FI63843C - FOERFARANDE FOER RETABLERANDE AV DET INRE HALVLEDANDE SKIKTET VID HOPFOGNING AV KABLAR SAERSKILT HOEGSPAENNINGSKABLAR SAMTREDSKAP FOER BRUK VID FOERFARANDET - Google Patents

Description

RSSF ^ l rB, ANNOUNCEMENT, χ * Αχ jSTg m v1) utlAgg n I ngsskri pt 638 4 3 (51) Kv.ik? /Int.ci.3 H 02 G 1/14, 15/08 FINLAND —FINLAND (2.1 ) P * Mnttlh * k * mu «—P * Unt« n * eWn | 7721 ^ 1 (22) HakamlspUvi - Anaeknlngidag 08.0T.T7

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(41) Tullut (ulklMkal - Bllrtt offuntNg 10.01.78 !! * tWlttl ~ ** reklrterHmltitU »(44) Nlhtivilulpunon | ) (33) (31) Pjnrdutty utuolkuut-lUjIrd priorftut 09-07.76

Denmark-Danmark (DK) 3106/76 (71) Aktieselskabet Nordiske Kabel- og Traadfabriker, Le Cours Vej 7, DK-2000 K ^ benhavn F, Denmark-Danmark (DK) (72) Ole Kjaer Nielsen, K ^ ge, Denmark -Danmark (DK) (7 ^ +) Oy Roister Ab (5U) Procedure for renewing the internal semiconductor layer by connecting cables, especially high-voltage cables, and the tool used in the procedure - The present invention relates to a method according to the preamble of claim 1 for renewing an internal semiconductor layer by connecting cables, in particular high-voltage cables, and to a tool used in the method.

When connecting cables, the conductor is exposed to a suitable length at the cable ends and then connected by soldering or welding, after which the inner semiconductor layer is renewed using similar materials as in the corresponding layers of the cable, if possible.

Renewal of the inner semiconductor layer is generally performed by beveling the insulating layer so as to expose a portion of the inner semiconductor layer at both cable ends and then wrap a semiconductor material possibly having cross-linking capability around the exposed portions and conductor connection. Instead of wrapping, molded moldings can be used.

The regenerated semiconductor layer is heated, e.g., by placing it in a heated mold, so that the layer melts and binds to the internal semiconductor layers of the cable ends and, if desired, crossbinding or bonding takes place therein.

According to an alternative method, e.g. as described in German patent specification DT-AS 2418025, an insulating layer is wrapped outside the inner semiconductor layer without occasional heat treatment, and then a rubber compression bandage and a heat source are placed around the joint and both layers are melted together.

However, both options have considerable drawbacks, as in both feps the cutting devices shaped in the shape of a standard pencil sharpener are often used to avoid the necessary insulation and to expose the inner semiconductor layer, which is generally less than 1 mm thick. they are equipped with an oblique blade and are designed to be placed on top of the cable and rotated around it. The use of such pencil sharpeners inevitably results in a helical, complete or partial cut into the semiconductor layer, which results in poorer connection properties if no processing is performed. Since the inner semiconductor layer must be completely exposed by a distance of about 5-10 mm and the sharp edges provided by the cutting tool must be smoothed to avoid concentrations of field force, grinding is performed at the end of the chamfer, which is usually done from the conductor end inwards along the cable.

In this grinding, semiconductor particles inevitably move to the outermost, thin part of the insulation, causing electric field disturbances in the finished connection.

The grinding itself is cumbersome and must be performed very carefully because it is very easy to perform harmful abrasion in the semiconductor layer, resulting in exposure of the conductor.

In said alternative, in which the renewed semiconductor layer has melted and bonded to the inner semiconductor layers before wrapping the insulating layer, a surface treatment of the finished layer must be performed to remove that the inner semiconductor layer is ground away, exposing the conductor.

In the alternative where the wound inner semiconductor layer is not heat treated until the insulation is placed on it, there is also a risk of field interference at cable crossings, as the inner end of the cable ends must be overlapped and the edge of these overlaps can cause fields.

Po. the object of the invention is to avoid the above-mentioned disadvantages and this is achieved according to the invention by proceeding as defined in claim 1.

First, this method achieves easier beveling without the risk of contamination of the insulation and harmful exposure of the conductor. Said extension of the end of the beveled area further results in a relatively large material thickness being given to the transition point between the renewed semiconductor layer and the cable ends internally, so that after cooling the connection, both the beveled area and the renewed semiconductor layer can undergo machining, milling or milling. without the risk of exposure of the conductor and so as to obtain a flat transition point to the cable insulation.

Finally, the extension achieves a surface of the semiconductor layer which ensures a good field distribution in the insulation, since the surface of the transition points is formed by the original semiconductor layers in the cable attached in the extended position.

After surface treatment, the other layers are applied in a manner known per se, e.g. as described in the Danish pat. in Application No. 6380/73, in Finnish Patent Application No. 76.2001 or in Swedish Patent Application No. 73.09706.

The invention further relates to a tool for use in the method according to the invention, the properties of which are defined in claim 5. The outer diameter of the tool is adapted to the internal bore so that the edge is so sharp that it can be easily inserted between the semiconductor layer and the conductor, but is not so sharp that it would damage the semiconductor layer. The outer diameter can, for example, decrease linearly or logarithmically.

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The invention will now be described in more detail with reference to the drawing, in which: Fig. 1 shows a cable connection after welding and wire beveling, Fig. 2 shows a connection after the ends of the beveled areas have been extended, and a tool according to the invention pushed to one side; Fig. 3 shows the connection after semiconductor strips have been wrapped around the conductor connection; and Fig. 4 shows a joint in which a renewed semiconductor layer is completed, which after heating is bonded to the internal semiconductor layers in the cable, after which the insulation and the semiconductor layer are planed to the desired thickness.

The figures show a multicore conductor 1 and a welded conductor connection 2. Outside this there is an internal semiconductor layer 3 and an insulation 4 which has been chamfered as shown in the figures, so that the outside of the underlying semiconductor layer is not exposed. The outer semiconductor layer 5 is shown as the outermost.

Figure 2 shows a divisible tool 6 inserted between the conductor and the inner semiconductor layer and extending the end of the beveled region (3a, 4a). To facilitate insertion and subsequent attachment of the tool, the head is preferably heated to soften, after which the head is allowed to cool while the tool is inside, allowing it to cure into the expanded space. On the opposite side, the end (3b, 4b) thus expanded and hardened is seen.

When both ends are attached, the tool 6 is removed and a wrapper 7 is formed, which is formed by strips of semiconductor material according to Fig. 3. Alternatively, one or more molded parts may be replaced.

After this arc? and a heatable mold or a pressure and heat distributing housing is placed around the partially chamfered parts and a pressure hose and a bent metal plate and a heating element are placed outside it in the same way as described in Finnish pat. in Application No. 76.2001. During this effect of heat and pressure, the semiconductor layer melts and binds to the internal semiconductor layers of the cable. The cooling of the joint preferably takes place under constant pressure to avoid the formation of bubbles, but it can be carried out after the removal of the pressure and heating means, especially if a non-transverse bonding duct conductor has been used.

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Depending on the care with which the wrapping has been carried out and the device used for heating, a perfectly smooth surface or a surface which requires a certain post-treatment can also be achieved.

According to the invention, the post-treatment of the chamfered area and the joint is preferably carried out by cutting, e.g. milling or planing. In this way a completely smooth surface can be obtained. In addition, the weakly conical transition 3c shown in Fig. 4 without sharp edges is obtained from the renewed layer 7a to the semiconductor layer 3 of the cable.

Claims (5)

6 3 8 4 3 A procedure for regenerating an internal semiconductor layer when joining cables, in particular high-voltage cables, in which the cable ends, after their insulation has been removed and joined together, are provided with a polymeric semiconductor material, preferably similar to a cable, wrapped in one or more in the form of a mold and heated to bind to the inner semiconductor layer of the cable ends, after which the joint is cooled and possibly post-treated to obtain a smooth surface, characterized in that the insulation is removed without exposing the outer semiconductor layer and the tool is inserted between the conductor and the inner semiconductor layer, from which the insulation has been removed, to expand the head and to expose and maintain this part of the conductor below, and that the tool is removed and the space between the expanded ends is filled with a polymeric semiconductor material la. Procedure according to Claim 1, characterized in that the area from which the insulation is posed is heated before and / or when the tool is introduced. Procedure according to Claim 1 or 2, characterized in that the filled part and part of the cable ends, after filling with the polymeric substance and before heating this substance, are surrounded by a pressure-distributing and heat-conducting housing around which the pressure hose is wound and tensioned. inside the metal plate, after which the pressure fluid is supplied to the pressure hose and heat is supplied to the connection from a suitably located heat source. Method according to Claim 1, 2 or 3, characterized in that, after cooling the connection, machining of the area from which the insulation has been removed is carried out in order to obtain a smooth surface. Tool for use in connection with the method according to claims 1 to 4, characterized in that it is in the form of a divisible rotating body, the outer diameter of which decreases towards its free ends, and has a through-going axial bore having a diameter corresponding to the diameter of the conductor and substantially at the ends.