EP0980078A1 - Gas - insulated connecting cable, manufacturing and laying method of such a cable - Google Patents

Abstract

When installed, the inflatable liner (6) is forced by the pressure of insulating gas (10), e.g. nitrogen, against the inner surface of its support tube (7). The conductor (1) is suspended centrally from the tube's highest point (25) by a cradle formed by an insulating web (11,17) e.g. of glass fibre. The web edges (19,20) are embedded in side-bands trapped between the liner and a broad cover-band (26) which seals the liner's axial seam. The conductor is stabilised laterally by a second web (13) stitched (22) to the first along each side of the conductor, its edges being bonded to the liner by narrow bands (15,16) parallel to the conductor. The liner and all it encloses, including the conductor, are factory-assembled in a deflated state, loose pouches in the liner on either side of the conductor being carefully folded against the latter and secured by regularly spaced girth straps - opt. by a plastic binding sheath. This compact bundle is drummed and sent to site where, with straps or temporary sheath removed, it is passed through a finishing machine which encloses it in the clip-fastened support tube (7) and applies helical screen conductors (8) and a protective oversheath (9). After partial inflation to confirm component positioning and rectify any leaks, it is laid in a prepared trench and fully pressurised.

Description

The present invention relates to the field gas-insulated cables.

Such cables are used for the transport of electrical energy. The general principle of such cables is known in the state of the art, by example by French patent FR2738946 which describes a gas insulated cable with three conductors metallic inside a metallic envelope waterproof, the cable being made of elements of about ten meters in length assembled end to end, ten approximately of elements thus assembled constituting a section of cable. This cable according to the prior art comprises special elements to allow changes in the cable direction.

Another document of the prior art, the French patent FR2714204 describes a gas-insulated single-phase cable comprising a cylindrical steel tube filled with nitrogen under a pressure at least equal to 10 ⁴ hectopascals, a metallic conductor based on aluminum. or of copper held axially inside the steel envelope by closed insulating cones, and an aluminum envelope forming for the steel envelope a magnetic screen vis-à-vis the magnetic field created by the current flowing through the conductor. The steel casing is separated from the aluminum casing by rings of charged plastic or polymer material each placed in a groove of a metal collar.

The gas-insulated cables (CIG) according to the prior art have a large outside diameter which results from their high voltage and from the limited value of the electric field E ₁ admitted in the gas insulation. The outside diameter of the insulation space of these cables is minimized when the core of a unipolar cable subjected to the voltage U has the diameter (2.U / E ₁ ) and when the insulation space has for outside diameter (2 U / E ₁ ) * exp (1).

The lengths of the connections by C.l.G. art are limited due to the high cost of these cables, due in particular to the routing of short sections, because of the diameter of the cables, implying the connection in situ of tubular elements or short lengths of corrugated tubes with a diameter close to 0.4 meters, transported on drums of about 4 meters diameter.

In addition, the dielectric strength of gas insulation is strongly affected by contamination by metallic dust and imperfections of the equipotential surfaces resulting from mounting. It has been proposed to overcome this drawback by methods of detecting arcs forming in such cables, as in French patent FR2719125.

The object of the invention is to remedy these different drawbacks by offering an insulated cable carbon dioxide of lower manufacturing cost, of a section outer lower than art cable section previous presenting the same performances and whose break is made easier.

To this end, the invention relates to a inflatable structure which will first allow transport, deflated under a reduced diameter practically by a factor exp (1) = 2.72, sections of link whose length can then be increased considerably by reducing the internal diameter of the reel and by the unit section reduced practically by exp (2).

In its most general sense, the invention relates to a gas-insulated cable comprising a core and an outer sheath, the space annular between the core and the envelope being filled an insulating gas, characterized in that the core is surrounded by a pneumatic chamber which presents after inflating a cylindrical shape whose diameter is that cable sheath.

Advantageously, the cable has links flexible extending between the conductive core and the wall inside the pneumatic chamber, to ensure the maintaining the conductive core in the center of the space gas insulation after inflation of the chamber pneumatic.

Preferably, the flexible links are made by non-discontinuous glass fabrics, both of which banks were previously drowned in strips narrow side tires of the same type as the pneumatic chamber.

Alternatively, the cable has a leaktight tubular wall formed by winding a metal strap around the inflatable structure.

According to another variant, the strip is constituted by a stapled tube containing the structure inflatable.

According to a particular embodiment, the cable further comprises a conductive sheet disposed on along the strip surrounding the inflatable structure. According to a variant, it comprises a structure radially armed tire.

According to an advantageous embodiment, the core of the cable is constituted by a cylindrical assembly of conductive strands isolated from each other, and transposed between them, for example inside sectors cylindrical and by an equipotential phase surface produced by taping a semiconductor tape, covered by a mechanically protective coating.

According to a variant, the sheath is a tube stapled surrounded by an envelope consisting of conductors arranged in a helix having channels delimited radially by the stapled tube and by the protective envelope, and delimited laterally by lateral spacing between the elements of the sheet sheath conductor.

According to another variant, the flexible links are made using insulating fabric obtained from one or more fiber materials.

The invention also relates to a method of manufacture of a gas-insulated cable characterized in what we prepare a conductive core and a chamber pneumatic and in that we proceed to the establishment of the pneumatic chamber containing the links in enveloping the soul step by step through the room equipped tire, previously unrolled flat in below the core, the two sides of this room being then arranged edge to edge along an axial line located vertically above the cable core, the pneumatic strips bordering the upper links being superimposed on the banks and made adherent, and in that we then place a cover strip on this set thus prepared.

According to a variant, the pneumatic chamber deflated is placed against the conductive core in now simultaneously in final angular position the upper part of the chamber along the axial line as well as the lower part of the cylindrical periphery of the chamber and laterally pressing against the core conductive the deflated pneumatic chamber in the vicinity tapes. The pneumatic chamber forms two pairs of pockets of similar length on either side of each of the two side bands. These four pockets are folded upwards, stacked two by two and pressed against the conductive core, then held in this position for transporting the structure. This fold up prevents folded side parts of the chamber pneumatic encroach on the bottom of the cylindrical periphery of the chamber. The quadruple withdrawal of lateral parts of the chamber also prevents the side links and that the upper links are not tensioned and do not modify the angular position of the strips tires adhering to the chamber and the common anchor tapes. The invention also relates to a method of laying a gas-insulated cable characterized in that the permanent holding of the pneumatic chamber deflated pressed against the conductive core is provided by a plastic film surrounding the deflated structure, this protective film finally tearing when performs partial inflation of the structure during laying of the cable after the end of its development.

According to a particular mode of implementation, we pass a deflated structure constituting the cable to using a reel and we proceed to the unwinding. A reel develops the tube stapled around the structure deflated after removal of peripheral links so that the structure can be re-inflated, in that one deposits the deflated structure in an axial position and final angular on the bottom of the stapled tube and in that the winder then installs the web conductive bearing on the stapled tube, then laying the protective envelope.

According to a variant of this mode of implementation work, the peripheral links surrounding the structure deflated are replaced by a plastic film which continues to wrap the structure during development stapled tube and conductive sheet, this film plastic then tearing under the effect of partial pressurization of the cable.

According to a variant, the inflation is carried out partial of the structure taking place before the structure be buried.

This structure will also allow achieve electrical insulation including the envelope of gas insulation and spacers will be installed at the factory, thus avoiding access and the risk of contamination during installation of the connection.

The inflatable connecting structure is characterized in that each unipolar cable is surrounded by a pneumatic chamber which after inflation a cylindrical shape whose diameter is that of the cable sheath.

Inside this isolation space gas, links set up in the factory at the same time as the chamber become tense after inflation of the chamber and keep the conductive core in the center of the gas insulation space.

The sheath of each unipolar cable is constituted by an elaborate non-waterproof tubular wall in the field, by winding a metal strip around the inflatable structure from the drum. For example, this strip constitutes a tube stapled containing the inflatable structure.

Around this metal strip, we have along the straight cable a conductive sheet. This tablecloth lowers the electrical resistance of the sheath. She is surrounded by a structure ensuring the protection of strip and conductive sheet against corrosion and giving the conductive sheet the resistance mechanical to electrodynamic forces created in the presence short-circuit current.

a) Il crée l'armature contre laquelle la chambre pneumatique vient se plaquer sur tout son pourtour cylindrique lors du gonflage, et il supporte les efforts mécaniques ainsi créés par la pression du gaz d'isolation électrique.

b) Associé à la chambre gonflée, il constitue un ensemble flexible apte à être déposé dans une tranchée parallèle à la piste le long de laquelle s'est effectué préalablement le déroulement du câble et son assemblage avec le tube agrafé élaboré de proche en proche.

c) Il protège le câble enterré pressurisé contre les forces d'écrasement transmises par le remblai, et contre les efforts locaux créés, par exemple par les racines d'arbres.

d) Par son coefficient de frottement élevé, il maintient en place la chambre pneumatique contenant le câble, dans la position initiale d'élaboration, empêchant ainsi d'une part la reptation du câble dans ses déclivités, et d'autre part la rotation de la chambre pneumatique, ces deux déplacements risquant de modifier le centrage de l'âme du câble à l'intérieur de l'espace d'isolation électrique.

e) L'absence d'étanchéité du tube agrafé assure le maintien de la chambre au contact de celui-ci sur la totalité du périmètre cylindrique, même en présence d'une fuite locale du gaz d'isolation altérant peu la pression intérieure de ce gaz.

f) La température est uniformisée sur le périmètre de la gaine, soit en présence d'une évacuation de la chaleur par un remblai de propriétés thermiques hétérogènes, soit en présence d'une canalisation d'eau placée à proximité de la liaison pour en limiter la température.

The stapled tube containing the inflatable structure performs several functions:

a) It creates the frame against which the pneumatic chamber is pressed over its entire cylindrical periphery during inflation, and it supports the mechanical forces thus created by the pressure of the electric insulating gas.

b) Associated with the inflated chamber, it constitutes a flexible assembly capable of being deposited in a trench parallel to the track along which the unwinding of the cable was carried out and its assembly with the stapled tube developed step by step.

c) It protects the buried pressurized cable against the crushing forces transmitted by the fill, and against the local forces created, for example by tree roots.

d) By its high coefficient of friction, it keeps in place the pneumatic chamber containing the cable, in the initial working position, thus preventing on the one hand the crawling of the cable in its declivities, and on the other hand the rotation of the pneumatic chamber, these two movements being liable to modify the centering of the cable core inside the electrical insulation space.

e) The absence of leaktightness of the stapled tube ensures that the chamber remains in contact with it over the entire cylindrical perimeter, even in the presence of a local leak of the insulating gas slightly altering the internal pressure of this gas.

f) The temperature is uniform on the perimeter of the sheath, either in the presence of a heat dissipation by an embankment of heterogeneous thermal properties, or in the presence of a water pipe placed near the connection to limit it temperature.

During a short-circuit current, the sheath carries a return current which differs little from the current phase; the electrodynamic forces created on the phase conductor tend to center it in the cylindrical volume delimited by the sheath; these forces grow as the driver's initial off-center phase. Given their brevity, and given the mass of the conductor phase, they act especially until the first passage of the soul in a centered position. The shape of the links and their mechanical strength are adapted to the presence of a initial off-center from any direction; the links limit the lateral movement of the conductor phase, so as not to alter the dielectric strength of the link.

A variant of this device consists of remove the metal reinforcement used as a sheath and replace the pneumatic chamber mechanically little resistant by a pneumatic structure radially army. Not being able to undergo a temporary deflation at the bottom of trench, such a structural variant cannot be used than in the gallery.

Several arrangements of the links between the pneumatic chamber and cable core are possible; of even, several methods of making the cable surrounded by the room, in the factory, are possible; finally, several sheath types can be developed in the field. Advantageously, the flexible links are produced by means insulating fabric obtained from one or more fiber materials. Material will exhibit toughness sufficient, no long-term creep, resistance to degradation by cable temperature or by electrodynamic vibrations and brittleness reduced compatible with the process of developing the liaison.

By way of illustration, and for the purpose of show the feasibility of the link, we describe below a connection comprising a particular arrangement of links, a particular process for developing the cable and the factory room, and the development of a type particular sheath on the place of installation of the connection.

• La figure 1 représente une vue en coupe de l'âme du câble ;
• La figure 2 représente une vue en coupe d'un tronçon de câble ;
• La figure 3 représente une vue en coupe de l'ensemble constitué par les liens et la chambre pneumatique, avant l'élaboration du câble ;
• La figure 4 représente une vue de détail de la chambre pneumatique au niveau d'un lien ;
• La figure 5 représente une vue en coupe de la chambre pneumatique dégonflée entourant l'âme du câble ;
• La figure 6 représente une vue schématique du câble en cours de pose.

The invention will be better understood on reading the description which follows, referring to the accompanying drawings in which:

• Figure 1 shows a sectional view of the cable core;
• Figure 2 shows a sectional view of a cable section;
• FIG. 3 represents a sectional view of the assembly constituted by the links and the pneumatic chamber, before the cable is made;
• FIG. 4 represents a detailed view of the pneumatic chamber at the level of a link;
• FIG. 5 represents a sectional view of the deflated pneumatic chamber surrounding the cable core;
• Figure 6 shows a schematic view of the cable being laid.

• un assemblage cylindrique (2) de brins conducteurs isolés l'un de l'autre, et transposés entre eux, par exemple à l'intérieur de K secteurs cylindriques accolés, la section de chaque secteur étant délimitée par deux segments rectilignes formant un angle de 2¹/K et par un arc du cercle dont le diamètre est celui de l'âme du câble ;
• une surface équipotentielle de phase (3) réalisée par rubanage d'un ruban semi-conducteur (4), recouvert par un revêtement mécaniquement protecteur (5).

FIG. 1 represents the core of the cable (1), comprising:

• a cylindrical assembly (2) of conductive strands isolated from one another, and transposed between them, for example inside K contiguous cylindrical sectors, the section of each sector being delimited by two rectilinear segments forming an angle of 2 ¹ / K and by an arc of the circle whose diameter is that of the cable core;
• an equipotential phase surface (3) produced by taping a semiconductor tape (4), covered by a mechanically protective coating (5).

Figure 2 shows a sectional view of the final structure intended to be deposited in the trench after applying reduced pressure to press the pneumatic chamber (6) around the perimeter cylindrical sheath produced by a stapled tube (7) able to contain the forces due to the internal pressure of the insulation gas.

Around the stapled tube (7), there is a conductive sheet (8) capable of transporting the current of sheath, as well as an envelope (9) protecting the tube stapled (7) and the conductive sheet (8) against corrosion and now mechanically these elements in the presence of a short circuit current.

Maintaining the core (1) in a central position in the gas insulation space (10) is obtained by means flexible links (11).

The conductive sheet (8) of the sheath is constituted by conductors arranged in a helix. Of channels (12) are delimited radially by the stapled tube (7) and by the protective envelope (9), and delimited laterally by lateral spacing between the elements of the conductive sheet (8) of the sheath. These channels keep the air pressure around stapled tube despite the tightness of the envelope protection (9).

The flexible links (11) are for example produced by non-discontinuous glass fabrics whose two banks were previously drowned in bands narrow side tires of the same type as the pneumatic chamber (6).

a) On élabore une bande pneumatique de grande longueur, dont la largeur est égale au périmètre de la chambre pneumatique (6).

b) Séparément, on élabore les liens latéraux (13) au moyen d'une bande de tissu de verre (14) de grande longueur dont les rives sont noyées sur leur longueur dans des bandes pneumatiques latérales (15) et (16) étroites

c) Séparément, on élabore de même les liens supérieurs (17) au moyen d'une bande de tissu de verre (18) de grande longueur, dont les rives sont noyées sur leur longueur dans des bandes pneumatiques (19), (20) étroites.

d) On superpose à plat les liens latéraux (13) et les liens supérieurs (17) afin de réunir ces liens au moyen de 2 coutures rectilignes axiales (21) et (22).

e) On étale à plat cet ensemble de façon centrée, sur la chambre pneumatique (6) et on réalise l'adhérence des bandes pneumatiques latérales (15), (16) sur la paroi interne de la chambre pneumatique (6)

f) On enroule cet ensemble qui sera utilisé ultérieurement en usine pour la mise en place de la chambre pneumatique autour de l'âme (1) du câble.

An arrangement of these links and a method of developing the pneumatic chamber containing the links are proposed as follows.

a) A very long pneumatic strip is produced, the width of which is equal to the perimeter of the pneumatic chamber (6).

b) Separately, the lateral links (13) are produced by means of a strip of glass fabric (14) of great length, the edges of which are embedded over their length in narrow pneumatic lateral strips (15) and (16).

c) Separately, the upper links (17) are likewise produced by means of a strip of glass fabric (18) of great length, the edges of which are embedded over their length in pneumatic strips (19), (20) narrow.

d) The lateral links (13) and the upper links (17) are superimposed flat in order to join these links by means of 2 axial rectilinear seams (21) and (22).

e) This assembly is spread out flat in a centered fashion on the pneumatic chamber (6) and the lateral pneumatic strips (15), (16) are adhered to the internal wall of the pneumatic chamber (6)

f) This assembly is wound up which will be used later in the factory for the establishment of the pneumatic chamber around the core (1) of the cable.

Figure 3 shows this arrangement of the pneumatic chamber (6) containing the flexible links (11), this room being stored rolled up before being put in place around the core (1) of the cable.

The installation of the pneumatic chamber (6) containing the links is done by wrapping close in close to the cable core by the pneumatic chamber fitted, previously unwound flat below the core. The two edges (23, 24) of this chamber are then arranged edge to edge along an axial line (25) located at the vertical above the cable core. Groups tires (19, 20) bordering the upper links are superimposed on the banks (23, 24) and made adherent. Finally, a cover strip (26) placed on this assembly fences the pneumatic chamber, ensuring sealing and strengthening the mechanical resistance of this region.

Later, when you pressurize the chamber that rests on the entire internal perimeter of the stapled tube (7), the upper links constitute a continuous cradle (27) containing the core (1) of the cable. The lateral links (13) also become tense and prevent lateral movement of the core (1). The central part of these lateral links (13), located between the axial seams (21, 22) is pressed along the underside of the core (1) of the cable; on the part and on the other, the two side parts of the side links (13), located between the seam (21) and the side band (15), and between the seam (22) and the pneumatic strip lateral (16), are distributed along two inclined planes forming the 2 lateral branches of an inverted Y.

The adhesion of the cover strip (26) carried out in the factory before cable reel surrounded by the deflated chamber is the only one that requires a seal. Its execution is facilitated by the axial arrangement, without discontinuity, of the links and bands constituting their banks.

Figure 4 shows the arrangement of the chamber pneumatic (6) at the level where the upper links (17) are attached to this chamber, forming the upper end (25) from the cradle (27). The connections between the part free of glass fabric (17) and pneumatic strips (19) and (20) are grouped at the upper end (25) of the cylindrical periphery of the pneumatic chamber (6). The pneumatic strips (19) and (20) containing the edges embedded, not overflowing, glass cloth are arranged in T covering the outside face of the chamber pneumatic on either side of this end upper (25). Finally, a pneumatic cover strip (26) covers the bands (19) and (20), ensuring sealing and strengthening the mechanical strength of this region.

When the cradle links surround a core of diameter D _i centered in a sheath of diameter D _e = D _i * exp (l), the part of the glass fabric located in the electrical insulation space, suspended at the end upper (25) of the cradle (27) comprises two flat parts of the upper links (11) and (17), on either side of the curvilinear central part in contact with the cable core. The width of the glass fabric located in the electrical insulation space is: L = D i * [ 1 / 2 + arc sin (1 / exp (1)) + (-1 + exp 2) 1/2 ] = 4.48 D i

The total width of this glass fabric obtained by adding the widths of the flooded ends in the pneumatic belts (19 and 20).

Figure 5 shows a section of the cable surrounded by the deflated chamber, and suitable for being rolled up on a reel.

The cable core, arranged horizontally rests on the lower end (36) of the periphery cylindrical of the pneumatic chamber. Bedroom deflated surrounds the sides of the core (1) of the cable. The glass fiber upper links (17) fixed to the chamber deflated are present between the core (1) and the chamber deflated. They are not mechanically stressed. For that the lateral links (13) do not hinder the folding of the deflated pneumatic chamber (6), the walls of the pneumatic chamber (6) are also supported on the cable core at the axial seams (21) and (22). After which, the excess lengths (28 to 31) of the deflated pneumatic chamber (6) are all folded up along the cable core (1), then held against the soul (1) by means of ties peripherals (32) intended to facilitate installation on a reel of this deflated structure (33) of outline almost cylindrical.

Before placing on a reel, the core (1) of the cable based on a single thickness of the pneumatic chamber deflated (6). Maintaining an angular position unchanged after unwinding of the drum, on the ground of installation, thus avoiding the final inflation of the structure creates a rotation of the core (1) of the cable or of the chamber pneumatic (6).

Figure 6 shows the installation site a connection, with the trench (40) which contains a part of the connection cables, already in place. The development of the connection is carried out along a track (41) parallel to the trench (40). A reel (42) has been routed on this track.

It contains the deflated structure (33). The unfolding takes place by visually checking that the upper position of the upper end (25) of the periphery of the room is respected. The winder (43) develops the stapled tube (7) around the deflated structure (33) after the elimination of the peripheral links (32) so that the structure can be re-inflated. The deflated structure (33) then rests in the final axial and angular position on the bottom (44) of the stapled tube. The four lengths surplus (28 to 31) of the deflated chamber do not encroach under the bottom (44) and will therefore not induce of rotation of the structure upon inflation.

The peripheral links (32) can be constituted by a protective plastic film; this film tears when the inflation of the structure begins.

The winder (43) then performs the installation of the conductive sheet (8) bearing on the stapled tube (7), then the installation of the protective envelope (9).

• Assurer la mise en place définitive de la structure
• Vérifier cette mise en place, par exemple par gammagraphie, et corriger la position angulaire de l'extrémité supérieure (25) de la structure par une rotation locale du tube agrafé
• Détecter les fuites éventuelles et y remédier. Le gonflage final de la structure (33) a lieu lorsque la structure est enterrée.

Partial inflation of the structure (33) takes place before the structure is buried. This partial inflation is intended for:

• Ensure the final establishment of the structure
• Check this positioning, for example by radiography, and correct the angular position of the upper end (25) of the structure by local rotation of the stapled tube
• Detect and remedy any leaks. The final inflation of the structure (33) takes place when the structure is buried.

When the connection is cooled by a water pipe arranged against the cables, the trench depth has little influence on the elimination of the heat; this depth which depends on the diameter of the cables, the maximum pressure allowed and therefore of the nature of the electrical insulating gas, may be then chosen in order to eliminate the risk run above a cable in the event of accidental rupture of its enclosure pressurized.

Claims (15)

Gas-insulated cable with a core and an outer sheath, including the annular space between the core and the envelope being filled with a gas of insulation, characterized in that the core is surrounded by a pneumatic chamber which after inflation has cylindrical shape whose diameter is that of the sheath of the cable. Gas-insulated cable according to claim 1 characterized in that it comprises links flexible extending between the conductive core and the wall inside the pneumatic chamber, to ensure the maintaining the conductive core in the center of the space gas insulation after inflation of the chamber pneumatic. Gas-insulated cable according to claim 2 characterized in that the flexible links (11) are produced by non-discontinuous glass fabrics whose two banks were previously drowned in narrow side pneumatic strips of the same type as the pneumatic chamber (6). Gas-insulated cable according to one at less of the preceding claims characterized in that it has a non-sealed tubular wall formed by winding of a metal strip around the inflatable. Gas-insulated cable according to claim 4 characterized in that the strip is constituted by a stapled tube containing the structure inflatable. Gas-insulated cable according to claim 4 or 5 characterized in that it comprises in addition to a conductive sheet arranged along the strip surrounding the inflatable structure. Gas-insulated cable according to one at less of the preceding claims characterized in that it includes a radially pneumatic structure army. Gas-insulated cable according to one at less of the preceding claims characterized in that the cable core (1) consists of an assembly cylindrical (2) of insulated conductive strands one of the other, and transposed between them, for example to inside cylindrical sectors and by a surface equipotential phase (3) produced by taping a semiconductor tape (4), covered by a coating mechanically protective (5). Gas-insulated cable according to one at less of the preceding claims characterized in that the sheath is a stapled tube (7) surrounded by an envelope formed by conductors arranged in a helix having channels (12) delimited radially by the tube stapled (7) and by the protective casing (9), and delimited laterally by a lateral spacing between the elements of the conductive sheet (8) of the sheath. Gas-insulated cable according to one at less of claims 1 or 2 characterized in that the flexible ties (11) are made using insulating fabric obtained from one or more fiber materials. Method for manufacturing a cable gas insulation according to claim 1 characterized in that a conductive core is prepared and a pneumatic chamber and in that one proceeds to the installation of the pneumatic chamber (6) containing the ties (11) by gradually wrapping the soul (1) by the equipped pneumatic chamber, previously unrolled flat below the core, the two edges (23, 24) of this chamber then being arranged edge to edge along an axial line (25) located vertically above the cable core, the pneumatic bands (19), (20) bordering the upper links being superimposed on the banks (23, 24) and made adherent, and in what we place next a cover strip (26) on this assembly thus prepared. Method for manufacturing a cable gas insulation according to claim 11 characterized in that the deflated pneumatic chamber (6) is placed against the conductive core by simultaneously maintaining in final angular position the upper part of the chamber along the axial line (25) as well as the lower part (36) of the cylindrical periphery of the chamber and laterally pressing against the core conductive the deflated pneumatic chamber in the vicinity side bands (15 and 16), the pneumatic chamber forming two pockets (28 and 30) of lengths close to on either side of the side strip (15) and forming two other pockets (29 and 31) on either side of the strip side (16), these four pockets being folded towards the high, stacked two by two and pressed against the core conductive and then held in this position for the transport of the structure. Method of laying an insulated cable gas according to claim 11 or 12 characterized in that that keeping the room in place deflated tire pressed against the conductive core is secured by a plastic film (32) surrounding the deflated structure, this tearing protective film finally when the partial inflation of the structure when laying the cable after the end of its elaboration. Method of laying an insulated cable gas according to claim 1 characterized in that a deflated structure (33) is conveyed constituting the cable using a reel (42), in that one proceeds during unwinding, in that a winder (43) develops the stapled tube (7) around the deflated structure (33) after the elimination of the peripheral links (32) so that the structure can be re-inflated, in that one deposits the deflated structure (33) in the axial position and final angular on the bottom (44) of the stapled tube and in this that the winder (43) then performs the laying of the web conductive (8) resting on the stapled tube (7), then the installation of the protective envelope (9). Method of laying an insulated cable gas according to claim 14 characterized in that the partial inflation of the structure is carried out (33) taking place before the structure is buried.

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