IL106095A

IL106095A - Protective plug for terminal and disconnect blocks of the telecommunication and data technique

Info

Publication number: IL106095A
Application number: IL10609593A
Authority: IL
Original assignee: Krone Ag
Priority date: 1992-07-30
Filing date: 1993-06-22
Publication date: 1996-10-31
Also published as: SK278460B6; TR27167A; JPH06223953A; EP0582779A1; AU665692B2; DK0582779T3; AU4135993A; DE59301306D1; EG20120A; ZA935461B; IL106095A0; NO932487D0; NO932487L; DE4225484C1; FI107571B; CZ279214B6; GR3018979T3; EP0582779B1; PL172498B1; ATE132666T1

Abstract

The invention relates to a safety plug for connecting and isolating strip connectors for telecommunications and data technology. Said safety plug consists of a flat plastic body 1 having cutouts 2 for accommodating overvoltage suppressors 3, and of a cage 5 which is plugged onto the plastic body 1 and consists of a plurality of U-shaped holders 6 whose front limbs 11 press against one electrode 13 of the overvoltage suppressor 3 and whose rearward limbs 14 rest against the rear side of the plastic body 1. A plug contact 7, which forms the contact element 8, is embedded in the safety plug. A fuse link 4 is arranged between the contact element 8 and the other electrode 16 of the overvoltage suppressor 3. In order to ensure the continuous short-circuit state in the event of the failsafe tripping, a contact spring is provided according to the invention as an extension of the rearward limb 14 of the U-shaped holder 6, which contact spring projects into the cutout 2 for accommodating the overvoltage suppressor. <IMAGE>

Description

Protective plug for terminal and disconnect blocks of the televommunication and data technique v) πρ·»: οί> 0">ηΌ30Ί d^aio D ■» 3 n » ί? IAIO ypn Krone Aktiengesel Ischaft PROTECTIVE PLUG FOH TERMINAL AMD ISCOMMECT BLOCKS OF THE TELECOMMUNICATION AMD DATA TECUMIQUK The invention relates to a protective plug for terminal and disconnect blocks of the telecommunication and data technique.

There is known in the art a protective plug of this kind, from DE 27 38 851 C3. By means of the melt element disposed between the contact member and the voltage surge arrester, the free end of the rear-side leg of the U-shaped holder has a distance to the assigned electrode of the voltage surge arrester, which will be bridged by melting of said melt element after a long time of an existing voltage surge only, said voltage surge driving a current through the voltage surge arrester and heating the latter.

In such protective plugs having a thermal protection (fail-safe), it is known that with short-time voltage surges driving a low current through the voltage surge arrester, there will be no melting of the melt element. Arresting of the voltage surge is performed over the voltage surge arrester and over the U-shaped holder to ground. A longer-time voltage surge and the dissipation of power in the voltage surge arrester only will cause sufficient heat in the arrester bringing the melt element into the plastic condition. When the melt element melts, the arrester is displaced towards the contact member. By pressing-on the voltage surge arrester at the contact member and at the free rear-side end of the U-shaped holder, a contact is made so to electrically bridge the voltage surge arrester .

By making the contact, a reduction of the dissipated power in the protective plug is effected, with the consequence of a cooling-down and resolidifi-cation of the remaining portion of the melt element. This construction of the fail-safe contact may, due to different material combinations and the different thermal expansions caused thereby, affect the quality of the contact. The consequence is that the short-circuit contact is not guaranteed in each case, but that the protective function may again exist. This new protective function does, however, not meet the required insulation conditions, i.e. the necessary distance between the free rear-side end (electrode) of the U-shaped holder and the electrode of the arrester assigned thereto. As long as this distance is present, but is smaller than required, and than originally given by the non-plasticized melt element, the protective plug must not be used anymore, since the arresters are changed in their characteristics. In principle, after each release of fail-safe (thermal protection), a replacement of arrester and melt element should be performed.

It is therefore the object of the invention to guarantee the permanent short-circuit after the first release of fail-safe (thermal protection).

The solution of this object is achieved by that the extension of the rear-side leg of the U-shaped holder is adapted as a contact spring projecting into the recess of the voltage surge arrester. Thereby, the arrester will come, after fusion of the melt element, into a position between the two spring members, namely the resilient front leg of the U-shaped holder disposed on the front side of the plastic body, and the contact spring as an extension of the rear-side leg of the U-shaped holder, which is re-si liently moved under the counter-pressure exerted by the contacting electrode of the voltage surge arrester. Resolidification of the melt element and the possible expansion thereof in the order of microns will effect that the voltage surge arrester is moved back by a corresponding amount in the order of microns, but that the contact spring as an extension of the rear-side leg of the U-shaped holder can nevertheless follow this path, so that a permanent short-circuit is guaranteed. Therein, the contact spring as an extension of the rear-side leg of the U-shaped holder is dimensioned such that it will be tensioned, when the melt element melts by the action of the voltage surge arrester, by the opposite front leg of the U-shaped holder, and establishes thus a safe contact. The modes of operation of the two spring members, clamping the voltage surge arrester therebetween in case of a voltage surge, are performed nearly separately.

The contact spring may be adapted as a blade spring, the inner side of which has a smaller distance to the rear-side electrode of the voltage surge arrester than the inner side of the contact member forming the plug contact, against which the melt element rests. Thereby, it is guaranteed that the electrode of the voltage surge arrester already contacts the contact spring adapted as a blade spring and displaces the latter, when the melt element is not yet fully molten off or pressed into the recess of the voltage surge arreester adapted in a button shape.

The support point of the contact spring may be upwardly displaced on the rear side of the plastic body, in order to form the contact spring from the material of the U-shaped holder and to guarantee the support of the spring member in the rear-side leg.

The plug according to the present invention may comprise several, preferably two parallel rows of offset voltage surge arresters and a holder adapted as a cage, in which the front legs are cut free by cuts extending as far as into the base of the U-shaped holder.

Thus, it is achieved that the individual legs on the front side of the U-shaped holder are resiliently adapted nearly independently from each other, so that a substantially larger spring travel is gained for supporting the front spring leg.

Finally, in the plug according to the present invention, the plastic body for each holder may comprise a web, having a decreasing height from the above edge of the plastic body, on said web, - 3A - during assembly of the protective plug with inserted voltage surge arresters and melt elements, the front legs being guided onto the voltage surge arresters.

Thus, it is achieved that the cage formed of a multitude of U-shaped holders is easy to mount, by that the front free ends of the individual holders slide, when sliding the cage onto the plastic body, over the respectively assigned webs, and are then slid onto the arresters provided directly at the end of the webs.

In the following, the invention will be described in more detail, with reference to an embodiment of a protective plug for terminal and disconnect blocks of the telecommunication and data technique represented in the drawings. There are: Fig. 1 a cross section through the protective plug formed of a flat plastic body with - 4 - attached cage of U-shaped holders, of voltage surge arresters and solder rings, in an enlarged scale, Fig. 2 a front view of the cage formed of several U-shaped holders, in a natural size, Fig. 3 a rear view of the cage, in an enlarged scale, Fig. 4 a top view of the cage according to Fig. 3, - Fig. 5 a section of the cage, in an enlarged scale, Fig. 6 a top view of the flat plastic body, in a natural size, Fig. 7 a section of the plastic body, in an enlarged scale, and Fig. 8 a section of the protective plug according to Fig. 1 after fusion and pressing- away of the melt element.

The protective plug for terminal and disconnect blocks of the telecommunication and data technique comprises a flat plastic body 1 having ten recesses 2 for receiving one,, voltage surge arrester 3 said holders being each assigned to a voljtage surge *-j " 1 arrester 3.

Int'o the plastic body 1 shown in a front view in Fig. 6 and in a section in Fig. 7, in the lower portion thereof, one contact member 8 forming the plug contact 7 is embedded for each recess 2, the end of which opposite to the plug contact 7 terminating in the area of the recess 2 and forming the bottom of said recess. The upper portion of the flat plastic body 1 shown in Fig. 7 is provided, on its front side, with shorter and longer webs 9, 10, which are alternately disposed and are each assigned to a recess 2 (Fig. 6).

The cage 5 formed as one piece of the ten U-shaped holders 6 engages over the free upper end of the plastic body 1, as is shown in Figs. 1 and 8. Each U-shaped holder 6 comprises a front leg 11 terminating in a curved spring member 12, which loads the front - 5 - electrode 13 of the button-type voltage surge arrester 3, as is shown in Figs. 1 and 8. The rear-side leg 14 of each U-shaped holder 6 rests against the rear side of the plastic body 1, as is shown in Figs. 1 and 8. Each U-shaped holder 6 forms a narrow contact spring 15 as an extension of its rear-side leg 14, as is shown in particular in Fig. 3, said contact spring being adapted as a blade spring and the inner side of which having a smaller distance to the rear-side electrode 16 of the voltage surge arrester 3 than the inner side of the contact member 8 forming the plug contact 7. An offset of the mentioned inner sides results therefrom. The support point 18 of each front leg 11 is in a distance of approximately the radius of the voltage surge arrester 3 from the recess 2, for which purpose the rear side of the plastic body 1 is provided with a recess 17. Each contact spring 15 forms a contact being achieved by a spring member. The latter is dimensioned such that it will be tensioned by the spring member 12 when the melt element 4 melts by the voltage surge arrester 3, and forms thus a safe contact. The design of the spring members 12 is such that they will operate nearly independently from the contact spring 15.

Between the inner side of the contact member 8 forming the plug contact and the rear-side electrode 16 of the voltage surge arrester 3, there is a horseshoe-type melt element 4, as is shown in Fig. 1. It holds the respective electrode 16 in a distance to the contact spring 15 of the assigned U-shaped holder 6.

The protective plug described above operates as fol lows : From the spring material of the cage 5 of approximately 0.4 mm thickness or of the U-shaped holders 6 forming the latter, two spring members are formed for each voltage surge arrester 3, namely on the front side the spring member 12 formed of the front leg 11 and on the rear side the contact spring 15 forming an extension of the rear-side leg 14. Both spring members are disposed at one component, the U-shaped holder 6 or the cage 5, resp., and operate nearly independently from each other, in their overall design. The front spring member 12 presses, over the - 6 - voltage surge arrester 3, against the horseshoe-type melt element 4, which in turn rests against the inner side of the contact member 8. In case of a voltage surge with higher power, a heating will occur causing element 4. The the front side a displacement of the the voltage surge arrester 3 against the contact member 8, and thus a contact of the assigned electrode 16 of the voltage surge arrester 3 to the contact spring 15 being at ground potential, over the cage 5. A short-circuit will result.

By making the contact connection between the contact member 8 and the contact spring 15 over the assigned electrode 16 of the voltage surge arrester 3, thus a reduction of the power dissipated at the protective plug will result, with the consequence of a cooling-down and a resol idification of the remaining portion of the melt element 4. Movements occurring during this will not affect the quality of the contact, due to the provision of the contact spring 15 at the rear-side leg 14 of the cage 5, so that a safe contact connection is guaranteed.

For decoupling from each other and for guaranteeing a small spring constant of the individual spring members 12 of the front legs 11 of each U-shaped holder 6, cuts 20 are provided as far as into the base 19 of the U-shaped holder 6, as is shown in Fig. 4. Fig. 5 shows the differently long design of the front legs 11 of the adjacent U-shaped holders 6, alternately a long and a short spring member 12 being assigned to the voltage surge arrester 3 disposed in two rows and offset to each other.

To each recess 2 for a voltage surge arrester 3 is assigned a web 9, 10 in the plastic body 1, having an increasing height from the upper edge 21 of the plastic body 1 towards the recess 2, as is shown in Fig. 7. Said webs 9, 10 allow, during assembly of the protective plug with inserted voltage surge arresters 3 and solder rings 4, an easy sliding of the front legs 11 of the U-shaped holders 6 onto the voltage surge arresters 3. By the webs 9, 10 thus having an increasing inclined portion, the spring members 12 - 7 - formed of the front legs 11 of the U-shaped holders 6 are automatically pretensioned during assembly.

Claims

1. A protective plug for terminal and disconnect blocks of the telecommunication and data technique, comprising a flat plastic body. having at least one recess, a U-shaped holder attached at the plastic body, the front leg of said holder pressing against the one electrodeAof the voltage surge arrester and the rear-side leg of which resting against the rear side, of the plastic body and projecting with its end into the recess, further compris-ing a contact member forming the plug contact, and a melt element disposed between the contact member and the other electrode of the voltage surge arrester, characterized by that the extension of the rear-side leg of the U-shape^d holder is adapted as a contact spring projecting into the recess for receiving the voltage surge arrester.

2. A protective plug according to claim 1, characterized by that the contact spring is adapted as a blade spring, the inner side of which has a smaller distance to the rear-side electrode of the voltage surge arrester than the inner side of the contact member forming the plug contact.

3. A protective plug according to claim 1 or 2 , characterized by that the support point of the contact spring is in a distance to the outer periphery of the. voltage surge arrester corresponding approximately to the radius thereof.

4. A protective plug according to any of claims 1 to 3, comprising several, preferably two parallel rows of offset voltage surge arresters and a holder adapted as a - 9 - characterized by that the front legs are cut free by cuts extending as far as into the base of the U-shaped holder.

5. A protective plug according to claim 4, characterized by that the plastic body for each holder comprises a web having a decreasing height from the upper edge of the plastic body, on said web, during assembly of the protective plug with inserted voltage surge arresters and melt elements, the front legs being guided onto the voltage surge arresters.

6. A protective plug according to claim 1, substantially as hereinbefore described with reference to the accompanying drawings . FOR THE APPLICANT: Dr.