EP0286480B1 - Insulating strengthening for supporting poles for electric lines and manufacturing method - Google Patents

Abstract

Insulating equipment (100) includes a flexible arm (1) having at one of its ends a means for attachment to a pole and at the other end means for attaching an electric line substantially perpendicular to the arm (1). The thickness of the arm (1) decreases regularly from the means fo attachment to the pole toward the means of attachment to the electric line, while the height of the cross section of the arm is constant. The arm (1) has in the direction of its thickness a series of layers (7a, 7b, 7c, 7d) of continuous mineral fibers extending in the direction of the arm's length and separated by layers (8a, 8b, 8c, 8d) of randomly-oriented short mineral fibers. These layers are bonded by a synthetic resin in which a layer (9a, 9b) of fabric of mineral fibers may be placed on each side of the arm (1) between the first layer of short fibers and the following layer of continuous fibers. To be used for improving longitudinal flexibility and resistance to vertical loads.

Description

The present invention relates to an insulating armament for an overhead power line support post according to the preamble of claim 1.

The invention also relates to the method for the manufacture of such armament.

The power lines used for transport under low, medium and high voltage, are supported by poles or pylons via consoles called "armaments" equipped with insulators.

In known embodiments, these armaments consist of metal profiles provided with means for fixing to the pole and means for hanging the electric line in a direction perpendicular to the armaments.

These reinforcements are rigid and therefore cannot bend under the effect of the forces applied to the power line. However, the power line can be subjected to exceptional loads resulting from frost, snow or wind.

Since these loads do not cause any deformation of the armaments, the above exceptional loads can cause the line to break, which itself can generate a torque that can cause the post to break.

To avoid these drawbacks, it has been proposed to produce armaments made of flexible material, based on synthetic resin reinforced by means of glass fibers and having a regularly decreasing section from the post.

The ideal armament must have the greatest possible longitudinal flexibility, while being able to support the greatest possible vertical loads. It is understood that in practice, such a compromise is difficult to achieve.

The object of the present invention is to create an armament which makes it possible to achieve the abovementioned objective, while being inexpensive.

The armament targeted by the invention consists of a flexible arm comprising at one of its ends means for fixing it to the pole and at its other end, means for fixing an electric line substantially perpendicular to the arm, this arm having a rectangular cross section, the width of this section measured in a plane perpendicular to the power line being greater than the thickness of this section measured in a direction parallel to the power line.

According to the invention, the thickness of this section decreases regularly from the means for fixing to the pole towards the means for fixing to the power line, while the width of this section is constant, the arm present in the direction of its thickness, a succession of layers of continuous mineral fibers extending in the direction of the length of the arm, separated by a layer of short mineral fibers randomly oriented, these fibers and these layers being linked together by a synthetic resin.

This succession of layers of mineral fibers coated in a synthetic resin gives the armament, in combination with the geometry thereof, great longitudinal flexibility as well as great resistance to vertical loads.

The layers containing continuous fibers extending lengthwise of the armament and embedded in the synthetic resin, give the armament, because they are located in vertical planes, a great resistance to vertical loads as well as a high breaking strength at break. Furthermore, the fact that the cross-section of the armament has a dimension in the vertical direction which is greater than in the longitudinal direction of the electrical line and the fact that this section decreases regularly from the pole, the armament has a great longitudinal flexibility.

The layer containing randomly oriented short fibers allows stress to be distributed thermal and mechanical between the above layers with continuous fibers.

Furthermore, this randomly oriented short fiber intermediate layer allows the arm to be pierced. Indeed, if the armament only had layers with continuous longitudinal fibers, the piercing of the armament would cause delamination.

To increase the rigidity of the armament to torsional forces, a layer of mineral fiber fabric is placed on each side of the arm between the first layer of short fibers and the next layer of continuous fibers. This fabric preferably contains son of fibers arranged at + 45 ° and _45 ° from the direction of the length of the armament, which makes it possible to obtain optimum resistance to torsion.

Thus, the functions of the various successive layers of the armament according to the invention contribute with each other to obtain an armament having the desired mechanical properties.

According to an advantageous version of the invention, the proportion of continuous fibers is greater than that of short fibers.

This measurement results from the predominant role of continuous fibers in obtaining the desired mechanical properties. It is thus advantageous to use a maximum of continuous fibers.

According to a preferred version of the invention, certain layers of short fibers are separated from the next layer of continuous fibers by an additional layer of short fibers which extends over only part of the length of the arm from the fastening means to the pole, the length of this layer of short fibers gradually decreasing from the outside towards the middle of the thickness of the arm to achieve a thickness decreasing regularly, from the pole towards the end of the armament intended to support the electric line.

Preferably, the outer surface of the arm is covered by a plastic coating resistant to electric arc, weathering and ultraviolet radiation, such as an ethylene-propylene-diene methylene copolymer.

• on réalise des bandes renfermant une couche de fibres continues s'étendant dans le sens de la longueur de la bande et une couche de fibres courtes de directions aléatoires préimprégnées de résine polyester et éventuellement des bandes de tissu de fibres à  ±45° de la direction de la longueur de la bande,
• on découpe ces bandes aux dimensions de la longueur et de la largeur désirées de l'armement,
• on empile les différentes bandes selon la disposition désirée,
• on préchauffe cet empilage à une température inférieure à la température de polymérisation de la résine polyester,
• on place l'empilage dans un moule, et on moule cet empilage en le chauffant et en appliquant une pression sur celui-ci.

According to another aspect of the invention, the method for manufacturing an insulating armament for a pole for supporting power lines, in accordance with the invention comprises the following steps:

• strips are produced containing a layer of continuous fibers extending in the direction of the length of the strip and a layer of short fibers of random directions prepreg of polyester resin and optionally strips of fiber fabric at ± 45 ° from the direction the length of the strip,
• these strips are cut to the dimensions of the desired length and width of the armament,
• we stack the different strips according to the desired layout,
• this stack is preheated to a temperature below the polymerization temperature of the polyester resin,
• the stack is placed in a mold, and this stack is molded by heating it and applying pressure thereon.

Other features and advantages of the invention will appear in the description below.

• la figure 1 est une vue en élévation montrant la partie supérieure d'un poteau portant un armement conforme à l'invention,
• la figure 2 est une vue de dessus de la figure 1,
• la figure 3 est une vue en coupe transversale à plus grande échelle de l'armement,
• la figure 4 est une vue schématique en plan partielle d'une couche renfermant des fibres continues longitudinales,
• la figure 5 est une vue schématique en plan partielle d'une couche renfermant des fibres continues orientées de façon aléatoire,
• la figure 6 est une vue schématique en plan partielle d'un tissu à fils de fibres disposées à ± 45°,
• la figure 7 est une vue en coupe schématique montrant la juxtaposition des couches selon les figures 4, 5, 6,
• la figure 8 est une vue schématique en coupe suivant un plan parallèle au plan de la figure 2, montrant les différentes couches d'un armement conforme à l'invention,
• la figure 9 est une vue en coupe longitudinale d'un moule illustrant le procédé de fabrication d'un armement conforme à l'invention.

In the appended drawings, given by way of nonlimiting examples:

• FIG. 1 is an elevation view showing the upper part of a post carrying an armament according to the invention,
• FIG. 2 is a top view of FIG. 1,
• FIG. 3 is a cross-sectional view on a larger scale of the armament,
• Figure 4 is a schematic plan view partial of a layer containing longitudinal continuous fibers,
• FIG. 5 is a schematic partial plan view of a layer containing continuous fibers randomly oriented,
• FIG. 6 is a schematic partial plan view of a fabric with threads of fibers arranged at ± 45 °,
• FIG. 7 is a schematic sectional view showing the juxtaposition of the layers according to FIGS. 4, 5, 6,
• FIG. 8 is a schematic sectional view along a plane parallel to the plane of FIG. 2, showing the different layers of an armament according to the invention,
• Figure 9 is a longitudinal sectional view of a mold illustrating the method of manufacturing an armament according to the invention.

In the embodiment of FIGS. 1 and 2, the lateral armament 1 is constituted by a flexible arm comprising at one of its ends a support 2 for fixing it to a post 3 and at its other end a nozzle 4 carrying a clamp cable 5 to which is fixed an electric line 6 extending perpendicular to the arm 1. The arm 1 has a rectangular cross section (see FIG. 3). The width l of this section measured in a plane perpendicular to the power line 6 is significantly greater than the thickness e of this section measured in a direction parallel to the power line 6, that is to say in the plane of the figure 2.

As can be seen in FIG. 2, the thickness e of the section of the arm 1 decreases regularly from the support 2 for fixing to the pole 3 towards the end piece 4 for fixing to the power line 6. Furthermore, the width l of this section is constant (see figure 1).

The arm 1 has, in the direction of its thickness e , that is to say in the plane of FIG. 2, a succession of layers 7a, 7b, 7c, 7d of continuous glass fibers 10 (see Figures 4, 7, 8) extending in the direction of the length L of the arm 1. These layers 7a, 7b, 7c, 7d are separated by a layer 8a, 8b, 8c, 8d of short glass fibers 11 (see Figures 5, 7, 8) oriented randomly. These two layers and the fibers thereof are linked together by a synthetic resin, such as a polyester resin.

Furthermore, a layer 9a, 9b of glass fiber fabric is arranged (see FIG. 8) on each side of the arm 1 between the first layer of short fibers 11 and the layer 7b of continuous fibers 10 below.

The distribution of the different layers is symmetrical on either side of the neutral fiber N of the arm 1.

The connection between the different layers such as 7a, 8a, 9a is carried out by polymerization of the synthetic resin during a pressure molding operation which will be described later.

Preferably, the proportion of continuous fibers 10 is greater than that of short fibers 11. Preferably, the mass ratio of continuous fibers 10 is substantially equal to 80% of the totality of fibers, that of short fibers 11 therefore being substantially equal to 20%.

Preferably, the mass content of continuous fibers 10 and short fibers 11 is between 50 and 60% of the total mass, the proportion of synthetic resin therefore representing 40 to 50%.

The fabric 9a (or 9b) (see FIG. 6) comprises a first series of wires 12a of parallel glass fibers arranged at + 45 ° to the direction of the length L of the arm 1 and a second series of wires 12b of parallel fibers arranged at _45 ° from this direction.

It can also be seen in FIG. 8 that certain layers of short fibers are separated from the next continuous fiber layer by a layer of short fibers such as 13a, 13b, 13c which extends over only part of the length L of arm 1 from support 2 for fixing to the post 3. The length of these layers of short fibers 13a, 13b, 13c decreases progressively from the outside towards the middle N of the thickness of the arm 1 to achieve a thickness e decreasing regularly, as indicated in FIG. 2.

Furthermore, the outer surface of the arm 1 is covered (see FIG. 3) by a coating 14 of elastomer resistant to electric arc, weathering and ultraviolet radiation, such as an ethylene-propylene-diene-methylene copolymer (EPDM).

The support 2 for fixing the arm 1 to the post 3 and the end piece 4 are preferably made of aluminum and are fixed to the arm 1 by gluing. Aluminum is one of the common metals that presents the coefficient of expansion closest to the composite material (glass fibers, polyester resin) which constitutes the arm 1, so that the connection of the support 2 and the end piece 4 to the arm 1 is not likely to be affected by temperature variations.

We will now detail the method of manufacturing the armament according to the invention.

In a first step, a strip is produced comprising successively a layer of continuous glass fibers 10 oriented lengthwise of this strip, a layer of short glass fibers 11 of random orientation and a layer of fabric 9a comprising fiberglass yarns 12a, 12b forming an angle of ± 45 ° with respect to the length L of the strip. All of these layers are prepreg with polyester resin.

• résine polyester: 18%
• agent thermoplastique anti-retrait: 12%
• adjuvant, catalyseur colorant: 3%
• charges minérales: 12%
• fibres de verre: 55%

The composition of this strip is for example as follows:

• polyester resin: 18%
• anti-shrinkage thermoplastic: 12%
• adjuvant, coloring catalyst: 3%
• mineral charges: 12%
• glass fiber: 55%

The strips thus pre-impregnated with polyester resin are then cut to the dimensions of arm 1.

The strips are then stacked following the distribution shown in FIG. 8.

The stack thus produced is placed in a high frequency preheater so as to heat this stack to around 70 ° C. (temperature below the polymerization temperature of the polyester resin).

This preheating makes it possible in particular to reduce the thermal stresses inside the material, during molding.

The stack obtained 15 is then placed in a mold (see FIG. 9) in two parts 16 and 17 placed in a press. The stack 15 is heated to the polymerization temperature of the polyester resin, while applying pressure (see arrows F in FIG. 9).

The stack 15 is then removed from the mold, deburred, cooled, then sanded or sanded to obtain a surface condition as good as possible.

Then glued to the ends of the stack, the support 2 and the end piece 4 of aluminum.

The glue used for this purpose can be a semiconductor glue to avoid the problems of partial discharges. The outer surface of the arm thus obtained is then coated with an adhesion primer and then with an EPDM coating.

The armament thus produced makes it possible, for a given flexibility, to have better resistance to vertical loads than an armament with constant section and inertia produced for example by pultrusion.

Thus, an armament produced in accordance with the invention, having a length L equal to 150 cm, a width l equal to 90 mm and a thickness e decreasing between 25 and 20 mm supports a static vertical load greater than 240 daN and has a longitudinal flexibility greater than 5mm / daN.

These mechanical properties result from the fact that the armament contains a large proportion of continuous longitudinal fibers 10. The fabric having glass fiber threads 12a and 12b forming an angle equal to ± 45 ° and _45 ° with the direction of the length L of the armament makes it possible to increase the resistance to torsion of the armament, while the layers containing the short glass fibers 11 randomly oriented, make it possible to distribute the thermal and mechanical stresses between the fabric and the layers adjacent to long fibers and allow the drilling of arm 1 without risk of delamination.

In the case where the armament is intended to undergo lesser torsional forces, the presence of the fabric 9a, 9b is not necessary.

Of course, the invention is not limited to the embodiments which have just been described and numerous modifications can be made to them without departing from the scope of the invention.

Glass fibers can thus be replaced by other mineral fibers, such as rock fibers.

Furthermore, the polyester resin can be replaced by another synthetic thermosetting or thermoplastic resin.

On the other hand, the dimensions of the arm 1 can be modified as required.

In addition, this arm 1, instead of being perpendicular to the post 3 could be oblique.

On the other hand, in the armament manufacturing process, instead of stacking on each other pre-impregnated strips of fibers, cut to the dimensions L and l of the armament, one can proceed as follows:

using a sheet having the length L of the armament and having a layer of continuous fibers and a layer of short fibers pre-impregnated with resin, and this sheet is rolled up so as to form a flattened spiral composed of strips of maximum width equal to l connected to each other. Thus, a stack is made up successively of layers with continuous fibers and short fibers.

To obtain a decreasing thickness, strips of variable length, such as the short fiber layers (13a, 13b, 13c) shown in FIG. 8, are inserted between the layers of the spiral.

Claims (13)

1. Insulating equipment for a pole (3) to support electric lines (6) constituted by a flexible arm (1) comprising at one end means (2) for attaching it to the pole (3) and at the other end means (4, 5) for attaching an electric line (6) in a way substantially perpendicular to the arm, this arm (1) having a rectangular transverse section, the height (1) of this section measured in a plane perpendicular to the electric line (6) being greater than the width (e) of this section measured in a direction parallel to the electric line (6), characterized in that the width (e) of this section decreases regularly from the means (2) for attaching it (2) to the pole (3) towards the means (4) for attaching it to the electric line (6), the height (1) of this section being constant, in that the arm (1) has in the direction of its width, a succession of layers (7a, 7b, 7c, 7d) of continuous mineral fibers (10) extending in the direction of the length (L) of the arm, separated by a layer (8a, 8b, 8c, 8d) of short mineral fibers (11) randomly oriented, these fibers and these layers being bonded to each other by a synthetic resin.

2. Equipment according to claim 1, characterized in that a layer (9a, 9b) of fabric of mineral fibers is placed on each side of the arm (1) between the first layer of short fibers and the following layer of continuous fibers.

3. Equipment according to claim 1, characterized in that the proportion of continuous fibers (10) is greater than the proportion of short fibers (11).

4. Equipment according to claim 3, characterized in that the proportion of continuous fibers is superior to the proportion of short fibers.

5. Equipment according to one of claims 1 to 4, characterized in that the mass of fibers (10, 11) accounts for 50 to 60% of the total mass.

6. Equipment according to one of claim 1 to 5, characterized in that the synthetic resin is a polyester resin.

7. Equipment according to one of claims 2 to 6, characterized in that the fabric (9a, 9b) has a first series (12a) of parallel fiber filaments placed at +45° with respect to the direction of the length (L) of the arm (1) and a second series (12b) of parallel fiber filaments placed at _45° with respect to this direction.

8. Equipment according to one of claims 1 to 7, characterized in that certain layers of short fibers 11 are separated from the next layer of continuous fibers (10) by a layer of short fibers (13a, 13b, 13c) or of continuous fibers that extends over only a part of the length (L) of the arm from the means of attachment (2) to the pole, the length of this layer (13a, 13b, 13c) of short fibers or continuous fibers diminishing progressively from the exterior towards the middle (N) of the width of the arm resulting in a width (e) that decreases regularly.

9. Equipment according to one of claims 1 to 8, characterized in that the exterior surface of the arm (1) is covered by a coating (14) of elastomer resistant to the electric arcing, inclement weather, and ultraviolet radiation.

10. Equipment according to claim 8, characterized in that coating (14) is an ethylenepropylene-diene-methylenic copolymer.

11. Method for manufacturing insulating equipment for a pole (3) to support electric lines (6), in accordance with one of claims 1 to 10, characterized in that it comprises the following stages:

- strips enclosing a layer (7a, 7b, 7c, 7d) of continuous fibers (10) extending along the length of the strip and a layer (8a, 8b, 8c, 8d) of randomly-oriented short fibers (11) are made pre-impregnated with polyester resin and possibly strips of material (9a, 9b) of fibers at ±45° with respect to the direction of the length (L) of the strip.

- one cuts strips down to the dimensions of the length (L) and of the height (l) desired for the equipment.

- one stacks the different strips according to the placement desired.

- one preheats the stack (15) obtained at a temperature lower than polymerization of the polyester resin.

- one places the stack (15) in a mold (16), and one molds this stack applying pressure on it.

12. Method according to claim 11, characterized in that the stack (15) of strips is preheated at about 70°C in a high-frequency preheater.

13. Method for the manufacturing of insulating equipment in accordance with one of claims 1 to 10, characterized in that one uses a sheet having the length L of the equipment and with a layer of continuous fibers and a layer of short fibers pre-impregnated with resin, one rolls this sheet so as to form a flattened spiral made up of strips bonded to one another to make a stack with the successive placement of continuous-fiber layers and short fiber layers and, to obtain a decreasing width, one intercalates between layers of the spiral, layers of variable length having short fibers (13a, 13b, 13c) or continuous fibers.

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