Patent Application
20080247112
The invention relates to a protective plug for a connection module, in particular in a terminal distribution box.
Terminal distribution boxes or cable terminal distribution boxes typically represent the last connection point between the system side and the subscriber. Terminal distribution boxes are therefore arranged locally, even in the vicinity of the subscriber, for example on a house wall. A terminal distribution box typically comprises a housing, in which two or more connection modules are arranged, which are designed to connect twin wires. In this case, the contacts for the purpose of connecting the twin wires are preferably arranged in two parallel rows, the incoming system wires being connected to one row, and the outgoing twin wires to the subscriber being connected to the other row. It is known to use surge arresters for the purpose of limiting interference voltages owing to atmospheric discharges and short-term exposure to high-voltage currents. In order to loop-in the surge arresters, the connection modules have, for example, protruding contact springs, which are connected to the connection contacts of the connection module. In this case, typically two mutually opposing connection contacts are connected to one another. A protective plug or a protection magazine is plugged onto these contact springs. A protective plug is generally used when one twin wire is being protected, whereas a magazine is used to protect a plurality of twin wires at the same time. However, the term “protective plug” used below is intended also to include protecting a plurality of twin wires. These protective plugs have a corresponding number of two-pole surge arresters corresponding to the number of wires to be protected, the ground connections being connected to a grounding rail via a contact.
DE 33 06 263 C2 has disclosed a connection strip, in particular for a terminal distribution box in telecommunications engineering, having a generic protective plug.
Starting from such a prior art, the invention is based on the technical problem of providing a protective plug which has a simple design and by means of which a connection module having contact springs arranged can be protected against overvoltages.
The solution to the technical problem results from the features of claim 1. Further advantageous refinements of the invention are described in the dependent claims.
For this purpose, the surge arrester is arranged on a printed circuit board, the connection contacts in the form of twin fork contacts being formed with a stop, which stops at a stop edge in the housing. This firstly makes it possible to replace defective surge arresters very simply and easily. Secondly, it is also easier to initially fit the protective plug since the surge arresters soldered onto the printed circuit board are inserted at the same time by inserting the printed circuit board. A further advantage is the fact that the fork contacts can compensate more effectively for the manufacturing tolerances of the contact springs. In order to produce the protective plug, initially the twin fork contacts are preferably inserted into the housing from the rear, the twin fork contacts abutting the stop edge with their stop. Subsequently, the printed circuit board is then inserted, as a result of which in each case one fork contact of the twin fork contact is pushed onto the printed circuit board and makes contact there with a conductor track leading to the surge arresters. The surge arresters are preferably in the form of three-pole surge arresters such that in each case one surge arrester protects a twin wire.
In one further, preferred embodiment, the ground contact is in the form of a twin fork contact, which is inserted from the front and is locked by means of the printed circuit board. Here too, the advantages of the fork contacts with respect to manufacturing tolerances of the grounding rail and the printed circuit board again come to bear.
The twin fork contact is preferably formed with an angled section. This makes it possible for one fork contact to make contact with the printed circuit board and the other fork contact, for the purpose of making contact with the grounding rail, to lie below the fork contacts of the connection contacts for the contact springs of the connection module. The ground contact in the form of a twin fork contact is in this case preferably inserted obliquely into an opening from the front and rotated. This takes place before the printed circuit board is inserted, this printed circuit board then locking the twin fork contact in the inserted state.
In one further, preferred embodiment, the housing of the protective plug is formed with a latching element, which fixes the printed circuit board.
In one further, preferred embodiment, the surge arrester is formed with a failsafe contact, such that, once an overvoltage has occurred, the twin wires are connected permanently to ground.
In one further, preferred embodiment, the protective plug comprises at least two surge arresters, which are arranged next to one another, said surge arresters being arranged such that they are offset with respect to one another in the longitudinal direction. When the printed circuit board has a narrow width, this makes it possible to ensure that the failsafe function is in no way impeded, in particular in the embodiment with a failsafe contact.
In one further, preferred embodiment, one ground contact is associated with each surge arrester. As a result, the ground currents are distributed evenly over the ground contacts, with the result that the necessary requirements as regards the current-carrying capacity of the individual contacts are not too stringent.
The invention will be explained in more detail below with reference to a preferred exemplary embodiment. In the figures:
The housing 2 is preferably of integral design and is preferably made from plastic, further preferably from PC-ABS. Each of the four connection contacts in the form of twin fork contacts 3 has a fork contact 3a, 3b at its opposite ends. In this case, one fork contact 3a serves the purpose of making contact with a conductor track 4a, 4c on the printed circuit board 4, and the other fork contact 3b serves the purpose of making contact with a contact spring 31 of a connection module 30. A stop 3c is arranged between the two fork contacts 3a, 3b. A pair of in each case three conductor tracks 4a, 4b, 4c, which extend parallel next to one another, is arranged on the printed circuit board 4, said conductor tracks 4a, 4b, 4c being associated with a surge arrester 5 such that two three-pole surge arresters 5 with a failsafe contact 6 are arranged on the printed circuit board 4. The central conductor track 4b in this case makes contact with the central contact 7, and the outer conductor tracks 4a, 4c make contact with the outer electrodes 8, 9 of the surge arrester 5. Contact is made, for example, via a soldered connection. A failsafe contact 6 is formed in the region of the two outer electrodes 8, 9, said failsafe contact 6 having short-circuiting links 10 by means of which the two outer electrodes 8, 9 are short-circuited to the ground connection when a plastic film fuses. Furthermore, the protective plug 1 comprises two twin fork contacts 11, which each have fork contacts 11a and 11b at both opposite ends. The twin fork contacts 11 form the ground contacts of the protective plug 1. In this case, the fork contact 11a serves the purpose of making contact with the central conductor track 4b on the printed circuit board 4 in order to produce an electrical connection to the central contact 7 of the surge arrester 5. The fork contact 11b serves the purpose of making contact with a metallic grounding rail 32. The two fork contacts 11a, 11b are connected to one another via an angled section 11c.
The housing 2 comprises a partition wall 13, at whose lower end a latching element 14 is arranged on the rear 19 of the housing 2. Furthermore, the housing 2 comprises four rib-shaped elements 15, two opening slots 16 and a plate 17.
In order to mount the protective plug 1, initially the four twin fork contacts 3 are inserted into the housing 2 from the rear 19. In this case, the housing 2 is preferably structured such that chamber-like regions are formed, into which the twin fork contacts 3 can be inserted. The twin fork contacts 3 then abut a stop edge in the housing 2 with the stop 3c. Subsequently, the two twin fork contacts 11 on the front 20 are plugged into the two opening slots 16 from above at an angle and are rotated downwards. As the last step, the printed circuit board 4 is then inserted into the housing 2 from the rear 19. In this case, the fork contacts 3a, 11a are pushed over the printed circuit board 4 and make contact with the conductor tracks 4a, 4b, 4c arranged on the upper side and/or underside of the printed circuit board 4. In the completely inserted state, the latching element 14 latches behind the printed circuit board 4 and fixes it. The printed circuit board 4, on the other hand, fixes or locks the twin fork contacts 3, 11.
The contact springs 31 are connected to connection contacts (not illustrated) of the connection module 30. In this case, the connection contacts are preferably in the form of insulation displacement contacts. In the example illustrated, the connection module 30 would have 2×4 connection contacts in order to connect in each case two twin wires on the system side and the subscriber side, in each case one connection contact associated with the system side being arranged with one connection contact of the subscriber side. The connection contacts are in this case preferably accessible from the upper side opposite the underside 33.
Finally,
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2005 042 163.6 | Sep 2005 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2006/008299 | 8/24/2006 | WO | 00 | 3/3/2008 |
