WO2008151861A1

WO2008151861A1 - Overvoltage protection device with mechanical arresting device activated in the case of thermal overload

Info

Publication number: WO2008151861A1
Application number: PCT/EP2008/053750
Authority: WO
Inventors: Edmund ZÄUNER; Georg Wittmann; Sascha Ludewig
Original assignee: Dehn + Söhne Gmbh + Co. Kg
Priority date: 2007-06-11
Filing date: 2008-03-28
Publication date: 2008-12-18
Also published as: ATE469427T1; PL2047487T3; EP2047487B1; DE502008000709D1; DE102007042991B4; DE102007042991A1; RU2009146876A; CN101711417A; CN101711417B; EP2047487A1

Abstract

The invention relates to an overvoltage protection device with a mechanical arresting device which is activated in the case of thermal overload, wherein said devices comprise connector elements which can be moved by means of a spring-loaded or pretensioned slider (4) from a closed position to a position in which current is interrupted or voltage is cut off, and wherein the closed position of the connector elements is maintained by a solder material or a thermally detachable adhesive. According to the invention, the connector elements consist of a pair of current-dividing metallic brackets (1, 1'), wherein the ends of said brackets (1, 1') which are directed toward the overvoltage protection element run parallel and include the corresponding contact lug (14) therebetween. The ends of the brackets (1, 1') which are turned away from the overvoltage protection element are connected to each other, enclosing a free space, and have a section (12) for external connector components or connector clamps. The slider (4) with pretensioned spring (2) is set in the free space, wherein the spring pretensioning is directed in the direction of the contact lug (14) of the overvoltage protection element. Furthermore, the slider (4) has a wedge shape and/or sections of the brackets have an inclined surface in order to generate a force component on the parallel ends of the brackets when the slider moves in such a way that said ends of the brackets can be moved away by the contact lug. The aforementioned solder or adhesive connection is formed in the area of the parallel ends of the brackets and the contact lug.

Description

Surge protection device with mechanical disconnection device activated in thermal overload

description

The invention relates to an overvoltage protection device with activated in thermal overload case mechanical separating device, this comprising connection elements which are moved by means of spring loaded or biased slide from a closed to a current interrupting or potential separating position and wherein the closed position of the connection elements is secured by a solder or thermally releasable adhesive , according to the preamble of claim 1.

Overvoltage protection devices with a thermal cut-off device have long been part of the known state of the art. The task of the separation device is, in the event of inadmissible heating of the surge protection unit, z. B. a varistor, to disconnect it from the grid before a destruction of the arrester occurs.

From EP 0 987 803 B1 or EP 0 905 839 Bl separating devices are known, which are designed as solid slide. The corresponding slide is spring preloaded and protects each a varistor from an inadmissible thermal heating. The closed position of the corresponding connection elements is secured by a solder. This solder is exposed to the constant spring biasing force transmitted via the slider, which is a significant disadvantage. Depending on the performance, d. H. the desired surge current carrying capacity, more separators are required, which is a cost disadvantage. It has also been shown that in the cited solutions of the prior art in the separation process with movement displacement of the slider solder particles are entrained to form solder filaments with the result of insufficient electrical isolation.

From the utility model DE 295 19 313 U l a surge protection device with a separation device of the thermal type has become known wherein the separation device is positioned separately from the actual varistor via a partition wall. The local separation device has only a low surge current capability. Also, in this prior art, the soldering point is exposed to a constant spring biasing force.

In the interconnection of several separation devices according to EP 0 716 493, a separate separation device is necessary for each varistor provided there, with even several separation devices per protection path being required.

From the foregoing, it is therefore an object of the invention to provide a developed overvoltage protection device activated in thermal overload case mechanical separation device, the particular solder joint of the connection elements, which is opened in Abtrennfall not constantly subject to the action of a mechanical force-side load. Another object of the invention is that the connection elements of the separating device are designed so that there is a high surge current carrying capacity and the goal is to produce the quasi-contact pressure for the discharge process by the surge current itself.

In order to limit the cost of surge protection devices, according to the present invention, the use of materials to which special electrical, thermal or mechanical requirements are imposed, only at selected locations.

The object of the invention is achieved according to the combination of features according to claim 1, wherein the dependent claims represent at least expedient refinements and developments.

Accordingly, the separating device according to the invention is structurally designed so that the supply to the voltage-limiting overvoltage protection units, in particular varistors, is formed by two conductor portions through which current flows in the same direction, which in the end rich parallel and pass into a common junction, which is secured by a Lot.

Due to the parallel current flow and the associated force effects in the surge current case, the corresponding sections of the conductors or brackets and cause at this time the desired increase in the contact force at the solder joint.

This makes it possible to design the Lotstelle only for fixing the respective sections of the bracket. This makes it possible to limit the mechanical dimensioning of the soldering point to an absolute minimum and thus make it particularly thermally sensitive. The Lotstelle thus has only a very small heat capacity. The necessary contact pressure for the discharge process is produced according to the theory of the invention by the surge current itself.

The connection elements, which consist of a pair of current-dividing metallic straps, can be made of a mechanically less solid material. By dividing into the two parallel current paths, the dimensioning of the conductor sections can be carried out more cost-effectively, since the current density is halved.

The spring of the separating device, whose task is to shift in the case of melting the Lotstelle the slide between the current paths and thus interrupt the circuit can be performed with less spring force, so that a low continuous load of Lotstelle is the result.

A particularly positive symmetrical design of the bracket sections respectively the entire bracket allows a centric and thus force-neutral positioning and guiding the slider through it. A z. B. wedge-shaped design of the slide supports the separation process directly. Since the slider moves in Abtrennfall directly into the Lotstelle into, negative effects in the separation process, z. As in the prior art existing soldering effectively prevented and achieved a safe, stress-free separation.

According to the prior art, in the case of overvoltage protection devices with varistors, the latter are positioned in an outer housing. The varistor units are electrically isolated from other components by means of potting or powder coating. The varistors are used with the respective connection elements as a prefabricated module in the outer housing. In this variant of the prior art, a part of the electrical and mechanical properties of the varistor unit, for. B. the overload behavior in case of failure by the particularly auszulegenden material of the outer housing. It is not readily possible according to the prior art, to use the most cost-effective material for the outer housing, but it is a material to select, for. B. must be resistant to high temperatures and non-flammable.

To avoid this disadvantage, the invention proposes to encapsulate the overvoltage protection units, in particular varistors, separately, d. H. to introduce these into a housing encapsulation. Only the material of this housing encapsulation is to be selected according to the special requirements.

According to the invention, the connection elements consist of a pair of current-dividing metallic stirrups whose overvoltage protection unit, for. B. a varistor, directed ends run parallel and record in their midst the respective contact lug of the overvoltage protection unit.

The over-voltage protection unit facing away from the ends of the bracket include a space and are connected to each other. These ends of the brackets also have a section for external connection parts or terminals.

In the free space of the already mentioned slider is used with biasing spring, wherein the spring bias in the direction of the contact lug of the overvoltage protective unit is oriented. Furthermore, either the slider is designed to have a wedge shape and / or have portions of the bracket has an inclined surface to generate a slider component in a force component on the parallel ends of the bracket such that they are movable away from the contact lug. In the region of the parallel ends of the bracket and the contact lug, the at least one solder or adhesive connection is formed.

The slider has in one embodiment of the invention has a substantially planar surface portion for optical signaling of the respective slide position, with respect to a corresponding window, which is arranged in the outer housing.

Below this surface portion of the movable slider, a releasable from the slider further surface for optically signaling the Abtrennzustands is provided. The surface portion of the slider and this further surface is preferably designed in different colors.

The movable slide has a cavity in the longitudinal direction for receiving one end or a portion of the biasing spring. In addition, in the foot of the slider, a guide groove may be introduced to prevent tilting in the movement to be performed.

The parallel ends of the stirrups are fixed in position by the solder or the adhesive. During the separation process, however, these ends strive by a predictable mechanical residual stress apart, which supports the separation process.

In the separation case, the slider moves into the solder or adhesive connection area and penetrates this area to avoid soldering threads in particular, so that a complete and safe separation is achieved.

The slider itself consists of an electrically insulating, in particular plastic material. As already explained, the at least one overvoltage protection unit is arranged in a housing encapsulation which has openings for electrical contacting and wherein the slider is arranged on this housing encapsulation. The housing encapsulation may in this case have a rail which engages in the guide groove at the foot of the slider.

The portion of the stirrups for connecting external terminals or other connection parts is fastened or supported on the housing encapsulation.

Several overvoltage protection units, in particular varistor disks, can be arranged in parallel within the housing encapsulation.

A plurality of such housing encapsulations with overvoltage protection units therein and respective stirrups and slides can be connected in parallel to one another with a group display element in order to indicate in a logical OR operation the possible disconnection case.

The sections for the outer connection parts or outer connection terminals are designed in particular for screw connections which can be realized cost-effectively and have a corresponding bend and possibly one or more holes.

The overvoltage protection units in each case in the housing encapsulation are used in a series connection outer housing, which can be manufactured from a cost-effective plastic material.

In addition, it is possible within the series connection housing to arrange at least one gas discharge conductor in a corresponding electrical connection to the further overvoltage protection units. The invention will be explained below with reference to an embodiment and with the aid of figures.

Hereby show:

1 shows an exploded view of a varistor disk located in a housing encapsulation, this assembly being used in a series connection outer housing, and additionally providing a gas discharge arrester in a 1 + 1 circuit;

Fig. 2 is an exploded view similar to that of Figure 1, but with a total of three varistor disks, which are each located in a housing encapsulation, and further provided with gas discharge, everything in turn inserted into a series terminal outer housing.

3 shows a detailed representation of an encapsulated varistor unit with a recognizable separating device;

4 shows a further detailed illustration of the varistor unit located in the housing encapsulation, wherein the disconnecting device is in the untripped state;

Fig. 5 is a view similar to that of FIG. 4, but in tripped condition;

6 shows a view from below of the housing encapsulation with a recognizable connecting lug of the varistor disk and connecting part, which has a slot-shaped opening for receiving the connecting lug for the purpose of soldering;

Fig. 7 is a view similar to that of FIG. 6, but with two varistor disks within a package encapsulation; 8 is a view similar to that of FIG. 7, but already with connection unit and connection terminals and mounted gas discharge arrester;

9 shows a multi-pole arrangement of several surge arresters in housing encapsulations with bus bar as status indicator (see also FIG. 2);

10 shows a multi-pole arrangement of several surge arresters located in housing encapsulations with busbar as status display and recognizable housing section with viewing window, which allows a view of the group display element;

Fig. I Ia and I Ib a representation similar to that of FIG. 10, but with a left side separated in the image arrester and corresponding shifted position of the group display element;

12a and 12b is a representation similar to that of FIGS. I Ia and I Ib, but with the centrally located surge arrester in the separated state;

Fig. 13a and 13b is a view similar to that of FIGS. I Ia to 12b, wherein the arranged at the top right in the image arrester is in a separated state, and

Fig. Figs. 14a and 14b are views similar to those of Figs. Ia to 13b, with all the arresters in the severed state.

In the illustrations according to FIGS. 1 and 2 takes a series terminal outer housing 11, the housing enclosure 6 with therein Varistorscheiben 7, 7 '. At the top of the housing enclosure 6 is the separating device according to the invention, which has a slide 4 as a separating element. A pair of brackets 1, 1 'is designed as a metallic stamped and bent part, wherein the right side in the image ends of the bracket in the Have substantially parallel course. In addition, the bracket enclose a space for receiving the slider 4 in the mounted state.

The bracket 1, 1 'go into a section 12 for contacting with other elements 13, wherein the connection between the parts 12 and 13 z. B. can be realized by screwing.

For the 1 + 1 circuit of FIG. 1 is still a Gasabieiter 8 contacted via corresponding electrical means and used in the series terminal outer housing 11.

According to FIG. 2, which comprises a 3 + 1 circuit of a total of three varistor groups 7, 7 'located in each case encapsulation 6, there is a group display element 5 which interacts with the sliders 4 in OR connection, i , H. can be actuated accordingly, so that failures of the varistor groups 7, 7 'are correspondingly recognizable.

3 shows the state of the part of the housing encapsulation 6 which is already prefabricated with the separating device, including the contacting element 13 connected by screw connection 10.

The varistor 7 is inserted into the housing enclosure 6, which is open at the bottom, the contact lug 14 of the varistor 7 occupying its space between the two temple ends. The Lotstelle 3 then fixes the contact lug 14 with the parallel ends of the bracket 1, 1 '.

The plan view of FIG. 4 again shows the slider 4, which has a surface portion 15, which differs in color from a further surface portion 16 located underneath. In the undelivered situation as shown in FIG. 4, the surface portion 15 covers the underlying surface portion 16 almost completely. In the triggered position of FIG. 5, the slider 4 has moved in the image to the top right, so that the further surface portion 16, the z. B. is held in red, is exposed and represents the error state.

The slide 4 is set by the spring 2 and the spring force released when opening the solder joint in the desired sliding movement and penetrates the portion of the solder joint 3 (see FIG. 3). In the interior of the slide 4, a cavity 17 is introduced, which receives a spring portion.

The Fig. 6 and 7 show the underside of the housing encapsulation 6 with an inserted varistor (FIG. 6) or in a complete filling with two varistors 7, 7 'connected in parallel, which are connected in the region 9 by soldering to a connection bridge 18.

The connecting bridge 18 is used in accordance with the illustration of FIG. 8, the contacting and mechanical attachment of a gas discharge arrester 8 and the inclusion of Schraubklemmteilen 19 for corresponding leads.

According to FIG. 9, which represents a multi-pole arrangement of encapsulated varistor units with status display, a group display element 5 is designed so that it can be controlled individually by each slider, in the sense of a logical OR operation.

With the help of Fig. 10 to 14, the effect of the group display element with status display is explained in more detail.

In the Figs. 10, I Ia, 12a, 13a and 14a, a housing portion 20 is shown in each case, which has a viewing window 21.

About the viewing window 21, the position of the collective display element 5, which is located below the viewing window 21, recognizable. In a position according to the illustration of FIG. 10 is in the viewing window 21, for example, a recognizable green color corresponding to the corresponding color marking on the collective display element 5.

If z. B. a separation process at the lower, left-side Überspannungsab- conductor according to FIG. I Ia completed, a movement of the Sammelanzeige- element 5 takes place in the arrow direction, d. H. the green-colored or green-colored part of the collective display element 5 emerges from the viewing window 21 and an underlying color is released, preferably the color red, in order to signal a fault.

The position of the group display element 5 shifted in this respect is shown omitting the illustration of the housing section 20 in FIGS. 11b, 12b, 13b and 14b, respectively.

The mobility of the collective display element ensures the desired displacement position in Abtrennfall even in a completed separation process of the medium surge arrester (Fig. 12b) and the right above in the figure above surge arrester shown in FIG. 13b or when disconnecting all surge arrester according to FIGS. 14a and 14b.

LIST OF REFERENCE NUMBERS

1, 1 'conductor section / bracket

2 spring

3 Lotstelle

4 slides

5 group display element

6 Enclosure encapsulation 7, 7 'varistors

8 gas discharge arresters

9 fasteners

10 screw connection

11 row connection outer housing

12 section

13 contacting element

14 contact lug

15 surface section

16 area section

17 cavity

18 connection bridge

19 screw clamp

20 housing section

21 viewing window

Claims

claims

1. Overvoltage protection device with activated in thermal overload case mechanical separating device, this comprising connection elements which are moved by means of spring loaded or biased slide from a closed to a current interrupting or potential separating position and wherein the closed position of the connecting elements is secured by a solder or thermally releasable adhesive, characterized in that the connection elements consist of a pair of current-dividing metallic stirrups whose ends directed towards the overvoltage protection unit run parallel and receive in the middle the respective contact lugs of the overvoltage protection unit, the ends of the stirrups facing away from the overvoltage protection unit, including a free space, and a section for have outer connecting parts or terminals, in the free space of the slider is inserted with biasing spring, wherein the spring bias in the direction of Ko Furthermore, the slider has a wedge shape and / or portions of the bracket having an inclined surface to generate a slider component, a force component on the parallel ends of the bracket so that they are movable away from the contact lug and that in the parallel ends of the bracket and the contact lug the solder or adhesive connection is formed.

2. Overvoltage protection device according to claim 1, characterized in that the slide has a flat surface portion for optical signaling of the respective slide position.

3. Overvoltage protection device according to claim 1 or 2, characterized in that below the surface portion of the movable slide one of Slider releasable surface is provided for optical signaling of Abtrennzustands.

4. Overvoltage protection device according to one of the preceding claims, characterized in that in the movable slide in the longitudinal direction, a cavity for receiving one end of the biasing spring is befindlich.

5. Overvoltage protection device according to one of the preceding claims, characterized in that in the foot of the slide, a guide groove is introduced.

6. Overvoltage protection device according to one of the preceding claims, characterized in that the parallel ends are fixed in position by the solder or the adhesive, but diverge during the separation process by a mechanical residual stress.

7. Overvoltage protection device according to one of the preceding claims, characterized in that the stirrups are designed symmetrically.

8. Overvoltage protection device according to one of the preceding claims, characterized in that, in the separation case, the slider moves into the solder or adhesive connection region and penetrates this region in order to avoid, in particular, solder filaments.

9. Overvoltage protection device according to one of the preceding claims, characterized in that the slide consists of an electrically insulating material.

10. Overvoltage protection device according to one of the preceding claims, characterized in that the overvoltage protection unit consists of one or more varistors.

11. Overvoltage protection device according to one of the preceding claims, characterized in that the at least one overvoltage protection unit is arranged in a housing encapsulation, which has openings for electrical contacting and wherein the slide is arranged on this housing encapsulation.

12. Overvoltage protection device according to claim 11, characterized in that the portion for external terminals of the bracket is supported on the housing encapsulation or secured there.

13. Overvoltage protection device according to claim 11 or 12, characterized in that a plurality of overvoltage protection units are arranged in parallel within the housing encapsulation.

14. Overvoltage protection device according to one of claims 11 to 13, characterized in that a plurality of housing encapsulations with therein overvoltage protection units and respective brackets and sliders are in communication with a collective display element in order to indicate the possible disconnection in a logical OR connection.

15. Overvoltage protection device according to one of the preceding claims, characterized in that the sections are designed for external connection parts or terminals for Schraubkontaktierung.

16, overvoltage protection device according to one of claims 11 to 15, characterized in that the located in the housing encapsulation overvoltage protection units are used in a series terminal outer housing.

17. Overvoltage protection device according to claim 16, characterized in that located in the respective housing encapsulation overvoltage protection units are designed as disk-shaped varistors, wherein within the series terminal outer housing additionally at least one gas discharge arrester is arranged.