off. At the same time, the red LED 67 starts to emit light, thereby indicating a fault condition. The light of the LEDs 66, 67 reaches the display window on the top face of the housing half 7 through a light conductor 70. As a remotely transferable function display, the second heat shield 68 can be called up by means of the plug 65. The reaching of the switching temperature of the short-circuit switch can be detected by means of a third heat protection 68, the switch-off temperature of which matches the switch-on of the short-circuit switch.

Claims (22)

1. An overvoltage protection element with a housing, a terminal (2, 3) for electrically connecting the overvoltage protection element (1) to a current or signal line to be protected, two varistors (4, 5) arranged inside the housing and electrically connected in parallel, an intermediate electrode (6) arranged at least partially between the varistors (4, 5), wherein the housing has two housing halves (7, 8) made of metal and electrically connected to one another, wherein the intermediate electrode (6) is insulated with respect to the housing halves (7, 8) and the mutually opposite sides of the intermediate electrode are electrically connected to a first connection region (9) of the varistors (4, 5) in each case, wherein the two varistors (4, 5) and the intermediate electrode (6) are arranged in a sandwich-like manner between the two housing halves (7, 8),

it is characterized in that the preparation method is characterized in that,

one housing half (8) is designed as a cover having a cover section (10) and a retracted engagement section (11), wherein, in the connected state of the two housing halves (7, 8), the engagement section (11) is inserted into a corresponding receiving space (12) formed by the other housing half (7), and the cover section (10) covers the receiving space (12);

the two housing halves (7, 8) are designed and can be connected to one another in such a way that a clear gap (13) is present between the two housing halves (7, 8) in the connected state;

wherein the width (B) of the display slot (13) varies as a function of the thickness of the two varistors (4, 5), but the maximum width (B) of the display slot (13) is smaller than the corresponding distance of the engagement section (11) of the housing half (8) designed as a cover.

2. Overvoltage protection element according to claim 1, characterized in that the intermediate electrode (6) has a planar section (14) whose dimensions are substantially equal to the dimensions of the varistor (4, 5); the connection regions (9) of the varistors (4, 5) each make planar contact with a side of the intermediate electrode (6).

3. Overvoltage protection element according to claim 1 or 2, characterized in that the intermediate electrode (6) is formed by two metal parts (6a, 6b) arranged parallel to one another and electrically connected to one another, wherein the two metal parts (6a, 6b) have a spacing from one another at least in the region between the two varistors (4, 5), in which region preferably an elastic element (17) is arranged, the mutually facing sides of the two metal parts (6a, 6b) each pressing against a connection region (9) of the varistor (4, 5).

4. Overvoltage protection element, in particular according to one of claims 1 to 3, with a housing, a terminal (2, 3) for electrically connecting the overvoltage protection element (1) to a current or signal line to be protected, two varistors (4, 5) arranged inside the housing and electrically connected in parallel, an intermediate electrode (6) arranged at least partially between the varistors (4, 5), wherein the housing has two electrically connected housing halves (7, 8) made of metal, wherein the intermediate electrode (6) is insulated with respect to the housing halves (7, 8) and the mutually opposite sides of the intermediate electrode are electrically connected in each case to a first connection region (9) of the varistor (4, 5), wherein the two varistors (4, 5) and the intermediate electrode (6) are arranged in sandwich fashion between the two housing halves (7, b), 8) In the above-mentioned manner,

it is characterized in that the preparation method is characterized in that,

at least one temperature-dependent short-circuit switch is arranged in the housing such that a predetermined limit temperature T is reached as a result of overheating of the at least one varistor (4, 5)₁At least one varistor (4, 5) is short-circuited.

5. The overvoltage protection element as claimed in claim 4, characterized in that the two housing halves (7, 8) are electrically connected to the second connection regions (15) of the varistors (4, 5), respectively;

the short-circuit switch has a short-circuit bar (19), an insulating holding element (20) which is mechanically connected to the short-circuit bar (19), at least one spring element (21) and a metal holding part (22);

wherein, in the normal state of the varistor (4, 5), the holding element (20) is supported on a metal holding part (22) connected to the intermediate electrode (6) by means of a solder connection by means of a spacer element (24) protruding through an opening (23) in the intermediate electrode (6), the short-circuit strip (19) being thereby arranged spaced apart from the intermediate electrode (6) against the spring force of the spring element (21) acting on the holding element (20);

when the soldered connection is broken by heating of the varistor (4, 5), the holding element (20) and the shorting bar (19) are transferred by the spring force of the spring element (21) into a second position, in which the shorting bar (19) contacts both the intermediate electrode (6) and the housing, so that the varistor (4, 5) is short-circuited by the shorting bar (19).

6. Overvoltage protection element according to claim 5, characterized in that the short-circuit strip (19) has a U-shaped back (25) and two U-shaped legs (26), wherein in the event of a short circuit the ends of the U-shaped legs (26) bear against corresponding contact sections (27) on the housing halves (7).

7. The overvoltage protection element as claimed in claim 6, characterized in that the housing half (7) has two contact ribs (28) which are each arranged adjacent to a contact section (27); the ends of the U-shaped legs (26) of the short-circuit strip (19) each have a bent-back end section (29), wherein the end sections (29) of the U-shaped legs (26) always bear against the contact ribs (28) in the event of a short circuit, and opposite regions of the U-shaped legs (26) bear against the opposite contact sections (27).

8. Overvoltage protection component according to claim 4, characterized in that the intermediate electrode (6) is connected to a first connection (2) for connecting at least one active conductor (L) of the current or signal line to be protected; a metal connection (32) is provided between the two housing halves (7, 8) and the associated second connection region (15) of the two varistors (4, 5), wherein the metal connection (32) is insulated from the housing halves (7, 8) by means of an insulating element (33);

each of the two varistors (4, 5) is associated with a short-circuit switch, wherein each of the short-circuit switches has a flexible conductor section (34), an actuating pin (35) and an elastic element (36);

the first ends (37) of the flexible conductor sections (34) are each electrically connected to a contact section (38) of the metal connection (32), and the second ends (39) of the flexible conductor sections (34) are each connected to an end (40) of the associated actuating pin (35);

wherein, in a normal state of the varistor (4, 5), the actuating pin (35) is held in its first position by means of the heat-sensitive element (42), whereby the second end (39) of the flexible conductor section (34) is arranged spaced apart from the contact section (41) of the intermediate electrode (6) against the spring force of the spring element (36) acting on the actuating pin (35);

wherein, when the thermistor element (42) softens due to heat generation of the varistor (4, 5), the second end (39) of the flexible conductor section (34) is transferred by means of the spring force of the spring element (36) acting on the actuating pin (35) into a second position in which the second end (39) of the flexible conductor section (34) contacts the contact section (41) of the intermediate electrode (6), so that the respective varistor (4, 5) is short-circuited by the flexible conductor section (34).

9. Overvoltage protection element according to claim 8, characterized in that the actuating pins (35) each pass through a hole (42) in the associated contact section (38) of the metal connection (32); elastic elements (36) are respectively arranged between the end (40) of the operating pin (35) and the contact section (38) of the metal connecting part (32); a thermally sensitive pin (42) is arranged in each case in a recess of the actuating pin (35), wherein, in the normal state of the varistor (4, 5), the pin (42) is located on the side of the contact section (38) of the metal connection (32) opposite the spring element (36), the pin (42) losing its strength when it heats up, so that the actuating pin (35) can no longer be held in its first position by the pin (42) counter to the spring force of the spring element (36).

10. The overvoltage protection element as claimed in claim 8 or 9, characterized in that a spare fuse (43), in particular a fuse, is assigned to each of the two varistors (4, 5); the metal connecting parts (32) each have a second contact section (44) which is electrically conductively connected to a first terminal (45) of the spare fuse (43).

11. Overvoltage protection element according to one of claims 1 to 9, characterized in that at least one fuse with a fuse is arranged inside the housing and is connected in an electrically conductive manner to the varistor (4, 5); the safety device is triggered either when a predetermined limit temperature is reached as a result of overheating of at least one varistor (4, 5) or when a short circuit occurs, so that the varistor (4, 5) is electrically disconnected from the circuit.

12. Overvoltage protection element according to claim 11, characterized in that the fuse has a fuse wire made of a low-melting material, such as zinc, and preferably has an arc extinguishing aid, such as sand.

13. Overvoltage protection element, in particular according to one of claims 1 to 12, with a housing, a terminal (2, 3) for electrically connecting the overvoltage protection element (1) to a current or signal line to be protected, two varistors (4, 5) arranged inside the housing and electrically connected in parallel, an intermediate electrode (6) arranged at least partially between the varistors (4, 5), wherein the housing has two electrically connected housing halves (7, 8) made of metal, wherein the intermediate electrode (6) is insulated with respect to the housing halves (7, 8) and the mutually opposite sides of the intermediate electrode are electrically connected to a first connection region (9, 9) of the varistor (4, 5), wherein the two varistors (4, 5) and the intermediate electrode (6) are arranged in sandwich fashion between the two housing halves (7, 5), 8) In the above-mentioned manner,

it is characterized in that the preparation method is characterized in that,

a further arrester (46), in particular a gas-filled arrester, is arranged between the terminals (2, 3) of the overvoltage protection element (1) and the parallel circuit of the two varistors (4, 5).

14. The overvoltage protection element according to claim 13, characterized in that the two housing halves (7, 8) are electrically connected to the second connection regions (15) of the varistors (4, 5), respectively; a first connection (47) of the further arrester (46) is electrically conductively connected to a first connection (2) for connecting at least one active conductor (L) of the current or signal line to be protected, and a second connection (48) of the further arrester (46) is electrically conductively connected to the intermediate electrode (6).

15. Overvoltage protection component according to claim 14, characterized in that in the region of the further arrester (46), an insulation (49) is provided in the housing, which insulation insulates at least the further arrester (46) and the connection region of the first connection (47) of the further arrester (46) to the first connection (2) of the overvoltage protection component (1) additionally relative to the housing.

16. Overvoltage protection component according to claim 13, characterized in that the intermediate electrode (6) is connected to a first connection (2) for connecting at least one active conductor (L) of the current or signal line to be protected; a metal connection (32) is provided between the two housing halves (7, 8) and the facing second connection regions (15) of the two varistors (4, 5), wherein the metal connection (32) is insulated from the housing halves (7, 8) by means of an insulating element (33); a first connection (47) of the further arrester (46) is connected directly or indirectly to the housing, and a second connection (48) of the further arrester (46) is connected directly or indirectly to the two metal connections (32).

17. Overvoltage protection element according to claim 16, characterized in that a backup fuse (43), in particular a fuse, is arranged between the second connection (48) of the further arrester (46) and the two metal connections (32); the metal connecting parts (32) each have a second contact section (44) which is electrically conductively connected to a first terminal (45) of the spare fuse (43).

18. Overvoltage protection element according to one of claims 1 to 17, characterized in that the housing has a fastening area (52) as the second connection (3), by means of which the housing can be connected to a mounting plate as a reference potential.

19. Overvoltage protection element according to one of claims 1 to 18, characterized in that the housing has a safety terminal (55) as the second terminal (3), by means of which the safety terminal can be electrically connected to the housing, wherein the safety terminal (55) is preferably arranged on the first housing half (7) and has a receiving groove (56).

20. Overvoltage protection component according to one of claims 1 to 19, characterized in that a high-current lead port (57) is provided as a first terminal (2) on the housing, preferably on the end side of the first housing half (7), for connection to at least one active conductor (L) of the current or signal line to be protected.

21. Overvoltage protection element according to one of claims 1 to 20, characterized in that an inner housing is formed inside the housing, which inner housing encloses at least the varistor (4, 5) and optionally also one or more temperature-dependent short-circuit switches, wherein the inner housing is of two-component design and is formed by a first housing part (60) connected to the first housing half (7) and a second housing part (61) connected to the second housing half (8), wherein the inner housing preferably also has at least one sealing element (62, 63).

22. Overvoltage protection element according to one of claims 1 to 21, characterized in that an optical and/or remotely transmittable display means for displaying the state of the varistor (4, 5) is constructed or arranged on the housing.