FI67119C - ANORDNING VID EN KRAFTLEDNINGSMAST AV LAMINERAT TRAE - Google Patents

Description

6711 9

The present invention relates to an arrangement for use in a power line mast made of laminated wood.

In the Nordic power line construction, it has been topical to use wood masts made of creosote-impregnated solid wood for up to 132 kv lines. As sufficiently large solid wood masts are increasingly available and the price is accordingly high, 132 kV lines have been built to a significant extent as steel masts. However, from the point of view of nature conservation, steel masts are not desirable because they are at war with nature's own matter and its own lines. In addition, steel masts require a much more durable and complex base than wooden masts. In addition, steel masts have very little flexibility compared to wooden masts. In the event of a line break or other abnormal load, the lack of flexibility therefore leads to breaks more easily.

The limited availability of natural wood masts, together with what has been stated above about steel masts, has led to an increasing interest in masts made of laminated wood structures (glulam). In the case of such masts, the design and dimensioning are in principle free. However, the glulam technique has been limited in terms of what diameters can be made in practice, because the largest diameter that can be joined together with good results has in practice not been greater than the thickness of the lamellae of about 45 mm. The new 2 671 1 9 types of adhesives with better filling properties have meant that the bonding constraints are no longer as tight. It has thus become possible to carry out the lamination process in several stages. Today, for example, large structures can be glued together, which can then be adjusted and joined together into even larger structures in a further process.

Deep impregnation of wood power line masts with creosote oil is absolutely necessary. However, there is a practical limit to how deep the impregnation can be penetrated into the wood. Large closed cross-sections cannot therefore be completely impregnated to the core. In naturally grown masts (trees), this is not particularly important because the kernel in pine, which is the wood most used in deep impregnation, is already impregnated and filled with resin at the base. Instead, when laminating larger cross-sections, impregnation is a major problem because, for durability, the impregnation must penetrate the center portion of the structure, which may contain non-naturally impregnated surface material.

Impregnation can therefore be a limiting factor in the production of power line masts made of laminated wood. Impregnation is necessary for protection against both rot and earth. An additional problem with wooden masts is darts. These beat themselves in from the side of the mast and form a cavity in it. This can lead to such a weakening of the mast that it actually breaks in strong winds.

For example, FI patent application 790799 mainly discloses a mast for lighting poles, which is made of glulam and has a rectangular cross-section. Although the mast has a through hole for the cable entry, it is closed in structure and all its wooden lamellae are parallel. Thus, this mast structure is not suitable for high transmission line poles, mainly due to the fact that it becomes too heavy and that the impregnation remains deficient unless it is carried out before gluing, which again is inconvenient and disadvantageous.

DE-A-2 122 458 discloses a power line pole made of laminated wood which has a rectangular cross-section and a hollow inside. It has four walls of a pylon housing made of wood lamellae parallel to the plane of the wall. When the column narrows upwards, in such a structure it is necessary to make the sides of the column by gluing from the prefabricated lamellae, and it is not possible e.g. In order for the structure to become sufficiently durable, it is also recommended to connect the different parts to each other, e.g. with dovetail joints, which naturally weakens the economic competitiveness of the column.

It is an object of the present invention to obviate the above-mentioned drawbacks and to provide an arrangement for use in a power line mast made of laminated wood, which is inexpensive to manufacture and allows complete impregnation and which does not impose practical limits on the cross-section.

This is achieved according to the invention, and the invention is characterized in that each side of the tubular cross-section consists of a laminated beam in which the glued longitudinal surfaces of the lamellae are transverse to the inner and outer surfaces of the mast side and that the wood is pressure impregnated on both the outside and inside.

4 67119

A suitable embodiment is characterized in that the pin has a tapering cross section towards the top in a manner known per se.

In a preferred embodiment, the mast according to the invention has a square cross-section and is assembled from four identical walls.

In order to obtain a tapered cross-section towards the top, the at least two opposite walls of the mast are formed of a laminated body made of a diagonal section or a nearly diagonal section of a laminated elongate, rectangular blank.

In practice, it is expedient to fill the cavity with a fibrous or porous substance. This material may, for example, be mineral fiber or other appropriate form of foam. The purpose of the filling is to prevent the formation of condensate on the inner walls.

Wood power lines dug into the ground are more prone to rot from the ground level and all the way down. Therefore, it is desirable to provide better protection in this part of the mast structure. In the mast according to the invention, this is achieved very simply by sealing the cross-section completely at the bottom and filling the cavity with creosote oil or other suitable rot protection agent above ground level. With the pressure thus obtained, only a very small amount of creosote oil penetrates the wall, thus ensuring that the lower part of the masts is always impregnated with creosote oil. Thus, it is desired to constantly replace leachable or volatile creosote oil. The strength of the mast is significantly improved. As the creosote oil decreases in the cavity, oil can be added, for example, through a hole made through the wall.

In order to save both weight and creosote oil, the cavity above the seal in the mast can be partially filled with a porous material having a honeycomb structure to which creosote oil does not penetrate, e.g. expanded polyurethane. Various granules can also be used. Even coarse gravel can be used. It is only necessary to fill the space between the solid particles, which can be filled with creosote oil to achieve the desired effect.

When making the force as conductors s to and consisting of rectangular, rather thin-walled pipes made of laminated wood, the problem is not through-impregnation of the wood material. These masts are therefore very resistant to rot and drilling insects. In relation to the problem posed by the sticks, it is of little importance that the sticks beat themselves through the wall of the pipe, as they do not need solid wood, since the mast is already hollow and dimensioned as a box profile. A hole three inches four inches in diameter means nothing to the durability of the mast. When the transport conditions are poor, eg there is a long distance from the road, the terrain is convex, etc., high-voltage masts are installed e.g. by helicopter.

However, the weights that helicopters can lift are limited and thus there are limits to how large solid wood masts can be used. Boxes with a cross-section of 6,671 1,9 allow a weight reduction of 40-50% compared to threshing glue masts.

Another and very essential advantage is that masts with a box cross-section can be made tapered towards the top in both directions. From a production point of view, this is very difficult and involves a great waste of material when this has to be done on a laminated solid mast.

In addition, the strength can be varied with respect to the two centerlines. It depends on the forces received whether the box cross section is made square or more or less rectangular. It is also possible to use other cross sections: triangles, pentagons, hexagons, etc.

Masts with a box cross section narrowing towards the top save a lot of raw material. Compared to solid wood, the saving is about 40-50%.

It is possible to make very large masts from small material dimensions. It is found that we no longer depend on the large dimensions that can only be obtained from 100-150 year old trees.

The invention will now be described in more detail with reference to the drawing, in which Figure 1 shows a side view of a power line mast according to the invention, Figure 2 is a section along line II-II in Figure 1, Figure 3 is a section along line III-III in Figure 1, and Figure 4 shows how a line 7 67119 wall is made of a rectangular laminated body.

The wiring harness according to Figures 1, 2 and 3 has a so-called The box profile / and consists of four walls 2/3, 4 and 5. In the example shown, the mast is square and consists of four similar walls. The four walls consist of laminated, tapered pieces made by gluing together a rectangular elongate body 6, as shown in Figure 4. This paragraph is divided almost diagonally from the short sides. Four such pieces are joined in the same way as bricks in one floor of a chimney. In a box cross-section assembled from obliquely cut sections, as shown in Figure 3, the second side edge covers the cut lamellae so that a visible oblique section at the end is avoided. This contributes to the prevention of cracking of obliquely cut surfaces. The cavity 7 of the mast can be filled with a fibrous or porous material. For example, as an alternative to creosote impregnation, the outer sides of the mast can be coated with fiberglass-reinforced polyester. This strengthens the structure and at the same time protects it. The method can also be used when high masts have to be used, which have to be transported to the installation site in two or more parts. The pre-applied fiberglass reinforcement can be used as a structural reinforcement as such, and at the same time provides an advantageous interconnectability.

A further advantage of the invention is that it simplifies the attachment. Namely, the fastening is a critical point in any erection of masts. The mast according to the invention is very light. It can be dug into the ground and kept upright either by helicopter or by a simple crane device while filling is taking place.

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Claims (4)

6711 9 8 An arrangement in a power transmission mast made of wood with a tubular rectangular cross-section, characterized in that each side (2, 3, 4, 5) of the tubular cross-section consists of a laminated beam with glued longitudinal surfaces of the lamellae transverse to the inner and outer surfaces of the mast side. is pressure impregnated on both the outside and inside. An arrangement according to claim 1, characterized in that the mast has a tapered cross-section towards the top in a manner known per se. An arrangement according to claim 1 or 2, characterized in that the mast has a square cross-section and is assembled from four identical walls. Arrangement according to one or more of the preceding claims, characterized in that the at least two opposite walls of the mast consist of a laminated body made of an elongate, rectangular blank laminated by oblique cutting or almost oblique cutting. ! ; - · ·