HK1153036A - Electrical surge protection element - Google Patents

Description

Overvoltage protection element

Technical Field

The invention relates to an overvoltage protection element, comprising a housing; at least one overvoltage limiting component, in particular a varistor, arranged in the housing; two connecting pieces which are each electrically conductively connected, in particular soldered or welded, to one pole of the overvoltage limiting component; two connecting elements for electrically connecting the overvoltage protection element to the current or signal path to be protected are also provided, wherein in the normal state of the overvoltage protection element, these connecting elements are each in electrically conductive contact with one connecting lug.

Background

Known overvoltage protection elements are generally designed as "protection plugs", which together with the lower part of the device form an overvoltage protection device. In order to install such overvoltage protection devices, which are intended to protect the conductors L1, L2, L3 of the transmission phases, for example, as well as the neutral conductor N and, if appropriate, the earth conductor PE, corresponding terminals for the individual conductors are provided on the lower part of the device in the known overvoltage protection devices. In order to simply bring the lower part of the device into mechanical and electrical contact with the corresponding overvoltage protection element, the connecting elements are designed as plug pins in the overvoltage protection element, and corresponding sockets connected to the terminals are provided in the lower part of the device, so that the overvoltage protection element can be simply plugged onto the lower part of the device. In this way, defective overvoltage protection elements can be replaced simply without having to remove the line connected to the terminal on the lower part of the device.

In this overvoltage protection device, the installation and assembly can be carried out very simply and in a time-saving manner by means of the pluggability of the overvoltage protection element. The overvoltage protection device also has, in part, switching contacts as signal generators for remotely transmitting the state of at least one overvoltage protection element, and also optical state displays in the individual overvoltage protection elements.

The status indicator indicates whether the overvoltage limiting component provided in the overvoltage protection element is still operational. As components for limiting overvoltages, use is made in particular of varistors, but gas-filled surge arresters, spark gaps or diodes can also be used depending on the purpose of use of the overvoltage protection element.

DE4241311C2 discloses an overvoltage protection element of the type described at the outset. In this overvoltage protection element designed as a protective plug, the first connecting element is connected directly to the first terminal lug on the varistor by a first flexible copper strip, while the second connecting element is connected to the rigid separating element by a second flexible copper strip, the end of the separating element facing away from the flexible copper strip being connected to the second terminal lug of the varistor by a solder joint. The separating element is acted upon by a spring system with a force which causes the separating element to be moved linearly apart when the soldered connection is separated from the connecting lug, so that the varistor is electrically separated in the event of a thermal overload. In this known overvoltage protection element, a thermal disconnection device is therefore provided for monitoring the state of the varistor. By means of the spring system, the remote notification contact is operated when the soldered connection is detached, so that the state of the overvoltage protection element can also be monitored remotely.

DE69904274T2 also discloses an overvoltage protection element with a thermal disconnection mechanism. In this overvoltage protection element, the end of the rigid spring-loaded slider is soldered both to the first connecting element and to a terminal lug connected to the varistor in the normal state of the overvoltage protection element. The unauthorized heating of the varistor also leads to heating of the solder joint, so that the slide slides out of the connection point between the first connection element and the terminal lug as a result of the spring force exerted on it, which leads to electrical separation of the varistor.

The pluggable connecting element, which is formed by the socket arranged in the lower part of the device and the plug pin on the overvoltage protection element, must be able to transmit relatively high pulse currents and short-circuit currents. Furthermore, the plug contacts, i.e. the plug pins and the socket, are mechanically loaded during insertion and removal of the overvoltage protection element, so that stable connection elements are used in the known overvoltage protection elements, which are connected to the terminal lugs by soldering or welding.

Disclosure of Invention

The object of the present invention is to provide an overvoltage protection element of the type mentioned in the introduction, which can be produced more simply and therefore more cost-effectively. Here, the overvoltage protection element has the same electrical and mechanical characteristics as the conventional overvoltage protection element.

This object is achieved in the overvoltage protection element described at the outset in that: the first connecting web and the first connecting element are connected to one another in one piece, wherein the free end of the first connecting element facing away from the overvoltage limiting component is designed as a plug contact (Steckkontakt). According to the invention, the first terminal of the overvoltage limiting component is thus designed in such a way that the free end of the first terminal itself serves as the connecting element. By integrally forming the first connecting web and the first connecting element, the additional manufacturing step, which is currently required in the prior art, in which the connecting web is connected to the connecting element by welding or soldering, is dispensed with. In addition to the simplification of the production process of the overvoltage protection element, the invention also ensures a minimum "contact resistance" between the terminal lug and the connecting element when the terminal lug and the connecting element are formed as one piece.

In practice, the terminal lug of the overvoltage limiting component generally has a relatively low material strength, so that the mechanical strength of the free end of the terminal lug which is operated as a connecting element may not be sufficient to continuously maintain the force with which the overvoltage protection element is inserted and removed without the connecting element being damaged and thus the pluggable electrical connection between the overvoltage protection element and the lower part of the device being degraded. According to a preferred embodiment of the invention, the first connection element is folded such that it has a plurality of layers (Lage) in the contact region. The contact region represents a region of the connecting element in which the connecting element is contacted by a corresponding socket in the lower part of the device in the inserted state of the overvoltage protection element. This folding of the connecting element is preferably effected perpendicularly to the longitudinal direction of the connecting element or web. In this case, it is generally sufficient to carry out one or two folds, so that the connecting element has two or three layers in the contact region.

According to a further preferred embodiment of the invention, the mechanical strength of the folded connecting element is increased by the individual layers of the folded connecting element being connected to one another in a force-locked, form-locked or material-locked manner. The connection region is located outside the contact region, so that the contact properties of the connection element are not changed by the already achieved interconnection of the individual layers.

In a particularly preferred embodiment of the overvoltage protection element according to the invention, a form-locking (formschlussig) connection is formed between the first connection element or the first connection lug and the housing. During the insertion and removal of the overvoltage protection element, a force proportional to the adhesive friction is exerted on the overvoltage limiting component arranged in the housing, which must be overcome in order to insert or remove the connecting element designed as a plug contact into or from the corresponding socket in the lower part of the device. By realizing a form-locking connection between the first connection element and the housing, the insertion and withdrawal forces are transmitted directly from the housing to the plug contact or the forces acting on the plug contact are received by the housing, so that the forces acting on the overvoltage limiting component during the insertion process or the withdrawal process are significantly reduced or even completely avoided.

According to a first embodiment variant, the free end of the first connecting element here has a bead which engages in a corresponding receptacle (Aufnahme) in the housing wall of the housing. Instead of the bead, one or two laterally projecting flanges are also formed on the first connecting element, which flanges likewise enter into corresponding receptacles in the housing wall of the housing and are held therein. According to another embodiment, at least one hole is formed in the first connecting element, through which hole a corresponding projection is passed, which projection is provided on the housing wall, through which housing wall the connecting element protrudes from the housing.

The force-locking (spring-locking) connection of the overvoltage protection element between the connecting element, which is designed as a plug contact, and the corresponding socket in the lower part of the device is generally achieved by the elastic properties of the socket. For this purpose, the socket can be formed, for example, in the shape of a tulip. According to an alternative embodiment, the force-locking connection between the connection element and the socket in the lower part of the device is made in such a way that not the socket but the connection element is formed elastically. For this purpose, at least two layers of the connecting element can be bent relative to each other, so that the connecting element is elastically formed perpendicular to its longitudinal extent. The connecting element can be designed to be substantially V-shaped.

As in the case of the known overvoltage protection elements described at the outset, the overvoltage protection element according to the invention preferably also has a thermal disconnection device for monitoring the state of the overvoltage limiting component. For this purpose, in the normal state of the overvoltage protection element, the second terminal is connected to the second connecting element by a weld, wherein the welded connection between the second terminal and the second connecting element, which is produced at the weld, is broken when the temperature of the overvoltage limiting component exceeds a predetermined limit temperature. In order to detach the weld when the limit temperature is reached, i.e. to move the end of the connecting element facing the connecting lug away from the connecting lug, the connecting element itself can be designed to be elastic or to be acted upon by a separate spring force.

The overvoltage protection element according to the invention is preferably designed as a "protection plug", so that it, together with the associated lower part of the device, forms an overvoltage protection device. In this case, a plurality of overvoltage limiting components, in particular parallel varistors, can also be arranged in the housing of the overvoltage protection element. If the overvoltage protection element has a double piezoresistor, in particular the central, inner connecting lug of the double piezoresistor can be connected integrally to the first connecting element of the overvoltage protection element.

Drawings

There are now a number of possibilities for constructing and expanding the overvoltage protection element according to the invention. To this end preferred embodiments in the claims following claim 1 and in the following description are explained with reference to the drawings. In the drawings:

figure 1 shows a perspective view of an embodiment of an overvoltage protection element,

fig. 2 shows a simplified diagram of a varistor of a first embodiment with a connection pad, which is inserted into a socket in the lower part of the device,

fig. 3 shows a simplified diagram of a varistor of a second embodiment with connection pads, which are inserted into a socket,

fig. 4 shows two separate views of the connection pieces according to fig. 2 and 3, which are each inserted into a socket,

figure 5 shows a variant of the connection piece according to figure 4 inserted into a socket,

figure 6 shows a simplified diagram of a varistor with connection pads similar to those of figure 3,

figure 7 shows two principle views of the first connection element of the varistor being fixed in the housing,

figure 8 shows a simplified view of an alternative contact of the connection element and the socket in the lower part of the device,

fig. 9 shows a view of an embodiment of a connecting plate according to the invention with a connecting element.

Detailed Description

Fig. 1 shows an overvoltage protection element 1 having a housing 2, wherein overvoltage limiting components are arranged in the housing 2. In the embodiment shown, the overvoltage limiting component is a varistor 3; alternatively, the overvoltage limiting component can also be formed by a plurality of parallel piezoresistors, in particular by a double piezoresistor. Likewise, gas-filled surge arresters can also be used as overvoltage limiting components.

The two poles of the varistor 3 are each connected in an electrically conductive manner, in particular soldered or welded, to a respective terminal lug 4, 5. The protective element 1 designed as a protective plug also has two connecting elements 6, 7 designed as plug contacts, which project through the housing 2 through corresponding openings on the bottom side of the overvoltage protection element 1. The plug-shaped connecting elements 6, 7 can be inserted into corresponding sockets 8 at the bottom of the device, not shown here, of which only one socket 8 is shown schematically in each of fig. 2 to 8.

In contrast to the overvoltage protection elements known from the prior art, in which the connection lugs 4, 5 and the connection elements 6, 7 are formed as separate components, in the protection element 1 according to the invention the first connection lug 4 is connected integrally to the first connection element 6, i.e. the end of the connection lug 4 remote from the varistor 3 is formed as a connection element 6.

In the exemplary embodiment according to fig. 2, the thickness of the connecting element 6 is equal to the thickness of the web 4, while in the exemplary embodiment shown in fig. 3, the connecting element 6 is folded such that the connecting element 6 has two layers 61, 62 which are substantially parallel to one another in the contact region 9; the connecting element 6 is thus formed as a double layer, so that the material strength of the connecting element 6 is also doubled in the contact region 9. By means of this folding of the connecting element 6, the strength and stability of the connecting element 6 can be increased in a simple manner, so that the connecting element 6 is not damaged even after multiple insertion into the socket 8 in the lower part of the device, although the connecting web 4 has a relatively low material strength. Instead of the single fold shown in fig. 3 and 4a, it is also possible to fold the connecting element 6 according to fig. 4b twice, so that the connecting element 6 has three layers 61, 62, 63 in the contact region 9.

As fig. 5 shows, the mechanical strength of the connecting element 6 can be further increased by the mechanical connection of the individual layers 61, 62 to one another, wherein the connection region 10 is arranged outside the contact region 9, i.e. above the contact region 9, so that the contact properties between the connecting element 6 and the socket 8 are not impaired.

As mentioned at the outset, the varistor 3 is arranged in the housing 2, wherein an opening is formed in the bottom side of the housing 2, through which opening the connecting elements 6, 7 project out of the housing 2. Due to the frictional forces between the connecting elements 6, 7 and the socket 8 in the lower part of the device, a force is exerted on the varistor 3 connected to the connecting element 6 via the connecting lug 4 when the overvoltage protection element 1 is inserted into the lower part of the device and when the overvoltage protection element 1 is removed from the lower part of the device. In order to reduce the forces acting on the varistor 3, a form-locking connection is formed between the first connection element 6 and the housing 2. According to fig. 6, the free end of the connecting element 6 has a bead (abkantsung) 11, which engages in a receptacle 13 formed in a housing wall 12 of the housing 2, so that the bead 11 is held in the housing wall 12.

In the exemplary embodiment according to fig. 7a, two laterally projecting flanges (Nase)14 are formed on the first connecting element 6, which flanges are held in two corresponding receptacles 15 in the housing wall 12. In the embodiment shown in fig. 7b, the form-locking connection between the first connecting element 6 and the housing 2 is realized by forming two holes 16 in the connecting element 6 and the housing wall 12 having two projections 17 corresponding to the holes 16 and which engage in the holes 16. If the overvoltage protection element 1 is detached from the lower part of the device, whereby a user grips the housing 2 of the overvoltage protection element 1 and pulls it out of the lower part of the device, the pulling-out force is transmitted directly from the housing 2 to the connecting element 6, so that no force, or only a significantly smaller force, acts on the varistor 3 arranged in the housing 2.

In the exemplary embodiment of the overvoltage protection element 1 according to the invention shown in fig. 1 to 6, the contact force required to ensure good electrical contact between the connection elements 6, 7 and the socket 8 is ensured by the elastic properties of the socket 8, i.e. the socket 8 is of elastic design, while the connection elements 6, 7 are of substantially rigid design. Fig. 8 shows an embodiment, in which, in contrast to this, the socket 8 is formed rigidly, while the connecting element 6 is formed elastically, so that the contact force between the connecting element 6 and the socket 8 is achieved by the elastic properties of the connecting element 6. For this purpose, the two layers 61, 62 of the connecting element 6 are bent over one another in such a way that the connecting element 6 is substantially V-shaped, whereby the connecting element 6 is elastically formed perpendicular to its longitudinal extent.

Fig. 9 shows a view of a preferred embodiment of a web 4 with a connecting element 6 integrally connected thereto, wherein the connecting element 6 is folded according to fig. 3 such that the connecting element 6 has layers 61, 62 parallel to one another. As shown in the illustration according to fig. 7a, two laterally projecting flanges 14 are formed on the connecting element 6, i.e. on the layer 62, which flanges serve to fix the connecting element 6 in the housing. In order to increase the stability of the connecting element 6, the two layers 61, 62 are fixedly connected to one another at two points 18 by means of rivet points.

As can be seen from fig. 1, a viewing window 19 is formed in the upper surface of the housing 2 through which the optical state display can be read. The optical status display is connected to the second connecting element 7 in such a way that it changes its state when the welded connection between the second connecting element 7 and the second connecting web 5 is opened. The green part of the optical state display is recognized in the normal state of the overvoltage protection element 1 or the varistor 3, for example, via the viewing window 19, whereas in the event of a fault of the overvoltage protection element 1 there is a red part of the state display below the viewing window.

Claims (8)

1. An overvoltage protection element has a housing (2); at least one overvoltage limiting component, in particular a varistor (3), arranged in the housing (2); two connecting pieces (4, 5) which are each electrically conductively connected, in particular soldered or welded, to one pole of the overvoltage limiting component; and two connecting elements (6, 7) for electrically connecting the overvoltage protection element (1) to a current or signal path to be protected, wherein in the normal state of the overvoltage protection element (1) the connecting elements (6, 7) are each in electrically conductive contact with one connecting lug (4, 5), characterized in that,

the first connecting web (4) and the first connecting element (6) are integrally connected to one another, wherein the free end of the first connecting element (6) facing away from the overvoltage limiting component is designed as a plug contact.

2. Overvoltage protection element according to claim 1, characterized in that the first connection element (6) is folded such that it has a plurality of layers (61, 62, 63) in the contact region (9).

3. Overvoltage protection element according to claim 2, characterized in that the individual layers (61, 62, 63) of the first connection element (6) are connected to one another, wherein the connection region (10) is located outside the contact region (9).

4. The overvoltage protection element according to one of claims 1 to 3, characterized in that a form-locking connection is formed between the first connection element (6) and the housing (2).

5. Overvoltage protection element according to claim 4, characterized in that a bead (11) or at least one laterally projecting flange (14) is provided on the first connection element (6), and in that a receptacle (13, 15) corresponding to the bead (11) or the flange (14) is formed in the housing wall (12) of the housing (2).

6. Overvoltage protection element according to claim 4 or 5, characterized in that at least one hole (16) is formed in the first connection element (6) and that at least one projection (17) corresponding to the hole (16) is formed in the housing wall (12) of the housing (2).

7. The overvoltage protection element according to one of claims 2 to 6, characterized in that at least two layers (61, 62, 63) of the first connection element (6) are bent over one another in such a way that the first connection element (6) is elastically formed perpendicular to its longitudinal extent.

8. The overvoltage protection element according to one of claims 1 to 7, characterized in that in the normal state of the overvoltage protection element (1), the second terminal (5) of the overvoltage limiting component (3) is connected to the second connection element (7) by means of a solder joint, wherein the solder connection between the second terminal (5) and the second connection element (7) effected at the solder joint is broken when the temperature of the overvoltage limiting component (3) exceeds a predetermined limit temperature.