WO1981002438A1

WO1981002438A1 - A pole arrangement for electric power

Info

Publication number: WO1981002438A1
Application number: PCT/SE1980/000052
Authority: WO
Inventors: R Lindqvist
Original assignee: R Lindqvist
Priority date: 1980-02-26
Filing date: 1980-02-26
Publication date: 1981-09-03
Also published as: GB2082226B; DE3050275A1; GB2082226A

Abstract

Reinforcement of existing, erected poles for electric power or telecommunication applications, in order to increase the strength of the pole. Reinforcing elements (2) are arranged at places along the outer surface of the pole, optionally with bias tension, and are fixed secured at one or more places (3, 4) along the pole (1) thereto. The reinforcing elements can also extend down into the ground along the pole.

Description

A pole arrangement for electric power

This invention relates to a pole arrangement for electric power or telecommunication applications, according to the introductory portion of the appended claim 1.

For the transmission of electric power mainly over¬ head lines supported by poles are used. This requires a relatively large consumption of ground. In order to satis¬ fy future desire for an increase of transmission capacity, a greater concentration of overhead lines to routes will probably be used for reasons of costs and environment, and these routes of lines are likely to be disposed on com¬ mon poles. An example may be mentioned of a combined dis¬ posal of an overhead transmission line, that is uninsulated conductors freely supported from each other by insulators-, and one or more insulated selfsupporting aerial cable, that is a line, in which at least the phase conductors are insulated and where all the conductors are placed together to a cable. In this way existing line routes can be utilized more effectively than before.

For telecommunication purposes it is correspondingly desired to utilize existing poles more effectively by disposing new, often thick and heavy cables together with already existing lines.

Such an increased use of existing poles causes strength problems, which must be considered and which may involve restrictions as to the possibilities of using existing poles.

Moreover, wooden poles are sometimes attacked by soft rot under the ground level, more specifically ^"10 to 30 cm below ground surface. In this normally humid area wood is attacked by rot fungi, for which cellulose is a natural foodstuff. Besides a certain humidity, also a certain temperature is required for destroying the sap-wood. The most favourable pre-requisites for soft rot appear at temperatures between +20 and +35 C and at a humidity rate between 40 and 60 % . Certain species of rot fungi attack the sap-wood and other ones the heart-wood, in spite of the fact that the latter is very resistant. By impregnating the poles with creosote oil or any of the modern impregnation salts it is considered that the life can be tripled or more. However, it is Utopian to believe that impregnation can prevent soft rot in poles for all future. Therefore, it must be expected that all poles will weak on sooner or later, inter alia due to attacks by soft rot. This especially applies to poles which have been impregnated with arsenic, zinc or chromium salts in the post-war period. Investigations in Sweden have shown that 98 % of poles used for 30 years or more is impaired by soft rot.

Therefore, it has been necessary, especially in view of operational safety and safety for maintenance per¬ sonnel, to take comprehensive measures, such as for in¬ stance replacement of poles damaged by soft rot, rein¬ forcements by means of additional poles close to exist¬ ing ones, staying and so on. These reinforcing measures are expensive and, moreover, in power transmission often require that the electric system is made dead.

The invention eliminates the described drawbacks through the measures defined in the characterizing por¬ tion of claim 1 and in the dependent claims.

Thus, according to the invention the pole at its surface is provided with longitudinal reinforcing ele¬ ments of a number corresponding to the desired rate of reinforcement, the reinforcing elements being secured to the pole at two or more places in spaced relation¬ ship. The reinforcing elements can be arranged from the free pole end or from a point on the pole between said end and the ground level and may extend substantially to the ground level or to the root end in the ground or to a point between these levels.

The invention will be described more in detail in connection with the attached drawings with their Figures 1 to 8. Fig. 1 diagri atically shows a part of a wooden pole placed into the ground. Figs. 2 and 3 show differ¬ ent ways of arranging clamping rings. Fig. 4 shows a cross section of a hollow pole with a clamping ring and a support means inserted inside the pole on a level with said ring. Fig. 5 shows a cross section of a tubular reinforcing element with an inserted steel wire. Fig. 6 shows a pole having reinforcing elements along the whole pole down to ground level. Fig. 7 shows in cross section how four reinforcing elements are arranged around the pole, and Fig. 8 shows an alternative method of securing the reinforcing elements at ground level.

When reinforcing a pole according to Fig. 1 verti¬ cal^' holes are bored through soil and stone along the part of the pole in the ground. In this embodiment the pole 1 is provided with four reinforcing elements 2, symmetric¬ ally arranged. The reinforcing elements are secured to the pole at two places by means of clamping rings 3, 4. The clamping rings may be of an arbitrary type, if they only, when used, clamp the reinforcing elements to the pole. They can embrace the pole and the reinforcing elements and may be clamped by means of a suitable clamping tool. They can also consist of several parts, according to Figs. 2 and 3. According to Fig. 2 four mounting clamp parts are used, each one adapted to embrace one reinforcing element. According to the Fi¬ gure, the mounting clamp parts may be connected by means of screw joints at outwardly bent flanges. Thus, in Fig. 2, four mounting clamp parts Sa' are used and are connected by means of screw joints 5a". In Fig. 3 two mounting clamp parts 5 ' are used and are held to¬ gether by means of screw joints 5b". In cases when the pole is hollow a support means 5c can be arranged on a level with a clamping ring 3, according to Fig. 4. The support means can be massive or, according to Fig. 4, have a number of arms in cross section abutting the inner mantle surface of the hollow pole. In the case

OMPI when this mantle surface is tapering towards the top of the pole the support means can be kept in position by the clamping effect. Otherwise it can be secured by means of elements extending through the pole or be welded or glued. Support, means can also be secured in a pole tapering to¬ wards the root end.

The holes bored along the pole through the soil can be made in such a number, to such a depth and with such a diameter as corresponds to the desired rate of pole reinforcement. A number of reinforcing elements corres- ponding to the number of holes and their dimensions may be inserted in the holes. The reinforcing elements can consist of massive steel rods, preferably rust protected, or of steel pipes. In general profiled rods or pipes may be used. These rods or pipes are extended upwards along the pole to a desired height, if necessary to the whole height of the pole, the number of clamping rings being dependent on the desired buckling safety. A steel wire can be inserted in- pipes, according to the cross sect¬ ion in Fig. 5 through a tubular reinforcing element. A suitable bias tension can be adapted to this steel wire, which will further increase the strength of the rein¬ forcement and consequently the safety against pole buckling and bending.

In Fig. 6 a pole 1 is shown, which, besides of wood, may also be of steel or concrete. According to Fig. 6, in combination with the associated cross section accord¬ ing to Fig. 7, the assembly consists of a pole 1, which may be made of wood, concrete, iron or another metal or may consist of or be reinforced by plastic or be massive or hollow and which is provided with four reinforcing elements 2, which are symmetrically placed around its periphery. The reinforcing elements extend from the top of the pole to a point of attachment on ground level. As the top securing is achieved by means of a steel plate 6, which is attached to the pole in a suitable manner. The reinforcing elements 2 are, for instance, drawn through holes bored in the steel plate and y^

OM

Λ r . ^WIF terminate upwardly in a threaded pin, on which and adjust ing nut 7 is adapted. On ground level a steel sleeve 8 is attached to the pole and supports another steel plate 9, to which the reinforcing elements are anchored in a suit¬ able way.

In Fig. 8 an alternative securing of the reinforcing elements on ground level is shown. This way of securing, meaning that the reinforcing elements are wound one or more turns around the pole to increase friction in the tension direction, can be used with wooden poles, in which it is not advisable to attach the securing elements for a steel sleeve, which would weaken the pole. The way of securing according to Fig. 8 can also be used at the top end.

The pole arrangement according to Fig. 6 to 8 allows the tension of the reinforcing elements 2 to be adjusted before raising the pole. This is achieved by means of the adjusting nuts 7 , which can be tightened up, for instance, by means of a dynamometric wrench, un¬ til a predetermined turning moment is obtained.

The reinforcing elements 2 according to Figs.. 6 to 8 may consist of steel wires or steel pipes or a combin¬ ation of both.

The suggested pole arrangements are well adapted for reinforcement of wooden poles damaged by woodpeckers. The method can also be used when building new lines. As it is possible to transfer part of the line load from the pole to the reinforcing elements the weight of the pole can be reduced and consequently the costs of transport and mounting.

An increased buckling safety of the pole can be obtained by moving out the reinforcing elements in radial direction. The moved-out distance can be differ¬ ently great at different heights of the pole and can for instance, be maximal at a height which is critical to buckling. The clamping rings around the pole must then be modified so that they allow the securing of the reinforcing elements, in the moved-out positions.

Claims

Patent Claims

1. A pole arrangement for electric power and tele¬ communication applications, with an arbitrary pole mater¬ ial, for optimizing the pole in view of strength, weight and costs, c h a r a c t e r i z e d in that longitudinal reinforcing elements (2) to a number corresponding to the desired rate of reinforcement are arranged along the outer ^"surface of the pole (1) without impairing the fastening of the pole in the ground during the reinforcing procedure, said reinforcing elements (2) consisting of a material having substantially round cross section or of wire and being so arranged that their longitudinal tension is ad¬ justable during the life of the pole.

2. A pole arrangement according to claim 1 , c h a r a c t e r i z e d in that the reinforcing ele¬ ments (2) in the form of wires are enclosed in pipes (10) along their whole length or part thereof.

3. A pole arrangement according to claim 1 or 2, c h a r a c t e r i z e d in that the reinforcing ele¬ ments (2) are secured close to or at the top of the pole (1) and close to or at the root end thereof.

4. A pole arrangement according to claim 1 , 2 or 3, c h a r a c t e r i z e d in that the lowermost securing point (8, 9) on an already erected pole (1) is arranged on ground level.

5. A pole arrangement according to any one of claims 1 to 4, c h a r a c t e r i z e d in that one or more clamping rings (3, 4) are arranged along the pole

(1) and embrace the longitudinal reinforcing elements

(2) and secure them to the pole.

6. A pole arrangement according to any one of claims 1 to 5, c h a r a c t e r i z e d in that inner support means (5c) are arranged in a hollow pole (1) on a level with one or more of the clamping rings (3, 4) embracing the longitudinal reinforcing elements. (2) and securing them to the pole (1).

_ C Λ. WI