DE19519785C1 - Pluggable overvoltage protection device for telecommunications terminal board - 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 of the Telecommunications technology according to the generic term of Claim 1.

Such an overvoltage protection is known from EP 0 471 167 A1 known and has a housing with one connection contact for the wire to be protected and for an earth drainage as well a surge arrester arranged in the housing. A mechanically pre-stressed thermal protection element is included can be triggered by heating the surge arrester. With this known surge protection, the thermal Protective element is a metallic slide that has a Solder joint is conductively connected to a sheet metal part. On the Sheet metal part is in contact with the surge arrester, by an internal gas discharge Discharges overvoltages to earth and heats up. Around if the heating of the Surge arrester to destroy the protective plug Avoid the thermal protection element that has a spring is mechanically biased by heating the solder joint  triggered and disconnects the contact of the Surge arrester with an earth plate.

However, such a known surge protection is disadvantageous in that the thermal protection element over a Solder joint as well as a just contacting on the Overvoltage arrester thermally supported sheet metal part the surge arrester is connected. This is on the one hand, no optimal heat transfer guaranteed, because several heat transfer parts can be used. On the other hand the production is relatively complex and it must be Soldering points are provided that are not normally associated with the desired accuracy is reproducible.

Another pluggable surge protection is out of the EP 0 338 187 A2 and consists of a one-piece, plastic housing open on one side, in which Surge arresters are arranged. With a permanent Ignition of the surge arrester melts through the resulting heat a so-called melting pill, whereby a springy shorting bar a connection with the common earth manufactures and short-circuits the surge arrester. Also here are several for the manufacture of the surge arrester Components required that are manufactured separately and need to be assembled.  

A similar surge protector is from the EP 0 548 587 A1 and has a spacer, which is made of thermoplastic.

Finally, EP 0 312 729 A1 Thermal protection device known in an upward open chamber with a U-shaped bracket spring Preload is used. Next to this chamber is in another chamber a surge arrester, where both chambers through a thin partition from one thermoplastic are separated from each other. By the heating of the surge arrester at high Temperatures this partition becomes plastic, so that the Spring arms of the bow spring pierce the partition and so the Short-circuit the surge arrester.

It is the basis of the present invention Problem (task), surge protection at the beginning mentioned type to the extent that a inexpensive manufacture, easy assembly and accurate Reproducibility of the trigger are guaranteed.

This problem is solved by the features of 1. According to the invention, the thermal  Protective element, which is caused by heating the Surge arrester can be triggered, made of plastic thermoplastic properties. This can the thermal protection element directly by the heat of the Surge arresters are triggered without a Heat transfer via additional components such as Legs Soldering point or a melting pill is required. At the same time, the thermal protection element can be removed Plastic with an extremely high reproducibility Manufacture so that no manufacturing or assembly-related Fluctuations in the triggering time can occur. By the solution according to the invention is considerable Cost savings due to the small number of used parts and easy assembly.

Because the thermal protection element has an insulation section has that between the surge arrester and one Earth contact is movable, the thermal protection element insulates the Connection between the surge arrester and a Earth contact in the normal case, but releases this connection, when the thermal protection element is triggered.

Advantageous embodiments of the invention are characterized by Subclaims marked.

So the thermal Protective element have a section that on the Surge arrester is present. This will turn on advantageously achieved that only a limited Part of the thermal protection element, namely the subsection, is present at the surge arrester and from there Ignition correspondingly strong when overvoltage is present is heated.  

After further training, a tongue can Lock the protective element against the mechanical preload, preferably in a recess in the earth contact. Hereby an exceptionally good triggering of the thermal Reach the protective element, since only the Tongue must be removed from the recess. After this Heating the section melts the molded on it Tongue and thereby releases the lock so that the thermal Protective element is moved by the bias and Contact between the surge arrester and one Earth contact releases.

According to a further advantageous embodiment of the invention the thermal protection element can have a recess for material have that through the thermal contact with the Surge arrester melts. This makes it easy Way ensured that the thermal protection element reproducible triggers and not despite melting the Section jammed because the melted material itself can go into the recess. It is particularly advantageous here if the recess is in the area in the melted material during the melting process is pressed by the force of the mechanical preload.

According to further advantageous developments of the invention the surge arrester is a three-pole arrester and the Earth contact can be applied to the surge arrester his. This resilient application ensures that that when the thermal protection element is triggered reliably Contact between the earth and the surge arrester will be produced. In connection with the subordinate Fine protection from diode arrays and resistors are used in the further cable routing lying against  inadmissible voltage influences protected. Here the fine protection component consists of three Suppressor diode chips on a ceramic substrate with the Advantage of higher pulse capacity, direct heat coupling of the three diode chips and small size, and two Resistances. A three-pole arrester is used for a pluggable surge protection for a to be protected Twin wire advantageous.

According to a further advantageous embodiment, the housing of the surge protection have a viewing window through that a part of the triggered thermal protection element is visible is. This means that it is immediately recognizable from the outside whether a thermal Protective element has been triggered by the viewing window is looked at. This part is not triggered of the thermal protection element is not visible. Advantageously the corresponding part of the thermal protection element or also the entire thermal protection element in a striking Color.

According to further advantageous developments of the invention the connection contact for the wire to be protected on one printed circuit board designed like a plug contact, on the other electronic components such as resistors and Semiconductors are contacted as fine protection. By such Training is a very compact and easy to assemble Surge protection device created that none requires separate plug contacts because the circuit board as Plug contact is used. If the circuit board is loose can be inserted into the housing is a special one easy assembly ensured. Here, too Surge arrester must be contacted on the circuit board, whereby separate cabling can be omitted.  

According to a particularly space-saving embodiment of the Invention can be a resistor and a semiconductor device, for example a diode array on the circuit board be arranged one above the other. This allows the pluggable surge protection particularly space-saving produce. A two-part design of the housing again facilitates assembly.

If the earth contact, which is triggered when the thermal Protective element contacted with the surge arrester, a spring-like section for engaging in has an earthing bar, are other components superfluous, which make this ground contact. Of the Surge protection according to the invention then only exists from the contacted with electrical components PCB, the thermoplastic thermal protection element, the Earth contact, the mechanical spring and the surrounding Casing. Such an embodiment has compared to that State of the art explained at the beginning much less Components.

According to a further advantageous embodiment, the Thermal protection element can be designed like a slide, wherein the tongue on a substantially U-shaped contour of the Thermal protection element is molded. Here, in advantageously the tongue and the contour to the Longitudinal extension of the thermal protection element in opposite directions run at an angle. This results in a special one good, resilient contact of the contour on the overvoltage arrester, which increases functional safety.

Since there are often several pluggable in a terminal block Surge protection devices are arranged, the Surge protection according to the invention according to a further  Embodiment advantageously one from the outside accessible contour, into which a pulling hook or a Screwdriver or the like can be used to to remove the surge protector from the terminal block.

In the following, the present invention becomes purely exemplary with reference to a preferred embodiment and the attached drawings. Show it

Figure 1 is a perspective view of the surge protector according to the invention, but without the housing and spring.

Figure 2 shows the thermal protection element according to the invention.

Fig. 3 is 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 being shown in the triggered state;

Fig. 4 is a partial view of the overvoltage protection 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 shown in Fig. 1 further shows, the circuit board is provided with brackets 74 10 contacting the middle ground terminal of the surge arrester 16 resiliently.

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 spherically shaped areas 20 and 21 , which allow the thermal protection element 18 to be partially in contact with 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 (cf. 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, shaped at the base of the U- section there is formed a recess 54 into which the non-triggered state of the thermal protection element 18, the tongue 26 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 mode of operation of the invention is described below Surge protection described.

The overvoltage protection is normally plugged into a terminal block 42 of the telecommunications technology, the regions 17 of the printed circuit board 10 designed in the manner of a plug contact being located in corresponding plug contacts of the terminal block and covering only one of two rows of contacts there. 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 melted 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 cutout 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 make contact with the wire contacts 60 and 61 of the surge arrester 16 under pressure, as a result of which 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 outside, 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 the latter can then be plugged together.

Claims (19)

1. Pluggable surge protection for terminal strips ( 42 ) of 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 and has an insulating section ( 62 , 64 ) which can be moved between the surge arrester ( 16 ) and an earth contact ( 19 ). 2. Device according to claim 1, characterized in that the thermal protection element ( 18 ) has a partial section ( 28 ) which bears on the surge arrester ( 16 ). 3. Apparatus according to claim 2, characterized in that a tongue ( 26 ) of the thermal protection element ( 18 ) this against the bias, preferably in a recess ( 54 ) of the earth contact, locked. 4. Apparatus according to claim 2 and 3, characterized in that a melting of the section ( 28 ) due to heating of the surge arrester ( 16 ) causes an unlocking of the thermal protection element ( 18 ). 5. Device according to one of the preceding claims, characterized in that the thermal protection element ( 18 ) has a recess ( 30 ) for melting material ( 28 ) by thermal contact with the surge arrester ( 16 ). 6. 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 ). 7. Device according to one of the preceding claims, characterized in that the surge arrester is a three-pole arrester ( 16 ). 8. 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 ). 9. Device according to one of the preceding claims, characterized in that the earth contact ( 19 ) resiliently abuts on the earth connection ( 74 ) of the surge arrester ( 16 ). 10. 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. 11. 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 plug-type printed circuit board ( 10 ) on the other electronic components such as resistors ( 14 ) and semiconductors ( 12 ) as Fine protection are contacted. 12. The apparatus according to claim 11, characterized in that the circuit board ( 10 ) is loosely inserted in the preferably two-part housing ( 40 ). 13. The apparatus of claim 11 or 12, characterized in that the surge arrester ( 16 ) on the circuit board ( 10 ) is contacted. 14. The apparatus according to claim 11, 12 or 13, characterized in that a resistor ( 14 ) and a semiconductor component ( 12 ) or a hybrid module on the circuit board ( 10 ) are arranged one above the other. 15. Device according to one of claims 1 to 14, characterized in that the earth contact ( 19 ) has a spring-shaped section ( 46 ) for engagement in openings ( 45 ) of an earth rail ( 46 ). 16. The device according to one of claims 3 to 15, characterized in that the thermal protection element ( 18 ) is designed slide-like and the tongue ( 26 ) is integrally formed on a substantially U-shaped contour ( 24 ). 17. The apparatus according to claim 16, characterized in that the tongue ( 26 ) and the contour ( 24 ) to the longitudinal extent of the thermal protection element ( 18 ) are angled in opposite directions. 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, into which a pulling hook ( 70 ) can be used to release the overvoltage protection from a terminal block ( 42 ).