Title of Invention

AN ELECTRICAL DEVICE FOE PROTECTING TELEPHONE OR COMPUTER RELATED LINE"

Abstract

This invention relates to a protection module for telephone or computer-related line, this module comprising a printed circuit board (23) receiving various components (14, 15) and a three-pole overvoltage arrester (20), in a casing formed by two clippable half-shells (24, 25). The overvoltage arrester (20) is removably received between two elastic contacts (26, 27). To ensure a determined angular positioning free of any danger of short-circuit, the two half-shells (24, 25) are provided with conjugate check studs (33, 35 and 34, 36) for exact angular positioning of this overvoltage arrester. If the overvoltage arrester (20) is not introduced in its correct angular position, total closure of the casing (24,25) is impossible.

Full Text

1A The present invention relates to an electrical device for protecting telephone or computer related line. Devices of this type, which are found on the market at the present time, are formed by a quadripole which is received on a printed circuit board and which is inserted in series on the telephone or computer-related line and which contains: . a three-pole overvoltage arrester, or lightning arrester, of cylindrical shape which is then connected in parallel on the line, with its central electrode connected to earth, . generally, in addition, a fuse, or a positive temperature coefficient resistor (or "PTC") per strand of line, this fuse or resistor being connected in series on the corresponding strand of line, . a double safety short-circuit, or "fail-safe", which is composed of a metal clip in the form of portion of cylinder which is elastically plugged over the cylinder constituted by the overvoltage arrester, closely tightening thereon, making contact with its central earth electrode but being maintained at a short distance from its two line electrodes by a fusible pellet. In manner well known per se, the intense heat which is released by the overvoltage arrester when it has triggered on, then melts this fusible pellet which, by reason of the elasticity of the "fail safe", places the latter in contact with the two line electrodes of the overvoltage arrester, in that case short-circuiting the latter and causing the overvoltage arrester to be extinguished. This quadripole is added on a printed circuit, itself received in an insulating casing composed of two half-shells adapted to be clipped on each other. In order to avoid the risk of the "fail-safe" touching electrical points of the printed circuit, the overvoltage arrester must be positioned precisely with respect to this printed circuit. In order to satisfy this condition in particular, the presently known devices contain an overvoltage arrester which is soldered in the correct position on the printed 2 circuit. The overvoltage arrester is in that case not removable, and the whole of the protection module must be changed after the overvoltage arrester has been triggered off. Other solutions, employing contact studs soldered on the printed circuit and adapted to receive, by plugging, an overvoltage arrester equipped with pins, make it possible to have a replaceable component. The drawback of this is, on the one hand, that it requires more space under the printed circuit to house the contact studs and, on the other hand, that it generates higher costs associated with the supply of the contact studs and an overvoltage arrester equipped with pins. It is an object of the present invention to overcome this drawback. To that end, it relates to a protection device as described herein above, but presenting at least the following combined particularities : . Its overvoltage arrester is removably received therein, between two elastic line contacts and an elastic earth contact; . In order to prevent a bad angular positioning of this overvoltage arrester, which would cause in particular a dangerous positioning of its "fail-safe" with respect to the printed circuit receiving the quadripole and to the elastic contacts for receiving this overvoltage arrester, the two clippable half-shells which form its casing are in addition provided with check studs which are respectively conjugate from one half-shell to the other and which are formed in order, when these two half-shells are assembled on one another, to form together an enveloping, virtually cylindrical cradle for reception and exact positioning of the overvoltage arrester and to allow total closure of the casing when this overvoltage arrester is introduced substantially in an angular position predetermined as desired, while, a contrario, they oppose total closure of the casing when this overvoltage arrester is introduced substantially in another angular position considered as bad. The invention will be clearly understood, and its advantages and characteristics will be more readily apparent, on reading the following description of a non-limiting embodiment of a plug-in protection module, with reference to the accompanying drawings, in which: Figure 1 is a view in perspective, with parts torn away, of an overvoltage arrester used in this telephone line protection module. 3 Figure 2 is a side view, with longitudinal section of its "fail safe". Figure 3 is an end view thereof. Figure 4 is an electrical diagram of this protection module. Figure 5 is an exploded perspective view. Figure 6 is an overall view with one of the half-shells removed. Figures 7 and 8 illustrate, in partial transverse section, the operation of closure of the casing of this module when the overvoltage arrester is correctly positioned. Figures 9 and 10 are views similar to Figure 1, but with the overvoltage arrester badly positioned, with the result that total closure of the casing is rendered impossible. Reference will firstly be made to Figures 1 to 3 to recall the constitution of an example of overvoltage arrester 20, available on the market, provided with a "fail safe" device, and to Figure 4 to recall the electrical diagram of a conventional protection module adapted to be plugged in, for example, a terminal block for telephone line interconnection. Such an overvoltage arrester is a gas release which is composed of a cylindrical body 1, made of refractory insulating material such as a ceramic, and which comprises two end electrodes 2, 3 in the form of dishes for closure of the cylinder 1, and an annular earth electrode 4 placed in median position on the cylinder 1, as shown. " This body contains a gas adapted to be ionized when an overvoltage is applied between at least two of its three electrodes 3, 4, 2. When an overvoltage arrester has triggered on, the corresponding arc releases such an intense heat that it is capable of damaging not only the whole of the protection module, but also the elements close to this module, for example the terminal block on which it is plugged. To avoid this, the arc should therefore be extinguished before the surface temperature of the overvoltage arrester becomes problematic for the neighbouring elements. To that end, the constructors equip their overvoltage arresters with a "fail safe" device 21 composed of a metal clip 5 in the form of a portion of cylinder which is elastically clipped over the body 1 and which comprises a small transverse bar 6. The two tabs 51 and 52 of the clip 5 are applied on the insulating body 1, on 4 either side of the median earth electrode 4, and as a whole they are less wide than the cylinder 1, with the result that they do not touch the end dishes 2 and 3 of the overvoltage arrester. On the other hand, the transverse bar 6 has the same length as the overvoltage arrester, with the result that it would touch the electrodes 2 and 3 if it were not held slightly apart by a fusible pellet 7 which is applied against the earth electrode 4. It should be noted that, for the overvoltage arrester shown in Figures 1 to 3, the two free ends of the bar 6 are coated in an insulating bead 8 made of plastics material melting at a temperature lower than the melting temperature of the fusible pellet 7. At their free ends opposite the bar 6, the two tabs 51 and 52 of the clip 5 are connected by a metallic bridge 9 in excess thickness. Figure 4 is an electrical diagram of a plug-in protection module, such as the one marketed by Applicants under the name "SOR-PU", and equipped with an overvoltage arrester such as the one shown in Figures 1 to 3. As is illustrated, the overvoltage arrester 20 is connected in parallel on the terminals of the telephone line on which the module is plugged in, its median electrode being connected to the earth terminal 22 as shown. There is placed in series on each of the corresponding line wires 12, 13, a respective P.T.C. resistor 14, 15 which serves as resistor for protecting the line circuits placed downstream. Between the two P.T.C. resistors 14 and 15 and the two line output terminals, there are two respective elastic connectors 18 and 19 for testing points, which are testing clamps making it possible, when the module is plugged in on its receiving terminal block, either to effect a line test by plugging a test plug therein, or to effect a line disconnection by plugging a disconnecting plug therein, in that case leaving the telephone line, on the line system side, in a protected situation. Conventionally, all the elements of this module are soldered on a printed circuit board, including the overvoltage arrester proper, with the result that it is necessary to change the whole of the module after its overvoltage arrester has triggered. Such is not the case for the module of the invention, which will now be described with reference to Figures 5 to 10. 5 As shown in Figures 5 and 6, this module employs the conventional electrical diagram according to Figure 4, and consequently the same reference figures designate the same elements as those of Figures 1 to 4. In Figure 6, the half-shell 25, which acts as lid, has been removed in order clearly to show the elements of the module. The majority of the elements of the circuit are connected on a printed circuit board 23, of rectangular and rangy shape as shown. This printed circuit 23, with its added elements, is received, with the elastic earth connection 22, in an insulating casing constituted by two half-shells 24 and 25 clipped on each other, which is a conventional arrangement. However, according to the invention, the overvoltage arrester 20 is not soldered on the printed circuit board 23, but it is removably received between two elastic contact tabs 26 and 27 which, for their part, are soldered on the board 23. This arrangement is particularly advantageous as it makes it possible to change the overvoltage arrester 20 only when the module is "at fault" after activation of its "fail-safe" 21. However, it was not able to be envisaged up to the present time due to the danger constituted by a bad angular positioning of the overvoltage arrester, or a rotation thereof after its installation between two elastic contacts such as contacts 26 and 27. The danger of a bad positioning will be understood on examining Figure 5, as well as Figures 1 to 3. The printed circuit 23 comprises in particular two tracks 28 and 29 which are electrically connected to the two line terminals 16 and 17. Now, the overvoltage arrester comprises two beads 9 (Figure 3) and 30 (Figures 1, 2 and 5) which are constructive parts of the "fail safe" 21. The fail safe 21 being connected to earth by the elastic contact 22, it will be understood that, if the overvoltage arrester is badly positioned angularly, or if it rotates accidentally, one or the other of the two beads 9 and 30 risks coming into contact with one of the tracks 28 and 29, in that case short-circuiting the telephone line. Similarly, the two free ends of the bar 6 of the fail safe 21 might touch the 6 respective bases 31, 32 of the two elastic contacts 26 and 27. This would not be damaging with the overvoltage arrester 20 shown here, since these two free ends are enveloped in insulating beads 8, but this might, on the contrary, provoke a short-circuiting of the two line contacts 26, 27 if the overvoltage arrester were of another type, also existing on the market, which does not present such insulating beads. According to the invention, all these dangers are avoided by the fact that the two clippable half-shells 24 and 25 are provided with check studs 33, 34 and 35, 36, respectively. As is clearly shown in Figures 5, 7 and 8, these check studs are respectively conjugate from half shell 24 (studs 33 and 34) to half-shell 25 (studs 35 and 36 respectively conjugate with studs 33 and 34). Furthermore, they are shaped in order, when these two half-shells 24 and 25 are assembled on one another (Figure 8), to form, all together, an enveloping and virtually cylindrical cradle for receiving and exactly positioning the overvoltage arrester 20, and then to allow the total closure of the casing 24, 25 when this overvoltage arrester is substantially introduced, in accordance with Figure 7, with the required angular position, therefore predetermined by the constructor as being danger-free. In Figure 7, the overvoltage arrester 20 is introduced in strictly exact angular position. This is in fact not critical to within a few degrees, as, due to the shape of the conjugate studs 33, 35 (as well as of studs 34, 36 not visible in this Figure), these studs angularly recentre the overvoltage arrester by pushing, in one angular direction or in the other, on the beads 8 that they imprison between their conjugate free ends 37 and 38 when the half-shells 24 and 25 are clipped on each other. In the correct position of Figure 8, the said beads 9, 30 and 8 are clearly distant from the tracks 28, 29 of the printed circuit 23 (Figure 5) and therefore do not risk touching them, all the more so as the overvoltage arrester 20 cannot rotate on itself since it is blocked in angular position by the fact that the beads 8 are wedged between the free ends 37, 38 of the studs 33, 35, on the one hand, and the corresponding free ends of the studs 34, 36 on the other hand. On the other hand, when the overvoltage arrester 20 is introduced, in accordance with Figure 9 or Figure 10, for example, with a bad angular position, total 7 closure of the casing 24, 25 is rendered impossible, as beads 8 oppose this, as is obvious from these two Figures. 8 1. An electrical device for protecting telephone or computer-related line, this device being formed by a quadripole which is inserted in series on the line and which comprises: . a three-pole overvoltage arrester (20), or lightning arrester, of cylindrical shape which is then connected in parallel on the line, with its central electrode (4) connected to earth, . a double safety short-circuit, or "fail-safe" (21), which is composed of a metal clip (5) in the form of portion of cylinder which is elastically plugged over the cylinder (1) constituted by the overvoltage arrester, closely tightening thereon, making contact with its central earth electrode (4) but being maintained at a short distance from its two line electrodes (2, 3) by a fusible pellet (7), this quadripole being added on a printed circuit (23), itself received in an insulating casing composed of two half-shells (24, 25) adapted to be clipped on each other, characterized in that: . Its overvoltage arrester is removably received therein, between two elastic line contacts (26, 27) and an elastic earth contact (22); . In order to prevent a bad angular positioning of this overvoltage arrester, which would cause in particular a dangerous positioning of its "fail-safe" (21) with respect to the printed circuit (23) receiving the quadripole and to the elastic contacts (26, 27) for receiving this overvoltage arrester, the two clippable half-shells (24, 25) which form its casing are in addition provided with check studs (33, 34, 35, 36) which are respectively conjugate from one half-shell to the other and which are formed in order, when these two half-shells are assembled on one another, to form together an enveloping, virtually cylindrical cradle for reception and exact positioning of the overvoltage arrester (20) and to allow total closure of the casing when this overvoltage arrester (20) is introduced substantially in an angular position predetermined as desired, while, a contrario, they oppose total closure of the casing when this overvoltage arrester is introduced substantially in another angular position considered as bad. 2. An electrical device as claimed in Claim 1 wherein said conjugate studs (33, 34 and 35, 36) are shaped to imprison, between two of their conjugate free ends (37, 38), the transverse portion (6, 8) of the "fail safe" (21). 3. An electrical device as claimed in Claim 1 wherein it is made in the form of a plug-in module. 4. An electrical device as claimed in Claim 1 wherein it comprises two elastic connectors (18, 19) for testing points which make it possible either to make a line test by plugging a test plug therein, or to effect a line disconnection by plugging therein a disconnecting plug, in that case leaving the telephone line, on the line system side, in a protected situation. This invention relates to a protection module for telephone or computer-related line, this module comprising a printed circuit board (23) receiving various components (14, 15) and a three-pole overvoltage arrester (20), in a casing formed by two clippable half-shells (24, 25). The overvoltage arrester (20) is removably received between two elastic contacts (26, 27). To ensure a determined angular positioning free of any danger of short-circuit, the two half-shells (24, 25) are provided with conjugate check studs (33, 35 and 34, 36) for exact angular positioning of this overvoltage arrester. If the overvoltage arrester (20) is not introduced in its correct angular position, total closure of the casing (24,25) is impossible.

Documents:

00036-cal-1999-abstract.pdf

00036-cal-1999-claims.pdf

00036-cal-1999-correspondence.pdf

00036-cal-1999-description(complete).pdf

00036-cal-1999-drawings.pdf

00036-cal-1999-form-1.pdf

00036-cal-1999-form-18.pdf

00036-cal-1999-form-2.pdf

00036-cal-1999-form-3.pdf

00036-cal-1999-letters patent.pdf

00036-cal-1999-p.a.pdf

36-cal-1999-granted-abstract.pdf

36-cal-1999-granted-claims.pdf

36-cal-1999-granted-correspondence.pdf

36-cal-1999-granted-description (complete).pdf

36-cal-1999-granted-drawings.pdf

36-cal-1999-granted-examination report.pdf

36-cal-1999-granted-form 1.pdf

36-cal-1999-granted-form 2.pdf

36-cal-1999-granted-form 3.pdf

36-cal-1999-granted-letter patent.pdf

36-cal-1999-granted-pa.pdf

36-cal-1999-granted-reply to examination report.pdf

36-cal-1999-granted-specification.pdf