DE3306501A1 - Heavy-current cable - Google Patents

Abstract

A heavy-current cable which is provided with a core, a screen, a protection sheath and, if required, reinforcement or armouring, has a metal foil in order to divert undesired internal changes, as a blocking layer of the protection sheath which is impermeable to moisture, in the case of which metal foil, one of the two covering layers which cover this metal foil is constructed to be electrically conductive, as a result of which electrical contact links to other electrically conductive parts of the cable can be produced, which contact links are located in the vicinity of the electrically conductive covering layer. An electrically conductive cushion strip is expediently used for this purpose, which surrounds an electrically conductive screen consisting, in particular, of copper wire.

Description

Power cables

DESCRIPTION The invention relates to a power cable of the in the preamble of claim 1 mentioned genus.

Such power cables are already known. Since such cables are multiple are laid in the ground, must be ensured by a suitable structure of the cable that even in the event of moisture, including damp vapors, there is no risk of electrically conductive bridges between the voltage leading ladder or the tensions leading ladders within the soul and the Shield of the cable or that material arise in which the power cable is embedded or inlaid. It is known (LUEGER, Lexikon der Energietechnik and Kraftmaschinen, 1965, pages 582/83) to use layered insulation, which consists of several layers. Aluminum is also used because this is well suited as moisture protection and due to its good electrical conductivity can also be used as an earth conductor. Corrugated copper sheet is also called electrical conductive screen used.

However, it has been shown that in the case of embedding a protective jacket between the electrically conductive screen and the outer one, in particular made of plastic existing sheath of the cable tension problems occur especially when the protective jacket made of a thermoplastic layer coated on both sides Metal foil is made, which is placed in a tubular shape around the electrically conductive screen and along the overlapping longitudinal edges of the metal foil below Application of pressure and heat is tightly fused.

The invention is based on the object of the power cable mentioned at the beginning to the effect that it is undesirable without increased expenditure for better degradation Tension in the metal foil, i.e. in the moisture-impermeable barrier layer of the protective jacket.

The invention consists in that at least one of the two cover layers the metal foil is designed to be electrically conductive. When the electrically conductive Cover layer facing the screen, in particular made of copper wire, creates a Numerous electrically conductive bridges between the metal foil and the screen Via the electrically conductive cover layer and its contact points with the contacting ones Split the copper wire shield.

This electrical multiple contact at many points along the cable axis and around the cable core builds through quickly and easily Induction build-up in the metal foil from voltages to the copper wire screen, see above that there is no need for additional ladder bridges, which involve considerable additional expense mean.

In the invention, the contact is made completely automatically during the manufacture of the Power cable, so that additional No more measures to be taken when installing the cable within the cable set required are.

The invention is explained in more detail below with reference to the drawing. 1 shows a partial cross section through a power cable according to FIG the invention; Fig. 2 is a partial cross-section through the moisture-impermeable Barrier, including the overlap zone.

According to FIG. 1, the cable core consists of a solid conductor 1 Aluminum, an electrically conductive plastic layer 2, an electrically insulating one Plastic layer 3 and a further electrically conductive layer 4. Instead of the one conductor, several individual conductors can each be isolated from one another can be used, and instead of aluminum, other electrically conductive materials can also be used Material, such as copper, find application.

An electrically conductive screen 5 is placed around the cable core, which is formed from copper wire and impregnated between electrically conductive Upholstery strips 6 can be embedded.

Around the screen, possibly surrounded by an outer upholstery band 6 5, a moisture-impermeable barrier layer 7 is arranged in the following manner Way: One according to FIG. 2 made of a metal foil 7a and two cover layers 7b and 7 c formed band is arranged in a tubular shape that the longitudinal edges of the same overlap in the area of the overlap zone ÜZ. By applying pressure and heat are the abutting parts of the inner cover layer 7c and the outer one Cover layer 7b fused or sealed to one another.

For this purpose, the cover layers 7c and 7b are particularly suitable thermoplastic plastic that softens at a certain temperature and below hardens again at a certain temperature, so that a solid bond between the two adjacent fused areas of the cover layers 7c and 7b and therefore also the metal foil 7a in the area of the overlap zone UZ is.

Around this moisture-impermeable barrier layer 7 can be a further cushioning layer 8, which is finally covered by an outer jacket 9 is surrounded by plastic.

According to the invention is the radially inner or lower cover layer 7c, in contrast to the radially outer or upper cover layer 7b, is not only made of electrical insulating thermoplastic material. Rather, this is inner or lower cover layer 7c made electrically conductive in that electrically conductive particles are embedded in the plastic. Above all, they are suitable for this Graphite and carbon black.

Claims (6)

PATENT / PROTECTION CLAIMS Power cables with one core, one screen and a protective jacket and, if necessary, with reinforcement or armouring, in which the soul is a vein or a group of veins, each consisting of a conductor and an insulation surrounding it in an electrically insulating manner, and the protective sheath have a moisture-impermeable barrier layer, which is of a double-sided is formed with a metal foil coated in each case, which is tubular around the core and an electrically conductive screen surrounding it Copper wire and laid along their overlapping longitudinal edges by means of a a hotmelt adhesive or a thermoplastic covering layer is tightly sealed or is welded, characterized in that at least one of the two cover layers (7b, 7c) of the metal foil (7a) is designed to be electrically conductive. 2. Power cable according to claim 1, characterized in that the electrically conductive cover layer (7c) faces the screen (5). 3. Power cable according to claim 1 or 2, characterized in that that the electrically conductive cover layer (7c) consists of hot-melt adhesive or lacquer, which are filled with electrically conductive particles made of graphite and / or carbon black are. 4. Power cable according to claim 3, characterized in that the electrically conductive particles have a particle size of the order of 1 - 100 µm. 5. Power cable according to one of the preceding claims, characterized characterized in that between the screen (5) and the electrically conductive cover layer (7c) an electrically conductive upholstery tape (6) is arranged, which is made of conductive Textile material (fabric or fleece) or paper interspersed with particles. 6. Power cable according to claim 5, d a d u r c h g e k e n n z e i c h n e t that the electrically conductive upholstery tape (6) with graphite and / or carbon black is impregnated.