EP3958406A1 - Branching system for electric conductors - Google Patents

Abstract

The branching system comprises a protective housing (1) with through openings (17, 17') for passing through a multi-core main cable (19) and at least one branch terminal (33) with an electrical connecting element (49) for the uninterrupted connection of one core (29) of the main cable ( 19) with a branch cable. Inside the protective housing (1), the exposed cores (29) of the main cable (19) are held at a distance from one another by a spreading device with at least one non-combustible spacer (31).

Description

The invention relates to a branch system and a method for securely connecting at least one branch line to one of the cores (29) of a multi-core main cable (19) according to the preamble of patent claims 1 and 10.

In tunnel systems, electrical consumers such as lighting, escape route signalling, ventilation, etc. must be able to be reliably supplied with electricity. Such consumers are arranged distributed along the respective tunnel and are electrically conductively connected via branch cables to corresponding conductors of a multi-core main power cable, also called main cable or through cable. Such main cables are usually in the form of round cables, with a number of cores being embedded in an electrically insulating sheath. Each core includes an individually insulated elongated conductor. A main cable typically comprises two to five such conductors, each with a cross-sectional area in the range from about 10mm2 to about 50mm2.
It is known to use terminals located within a housing to connect a branch cable to a main cable. The housing protects the terminal points from environmental influences such as dust or water and from physical contact.

The housing includes openings for inserting an incoming and outgoing leg end of the main cable and a leg end of the branch cable. The cable ends are usually inserted into the housing through cable glands or membranes. As a result, the space between each cable and the respective housing opening can be closed or sealed. In addition, the cables can be held in the desired position on the housing. Inside the housing, the end areas of the outer insulation jacket are removed from the three cable strands and the end areas of the core insulation from the wires. Each terminal includes openings for inserting the stripped ends of an incoming and outgoing wire of the main cable and the associated wire end of the branch cable. By tightening a clamping screw or generally by a clamping mechanism, the three stripped conductor ends are connected to one another in an electrically conductive manner via a connecting conductor of the terminal. The main cable therefore comprises a large number of sections which are mechanically and electrically connected to one another by the terminals at the branch points. The installation of each drop cable typically requires a continuous section of each trunk to be separated into two sub-runs. The severed conductors are then reconnected to one another and to the associated conductors using the clamps of the branch cable. This is comparatively complex. The electrical connections at the terminals are weak points with a lower electrical conductivity. They can cause losses in energy transmission.

From the EP0338952A1 a branch connector is known which enables two wires to be connected without prior stripping. The branch connector comprises two clamping jaws, between which the wires arranged parallel to one another are clamped by means of a clamping screw. One of these clamping jaws comprises a metal perforator with a metal plate and cutting prongs protruding thereon in the direction of the veins. When tightening the clamping screw, the cutting prongs perforate the insulation of the adjacent wires and thus establish electrical contact with the respective conductors. The two conductors are electrically connected to each other via the metal plate.

From the EP2658542A1 a branching device with a disconnecting device is known which is designed to automatically, reversibly or irreversibly interrupt an electrical connection between a branch line and a continuous conductor of a flat cable when the ambient temperature rises above a predetermined fire-typical value. This can the functional integrity of the through line must be ensured in the event of a fire. A screw terminal designed to receive a stripped end of the branch line is connected via the separating device to a contact element which penetrates the electrical insulation of a wire of the through line and is electrically connected to the respective conductor.

DE10218103348A1 discloses a further junction device with a fuse element for interrupting the electrical connection between contacting elements for two conductor sections when a predetermined limit temperature is exceeded. The fuse element and the contacting elements are arranged inside the housing on a ceramic base element. The ends of the conductor sections are inserted into the housing through moisture-insulating cable entries.

In the event of a fire, safety power supplies must be able to maintain the functionality of main cables for a minimum of 30 to 90 minutes. As a rule, in the case of corresponding branching devices, connection units with a plurality of terminals are used, which are made of a high-temperature-resistant, non-combustible material, for example ceramic materials. Such components are comparatively expensive and sensitive to impact. Such clamping units are known to be placed in halogen-free, self-extinguishing plastic housings together with fuses for interrupting connections of one or more branch circuits to the respective main conductors. Such branching devices are usually attached directly to walls or ceilings.

One object of the present invention is to create a branching system suitable for safety power supplies, which enables the reliable and safe connection of at least one branch line to one of several cores of a main cable, in particular a round main cable.

This object is achieved by a branching system and by a method according to the features of patent claims 1 and 10.

The branching system includes a protective housing, which can be made of metal, in particular coated steel, stainless steel or coated stainless steel or a self-extinguishing or flame-retardant plastic or includes corresponding parts depending on the environmental conditions at the place of use. The protective housing comprises a housing base and a cover which can be connected tightly to this housing base. A secure connection can, for example, by screwing the adjoining housing parts, preferably with a sealing element arranged in between.
The housing includes two through openings through which a main cable can be passed through the protective housing. These passage openings are preferably designed as recesses on the edge of two opposing sections of the wall of at least one of the two housing parts. If the housing parts are separated or the protective housing is open, the main cable can simply be inserted into the recesses and passed through the protective housing without interruption.
In the area of the recesses, the protective housing preferably includes structures for attaching elastic cable bushings.
Such cable bushings can be, for example, two profile bodies each with a preferably rectangular cross section and each with a recess adapted to the contour of the main cable. In the case of profile bodies for round cables, the cross section of the recesses is semicircular.
When inserting the main cable into the protective housing, two profile bodies are placed on the outside of the main cable at each of the passage openings on both sides, with these profile bodies being held on the housing by the fastening structures. When screwing the two housing parts, the two housing parts and the profile body are each Cable bushing pressed together so that the main cable is tightly and non-positively connected to the protective housing at each of the passage openings. The profile bodies of each of the cable bushings therefore also act as strain relief for the main cable. By using cable bushings with different diameters of the recess, a protective housing can be used without further adjustments in combination with main cables that have an outside diameter of the order of about 10 mm to about 54 mm and each have two to five cores. Such profile bodies preferably comprise a plurality of shells which lie tightly against one another. In the case of profile bodies for round cables, these shells have the shape of half cylinder jackets with different diameters. The binding forces between adjacent shells are comparatively small, so each profile body can be split along the boundaries between adjacent shells without tools. As a result, the inner diameter of the central recess can easily be adapted to the outer diameter of different main cables. Such protective housings can be used in connection with main cables of different outer diameters simply by adapting the cable bushings. The material composition of cable bushings is preferably heat-resistant. Destruction of the cable bushings in the event of a fire is tolerable if no electrically conductive materials are involved develop. Other measures such as self-extinguishing core insulation of fire protection cables and a spreading device with at least one non-flammable spacer can be used to ensure that the conductors of the main cable do not touch inside the protective housing even if the cable bushings are defective or missing.
Star-shaped or round ceramic disks with peripheral recesses for laying one core of the main cable inside the protective housing can be used as spacers, for example. The outer insulating sheath of the main cable is removed on a section inside the protective housing. This exposes the usually twisted wires. By inserting and aligning at least one spacer between the cores, these cores are spread and reliably held relative to each other within the housing. Preferably, two star-shaped ceramic disks are placed between the veins so that each vein lies in one of the peripheral recesses of each ceramic disk. By exerting an axial compressive force on each of the ceramic discs in the direction of the respective through-opening of the protective housing, the cores are reliably spread and held in this position. For applications in which at least local vibrations can occur, for example in the case of cabling in ships, two star-shaped spacers can be used if required additionally held in the respective position with a non-combustible and non-conductive spacer bolt, for example.
The conductors of one or more of the exposed cores inside the housing can be contacted individually without prior removal of the core insulation using a branch terminal with a cutting electrical connection element. The corresponding conductor of a branch cable is connected to the connecting element via a further connection contact of the branch terminal.
Preferably, each branch terminal comprises two jaws which can be pressed together by means of a clamping device. A suitable clamping device is, for example, a lead screw protruding from one jaw in combination with a nut for clamping the second jaw.
A connecting element with a protruding cutting element is arranged on at least one of these jaws, which penetrates the insulation of the wire to be connected when the jaws are pressed together and contacts the respective main conductor. In order to position or align the wire section to be connected, the branch terminal can have a guide structure, for example a guide groove, on at least one of the jaws.
The nut can, for example, comprise a front section with an internal thread and a rear section with a larger inner diameter without an internal thread. the The nut can have a predetermined breaking point between the two sections, for example a thin area formed by a circumferential groove. When tightening the nut, the two sections are separated when a maximum torque that can be defined by the thin point is exceeded. As soon as the cutting element has severed the insulation of the wire to be connected when the jaws are pressed together and is in contact with the hard metallic conductor, the rear section of the nut is sheared off due to the higher torque acting. The wire is now held in a defined manner between the jaws, and the connecting element is securely connected electrically to the conductor of the wire. The connecting element preferably comprises a further protruding cutting element, with which the respective branch conductor can also be connected to the connecting element of the branch terminal in an analogous manner. This has the advantage that only one screw or nut has to be tightened to connect the branch conductor to the main conductor.
Alternatively, the branch terminal could also include another means for connecting a branch line, for example an additional screw terminal.
Electrically conductive parts of the branch terminal, in particular those that can come into contact with the main conductor and/or the branch conductor, are preferably at least partially electrically insulated. Plastics, in particular self-extinguishing, can be used as insulating materials, for example plastics are used. Even if the insulation of such branch terminals should lose its effectiveness in a fire due to extreme heat, spreading the cores with spacers can ensure that the conductive parts of branch terminals do not touch each other.
The protective housing comprises at least one further passage opening for inserting an end section of the branch cable or individual wires thereof. Each such further passage opening is preferably a borehole in a wall section of the housing base. Adjacent to this wall section, a docking housing can be attached to the outside of the protective housing. Screws or metal retaining brackets, for example, are suitable as fastening means. Electrical and/or thermal safety elements, for example, can be arranged in this docking housing, which bring about the safe separation of a continuing section of the branch cable in the event of a short circuit and/or fire. The arrangement of branch terminals and any additional safety elements in separate housings enables branch systems to be flexibly adapted to different requirements. The optimally protected, uninterrupted contacting of the main lines within the fire-resistant protective housing means that the functionality of the main line can be ensured in the best possible way.

The branching system is robust, impact-resistant and tight. Assembly at the respective place of use is easy, since application-specific parts can be assembled in advance. After attaching the protective housing, to which a docking housing is optionally already attached, only the required branch terminals have to be connected to the cores of the main cable. Even in the event of a fire, it is ensured that the continuous main cable is not interrupted and retains its function. Using thermal fuses in the docking housing, local branch lines can be reliably isolated from the mains independently of the main lines.

Figur 1

eine perspektivische Ansicht eines Abzweigsystems,

Figur 2

das Abzweigsystem aus Figur 1 mit einem angeschlossenen Hauptkabel, jedoch ohne Gehäusedeckel in einer Frontansicht,

Figur 3

eine Seitenansicht der Anordnung in Figur 1,

Figur 4

eine Kabeldurchführung,

Figur 5

einen Abstandhalter,

Figur 6

eine Abzweigklemme.

The invention is described in more detail below with reference to some figures. show it

figure 1

a perspective view of a branch system,

figure 2

the branch system figure 1 with a main cable connected, but without a housing cover in a front view,

figure 3

a side view of the arrangement in FIG figure 1 ,

figure 4

a cable bushing,

figure 5

a spacer,

figure 6

a branch terminal.

figure 1 shows parts of a preferred embodiment of a branching system in an external view. It comprises an essentially cuboid protective housing 1 made of metal with a housing base 3 and a cover 5 screwed to the housing base 3. The protective housing 1 can be attached to a wall or ceiling, for example by means of a retaining clip 4 screwed to the housing base 3. The housing parts preferably have the shape of right-angled trapezoids in cross section, the width B1 of the shorter trapezoidal leg of the housing base 3 being able to correspond at least approximately to the width B2 of the longer trapezoidal leg of the cover 5 .
Holding structures 7, 9 which correspond to one another are preferably formed on the corresponding longitudinal sections of the walls of these housing parts. When the cover 5 is separated from the housing base 3, it can be placed on the housing base 3 such that the support structures 7, 9 engage one another. This ensures that the cover 5 is held securely when the protective housing 1 is opened for installation or maintenance work. The wall edges of the two housing parts arranged in this way lie in a plane which is inclined relative to the base area of the housing base 3 at an angle of inclination α, which can be, for example, of the order of about 0° to about 45°. Preferably, this angle of inclination is α in Range from 10° to 30°. This makes the interior of the housing more accessible.
The edge regions of the housing base 3 and the cover 5 which adjoin one another in the closed state can comprise outwardly protruding flanges 11, 13 which can be screwed together. At least one of these flanges 11, 13 preferably forms a closed frame on the respective housing part, on which an elastic sealing ring 15 can be arranged. On each of the two trapezoidal wall sections, the housing base 3 comprises a U-shaped through-opening 17, for example, for inserting a continuous main cable 19. Parallel to this, at each through-opening 17, preferably adjacent to the respective edge section of the flange 11, there is a screen plate 21 with a further U-shaped through-opening 17' arranged. Each aperture plate 21 is connected to the respectively adjacent wall section of the housing base 3 by a metal strip 23 which is deformed twice at right angles. Together, these parts delimit a cuboid receptacle for attaching a cable bushing 25.
At the bottom of the housing base 3, a docking housing 27 is firmly connected to the housing base 3, for example by means of screws. The housing base 3 and the docking housing 27 comprise passage openings that correspond to one another, through which a branch cable or one or more wires of a branch cable can be routed directly from the protective housing 1 into the Docking housing 27 can be performed (not shown). Electrical or electronic components, in particular thermal and/or electrical safety elements, can be arranged in the docking housing 27 according to the requirements of different applications. Branch lines to local consumers can be continued, for example, via additional terminals or connection sockets.
figure 2 shows the arrangement figure 1 with the covers of the protective housing 1 and the docking housing 27 removed, with a main cable 19 being fed through the housing base 3 without any interruptions, with the outer insulation jacket of the main cable 19 having been removed on a section inside the protective housing 1, so that the five cores 29 of the main conductor 19 are exposed. Two disc-like spacers 31 made of a non-combustible and electrically insulating ceramic material with peripheral indentations for each of the wires 29 clamped between the wires 29 keep the wires 29 spread out in a central area of the protective housing 1 at a comparatively large mutual distance from one another. A branch terminal 33 is clamped to one, several or all cores 29 in such a way that an electrically conductive connecting element penetrates the core insulation locally and is electrically conductively connected to the respective main conductor. Also conductively connected to these branch terminals 33 ends of Branch wires that are routed into the adjacent docking housing are not shown. In the case of the branch terminals 33, however, the corresponding receptacles 35 for the branch wires are visible.
figure 3 shows the arrangement figure 1 in a side view looking in the direction of the main cable axis defined by the cable bushings 25. figure 4 shows the structure of a preferred embodiment of the cable bushing 25. This comprises two cuboid blocks made of an elastomer that is flame retardant or self-extinguishing. Combustible substances always produce carbon, which is electrically conductive. Each block comprises a plurality of layers 26 which lie close together and are semi-circular in cross-section, the inside diameters of which essentially correspond to the outside diameters of the different main cables 19 to be accommodated. The outside of the outermost cladding layer is adapted to the cuboid shape of the receptacles on the housing base 3 . figure 5 shows an example of a spacer 31 in the form of a circular disc with five peripheral indentations 37 and a central recess 39. figure 6 shows schematically a branch terminal 33 with two jaws 43 which are movable relative to each other along a threaded spindle 45. The jaws 43 include parallel guide grooves 47 for positioning the portions of a main core 29 and a branch core to be connected. A metal plate is used as the electrical connection element 49 provided with protruding into the two guide grooves 47 prongs 51 as cutting elements or contact areas. Preferably, the prongs 51 are protected under an elastic protective cap (not shown). When the two jaws 43 are pressed together by turning a nut 53 screwed onto the threaded spindle 45 , the prongs 51 penetrate the protective hoods and the insulation of the wires inserted into the guide grooves 47 .

Claims (10)

Branching system for securely connecting at least one branch line to one of the cores (29) of a multi-core main cable (19), comprising a protective housing (1) with through openings (17, 17') for passing the main cable (19) through and one branch terminal (33) each for each branch line to be connected, characterized in that each branch terminal (33) comprises two jaws (43) between which a continuous core section of the main cable (19) can be clamped by means of a clamping device, that at least one of the jaws (43) has an electrical connecting element ( 49) with a protruding cutting element which, when the jaws (43) are pressed together, penetrates the insulation of the wire (29) and contacts the conductor of this wire (29), so that the electrical connecting element (49) includes a contact area of a connecting clamp for connecting the branch line , and that a spreading device with at least one non-combustible spacer (31) to do so is formed to keep the cores (29) of the main cable (19) within the protective housing (1) spaced apart from each other. Branching system according to claim 1, characterized in that the contact area of the connection terminal for connection of a branch line comprises a further cutting element projecting from the connecting element (49), and that the clamping device comprises a threaded spindle (45) and a nut (53) which are arranged in such a way that the jaws (43) and the cutting elements of the electrical connecting element (49 ) are pressed against wires arranged between the jaws (43) when the nut (53) is tightened. Branching system according to Claim 2, characterized in that the nut (53) comprises a weak point for limiting the torque during tightening. Branching system according to one of Claims 1 to 3, characterized in that the spacer (31) is made from a non-combustible, electrically insulating ceramic material. Branching system according to one of Claims 1 to 4, characterized in that the spreading device comprises two disk-like spacers (31) with peripheral indentations for laying cores (29) of the main cable (19). Branching system according to one of Claims 1 to 5, characterized in that the protective housing (1) has a housing base (3) and a housing base (3). (3) screwable lid (5) made of metal, both of which have the shape of a right-angled trapezium in cross-section. Branching system according to Claim 6, characterized in that the through openings (17, 17') are recesses on the edge of the wall of the housing base (3). Branching system according to Claim 7, characterized in that the housing base (3) comprises receptacles for cable ducts (25) in the region of the through-openings (17, 17'). Branching system according to Claim 8, characterized in that cable bushings (25) are arranged at the through-openings (17, 17'), each comprising two elastic blocks with semi-circular cross-section recesses which can be combined with one another so that together they delimit a cylindrical opening , these blocks being made in one piece or comprising several layers (26) in close contact with one another, with semi-circular cross-sections and different diameters. Method for securely connecting at least one branch line to one of the cores (29) of a multi-core main cable (19), characterized in that that the outer insulating jacket is removed from a section of the main cable (19), that the exposed cores (29) in this section are spread using a spreading device, that each of the cores (29) to be connected is connected by means of a branch terminal (33) without interruption to the respective branch line is connected, and that the section of the main cable (19) with the exposed cores (29) is arranged within a protective housing (1) with through openings (17, 17') for the passage of the main cable (19).

Images