EP3111040B1 - Cable core for a cable, in particular an induction cable, cable, and method for producing a cable core - Google Patents

Description

The invention relates to a cable core for a cable, in particular for an induction cable, with a plurality of such cable cores, each having a conductor which is interrupted in the longitudinal direction at predetermined length positions at a number of separation points to form two conductor ends, an insulating intermediate piece being provided for connecting the conductor ends is on which the conductor ends are arranged on both sides. Furthermore, the invention relates to a cable with several such cable cores and a method for producing a cable core for a cable.

Such a cable is used in particular for use as a so-called induction cable (alternatively also called an inductor) for forming one or more induction fields. The cable is particularly intended for inductive heating of oil sands and / or heavy oil deposits. Such an application of such an induction cable is known, for example, from EP 2 250 858 B1 refer to. The technical boundary conditions resulting from this application are met by the cable described below.

To build up the induction fields and implement inductive heating, it is necessary that the individual cable wires of the cable are separated at defined separation points in a grid dimension with a defined length of, for example, several 10 m. Each of the cable wires is divided into a number of wire sections by the separation points.

Within the cable, a plurality of cable cores are preferably combined to form core groups, the separating points or interruptions in the cores of a respective core group lying essentially at the same length position. Typically there are two core groups, the separation points of which are shifted by half the grid dimension relative to one another. In other words: the separation points a first core group are arranged in the longitudinal direction halfway between two separation points of a second core group. This results in an overlap of the wire sections of different groups, which is used in particular to form an induction cable.

Such a cable is for example in the WO 2013 079 201 A1 described. This discloses a cable core for a cable, in particular for an induction cable, with a plurality of such cable cores, each of which has a conductor surrounded by insulation. Furthermore, the respective cable core, that is to say a conductor surrounded by an insulation jacket, is interrupted in the longitudinal direction of the cable at predetermined length positions at separation points with the formation of two wire ends. To connect this, a connector with an insulating intermediate piece is arranged and the wire ends are fastened to the connector on both sides of the intermediate piece. To connect the wire ends, the connector is formed like a sleeve on its opposite end faces, so that a respective wire end, that is to say in particular also part of the insulation jacket, is encompassed.

The connectors therefore have a larger diameter than the cable core and are correspondingly strong, thus leading to a thickening of the cable core in the area of the separation points.

To improve the stability of the cable core, it is also known that the connected core sections and the connectors are provided with a common banding. This means that an additional layer is applied, which increases the manufacturing effort. Furthermore, the diameter of the cable core is also increased, and consequently the flexibility is reduced, which makes it difficult to roll it up for the purpose of transporting a cable formed from such cable cores.

In order to produce such a cable core, a raw core is continuously fed to a processing machine and is recurrently separated at the specified length positions at a respective separation point, so that the two wire ends are present at the separation point. These are pulled apart in the longitudinal direction of the cable and reconnected to the connector. This means that they have to be conveyed from the processing machine briefly at different conveying speeds in order to set the distance. The distance must also be monitored to ensure that the specified distance is actually set.

The invention has for its object to provide an improved cable core that is as compact and easy to use. Furthermore, a cable based on the aforementioned cable core should be specified. In addition, an improved method for producing a cable core is to be specified, which is also suitable for producing the above-mentioned improved cable core.

The object directed to the cable core is achieved according to the invention by a cable core with the features of claim 1. Advantageous refinements, developments and variants are the subject of the dependent claims.

For this purpose, it is provided that a cable core for a cable comprising a plurality of such cable cores has a conductor which is interrupted in the longitudinal direction at predetermined length positions at a plurality of separation points to form two conductor ends. In particular, the cable core is provided for use with an induction cable with several such cable cores. To connect the conductor ends, an insulating intermediate piece is provided, on which the conductor ends are arranged on both sides. Furthermore, the conductor and the intermediate piece for forming the cable core are jointly surrounded by a continuous insulation jacket. As a result, a cable wire suitable for an induction cable is realized in particular. The continuous insulation jacket in particular ensures good stability and tensile strength of the cable core. The insulation jacket advantageously serves both for electrical insulation of the conductor in the radial direction and for connecting a number of conductor sections separated by separation points. This simplifies the construction of the cable core. This advantageously reduces the manufacturing outlay for such a cable core.

A common, continuous insulation jacket is understood here to mean that the insulation jacket is applied directly to the conductor and is guided continuously over the intermediate piece. From a manufacturing point of view, this manifests itself in the fact that initially only the electrical conductor is provided and the intermediate piece is inserted, before the insulation jacket is then brought over the conductor strand formed thereby, consisting of individual conductor sections and the intermediate pieces arranged between them. In contrast to the prior art, there is therefore no cutting of a cable wire with subsequent connection of the wire ends by means of a connector. A cable core is generally understood to mean a conductor surrounded by a core jacket. In the prior art, a conductor surrounded by the wire jacket is therefore cut through and then reconnected via the connector. At the conductor ends, which are connected to one another via the intermediate piece, there is therefore no additional wire sheath between the insulation sheath and the actual conductor.

In this case, a core sheath is understood to mean a sheath which is usually extruded from an insulating material, in particular PFA, and which typically has a wall thickness in the range from greater than 0.1 to 0.8 mm, in particular in the range from 0.2 to 0.6 mm.

The conductor is either a stranded conductor or a solid conductor wire made of a suitable conductive material, in particular copper. The conductor preferably has a diameter in the range from 0.8 to 2 mm, in particular in the range from 1.0 to 1.4 mm.

The wall thickness of the insulation jacket is preferably in the range of a few tenths of a millimeter, in particular in the range of greater than 0.2 and up to 0.8 mm, preferably in the range of 0.2 to 0.6 mm.

The conductor is in particular a coated conductor, for example a copper conductor provided with a nickel layer. This additional coating eliminates destructive influences on the copper conductor at high Avoid temperatures when using the induction cable in the field. In a variant not belonging to the invention, the conductor is alternatively or additionally surrounded in particular by a conductor insulation, in particular made of PFA, which is correspondingly omitted at the conductor ends.

Such a nickel layer shows only a comparatively low conductivity compared to copper, in particular on the surface of the conductor, which is critical in particular with regard to the low penetration depth of the electric field due to the usually high frequencies in the range from 50 kHz to 200 kHz. A silver-coated conductor is therefore preferably used instead of a nickel-plated conductor. The layer thickness for both a nickel-coated and a silver-coated conductor is, for example, in the range from 0.8 to 1.5 μm.

As an alternative or in addition to the nickel / silver-coated copper conductor, a so-called enamelled wire is used as the conductor. The metallic conductor material is coated with a thin varnish. This typically only has a layer thickness in the range of less than 100 μm. To this extent, this varnish coating does not form a wire jacket. Rather, the additional insulation jacket is still required. In addition to protecting the conductor with the applied varnish, this also supports the insulation and thus provides additional protection against partial discharges.

In addition, the use of superconductors is fundamentally possible as the conductor material.

The insulation jacket is preferably applied to the conductor strand by an extrusion process. As an alternative, there is also the possibility, instead of or in addition to an extruded insulation sheath, to develop or further develop it by means of banding / wrapping.

The cable core is therefore formed overall by an internal conductor strand with the common insulation jacket surrounding it. The cable core is available as an endless piece. The conductor strand preferably extends together with the insulation jacket over the entire length. The conductor strand itself is in turn formed by a multiplicity of conductor sections which are each connected to one another or spaced apart from one another via the intermediate pieces. The conductor strand is therefore a conductor which is interrupted at defined, for example periodic, intervals and by means of insulating pieces.

The particular advantage of simplified quality control is achieved by arranging the intermediate piece on the (raw) conductor with the subsequent covering with an insulation jacket. This is because the conductor strand formed can already be checked for a desired good connection of the intermediate piece to the conductor ends and, if necessary, can be sorted out in the event of quality defects. This is therefore done at a very early stage of manufacture, which keeps the manufacturing costs low.

The conductor of the cable core is divided periodically into a number of conductor sections, which are separated from one another at the length positions, by the separation points. The separation points are separated from one another in a predetermined grid dimension of typically several 10 m, for example of approximately 100 m. When merging, in particular stranding several cable cores to form a cable, the process may result in the separation points of different cable cores being offset from one another; the conductor sections of different cable cores are then shifted against each other in the longitudinal direction. In other words: the longitudinal positions of, in particular, adjacent cable cores are not optimally aligned with one another with respect to the longitudinal direction, in particular not in a common plane transverse to the longitudinal direction of the cable.

The conductor ends formed at a respective separation point are then offset in the longitudinal direction, which can lead to disadvantageous partial discharges during operation. Therefore, in a preferred embodiment, the intermediate piece an intermediate piece length which is at least 0.5%, preferably at least 1% and more preferably at most 4% of the section length. Such an intermediate piece is also referred to as a long intermediate piece. In this way, despite a possible offset, an overlap of the intermediate pieces is realized and the partial discharge resistance at a respective separation point is significantly improved. The length of the intermediate piece is selected in particular in such a way that a process-related offset of the conductor ends at a separation point is compensated for. For example, there is an offset of approximately 2%, which is then approximately 2 m for a section length of, for example, 100 m. In this case, the length of the intermediate piece is selected such that it is approximately 2 m. Preferably, in particular in the case of a long intermediate piece described above, the respective conductor ends are prepared by means of an adapter element. For this purpose, the adapter element is placed on the conductor end. In a preferred embodiment, the conductor ends spaced approximately by the length of the intermediate piece are each connected to the intermediate piece via a preferably sleeve-shaped adapter element. The adapter element is, for example, a sleeve, wire end cap or sleeve. The intermediate piece is then arranged between two adapter elements and, in a suitable development, also fastened to these. A respective cable core then has the following structure in the longitudinal direction in the area of a separation point: conductor section, adapter element, intermediate piece, adapter element, conductor section.

The adapter element has only a fraction of the length of the intermediate piece and is, for example, only a few centimeters long. Its length is therefore typically in the range of less than 8% and in particular less than 4% or less than 2% of the length of the intermediate piece.

With an adapter element an intermediate piece made of an insulating material is selected accordingly from a conductive material.

The adapter element is preferably a sleeve made of brass. According to the invention, the intermediate piece is designed as a flexible, tensile element. The intermediate piece is preferably made from an insulating high-temperature material, for example from PFA, PTFE or aramid or generally an insulating and tensile material.

In a preferred development, the intermediate piece comprises a tensile core and an insulating sheath which surrounds the core. As a result, the intermediate piece is particularly robust, in particular in the event of a tensile load, and at the same time is particularly flexible. Here, the core is preferably made of aramid or alternatively of another tensile and insulating material, and the sheathing is made of PFA. In particular, the sheathing is selected in such a way that there is a particularly good connection with the insulating sheath subsequently applied.

In a suitable embodiment, the insulation jacket is applied directly to the intermediate piece, the adapter piece and the conductor in the manner of a hose. In a suitable alternative, however, the insulation jacket is designed as a banding directly around the intermediate piece, the adapter piece and the conductor. In a preferred alternative, however, a respective conductor end is surrounded by a sleeve, which is in turn surrounded by the continuous insulation jacket, in particular to improve the partial discharge safety. By attaching the additional sleeve, the risk of air pockets when applying the insulation jacket is significantly reduced and the resistance to partial discharge is considerably improved. For this purpose, the sleeve is preferably manufactured as an injection molded part or a cast part. Since an adapter element may be attached to the conductor end, the sleeve then only indirectly surrounds the conductor end, ie the sleeve is arranged around the conductor end and the adapter element, in particular sprayed around them. This will in particular Air pockets in the area of possible gussets between adapter element and conductor avoided.

The sleeve has only a fraction of the length of the intermediate piece and is, for example, only a few centimeters long. Their length is therefore typically in the range of less than 10% and in particular less than 5% of the length of the intermediate piece.

Preferably, the adapter element is completely enclosed by the sleeve, whereby a particularly firm hold of the entire arrangement is achieved. The sleeve extends in the longitudinal direction in particular over a length which is at least somewhat greater than the length of the adapter element, for example approximately twice as large. The sleeve is then in each case at the end in particular on the conductor or on the intermediate piece. The insulation jacket is attached throughout this entire arrangement.

In addition, the sleeve is then in particular designed in such a way that it leads to a particularly flat widening of the diameter of the cable core in the longitudinal direction, so that any air inclusions are avoided when the insulation jacket is applied, in particular extruded. For this purpose, it is particularly provided that the sleeve preferably tapers conically towards its end regions. The sleeve hugs the conductor with only a slight slope. For example, the diameter in the direction of the adapter only grows at about 0.5 mm per centimeter in the longitudinal direction, i.e. with a gradient of about 5% and decreases accordingly behind the adapter element.

In a preferred embodiment, the insulation jacket is formed at least in two layers, with two layers of different materials, which in particular have different dielectric constants. In this way, the partial discharge resistance is improved in the case of several adjacent cable cores. In a preferred development, the insulation jacket is constructed in three layers.

One of the layers of the insulation jacket is preferably made of PTFE and in particular sintered. This enables a particularly robust and effective insulation of the cable core. The sintering then preferably takes place after the application of the PTFE layer and before the application of a further layer. The second layer is then preferably made of PFA as a material with a different dielectric constant. In a preferred embodiment, a PTFE layer is first applied as banding and then a PFA layer is extruded. In a suitable variant, two PTFE layers are applied to one another, in particular banded and sintered in each case, one of the PTFE layers being made from a modified PTFE. In general, a PFA layer preferably forms an outermost layer of the insulation jacket and a PTFE layer forms a layer arranged within the PFA layer.

In a variant that is not part of the invention, the conductor is surrounded by a conductor insulation, which is then in particular also interrupted at the separation points. The conductor insulation enables, in particular, an improved application of the insulation jacket. The conductor insulation is preferably also removed at least at the conductor ends in order to achieve a particularly good hold of the respective conductor end in the adapter element or on the intermediate piece. The conductor insulation is preferably selected in such a way that there is a particularly good connection with the insulation jacket and in particular also with a possibly present sleeve. Therefore, the conductor insulation is preferably made of PFA.

The connection of the conductor ends by means of a connector regularly leads to an undesirable thickening being formed in the area of the connection point. In contrast to this, there is preferably essentially no additional thickening in the region of the intermediate piece due to the common insulation jacket. The configuration with the common insulation jacket preferably realizes a cable core with essentially the same diameter, also in the area of the separation points. To this end, an advantageous further development provides that the intermediate piece and the conductor are aligned in the longitudinal direction. This results in particular in terms of diameter compact design of the cable core. The intermediate piece advantageously does not build up, which in particular makes the cable easier to handle. Since the conductor typically has a circular cross-sectional profile transverse to the longitudinal direction, the intermediate piece is suitably cylindrical.

The intermediate piece is made from an insulating material, for example from a plastic (for example PFA, FEP, MFA, PTFE or aramid). Partial discharges between the conductor ends facing the intermediate piece are prevented in the cable core. In an advantageous embodiment, the intermediate piece is made of a ceramic, which is particularly characterized by a good resistance to partial discharge. The material used is preferably transparent, which in particular facilitates an optical / visual quality control of the connection. The intermediate piece preferably has a length in the range of approximately 3 to 10 mm, whereby in particular an optimal efficiency of the overall arrangement is achieved. In the alternative variant described above, however, the intermediate piece is significantly longer and in particular has a length in the range of one or more meters.

In an advantageous embodiment, the intermediate piece has a lateral surface with an undulating profile, as a result of which leakage currents from one to the other conductor end are reduced or completely suppressed via the intermediate piece. In other words, the partial discharge resistance is improved. The partial discharge safety is further improved in particular in that the intermediate piece is formed with the conductor ends while avoiding the formation of air pockets. This high level of partial discharge safety is achieved on the one hand in particular by a suitable choice of material for the intermediate piece, preferably ceramic. By using in particular a prefabricated intermediate piece, these can already be subjected to a quality control beforehand. In contrast to a method in which the intermediate piece is formed directly by a spraying process to connect the conductor ends, it can therefore be reliably excluded in the present case, even when using plastic intermediate pieces, that partial discharge safety is reduced, for example due to air pockets in the event of a deficient spraying process.

In a preferred embodiment, the intermediate piece has a first end face and the conductor end has a second end face facing this first end face. It is then expedient for at least the first end face to be round. In particular, this means that the first end face is circular, in particular in a plane perpendicular to the longitudinal direction. Such a round design is particularly advantageous with regard to the electrical properties of the intermediate piece, that is to say in particular its insulating effect here. The first and second end faces are preferably each provided with a profile. In the case of the conductor end, the profile is advantageously formed directly by the separation process. Alternatively, the profile is formed by subsequent processing. Alternatively, a suitable dome is applied to the conductor end, that is, the conductor end is coupled. This dome is preferably made of metal and, for example, soldered or welded to the end of the conductor. If only a surface predetermined by the end faces is available for connecting the intermediate piece to the conductor ends, the surface is increased by a suitable profile, and in particular the stability of the connection is thereby improved.

The end faces are advantageously round. In a suitable embodiment, the first end face is convex and the second end face is complementary concave or vice versa. At least the conductor end is preferably designed without edges, that is to say in particular that the conductor end has no or only rounded edges in a cross section in the longitudinal direction. Rounded is understood to mean that the edge has a radius of curvature that does not fall below a minimum radius of curvature specified by field calculations. In particular, the radius of curvature is greater than 0.2 mm. This results in an edge in particular at the transition from the second end face to the outer surface of the conductor. An edge-free design results in an increased partial discharge resistance of the cable core in the area of the intermediate piece. Any edges are preferred Avoided at the end of the conductor, in that the second end face is round and curved outwards with respect to the conductor, that is to say in particular as a convex hemisphere surface. As a result, a corresponding hemispherical conductor end is formed, which is preferably surrounded by the complementarily designed intermediate piece. In a suitable alternative, a hemispherical dome or a dome with rounded edges is attached to the end of the conductor, for example soldered to it. The crest is expediently made of metal, in particular of the same material as the conductor. A conical design of the conductor end is also suitable, in which the second end face is correspondingly conical or frustoconical. Any edges are expediently rounded. A further embodiment is also suitable in which the second end face is circular and in particular has rounded edges in the longitudinal direction.

In a further suitable embodiment, the first and the second end face are configured similarly to a plug-in coupling. For this purpose, the intermediate piece or the conductor end optionally has an extension, pin or pin, which is inserted or inserted into a complementary recess in the conductor end or the intermediate piece.

The conductor is expediently designed as a hollow wire with a cavity extending in the longitudinal direction. On the one hand, the use of a waveguide advantageously saves material, and on the other hand there is a particularly circular opening at the end of the conductor. A suitably shaped intermediate piece is used in this.

The stability of the connection is improved, for example, by a press fit and / or suitably attached profiles. For example, the extension has a thread and is screwed into the complementary recess. Alternatively or additionally, the conductor end and the intermediate piece are glued or welded together.

In a suitable development, a strain relief is introduced in the cavity of the conductor designed as a waveguide. Advantageously, the intermediate piece also has a continuous cavity in the longitudinal direction and the strain relief is designed to be continuous, similar to the insulation jacket of the finished cable core, which in particular improves the tensile strength of the cable core. In other words: the intermediate piece is designed as a hollow cylinder.

In an alternative development, the intermediate piece is formed between two conductor ends to be connected by means of an injection molding process. In combination with a waveguide, an injection protrudes into the cavity, which in particular improves the stability of the connection. The injection molding is advantageously carried out in such a way that the intermediate piece and the conductor are aligned.

The conductor ends are welded to the intermediate piece, for example. For this purpose, the intermediate piece is advantageously metallized on the end face. In the case of an intermediate piece made from a ceramic, a particularly stable connection can be achieved by forming an enamelling. This is particularly the case in combination with a nickel-coated conductor. Suitably, the separated conductor has at least partially an in particular annular coating made of nickel on its end face. This makes it possible, in particular, to connect, preferably weld, an intermediate piece made of ceramic, aligned with the conductor, by means of enamelling to the end face. Alternatively, an intermediate piece made of ceramic, in particular a low-melting glass, is cast or pressed onto the conductor end.

In order to achieve a high flexibility of the entire cable core, the intermediate piece is advantageously cut through, in particular transversely to the longitudinal direction. Alternatively, the intermediate piece is simply notched. One or more notch or separation points are provided. The intermediate piece is therefore preferably generally designed as an element with low torsional or bending stiffness. This makes it possible, in particular, to prevent the cable core from being damaged by torsional forces, such as when a number is stranded of cable cores occur. Furthermore, due to the improved flexibility, the cable core is in particular easier to roll up and easier to transport.

In order to improve the stability and the tensile strength of the cable wires, the intermediate piece is expediently designed as a wire end cap (or also wire end sleeve) and the conductor end is seated in a recess made on the end face in the intermediate piece. This is, for example, cylindrical, conical or hemispherical. Either only a single wire end cap is provided, which is arranged between two conductor ends and is attached to one of the conductor ends, or a plurality of wire end caps are provided, preferably two, each of which is attached to a conductor end. In the latter case, the wire caps in particular form a separate intermediate piece with the advantages already mentioned above. In particular, the conductor end is suitably designed to be complementary to the recess. The conductor end is preferably round, which in particular improves the partial discharge resistance. The wire end cap is in particular made of a conductive material and is connected to the respective conductor end in an electrically conductive manner.

The wire end cap suitably comprises an end part and an in particular sleeve-shaped collar, collar, or jacket extending in the longitudinal direction therefrom. This advantageously encompasses the conductor end in the radial direction, as a result of which in particular the area available for establishing the connection is enlarged. The conductor end is preferably connected to the wire end cap by means of a press fit. This type of connection is particularly easy to carry out and particularly stable. Alternatively or additionally, the wire end cap is soldered, welded, sintered, crimped or crimped on the conductor end, for example. In particular for soldering, the recess of the wire end cap is preferably at least partially metallized, for example provided with a nickel layer. The wire end cap is advantageously glued to the conductor end, for example by means of a polyimide adhesive. In the case of an intermediate piece glued with an adhesive, the adhesive is preferably insulating. The gluing is suitably in addition to one of the above mentioned connection forms executed. The collar expediently has a number of teeth or clamping arms. In particular, squeezing the wire end cap on the conductor end is simplified. In a further alternative embodiment, the wire end cap is connected to the conductor end by a thermal aftertreatment, for example shrunk onto the conductor end in a manner similar to a shrink tube or fastened by means of a thermally curing adhesive.

In particular in the event that the wire end cap has a larger outer diameter than the conductor, the insulating jacket in the area of the wire end cap is suitably thinner, in order to ensure, in particular, a uniform cable wire diameter. In an alternative embodiment, the radius of the conductor is reduced in the region of the conductor end in such a way that the wire end cap is aligned with the remaining part of the conductor. For example, the radius of the conductor at the end of the conductor is reduced by turning, milling or etching. In a preferred development, the recess has a cylindrical and profiled inner wall. For example, it has teeth or barbs, which in particular provides pull-out protection. Alternatively, the wire end cap has an internal thread on the inner wall, as a result of which the conductor end is connected to the intermediate piece simply and stably by screwing. To produce a particularly firm screw connection, the conductor end has an essentially smooth outer surface and the thread is self-tapping. The intermediate piece can thus be screwed onto the conductor end in a precisely fitting manner. In particular, one or all of the developments and advantages of the above-described wire end cap can also be analogously and generally transferred to an intermediate piece which is not designed as a wire end cap.

In a suitable development, the intermediate piece is designed in the manner of a sleeve, that is to say similarly to two connected wire end caps. The above-mentioned developments and advantages with regard to an intermediate piece designed as a wire end cap can then be applied analogously to such an intermediate piece designed as a sleeve. For example, in a suitable embodiment, the intermediate piece has a thread on each of its faces, by means of of which the intermediate piece is screwed onto one end of the conductor. The threads are advantageously cut in the opposite direction of rotation, which facilitates the assembly of the intermediate piece.

In an advantageous embodiment, an adapter element is attached to the end face of the intermediate piece to form a prepared intermediate piece. For example, the adapter element is a conductor piece similar or identical to the conductor used for the cable core. By providing such prepared intermediate pieces, the manufacture of the cable core is simplified in particular in that only two identical or identical materials have to be connected to one another. The conductor and the adapter element are made of copper, for example. The end of the conductor and the intermediate piece are advantageously connected to one another by means of a welding process, in particular by means of a cold welding process.

The object is further achieved according to the invention by a cable, in particular a so-called inductor cable with a large number of cable cores, as described above.

Expediently, a plurality of groups of cable cores are formed, in particular two groups, the intermediate pieces of the cable cores of a group each being arranged on the same axial length. The intermediate pieces of the cable cores of the two groups are therefore offset from one another in the longitudinal direction and preferably exactly by half a distance between two successive intermediate pieces in a respective cable wire. The intermediate pieces are preferably arranged in a fixed, periodically recurring distance in all cable cores.

In order to compensate in particular for a manufacturing-related offset of the intermediate pieces of a group at a length position, the intermediate pieces arranged at this length position expediently have an intermediate piece length which corresponds to at least 0.5%, preferably at least 1% and further preferably at most 4% of a section length of the conductors. The section length is the length of a conductor section and corresponds approximately to the distance dimension mentioned above.

The entire inductor cable is preferably formed by several, in particular three, sub-cables, each consisting of several cable cores.

In particular, the cable and in particular each partial cable consists of several core bundles, which in turn consist of a large number of individual cable cores. For example, several core bundles, in particular seven core bundles, are arranged around a central strand, in particular for strain relief.

Each core bundle in turn preferably consists of several layers of individual cable cores, which are preferably also arranged around a central strand, in particular also for strain relief.

A plurality of cable cores are advantageously stranded together. Such a cable with stranded cable cores is particularly easy to manufacture. Furthermore, such a cable is particularly easy to transport. In particular, such a cable is easy to lay. To form the core bundle, several layers of cable cores are stranded together and in particular around a strain relief (for example made of aramid), advantageously in a SZ stranding. For example, an inner layer comprises six cable cores and an outer layer twelve cable cores. Several such wire bundles, for example seven pieces, are then stranded together to provide additional strain relief and form a partial cable. Several such partial cables, for example three pieces, are then stranded together to form the induction cable. The direction of lay is suitably set for each stranding, for example in such a way that two successive strandings form an SZ stranding.

In an alternative embodiment, a number of cable cores, core bundles and / or partial cables are each interwoven or knitted together. In particular, the induction cable has a capacitance value, which is advantageously adjustable, due to the cable cores partially overlapping in the longitudinal direction. In the case of a core bundle, partial cable or induction cable knitted with a selectable pitch, this capacitance value can be set by a suitable choice of the pitch.

A number of sheaths or tapes are suitably provided to combine a plurality of cable cores to form a core bundle, a plurality of core bundles to form a partial cable and / or a plurality of partial cables to form the induction cable. In other words: in particular one or more sheaths are provided after each sub-step in the manufacture of the cable.

However, additional sheaths and / or bandings are advantageously dispensed with, as a result of which, in particular, a compact construction of the induction cable is possible. In each case, the cable cores, the wire bundles and the partial cables are preferably stranded directly to one another and only one sheath is finally applied to combine the partial cables to form the induction cable.

A plurality of partial cables are preferably connected to form the induction cable, in particular stranded and provided with a sheath, in particular in the form of a banding, in such a way that the induction cable has a triangular profile with rounded corners in cross section to the longitudinal direction. In a preferred embodiment, the induction cable is in particular not circular in cross section. This saves material for the sheathing in particular. Furthermore, such an induction cable is easier to lay. Such induction cables are usually inserted or drawn into pre-routed pipes. The non-circular design of the cable, in particular with a triangular cross-sectional profile with rounded corners, enables the cable to be easily inserted into such pipes with little friction. In principle, the outer sheathing, which therefore surrounds the three sub-cables, can also be dispensed with. The total of three sub-cables lie in the corners of an imaginary triangle.

In a further alternative embodiment, a number of cable cores are in the form of a bundle, that is to say they are not stranded together. There are a number of cable wires for this straight in the longitudinal direction, that is to say in particular not guided in a spiral. For example, the cable cores of a core bundle are bundled together and a number of such core bundles are in turn stranded together. In this way, it is possible to manufacture the induction cable in a simplified manner and, in particular, to provide a certain amount of stranding at the same time.

In an advantageous embodiment, a number of cable cores are designed in the manner of a ribbon cable in such a way that these cable cores have an insulation jacket which is jointly applied to their conductor. In other words: a number of conductors are combined to form a ribbon cable by means of an insulation that is jointly applied to them. This means that the ribbon cable is designed like a number of combined cable cores. Instead of or in addition to stranding a number of cable cores to form a cable, it is thereby possible to form a multi-core cable by banding it with the ribbon cable. For this purpose, a strain relief is provided as the core, around which the ribbon cable is banded. In a suitable development, a plurality of flat ribbon cables are arranged, in particular in several layers, by means of banding to form a cable or a partial cable. For example, a six-core ribbon cable is banded around a strain relief and a twelve-core ribbon cable around the six-core ribbon cable. The two ribbon cables are suitably wound like SZ stranding, that is, they run in opposite directions to each other. For operation, the cable is connected in particular to a current source in such a way that a current flows in the cable and a voltage is present. In the case of an induction cable, the power source is typically an AC power source and the current and voltage have a frequency.

The cable preferably has a sensor module with at least one sensor for determining at least one value of an operating parameter of the cable. Operating parameters are understood to mean, for example, the current, the voltage and / or the frequency. Another operating parameter is, for example, a temperature measured in the cable. By determining the value of one of these operating parameters, monitoring of the Functionality of the cable possible. For continuous monitoring, several values of the operating parameter are suitably recorded over a predetermined period of time. A plurality of sensor modules are preferably arranged along the length of the cable.

The induction cable is regularly placed in a reservoir (or generally in the ground), for example in an oil sand field, or buried in it. Typically, a pipe is provided in the reservoir, into which the induction cable is drawn or inserted. The state of the reservoir is characterized by one or more environmental parameters, for example the temperature, density, viscosity or conductivity of the reservoir. A parameter can have different values at different points in the reservoir. In order to monitor the state of the reservoir, the sensor module (s) are additionally or alternatively designed to determine at least one value of such an environmental parameter.

A time-resolved determination of the operating parameters or the environmental parameters advantageously takes place. For example, the sensor module for carrying out seismic measurements is equipped with an acoustic signal transmitter and a microphone and carries out seismic measurements at predetermined time intervals. Since the sensor module suitably has a position that is essentially unchanged in time, this makes it possible, in particular, to characterize the reservoir and its state in a time-resolved and position-resolved manner. Different sensors or sensor modules are preferably integrated in the cable for the different parameters.

The sensor module advantageously also includes control electronics, in particular in order to evaluate the values determined. Furthermore, the control electronics advantageously generate control and / or warning signals, for example in order to interrupt the power supply in the event of a defect in the cable and to prevent further damage.

The sensor module and / or the control electronics are suitably connected to a central evaluation unit, for example a computer. In this way, in particular in the case of a plurality of sensor modules, data from different locations of the cable and / or the reservoir can be combined. The cable preferably has a data line which is used in particular to forward data determined by means of one or more sensor modules. The induction cable suitably comprises at least one optical waveguide which is designed, for example, for data transmission and / or as a temperature sensor. The optical waveguide is suitably inserted directly into the induction cable during manufacture, for example stranded together with the cable cores. Alternatively, the optical waveguide is guided along a strain relief or inserted instead of one.

In a preferred development, the sensor module and / or the control electronics are supplied with energy in such a way that energy is drawn from the induction field generated by the induction cable.

In a suitable development, the cable core has electronics, in particular for short-circuiting partial discharges at the conductor ends. For this purpose, the electronics are designed, for example, as a resonant circuit, high-pass filter or band-pass filter. The electronics are suitably electrically connected to the two conductor ends. Such electronics are advantageously provided for each opposite pair of conductor ends. In a suitable further development, the electronics can be switched on and off by a user. The electronics make it possible, in particular, to improve the partial discharge resistance of the induction cable. Partial discharges by means of the electronics are advantageously short-circuited.

The object is further achieved according to the invention by a method for producing a cable core according to claim 14. The advantages and design of the cable core already disclosed above also apply analogously to the method.

To manufacture the cable core, in particular according to the above-mentioned embodiments, it is provided that a sheath-free conductor is first provided, which is or is repeatedly separated at predetermined length positions in such a way that two conductor ends spaced apart by an intermediate space are formed. A conductor, in particular provided as a raw wire, is preferably recurrently separated. Separation takes place, for example, by means of a cutting or stamping process. An intermediate piece made of an insulating material is then introduced into the intermediate space, with which the conductor ends are connected in such a way that they lie opposite one another in the longitudinal direction. Then the conductor and the intermediate piece for forming the cable core are provided together with a continuous insulation jacket. This is extruded, for example, or applied in the form of a banding. In the present case, a sheath-free conductor is understood to mean a raw conductor, for example a solid raw wire, a stranded conductor or also a enamelled wire, which is free of a core sheath, that is to say is free of an extruded or wound insulation sheath.

As an alternative to cutting a raw wire, individual conductor sections with the desired length are provided and connected via the intermediate pieces. In both variants, a conductor strand is obtained which is composed of a large number of individual conductor sections, in particular of identical length, which are each connected to one another via the intermediate pieces. Overall, the conductor strand has sufficient mechanical tensile strength to treat it further for further process steps similar to a conventional raw wire and to apply the continuous insulation sheath, for example by an extrusion process or also by banding. When connecting the intermediate piece to the conductor ends, air pockets are preferably avoided, which improves the partial discharge safety. For this purpose, a particularly automated quality assurance procedure is provided, which is suitable for detecting air pockets. For example, an ultrasound or X-ray process. Especially in the case of an intermediate piece made of a transparent material, an optical method is preferably used, such as an image processing method using a camera operated in bright and / or dark field illumination.

A number of conductor strands arranged side by side, that is to say conductors provided with intermediate pieces, are suitably provided together with the insulation jacket in the manner of a ribbon cable, for example by an extrusion process. The conductors are preferably arranged such that only every second conductor is interrupted at a first predetermined length position of the ribbon cable. The conductors which are not interrupted at the first length position are then interrupted at a second predetermined length position following in the longitudinal direction. This ensures, in particular, an overlap of conductor sections predetermined by the separation points in the longitudinal direction that is suitable for forming an induction cable.

Since typically only every second conductor is cut to form an induction cable at a predetermined length position, in an alternative embodiment in the ribbon cable to form separation points a number of sections are cut out, for example punched, in such a way that only every second conductor and one at a predetermined length position this assigned section of the insulation are separated. Due to the remaining common insulation, the separation points are still correctly positioned relative to one another. The separation is preferably carried out in such a way that the intermediate pieces used at a predetermined length position continue to be present at the same length position in the finished, that is to say in particular in a cable stranded with a specific lay length. Advantageously, the sections are punched out in a suitably offset manner, taking into account the lay length. In an alternative embodiment, the sections are punched out in a non-offset manner, as a result of which the intermediate pieces are present at the predetermined length position, in particular when bundling cable cores into bundles as described above, for example.

In an advantageous development, the separated sections are provided with suitable intermediate pieces, for example in one of the above-mentioned versions. The intermediate pieces are advantageously each formed by means of an injection molding process. The intermediate pieces are suitably connected to the insulation jacket, for example sintered or vulcanized, as a result of which a particularly firm connection is produced.

In a preferred embodiment it is provided that the conductor - for example when using a raw wire - is separated at predetermined length positions by cutting out a section with a certain length from it. For example, the section is punched out of the conductor. Alternatively, the section is cut out, for example by means of a water jet or laser cutting process. This simplifies the formation of the conductor ends in such a way that a predetermined distance between them does not have to be subsequently set in an additional process step, but is instead produced directly by the length of the section which has been cut out. In other words, the distance is not set only after the separation, but rather already during the separation process itself. The length of the section which has been removed is suitably set as a function of the operating parameters of the cable core, such as voltage, current and / or frequency.

The connecting piece is suitably separated into at least two sections after the connection at a separation point, in particular transversely to the longitudinal direction. Alternatively, the intermediate piece is simply notched. This advantageously forms a separate intermediate piece with the advantages already mentioned.

Fig. 1a bis 1c

die Herstellung einer Kabelader,

Fig. 2

eine Kabelader im Längsschnitt, mit einem Zwischenstück,

Fig. 3

eine weitere Kabelader im Längsschnitt, mit einem vorbereiteten Zwischenstück zum Verbinden zweier Leiterenden,

Fig. 4

eine weitere Kabelader im Längsschnitt, mit einem alternativen Zwischenstück,

Fig. 5

eine weitere Kabelader im Längsschnitt, mit einem alternativen Zwischenstück,

Fig. 6

eine weitere Kabelader im Längsschnitt, umfassend einen als Hohldraht ausgebildeten Leiter,

Fig. 7

eine weiter Kabelader im Längsschnitt, mit einem langen Zwischenstück,

Fig. 8

eine weiter Kabelader im Längsschnitt, mit einem langen Zwischenstück,

Fig. 9

ein Kabel im Querschnitt, und

Fig. 10

im Querschnitt eine alternative Ausführungsform des Kabels gemäß Fig. 9.

Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. It shows schematically:

1a to 1c

the production of a cable core,

Fig. 2

a cable core in longitudinal section, with an intermediate piece,

Fig. 3

another cable core in longitudinal section, with a prepared intermediate piece for connecting two conductor ends,

Fig. 4

another cable core in longitudinal section, with an alternative intermediate piece,

Fig. 5

another cable core in longitudinal section, with an alternative intermediate piece,

Fig. 6

another cable core in longitudinal section, comprising a conductor designed as a hollow wire,

Fig. 7

another cable core in longitudinal section, with a long intermediate piece,

Fig. 8

another cable core in longitudinal section, with a long intermediate piece,

Fig. 9

a cable in cross section, and

Fig. 10

in cross section an alternative embodiment of the cable according to Fig. 9 .

The production of a cable core 2 in longitudinal sectional view is in the 1a to 1c shown. This shows Fig. 1a a conductor 4 designed as a raw wire, which is separated at predetermined length positions 6 to form a space 8. For this purpose, in the exemplary embodiment shown here, a punching tool 10 with a punching direction S is provided, which cuts out a section 14 with a predetermined length L from the conductor 4 to form two separation points 12, two conductor ends 16 being formed.

Fig. 1b shows the conductor ends 16 with an intermediate piece 18 arranged between them. This has two end faces 20 with a predetermined distance A from one another, this expediently being the same as the separated one Length is L1. The conductor ends 16 are connected to the intermediate piece 18, for example welded.

In the exemplary embodiment shown, the intermediate piece 18 and the conductor 4 each have the same diameter, that is to say they are aligned with one another.

After the insertion of the intermediate piece 18, a conductor strand is formed similar to a raw wire, which is provided as an endless strand, that is to say as so-called yard goods and can be used, for example, for the subsequent process steps and, if necessary, can also be temporarily stored rolled up on a drum. The conductor strand is composed of a large number of conductor pieces, in particular of the same length, which are each connected to an intermediate piece 18.

The respective conductor 4 typically has a diameter in the range of a few millimeters, in particular 1 to 3 mm. It is in particular a solid wire, in particular copper wire. This is preferably provided with a coating, for example nickel coating or silver coating. The layer thickness here is a few micrometers, for example 1 to 1.5 μm.

The intermediate piece 18 has a length in the range of a few millimeters, for example in the range of 3 to 10 mm and in particular of 5 mm. Correspondingly, the distance between the opposite conductor ends 16 is the length of the intermediate piece 18. In the exemplary embodiment, the intermediate piece 18 is designed as a cylindrical intermediate piece.

The distance between two intermediate pieces 18 which follow one another in the longitudinal direction and thus the length of a respective conductor piece is typically in the range of several 10 meters, for example in the range of 50 m or a multiple thereof, for example in the range of approximately 100 m. The spacers 18 are spaced apart from one another in such a defined grid dimension with this grid length. The total length of one Cable core 2 is in the range of several hundred meters to a few kilometers.

After the provision of such a conductor strand consisting of individual conductor sections, connected to the intermediate pieces 18, as in FIG Fig. 1c shown, an insulation jacket 22 applied, which is extruded here from a plastic. The insulation jacket 22 has a constant diameter D1 along the entire cable core 2, in particular also in the region of the intermediate piece 18.

The 2 to 6 schematically show another embodiment of the cable core 2 in a longitudinal sectional view. A section of the cable core 2 is shown in the area of the intermediate piece 18 seated in the intermediate space 8.

This in Fig. 2 Intermediate piece 18 shown is made in one piece and essentially cylindrical, with a lateral surface 24 which is provided with a wavy profile. As a result, leakage currents are avoided and the partial discharge security of the cable core 2 is increased. Furthermore, the intermediate piece 18 is aligned with the conductor 4. The end faces 20 are concave in the exemplary embodiment shown here. Each of the two end faces 20 is assigned an end face 21 of one of the conductor ends 16, which are correspondingly complementary, that is to say are convex here. The end faces 20 are metallized and welded to the respective conductor end 16.

The intermediate piece 18 is made of a ceramic in the embodiment shown here. Alternatively, the intermediate piece 18 is made of plastic. In a further alternative, not shown here, the intermediate piece 18 is designed as an injection molded part and is formed directly between the two conductor ends 16 by means of a suitable injection mold. As a result, it is expediently possible to manufacture the intermediate piece 18 with a precise fit.

Fig. 3 shows an alternative embodiment of the cable core 2, with a prepared intermediate piece 18, on the end faces 20 of each an adapter element 19 is attached, which is designed here as a conductor piece and in particular is made of the same material as the conductor 4. A prepared intermediate piece 18 is formed by the combination of the intermediate piece 18 with the adapter elements 19. This is connected to the conductor ends 16 by means of the adapter elements 19, in the exemplary embodiment shown here using a cold welding process, preferably using a soldering process, in particular brazing. The adapter element 19 is in particular a few millimeters long, for example 1 to 5 mm. It preferably consists of the same or at least similar material as the conductor 4.

Fig. 4 shows an alternative intermediate piece 18, which here comprises two wire end caps 26. In particular, the intermediate piece 18 shown here is separated at a separation point 28. The separation can either be realized directly by using two wire end caps 26 or alternatively by an intermediate piece 18 designed as a sleeve and severed after being connected to the conductor ends 16.

The wire end caps 26 each have a head 30, which in particular comprises the end face 20. An annular collar 32 extends from the head 30 in the longitudinal direction R. This collar has a profiling on its inner wall 34, which is a thread here. Furthermore, the collar 32 runs around a cylindrical recess with a predetermined depth T. The conductor ends 16 have a reduced diameter D2 over a length L2, which suitably corresponds to the depth T, and are screwed into the wire end cap 26. In an alternative embodiment, the recess is conical and the conductor ends 16 are also conically shaped to complement them.

In the exemplary embodiment shown here, the heads 30 of the wire end caps 26 abut one another, and the insulation jacket 22 is designed throughout. In an alternative embodiment, the two wire end caps 26 are connected to one another, for example glued or welded. The conductor ends 16 seated in the wire end caps 26 can also be additionally glued or welded.

Another embodiment shows Fig. 5 . In it, the intermediate piece 18 is designed as two wire end caps 26, which are placed on the conductor ends 16 and fastened by means of an interference fit. For this purpose, the respective conductor end 16 is cooled and inserted into the wire end cap 26. In an embodiment not shown here, the wire end cap 26 has a profiled inner wall 34 and / or a profiled end face 20 which is further developed in accordance with one of the above-mentioned configurations.

How Fig. 5 shows, the wire end cap 26 has a diameter D3 which is larger than the diameter D4 of the conductor 16. So that the intermediate piece 18 does not build up, the insulating jacket 22 is made thinner in the region of the intermediate piece 18.

Another embodiment of the cable core is in Fig. 6 shown. There, the conductor 4 is designed as a hollow wire with a cavity 4a extending in the longitudinal direction R. This has an inner diameter D5 transverse to the longitudinal direction. At the conductor ends 16, the intermediate piece 18 is inserted into the cavity 4a by means of suitably designed extensions 18a. In an embodiment not shown here, the extensions 18a have a thread or other profiling in the radial direction, that is to say on a lateral surface lying against the cavity 4a, in order to improve the stability of the connection. In a further alternative embodiment, the cavity 4a is filled with a strain relief, which is advantageously integrally connected to the extensions 18a.

In the 7 and 8 A preferred variant of the cable core 2 is shown in each case, in which the intermediate piece 18 is designed as a long intermediate piece 18. This is similar to that in Fig. 3 connected to the conductor end 16 by means of an adapter element 19 and is thus in particular in the form of a prepared intermediate piece 18. Here is in Fig. 7 A complete conductor section 4 'and an adjoining intermediate piece 18 are shown in each case. The intermediate piece 18 has at its ends a sleeve-like adapter 19 for connection with a respective conductor section 4 'at a respective length position 6. In Fig. 8 only one length position 6 is shown, ie only one of two ends of the intermediate piece 18, which is connected to the conductor end 16 via the adapter element 19; an analog connection takes place at the other end, not shown here. The conductor 4 is divided into conductor sections 4 ', each of which has a section length L3, which corresponds to the distance between two conductor ends 16 of a conductor section 4'.

In the in the 7 and 8 In the exemplary embodiment shown, the intermediate piece 18 has a certain intermediate piece length Z, which corresponds to approximately 1 to 4% of the section length L3. With a section length L3 of approximately 100 m, the intermediate piece 18 is then approximately 2 m long, for example. In this way, a manufacturing-related offset of several intermediate pieces 18 is compensated for at a separation point 12. The length of the intermediate piece Z ensures that the long intermediate pieces 18 overlap transversely to the longitudinal direction R of the cable 2.

The intermediate piece is also designed here as a flexible, tensile element and comprises a tensile core 18b made of aramide and an insulating sheath 18c made of PFA surrounding the core 18b.

The adapter element 19 is in the 7 and 8 formed as a brass sleeve, in which the intermediate piece 18 and the conductor end 16 of the conductor section 4 'are inserted at the end. The entire arrangement is surrounded by a sleeve 35, which is designed as an injection molded part and preferably made of PFA. The sleeve 35 completely surrounds the adapter element 19 and the conductor end 16 attached to it. Advantageously, the sleeve 35 also fills the gusset formed by the adapter element 19 with the conductor section 4 ′ and the intermediate piece 18.

To form the cable core, finally, the insulation jacket 22 is applied around this overall arrangement, which in the exemplary embodiments in FIGS 7 and 8 is carried out in three layers, not shown, namely with an internal banding made of modified PTFE, one applied to this further banding made of PTFE and an outer layer made of extruded PFA, the two bandings being additionally sintered.

In Fig. 7 a further insulation layer 22 ′ made of PFA is additionally arranged within the insulation 22. In a variant not belonging to the invention Fig. 8 on the other hand, the conductor section 4 'is surrounded by an additional conductor insulation 33, which is, however, omitted at the conductor ends 16.

The cable cores 2 of the 7 and 8 are then preferably produced in such a way that the conductor 4 is first divided into a plurality of conductor sections 4 ′ and an adapter element 19 is placed on each of the conductor ends 16 formed here. Subsequently, a long intermediate piece 18 is inserted into the respective remaining end of an adapter element 19, which is then arranged between the two conductor ends 16. The adapter element 19 is then squeezed in particular in order to fix the conductor end 16 and the intermediate piece 18 respectively seated therein. The respective adapter element 19 is then extrusion-coated with PFA to form the sleeve 35. The length of the entire arrangement is optionally surrounded by an insulation layer 22 'made of PFA. Finally, the continuous insulation jacket 22 is applied. For this, there is first a single or double banding with PTFE, which is then sintered; finally, an outermost layer of PFA is extruded.

To produce a cable 36, a number of cable cores 2 are stranded together. An embodiment of such a cable 36 is schematic and in cross section in FIG Fig. 9 shown. The cable 36 shown here comprises three sub-cables 38 stranded together. Each of the sub-cables 38 comprises six core bundles 42 stranded around a strain relief 40. Each of these core bundles 42 in turn has eighteen cable cores 2 which are arranged around a strain relief 44. The core bundle 42 has an inner layer 46 comprising six cable cores 2 and an outer layer 48 comprising twelve cable cores 2. The inner layer 46, the outer layer 48, the partial cable 38 and the entire cable 36 are preferably each surrounded by an additional sheath 50, which is extruded or designed as a banding, for example.

In one embodiment variant, the inner layer 46 and / or the outer layer 48 are each designed as a ribbon cable with six or twelve conductors 4 and are wound around the strain relief 44 in the manner of a banding method. As a result, the manufacturing effort of the wire bundle 42 and thus in particular of the entire cable 36 is reduced.

This in Fig. 9 The cable 36 shown additionally has a sensor module 52 with a sensor 54. To generate an induction field, each of the cable wires 2 is supplied with a current and a voltage at a predetermined frequency. The sensor 54 is then, for example, a Hall sensor, by means of which the sensor module 52 monitors the induction field. In an embodiment not shown here, a number of functional lines are provided in the cable 36, for example temperature sensors designed as optical waveguides. These are then connected to one or more sensor modules 52.

An alternative embodiment of the cable according to Fig. 9 is in Fig. 10 shown. Here the outermost jacket 50 surrounding the three partial cables 38 is designed as a banding. The resulting cross-sectional profile of the cable is therefore a triangle with rounded corners.

In the in the Figures 9 and 10 shown cables 36, the individual core bundles 42 are each formed as stranding elements with a 1-6-12 stranding of individual elements. The central strand is designed as a strain relief 44. The core bundle 42 produced in this way has, for example, a diameter in the range from approximately 8 to 15 mm, in particular approximately 12 mm.

The individual sub-cables 38 are in turn formed as a stranded composite consisting of the central strain relief 40 and six core bundles 42 stranded around it. In the exemplary embodiment, but not necessarily, this stranded composite is still surrounded by a jacket, which is used, for example, as an extruded jacket 50 or as a banding, for example by means of a jacket Polyester tapes is formed. This partial cable 38 preferably has a diameter in the range of a few centimeters, for example in the range from 2.5 to 6 cm and in particular in the range of approximately 4 cm.

A central strain relief wire is expediently additionally inserted between the three sub-cables 38 in a manner that is not shown in any more detail.

The maximum width of the cable 36, so in the case of Figure 9 the diameter and in the case of the triangular configuration according to Figure 10 a leg length of the isosceles triangle is again several centimeters, in particular approximately 6 to 12 cm and preferably approximately 8 cm. The three sub-cables 38 are in turn stranded together. Both cable types according to the Figures 9 and 10 are expediently still surrounded by a jacket 50, which is formed by means of an extrusion process. It expediently has a jacket thickness in the range of a few millimeters, in particular in the range of 2.5 to 5 mm.

The formed cable 36 preferably has a length of several 100 meters up to a few kilometers.

Reference list

2nd

Cable core

4th

ladder

4a

cavity

4 '

Conductor section

6

Length position

8th

Space

10th

Punching tool

12th

Separation point

14

section

16

Head end

18th

Spacer

18a

Process

18b

core

18c

Sheathing

19th

Adapter element

20

End face (intermediate piece)

21

End face (conductor)

22

Insulation jacket

22 '

Insulation layer

24th

Lateral surface

26

Wire end cap

28

Separation point

30th

head

32

collar

33

Conductor insulation

34

Interior wall

35

sleeve

36

electric wire

38

Partial cable

40

Strain relief (partial cable)

42

Core bundle

44

Strain relief (core bundle)

46

Inner layer

48

Outside location

50

coat

52

Sensor module

54

sensor

A

distance

D1

Diameter (insulation jacket)

D2

Diameter (end of conductor)

D3

Diameter (wire end cap)

D4

Diameter (conductor)

D5

Inside diameter

L1

length

L2

Length (conductor end)

L3

Section length

R

Longitudinal direction

S

Punching direction

T

depth

Z.

Adapter length

Claims (15)

1. Cable core (2) for a cable (36) with a plurality of such cable cores (2), which has a conductor (4) that is interrupted in the longitudinal direction (R) at predetermined length positions (6) at a plurality of separation points, forming two conductor ends (16), wherein an insulating intermediate piece (18) is provided for connecting the conductor ends (16), on which the conductor ends (16) are arranged on both sides, the intermediate piece (18) being designed as a flexible, tension-resistant element,
   characterized in
   that the conductor (4) and the intermediate piece (18) (2) are surrounded together by a continuous insulating sheath (22) to form the cable core, and in that the insulating sheath (22) is applied directly to the conductor (4) and is guided continuously over the intermediate piece (18).
2. Cable core (2) according to the preceding claim,
   characterized in
   that the conductor (4) has a number of conductor sections (4') which are separated from one another by the length positions (6) and each have a section length (L3), and in that the intermediate piece (18) has an intermediate piece length (Z) which is at least 0.5% of the section length (L3).
3. Cable core (2) according to any of the preceding claims,
   characterized in
   that the intermediate piece (18) comprises a tension-resistant core (18b) and an insulating sheathing (18c) surrounding the core.
4. Cable core (2) according to one of the preceding claims,
   characterized in
   that a respective conductor end (16) is surrounded by a sleeve (35), which in turn is surrounded by the continuous insulating sheath (22).
5. Cable core (2) according to one of the preceding claims,
   characterized in
   that the insulating sheath (22) is formed with at least two layers, with two layers of different materials.
6. Cable core (2) according to one of the preceding claims,
   characterized in
   that the intermediate piece (18) and the conductor (4) are aligned in the longitudinal direction (R) and/or in that the intermediate piece (18) has an outer surface (24) with an undulating profile.
7. Cable core (2) according to one of the preceding claims,
   characterized in
   that the intermediate piece (18) has a first end face (20) and the conductor end (16) has a second end face (21) facing this first end face (20), the end faces (20, 21) each being provided with a profile.
8. Cable core (2) according to one of the preceding claims,
   characterized in
   that the intermediate piece (18) is metallized on the end face.
9. Cable core (2) according to one of the preceding claims,
   characterized in
   that the intermediate piece (18) is cut through.
10. Cable core (2) according to one of the preceding claims,
    characterized in
    that the intermediate piece (18) is designed as a wire end cap (26) and the conductor end (16) is seated in a recess which is introduced into the end face of the intermediate piece (18).
11. Cable core (2) according to one of the preceding claims,
    characterized in
    that an adapter element (19) is attached to the end face of the intermediate piece (18) to form a prepared intermediate piece (18).
12. Cable (36), with a plurality of cable cores (2) according to one of the preceding claims.
13. Cable (36) according to claim 12, which has a non-circular cross-sectional area or in that a number of cable cores (2) are combined in the manner of a ribbon cable, in which a plurality of conductors (4) are arranged next to one another in one plane and have a common insulating sheath (22).
14. Method for producing a cable core (2) for a cable (36), wherein

    - a conductor (4) is provided which is repeatedly separated at predetermined length positions (6) in such a way that two conductor ends (16) spaced apart by an intermediate space are available,

    - an insulating intermediate piece (18) is inserted into the intermediate space (8), and

    - the conductor (4) and the intermediate piece (18) are provided together with a continuous insulating sheath (22) to form the cable core (2), so that the insulating sheath (22) is applied directly to the conductor (4) and is guided continuously over the intermediate piece (18),

    - wherein the intermediate piece (18) is formed as a flexible, tension-resistant element.
15. Method according to the preceding claim,
    characterized in
    that the conductor (4) is cut at the predetermined length positions (6) by cutting a section (14) with a specific length (L) from said conductor.

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