EP0746071A1 - Plug-in overvoltage protection device - Google Patents

Abstract

An array of diodes (12), two resistors (14) and a three-pole overvoltage diverter (16) are arranged on a circuit board (10) in a two-part housing (40). Plug-type zones (17) of the board are plugged into a row of contacts on a two-row connector moulding (42) with an earthing rail (44) into which the spring section (46) of an earth contact (19) is hooked. Between the earth contact and overvoltage diverter, two insulating sections (62, 64) of the thermoplastic protective element (18) are interposed. The element itself has two slightly concave sections and is spring-biased (36) to hold these in contact with the diverter.

Description

The present invention relates to a pluggable surge protection for terminal strips in telecommunications technology according to the preamble of claim 1.

Such an overvoltage protection is known from EP 0 471 167 and has a housing, each with a connection contact for the wire to be protected and for an earth conductor, and an overvoltage arrester arranged in the housing. A mechanically pre-stressed thermal protection element can be triggered by heating the surge arrester. In this known surge protection, the thermal protection element is a metallic slide which is conductively connected to a sheet metal part via a solder joint. The surge arrester is in contact with the sheet metal part, which discharges overvoltages to earth through a gas discharge taking place inside and heats up. In order to prevent the protective plug from being destroyed if the surge arrester is heated for a longer period of time, the thermal protective element, which is mechanically pretensioned by a spring, is triggered by the heating of the solder joint and thereby breaks the contact of the surge arrester with an earth plate.

However, such a known surge protection is disadvantageous in that the thermal protection element has one Soldering point and is thermally connected to the surge arrester by means of a sheet metal part which merely contacts the surge arrester. On the one hand, this does not guarantee optimal heat transfer, since several heat transfer parts are used. On the other hand, the production is relatively complex and a solder joint must be provided which is normally not reproducible with the desired accuracy.

Another pluggable surge protection is known from EP 0 338 187 and consists of a one-piece plastic housing that is open on one side and in which surge arresters are arranged. If the surge arrester is permanently ignited, a so-called melting pill melts as a result of the heat generated, as a result of which a resilient short-circuiting link establishes a connection with the common earth and short-circuits the surge arrester. Here too, several components are required to manufacture the surge arrester, which have to be manufactured and assembled separately.

A similar surge protection device is known from EP 0 548 587 A1 and has a spacer made of thermoplastic material.

Finally, a thermal protection device is known from EP 0 312 729 A1, in which a U-shaped bow spring with pre-tensioning is inserted in an upwardly open chamber. In addition to this chamber, there is a surge arrester in a further chamber, the two chambers being separated from one another by a thin partition made of a thermoplastic. By heating the surge arrester at high Temperatures this partition becomes plastic, so that the spring arms of the bow spring pierce the partition and thus short-circuit the surge arrester.

It is therefore the problem (object) on which the present invention is based, to further develop an overvoltage protection of the type mentioned at the outset in such a way that cost-effective manufacture, easy assembly and precise reproducibility of the triggering are ensured.

This object is achieved by the features of patent claim 1. According to the invention, the thermal protection element, which can be triggered by heating the surge arrester, is made of plastic with thermoplastic properties. As a result, the thermal protection element can be triggered directly by the heat of the surge arrester without heat transfer via additional components such. B. a solder joint, a melting pill or a partition is required. At the same time, the thermal protection element can be made of plastic with an extraordinarily high level of reproducibility, so that no fluctuations in the triggering time caused by manufacture or assembly can occur. The solution according to the invention results in considerable cost savings due to the small number of parts used and the easy assembly.

Advantageous embodiments of the invention are characterized by the subclaims.

For example, the thermal protection element can have an insulation section which can be moved between the surge arrester and an earth contact. Because of this advantageous In one embodiment, the thermal protection element normally isolates the connection between the surge arrester and a ground contact, but releases this connection when the thermal protection element is triggered.

According to a further embodiment of the invention, the thermal protection element can have a partial section which rests on the surge arrester. As a result, it is advantageously achieved that only a limited part of the thermal protection element, namely the partial section, bears against the surge arrester and is heated accordingly by the latter after ignition in the event of an overvoltage.

According to a further embodiment, a tongue can lock the thermal protection element against the mechanical bias, preferably in a recess in the earth contact. In this way, an exceptionally good triggering of the thermal protection element can be achieved, since only the tongue has to be removed from the recess for triggering. After the heating of the section, the tongue formed on it melts and thereby releases the lock, so that the thermal protection element is moved by the bias and releases the contact between the surge arrester and an earth contact.

According to a further advantageous embodiment of the invention, the thermal protection element can have a recess for material that melts due to the thermal contact with the surge arrester. This ensures in a simple manner that the thermal protection element triggers reproducibly and does not jam despite the melting of the section, since the molten material can go into the recess. It is particularly advantageous if the recess is located in the area into which the molten material is pressed by the force of the mechanical prestress during the melting process.

According to further advantageous embodiments of the invention, the surge arrester is a three-pole arrester and the ground contact can be resiliently applied to the surge arrester. This resilient application ensures that when the thermal protection element is triggered, contact is reliably established between the earth and the surge arrester. In connection with the subordinate fine protection consisting of diode arrays and resistors, the telecommunications systems located in the further cable run are protected against impermissible voltage influences. Here, the fine protection component consists of three suppressor diode chips on a ceramic substrate with the advantage of higher pulse resistance, direct heat coupling of the three diode chips and small dimensions, and two resistors. The use of a three-pole arrester is advantageous for a pluggable surge protection for a double wire to be protected.

According to a further advantageous embodiment, the housing of the overvoltage protection can have a viewing window through which a part of the triggered thermal protection element is visible. As a result, it is immediately apparent from the outside whether a thermal protection element has been triggered by looking at the viewing window. This part of the thermal protection element is not visible when not triggered. Advantageously, the corresponding part of the thermal protection element or the entire thermal protection element can be designed in a striking color.

According to further advantageous developments of the invention, the connection contact for the wire to be protected can be provided on a plug-type printed circuit board on which further electronic components such as resistors and semiconductors are contacted as fine protection. Such a design creates a very compact and easy-to-install surge protection device which does not require any separate plug contacts, since the printed circuit board is used as a plug contact. If the circuit board can be inserted loosely into the housing, particularly easy assembly is ensured. In this case, the surge arrester can also be contacted on the circuit board, which means that separate cabling can be omitted.

According to a particularly space-saving embodiment of the invention, a resistor and a semiconductor component, for example a diode array, can be arranged one above the other on the printed circuit board. This allows the pluggable surge protection to be produced in a particularly space-saving manner. A two-part design of the housing in turn facilitates assembly.

If the earth contact, which contacts the surge arrester when the thermal protection element is triggered, has a spring-like section for engaging in an earth rail, further components which produce this earth contact are superfluous. The surge protection according to the invention then consists only of the circuit board contacted with electrical components, the thermoplastic thermal protection element, the earth contact, the mechanical spring and the surrounding housing. Such an embodiment has compared to that State of the art explained at the beginning on significantly fewer components.

According to a further advantageous embodiment, the thermal protection element can be designed in the manner of a slide, the tongue being formed on an essentially U-shaped contour of the thermal protection element. In this case, the tongue and the contour can advantageously be angled in opposite directions to the longitudinal extent of the thermal protection element. This results in a particularly good, resilient contact of the contour on the surge arrester, which increases functional reliability.

Since several pluggable surge protective devices are often arranged in a terminal block, the surge protector according to the invention advantageously has a contour which can be gripped from the outside and into which a pulling hook or a screwdriver or the like can be inserted in order to detach the surge protector from the terminal block.

Fig. 1

eine perspektivische Ansicht des Überspannungsschutzes gemäß der Erfindung, jedoch ohne Gehäuse und Feder;

Fig. 2

das Thermo-Schutzelement gemäß der Erfindung;

Fig. 3

eine teilgeschnitte Querschnittsansicht des erfindungsgemäßen Überspannungsschutzes, der in eine Anschlußleiste eingesteckt ist, wobei das Thermo-Schutzelement im ausgelösten Zustand dargestellt ist;

Fig. 4

eine Teilansicht des in Fig. 3 dargestellten Überspannungsschutzes, wobei sich jedoch das Thermo-Schutzelement im nicht ausgelösten Zustand befindet.

The present invention is described below purely by way of example with reference to a preferred embodiment and the accompanying drawings. Show it:

Fig. 1

a perspective view of the surge protector according to the invention, but without the housing and spring;

Fig. 2

the thermal protection element according to the invention;

Fig. 3

a partially sectioned cross-sectional view of the surge protector according to the invention, which is inserted into a terminal block, the Thermal protection element is shown in the triggered state;

Fig. 4

a partial view of the surge protector shown in Fig. 3, but the thermal protection element is in the non-triggered state.

The overvoltage protection for terminal strips of telecommunications technology shown in FIG. 1 is built on a printed circuit board 10 on which a diode array 12 and two resistors 14 are soldered, the resistors 14 above the diode array 12 or a hybrid module consisting of diodes and resistors as SMD Component, are arranged to save space. A three-pole surge arrester 16 is also contacted on the basically elongated circuit board. The circuit board 10 has at its lower end two parallel plug-type regions 17.

A thermal protection element 18 and an earth contact 19 are also shown in FIG. 1 and cause earthing during prolonged heating of the surge arrester 16 in the pluggable surge protection and the subsequently connected components of the telecommunications system.

As FIG. 1 also shows, the printed circuit board 10 is provided with brackets 74, which contact the central earth connection of the surge arrester 16 in a resilient manner.

The thermal protection element 18 shown in FIG. 2 is made of plastic with thermoplastic properties and is essentially slider-like. In its lower area, the thermal protection element 18 has two crowned shaped areas 20 and 21, which allow partial abutment of the thermal protection element 18 on the cylindrical surge arrester 16. A rectangular opening 22 is formed between the spherical regions 20, 21, in which a U-shaped contour 24 projects, the two legs of the U-shaped contour 24 adjoining the lower region 20. At the base of the U-shaped contour 24, which forms a partial area 28, a tongue 26 is integrally formed.

As can be seen in FIG. 2, the tongue 26 and the contour 24 are arranged at opposite angles to the longitudinal extent of the thermal protection element, the contour protruding from the opening 22. As a result, the partial region 28, namely the base of the contour 24, can lie close to the surge arrester 16 (cf. FIG. 4). When the partial area 28 melts, the melting material can get into the recess 30, which is formed by the contour 24 in its interior.

In the upper area of the thermal protection element 18 shown in FIG. 2, a further rectangular opening 32 is formed, in which two guide pins 33 and 34 are arranged in the longitudinal direction of the thermal protection element. Here, the longer pin 33 and the shorter pin 34 serve to fix a spring 36 (see FIG. 3). The upper area 38 of the thermal protection element, which is shown rasterized in FIG. 2, is made in red color so that it can be easily recognized through a viewing window 66 in a housing 40 (see FIG. 3) after the thermal Protective element has been triggered.

As shown in FIG. 3, the circuit board 10 on which the diode array 12, the resistors 14 and the surge arrester 16 are contacted is inserted into a two-part housing 40, only one half of the housing being shown in FIG. 3. The plug-in extensions 17 of the printed circuit board 10 shown in FIG. 1 are inserted into a contact row of a two-row terminal block 42 (FIG. 3), the terminal strip having an inserted earth rail 44 which is C-shaped in cross section and in this area has openings 45, into each of which a spring-shaped section 46 of the earth contact 19 can be inserted.

The earth contact 19, which can also be clearly seen in FIG. 1, is made in one piece from metal and connects the spring-shaped section 46 to two further molded spring contacts 48 and 50, which in the triggered state of the thermal protection element 18 on the two wire contacts 60 , 61 of the surge arrester 16 are present (FIG. 3). The two contacts 48 and 50 are formed on a U-shaped section 52, a recess 54 being formed at the base of the U-shaped section, into which the tongue 26 of the thermal protection element 18 is in the non-triggered state of the thermal protection element 18 intervenes (see FIG. 4).

As shown in FIG. 3, both the printed circuit board 10 and the earth contact 19 are mounted in the housing 40, a peg-like housing contour 56 engaging in the U-shaped section 52 of the earth contact 19 in order to mount it firmly on the housing.

The thermal protection element 18 is, as shown in Fig. 3, biased by the spring 36 which is inserted over the short pin 34 and the long pin 33. To absorb the counterforce, the spring 36 bears against a housing projection 58 and thereby exerts a force directed vertically upwards in FIG. 3 on the thermal protection element 18.

Fig. 4 shows in detail the interaction of the earth contact 19, the thermal protection element 18 and the surge arrester 16 in the non-triggered state. As can be clearly seen, the spring 36, not shown in FIG. 4, presses the thermal protection element 18 upward in FIG. 4, but the tongue 26 engages in the recess 54 of the earth contact 19, so that the relative position between the earth contact 19 and Thermal protection element 18 which is shown in Fig. 4. In this position, the section 28 (cf. also FIG. 2) of the U-shaped contour 24 resiliently abuts the surge arrester 16 and is biased against the latter by the angled configuration of the contour 24. However, electrical contact between the wire contacts 60 and 61 of the surge arrester 16 with the spring contacts 48 and 50 of the earth contact 19 is avoided by insulation sections 62, 64 which are formed by the material section of the areas 21 and 20 (see FIG. 2).

The functioning of the surge protection according to the invention is described below.

The overvoltage protection is normally plugged into a terminal block 42 of telecommunications technology, the regions 17 of the printed circuit board 10 designed in the manner of plug contacts being located in corresponding plug contacts Terminal block and cover only one of two rows of contacts. The spring-like area 46 of the earth contact 19 is inserted into the opening 45 of the earth rail 44.

In the non-triggered state of the overvoltage protection, which is shown in FIG. 4, lower overvoltages between two wires are intercepted by the electronic components located on the printed circuit board 10. When larger overvoltages occur between the two wires, the surge arrester 16 ignites and heats up in the process. If longer-lasting overvoltages occur, the surge arrester 16 heats up very strongly, so that the section 28 of thermoplastic plastic which is in contact with it begins to melt. At this time, the thermal protection element is biased upwards by the action of the spring 36 in FIG. 4, but is held in this biased position by the tongue 26 which engages in the recess 54 of the earth contact 19.

After the section 28 has started to melt, the molten material can get into the recess 30 of the thermal protection element 18, since a pressure is constantly exerted by the spring 36 during the melting process. Thereupon, the state shown in FIG. 3 is established, ie the tongue 26 is released from the recess 54 of the thermal protection element 18 and thereby releases the thermal protection element 18, which is raised by the action of the spring 36 in FIG. 3 is pressed until a stop fixed to the housing. As a result, the insulation sections 62 and 64 are moved upward, so that the spring contacts 48 and 50 of the earth contact 19, the wire contacts 60 and 61 of the Touch surge arrester 16 contacting under pressure, whereby the surge arrester 16 is short-circuited to earth and does not heat up further. Since the area 38 (FIG. 2) of the thermal protection element is now in the position shown in FIG. 3, it can be easily recognized from the outside through the viewing window 66.

In order to be able to easily remove the surge protection according to the invention from a terminal block when several such devices are plugged in side by side, the housing 40 is provided with a contour 68 which can be gripped from the outside and into which a pulling hook 70 of a wiring instrument can be inserted.

The divided housing 40 is provided with corresponding locking lugs 72, so that only the component shown in FIG. 1 must be inserted into the housing 40 together with the spring 36, whereupon this can then be plugged together.

In the following claims, the reference numbers serve for better understanding and are not intended to limit the scope.

Claims (19)

Pluggable surge protection for terminal strips (42) in telecommunications technology, with - a housing (40), - one connection contact (17, 46) each for the wire to be protected and for an earth connection, - A surge arrester (16) arranged in the housing (40), and a mechanically prestressed thermal protection element (18) which can be triggered by heating the surge arrester (16), characterized in that the thermal protection element (18) consists of plastic with thermoplastic properties. Device according to Claim 1, characterized in that the thermal protection element (18) has an insulation section (62, 64) which can be moved between the surge arrester (16) and an earth contact (19). Device according to claim 1 or 2, characterized in that the thermal protection element (18) has a partial section (28) which bears against the surge arrester (16). Apparatus according to claim 3, characterized in that a tongue (26) of the thermal protection element (18) locks it against the bias, preferably in a recess (54) in the earth contact. Apparatus according to claim 3 and 4, characterized in that melting of the section (28) due to heating of the surge arrester (16) brings about an unlocking of the thermal protection element (18). Device according to one of the preceding claims, characterized in that the thermal protection element (18) has a recess (30) for material (28) melting through thermal contact with the surge arrester (16). Device according to one of the preceding claims, characterized in that the mechanical prestressing is carried out by a spring (36) which prestresses the thermal protection element (18) against a housing contour (58). Device according to one of the preceding claims, characterized in that the surge arrester is a three-pole arrester (16). Device according to one of the preceding claims, characterized in that the earth contact (19) can be resiliently applied to the wire contact (60, 61) of the surge arrester (16). Device according to one of the preceding claims, characterized in that the earth contact (19) rests resiliently on the earth connection (74) of the surge arrester (16). Device according to one of the preceding claims, characterized in that the housing (40) has a viewing window (66) through which a part (38) of the triggered thermal protection element (18) is visible. Device according to one of the preceding claims, characterized in that the connection contact (17) for the wire to be protected is provided from a printed circuit board (10) designed as a plug contact, on which further electronic components such as resistors (14) and semiconductors (12) make contact as fine protection are. Device according to claim 12, characterized in that the printed circuit board (10) is loosely inserted into the preferably two-part housing (40). Device according to claim 12 or 13, characterized in that the surge arrester (16) is contacted on the printed circuit board (10). Device according to claim 12, 13 or 14, characterized in that a resistor (14) and a semiconductor component (12) or a hybrid module are arranged one above the other on the printed circuit board (10). Device according to one of claims 2 to 15, characterized in that the earth contact (19) has a spring-shaped section (46) for engagement in openings (45) in an earth rail (46). Device according to one of claims 4 to 16, characterized in that the thermal protection element (18) is designed like a slide and the tongue (26) is formed on an essentially U-shaped contour (24). Device according to claim 17, characterized in that the tongue (26) and the contour (24) are angled in opposite directions to the longitudinal extent of the thermal protection element (18). Device according to one of the preceding claims, characterized in that the housing (40) has a contour (68) which can be gripped from the outside and into which a pulling hook (70) can be inserted to release the overvoltage protection from a terminal block (42).

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