DE9116565U1 - Cable protection arrangement for or on a cable arrangement to be laid underground and connectable to buildings, screed boxes or the like (case A) - Google Patents

Description

"Cable protection arrangement for or on a cable arrangement to be laid underground and connectable to buildings, screed boxes or the like" (Case A)

The invention relates to a cable protection arrangement for or on a line arrangement to be laid in the ground and connected to buildings, screed boxes or the like, which consists of several line sections that can be mechanically and electrically connected to one another and to the buildings, screed boxes or the like, the individual line section consisting of at least one cable protection pipe made of an insulating material, preferably plastic, and one or more conductors or cables that are inserted or pulled into the cable protection pipe, the cable protection pipe being provided with an electrically conductive, metal shield that is surrounded on the outside by a conductive protective layer (preamble of claim 1). Such a line arrangement is known from DE-PS 38 12 057. In this prior publication, a lightning current-carrying braid, e.g. made of

Copper. It is also stated that one of the ends of the respective cable protection pipe is widened so that it fits over the other, non-widened end of the adjacent cable protection pipe. It is also stated that the shielding of one cable protection pipe merges with the shielding of the other, adjacent cable protection pipe with the same cross-section and that the shielding effect must not be interrupted at such a connection point. However, the above-mentioned literature does not contain any further information on the design of these connections of the cable protection pipes and the shielding of each line section or their connection to buildings, sash boxes or the like.

DE-AS 27 10 620 describes a protective device made of corrosion-resistant metal nets for low-current cables to be laid underground. This protective device is designed as a Faraday cage to accommodate the cables. The cage, which is very large relative to the cables, has a U-shape in cross-section, which is open at the ends. It also includes a surface covering. Both the U-shape and the covering are made of nets made of ferromagnetic material. The individual bars of the nets are electrically connected to one another at the crossing points. The disadvantage here is that the cage's grid shape does not provide complete shielding; unless the mesh size of the grid is chosen to be very small, which would involve a correspondingly high manufacturing cost. The content of this literature reference gives

«&Ogr; no indication that this shielding is electrically conductive in the longitudinal direction of the arrangement. In particular, the lightning current-carrying electrical conductivity of the shielding in the longitudinal direction of the cable protection pipes, which is part of the present invention, is not mentioned.

The object of the invention is, in contrast, to ensure that the connection

the cable protection pipes of a line section among each other, as well as the connection of such line sections to buildings, sash boxes or the like in a mechanically robust, easy to handle and electrically flawless manner. In doing so, a continuous, lightning current-carrying shield should be maintained in accordance with the teaching of DE-PS 38 12 057.

To solve this task or problem, based on the generic term of claim I ₁ cited at the beginning, the invention provides that the electrical shielding of each cable protection pipe is a metallic, conductive foil which is capable of carrying lightning currents in terms of its dimensions and specific electrical conductivity and which is surrounded by an outer sheath made of an electrically conductive plastic, that at the end areas of each cable protection pipe serving for the connection, the sheath and the shielding are removed over a length which is at least about ten times greater than the wall thickness of the cable protection pipe, that a part of the outer sheath is then removed over a smaller area to form a cylindrical contact surface, the contact surface serving for the electrical connection to the adjacent cable protection pipe, line section, building, screed box or the like, and that means are provided for the corresponding connection of the exposed area of the shielding with metallic shields (characteristic of claim 1). Metallic foils are significantly more resistant than braids. This is important both for production and, above all, for the generally very rough operation during transport or on the construction site. It should be noted that the above-mentioned part of the outer jacket made of electrically conductive plastic is removed at the factory, and thus the cable sections must be transported and laid with the exposed areas of the shield. The metal foil is preferably made of copper. However, it can also be made of another metal such as aluminum.

-�Agr; Λ hen. Furthermore, a contact surface is created, preferably in the form of a ring-shaped, cylindrical section, which, in addition to the aforementioned mechanical stability, has contactability and current conductivity that meet the requirements of lightning current carrying capacity. Finally, the arrangement according to the invention with the above-mentioned extension of the cable protection tubes to the outside creates a sufficiently long sliding path, which flashovers from the contact surface of the shield to the

IQ lines. In principle, the creation of such a long sliding path is the subject of DE-PS 38 057, but not in the advantageous structural design according to the invention, with which the cable protection pipe can be simply pushed onto the

jg specified lengths of sheath and shield must be exposed. The outer sheath serves to provide electrical contact with the ground. It also protects the metal foil mechanically and against moisture.

The features of claim 2 provide an advantageous combination of the electrical connection and the mechanical connection of the contact points in the form of a single means, e.g. a pipe clamp.

The features of claim 3 include a preferred, sleeve-like connection according to the invention between the opposite ends of the cable protection pipes of two line sections. In contrast to the initially mentioned design according to DE-PS 38 12 057, this means that the cable protection pipes can have the same diameter at both ends. This is a significant simplification and relief for both production and assembly. Continuous, uninterrupted shielding is also ensured, including mechanically strong and electrically sufficient connections of the films mentioned, with the connections protruding from the sleeve being used to contact the exposed areas of the

-&dgr; shielding of the cable protection pipes. Both the cable protection pipes and the sleeves are available from the factory in the form described. On site, all that is required is to insert the ends of the cable protection pipes into the sleeve and to put on and tighten the clamps or similar connecting devices. The sleeve itself has the function of uninterruptedly conducting the electrical shielding and also ensures the required stability of the plug connection from this sleeve and IQ the relevant ends of the cable protection pipes.

A preferred embodiment of the sleeve according to claim 3 is the subject of claim 4. This ensures perfect positioning of the ends, i.e. front surfaces of the two cable protection pipes.

According to the teaching of claim 5, the lengths of the sleeve parts, which accommodate the cable protection pipe ends, are selected such that the required long sliding distance is also provided on the sleeve side.

The teaching of the invention according to one or more of claims 3 to 5, which was explained in detail above, can also be used in principle for introducing a line section into a building, a screed box or the like, wherein the sleeve or a corresponding sleeve part is provided on the building side.

Further advantages and features of the invention can be found in the further subclaims as well as the following description and the associated drawing of possible embodiments according to the invention. The drawing shows:

Fig. 1: schematically the example of a cable protection arrangement according to the invention, in connection with

buildings and a drawing box in a smaller scale than the other figures,

Fig. 2: partial cross-section of a socket connection of adjacent pipe sections,
5

Fig. 3: a plan view of the sleeve according to Fig. 2,

omitting the connection clamps and the seals,

Fig. 4: the embodiment of an introduction of a

line section according to the invention into a building, a sash box or the like,

Fig. 1 shows the embodiment of a cable protection arrangement, consisting of a first building 1, a second building 2, a screed box 3 with a metal shield 4, line sections 5, 6, 7 and 8 as well as the ground 9. In the building 1, a room 10 that is to be particularly protected against electrical overvoltages, interference fields, etc., e.g.

a space for accommodating a computer 11, which has a metal shield 12. Furthermore, only the electrical connections of the shields of the line sections 5 to 8 are shown in principle in Fig. 1, namely in the form of a connection 13 to the shield 12, a connection 14 to a potential equalization bar 15, the connections 16, 17 of the line sections 6, 7 with a sleeve 18, the electrical connections 19, 20 of the shields of the line sections 7, 8 with the shield 4 of the screed box 3, and finally an electrical connection or connection 21 of the shield of the line section 8 with the shield or reinforcement 22 of the building 2.

Fig. 2 shows a preferred embodiment of the connection between two line sections 6 and 7 using a sleeve 18. The respective cable protection pipe 23 consists of an insulating material, e.g. a plastic such as PVC,

PE, PP, PPO, PA, PC, ABS. The respective electrical shielding in the form of a metal, lightning current-carrying foil 24 is (see above) preferably made of copper. This shielding is surrounded by an outer jacket 25 made of a conductive plastic. This can be, for example, PE-conductive, PP-conductive or ABS-conductive or a polyacetylene with a corresponding electrical conductivity. For example, electrically conductive semi-crystalline polyvinylene sulfide molding compounds are known for this purpose, which can be mixed with glass fibers. Plastics with a correspondingly high carbon black content are also known for this purpose. In the above, the aim is preferably to achieve a conductivity of the outer jacket that roughly corresponds to the conductivity of the surrounding ground. This outer jacket achieves two things. Firstly, the electrical connection of the shielding with the surrounding soil and furthermore protection of the shielding against damage caused by objects in the soil such as sharp-edged stones, metal parts and the like, whereby the outer jacket 25 also prevents corrosion of the shielding.

The cable protection tubes 23 each have the same diameter and lie opposite one another with their end faces 26 at a small distance, whereby in the preferred embodiment of the invention the end faces 26 rest against a collar 27 which runs around the inside of the sleeve 18 made of insulating plastic. The sleeve 18 is also provided on the inside with circumferential grooves 28, each of which accommodates a seal 29 as a moisture barrier. This prevents moisture from penetrating the sliding section 30, which is located between the inner surface of the sleeve and the outer surface of the cable protection tube which is adjacent to it in the present embodiment. If necessary, a sealing insert which also acts as a moisture barrier could be located between the inner surface of the sleeve and the outer surface of the respective cable protection tube, so that in this case the outer surface of the cable

&Igr; protective pipe has a corresponding distance from the inner surface of the sleeve (not shown in the drawing). Here too, the aforementioned sliding section 30 is formed. This sliding section 30 has a length t that should be at least ten times as large as the thickness d of the wall of the cable protection pipes 23. In a practical embodiment, the thickness d of the cable protection pipe is approximately 3 mm and the distance t 30 mm. However, the invention should not be limited to these dimensions. This sliding section t is long enough to prevent any flashovers from the respective contact surface 32 of the shielding of the cable protection pipe to conductors or cables laid inside it, indicated schematically by 31. In addition, reference is also made to the explanations of the electrical conditions of such flashovers in DE-PS 38 12 057.

The advantage is that this distance t can be created simply by removing both the outer jacket 25 and the shielding 24 from the respective end faces 26 of the cable protection pipe 23 over the length t, with the outer jacket 25 also being removed by a further area s, which corresponds to the width of the contact surface 32 exposed in this way. The shielding 24 of this line section thus protrudes freely by the area s towards the end of the cable protection pipe and thus forms the cylindrically circumferential contact surface 32.

The sleeve 18 is provided on the outside with an electrical shield 33, which corresponds in its design and shielding effect to the shield 24. It should be mentioned that both the shields 24 and the shield 33 are circular in cross-section, i.e. have the shape of a cylinder, which surrounds the cable protection pipe 23 or the sleeve 18 and extends in the longitudinal direction thereof.

According to the present embodiment, to which the

Invention, however, is not limited, the shield 33 is led out at the front ends of the sleeve 18 and is provided with slots 35 in this led out contact area 34 (see in particular Fig. 3), between which there are flags or sections 36 made of the foil material of the shield 33. These slots make it particularly easy to move the sections 36 of the shield 33 protruding from the sleeve towards the interior of the cable protection pipes so that they come into contact with the contact surfaces 32 of the shields 24, in order to then be clamped to the contact surfaces 32 with the help of a pipe clamp 37 made of conductive material, preferably copper. Instead of such a clamp, a tension band or the like can also be provided. This creates a lightning current-carrying, conductive connection from the shielding 24 of the cable protection pipe of the line section 6 via the shielding 33 of the sleeve to the shielding 24 of the cable protection pipe of the line section 7, which is also sufficiently strong mechanically. Connecting cables, e.g. for connecting adjacent earthing cables or to a potential equalization bar or the like, can be attached to the respective clamp 37 or an ear 51 of this clamp or an analogous clamping device. The sleeve 18 holds the opposite end areas of the cable protection pipes 23 together mechanically firmly and torsionally.

Furthermore, the shielding 33 of the sleeve is surrounded on the outside by an outer jacket 38, which is the same in terms of material and function as the outer jackets 25 of the cable protection pipes 23. Overall, a mechanically strong and at the same time continuous, shielded connection of cable protection pipes or line sections 6, 7 is created.

It would also be possible to remove the outer sheath 25 over a part of the length of a line section, preferably all the way around, so that the

-&Igr;&Ogr;&Igr; shielding is exposed in order to attach a clamp or other contact means to it. This allows components, parts or the like that are to be earthed to be connected to the shielding at desired points along a line section.

Fig. 4 shows the introduction of a line section into a building or the like, e.g. in Fig. 1 the right end of the line section 7 into the screed box 3 or the right end of the line section 8 into the building 2.

The numbers from Fig. 2 are selected for the cable protection pipe and other elements. In the concrete or masonry 43 of the building or the like there is an opening 44 into which the cable section is to be inserted. The opening 44 is sealed to the outside by a building inlet consisting of two plates 45, 46 and a seal 47 located between them, e.g. made of rubber. The aforementioned parts 45, 46 and 47 are held together by clamping screws 48 and are provided on the inside with a cylindrical opening 49 into which the outer casing 25 of the relevant cable section is inserted with a tight fit. From the front face 50 of this cable section located inside the building in the direction of the building entry, the outer jacket 25 is removed by the length t+s, while the shielding 24 is only removed by the length t, with t also being approximately equal to or greater than 1Od. This also prevents creeping discharges here. A connecting cable 52 to a potential equalization bar 53 is provided on an ear 51 of the clamp 37.

The reinforcement 55 of the concrete of a building or the shielding 4 of the screed box 3 can be connected to this via a line 54. Similarly, in Fig. 1, a connection can be made to the left of a potential equalization bar 15 to the reinforcement 55 of this building, while the electrical connection 14 explained there corresponds functionally to the connecting line 52 of the embodiment according to Fig. 5. Fig. 1 shows a grounding 54 of the potential equalization

-11-level rail.

If another section of line is to be connected to the end of the line section shown on the right in Fig. 4, this can be done with a socket connection of the invention, as shown for example in Figs. 2, 3 and explained above. It is also within the scope of the invention to design the introduction into a building or the like shown in Fig. 4 with a socket arrangement according to Fig. 2, 3, whereby only the clamp located in the building needs to be provided with an ear according to item 51. In principle, the socket can be half of the connecting socket from the examples in Fig. 2, 3.

Instead, a part of a line section can protrude from the building, screed box or the like and be connected to the adjacent line section via a sleeve according to the invention (see e.g. Fig. 2, 3).

From the above it follows that the invention can be used to lay such cable connections from the inside of a building or the like to the inside of one or more other buildings or the like in a practical and functionally flawless manner. Since such connections

2g can extend over greater distances, it is important that the invention enables an electrical and mechanical coupling of the line sections that is both practical and functionally flawless.

- Expectations -

Claims (14)

1. Cable protection arrangement for or on a line arrangement to be laid in the ground and connected to buildings, sash boxes or the like, which consists of several line sections that can be mechanically and electrically connected to one another and to the buildings, sash boxes or the like, the individual line section consisting of at least one cable protection pipe made of an insulating material, preferably plastic, and one or more conductors or cables that are introduced or pulled into the cable protection pipe, the cable protection pipe being provided with an electrically conductive and lightning-current-carrying metallic shield that is surrounded on the outside by a conductive protective layer, characterized in that the electrical shield (24) of each cable protection pipe (23) is a metallic, conductive foil that is capable of carrying lightning currents in terms of its dimensions and specific electrical conductivity and is surrounded by an outer sheath (25) made of an electrically conductive plastic, that at the end regions of each cable protection pipe that serve for the connection, the outer sheath and the shield over a length (t) which is at least about ten times greater than the wall thickness (d) of the cable protection pipe, that a part of the outer jacket is removed over a smaller area to form a cylindrical contact surface (32), wherein the contact surface serves for the electrical connection to the adjacent cable protection pipe, line section, building, screed box or the like, and that means (37) are provided for the corresponding connection of the exposed area (s) of the shield (24) with metallic shields. 2. Cable protection arrangement according to claim 1, characterized in that the electrical connection means (37) are simultaneously designed as mechanical connecting means, e.g. in the form of a pipe clamp made of conductive material. 3. Cable protection arrangement according to claim 1 or 2, characterized in that for connecting the ends of two line sections (6, 7) their cable protection tubes (23) have the same diameter and with their end faces (26) lie opposite one another in the connecting position, that a hollow cylindrical sleeve (18) made of insulating material is provided, the inner diameter of which is equal to or larger than the outer diameter of the cable protection pipes such that in the connecting position the cable protection pipes are inserted into the sleeve either preferably with a snug fit or via an intermediate sealing insert, that the sleeve is also surrounded on the outside by an electrical shield in the form of a metallic, conductive and lightning current-carrying foil (33), which is led out at the two ends of the sleeve with a contact area (34) serving for the electrical connection, whereby this area (34) overlaps the exposed area of the shield (24) and is thus mechanically clamped, and is electrically connected. 4. Cable protection arrangement according to claim 3, characterized in characterized in that the sleeve (18) has a stop on the inside and centrally located in its longitudinal direction, which can be designed as a circumferential collar (27) which serves to stop the end faces (26) of the cable protection pipes (23) inserted into the sleeve. 5. Cable protection arrangement according to claim 3 or 4, characterized in that half the sleeve length or the distance from the stop (27) to the respective outer end face of the sleeve corresponds approximately to the length (t) of the end region of the cable protection pipe from which the shield (24) and outer jacket (25) are removed. 6. Cable protection arrangement according to one of claims 3 to 5, characterized in that the shield (33) of the sleeve (18) is surrounded on the outside by an outer jacket (38) made of an electrically conductive plastic, which, however, leaves the contact areas (34) of the shield of the sleeve free. 7. Cable protection arrangement according to one of claims 1 to 6, characterized in that the electrically conductive plastics which form the outer sheaths (25, 38) of the cable protection pipes and the sleeve have approximately the same electrical conductivity. 8. Cable protection arrangement according to one of claims 1 to 7, characterized in that the electrical conductivity of the outer sheaths (25, 38) of the cable protection pipes and 2Q of the sleeve approximately corresponds to the electrical conductivity of the surrounding soil. 9. Cable protection arrangement according to one of claims 3 to 8, characterized in that the contact areas (34) of the shield (33) protruding from the sleeve are slotted and are shifted by a certain amount towards the interior of the cable protection pipe and are thereby longitudinally the cable section rests on the contact surface (32) of the shield (24) of the respective cable protection tube and is thus clamped. 10. Cable protection arrangement according to one of claims 3 to 8, characterized in that the contact areas (34) of the shield (33) of the sleeve (18) are led out of the latter without displacement inwards and are connected to the contact surfaces (32) of the shields (24) of the cable protection tubes are conductively clamped. 11. Cable protection arrangement according to one of claims 3 to 10, characterized in that such a sleeve or a portion of such a sleeve is provided for the introduction and attachment of a line section into a building, a screed box or the like. 12. Cable protection arrangement according to one of claims 1 to 11, characterized in that the shields (24) of the Cable protection tubes (23) and, if necessary, the shielding (33) of a sleeve or part of a sleeve in a building (1, 2), a screed box (3) or the like with their shielding or reinforcement (4, 12, 22, 55). 13. Cable protection arrangement according to one of claims 1 to 12, characterized in that only the end of a line section with the outer sheath (25) removed over a partial area (s+t) and the shielding (24) of the cable protection pipe (23) removed over another partial area (t) is introduced into a building, screed box or the like and sealed to the outside, the exposed shielding (32), e.g. via a pipe clamp (37, 51), being connected to a potential equalization gc rail (53), a reinforcement (55) or the like is electrically conductively connected. -16- 14. Cable protection arrangement according to one of claims 1 to 13, characterized in that in the course of a cable protection pipe (23) its outer jacket (25) is removed over a certain area, e.g. a cylindrical ring section, and the shielding (24) exposed in this way is connected to a means for electrical contact.