RU2307223C1 - Pole for overhead transmission line cable suspension - Google Patents

Abstract

FIELD: power industry, particularly to repair overhead transmission lines, namely to replace damaged poles by new quickly-assembled ones.

SUBSTANCE: overhead transmission line pole comprises at least one free-standing post with cross-arms connected thereto. Post is composed of telescopically butt-joined conical sections in post height direction. The sections are connected by inserting narrow end of one conical section in wide end of another one with predetermined force. Butt-join length l_j of pole sections to be connected is selected from (1.75÷1.85)×d_sj. Section taper is within (0.015÷0.035). Force N necessary for prior telescopic section butt-joint compression is calculated from the following equation: N=5.0×Q×l_j/d_sj, where Q is crosscutting force, kgf, l_j - section joint length, cm, d_sj is mean cross-sectional diameter of pole sections to be connected with each other in section joint area, cm.

EFFECT: increased operational reliability of overhead transmission line poles, decreased maintenance time and elimination of temporary pole construction.

1 tbl, 6 dwg

Description

The invention relates to the field of electric power, and more specifically to self-supporting supports (single-column, double-column, portal, etc.) of optimal height for suspension of wires of overhead power lines of various voltage classes from 35 to 750 kV.

Known support for the suspension of wires of overhead power transmission lines of high voltage, which is a rack with traverses, the specified height of which is gained by telescoping the conical sections of polygonal or round in cross section; while the joints of the connected sections are additionally strengthened by devices made in the form of steel rings or bandages [1].

This technical solution has significant disadvantages, namely:

- in order to ensure the practical strength of the joints of the connected sections of the support, equal to the strength of the entire main body of the support, in this embodiment, these joints are reinforced with additional means - flanges, bandages - which leads to a significant increase in the cost of the support due to the need to bear the excessive consumption of expensive material (metal) , in addition, the aesthetic appearance (design) of such a support does not withstand any criticism;

- the length of the overlap, to which one section of the support enters another when they are connected together, is in the structure under consideration about the size of the diameter of the section, which is not enough to ensure maximum joint strength even when using additional reinforcing devices.

The closest technical solution in relation to the proposed one is a support for suspension of wires of an overhead power line, containing a free-standing at least one rack with traverses mounted on it, the height of which is recruited from the conical sections connected to the telescopic joint, inserted with a given force by a narrow part of one sections to the wide part of another section [2].

This support also has disadvantages. When telescoping the elements (sections) of the support in one single structure, it is important to achieve the required strength of the joints (joints) so that it reaches or even exceeds the strength of the support shaft in this section. In the known support structure, this cannot be achieved; during operation, the joints are upset, lose their solidity and, in the end, are destroyed. The fact is that the strength of the joint directly depends on the force with which the connected parts of the support strut are interconnected. With insufficient pulling force, the resulting frictional forces between the sections do not provide the perception of shear forces along the lateral faces during operation of the bend support strut; in this case, with excessive pulling forces, plastic deformations occur, leading to the destruction of the joint. This effort is practically achieved in the manufacture or assembly of the support by means of special devices (for example, turnbuckles, screw ties, hydraulic jacks, etc.). It is necessary to tighten the connected parts (sections) to such a preliminary stress of the metal so that, ultimately, the joined elements due to the friction forces along the side surfaces of the sections are one and work as a monolithic single structure. The optimal amount of screed of the joined parts depends on many parameters, in particular, such as diameter, wall thickness of the sheet of the joined sections, their taper (runoff), yield strength of the selected material and others; in the known solution under consideration, for example, the conicity of the connected parts of the support is chosen to be fixed and equal to 0.0239, which is clearly insufficient and does not cover the wide practical range of all specific cases of installing free-standing supports of overhead power transmission lines of various voltage classes. Therefore, this support cannot be left in continuous operation and must be replaced with a new support after a certain time.

For sections with a sheet wall thickness of up to 4 mm, the optimal taper value is 0.015 ÷ 0.019, and for walls with a thickness of 4 to 6 mm, the taper is 0.0191 ÷ 0.03, for walls with a thickness of more than 6 mm, the taper should be 0.03. As a result, the problem of the strength of the joints of the supports for this option is not removed from the agenda.

The applicant and the authors set the urgent task of developing the basic design of a unified metal fast-mounted support, which, for example, can be successfully used to eliminate accidents on overhead power lines 35 ÷ 750 kV (in case of accidents on overhead lines associated with damage to the supports).

The planned result is achieved by the applicant in a new technical solution due to a combination of essential design features, namely: “a support for suspension of wires of an overhead power line, containing at least one stand with a free-standing beam, traverses mounted on it, the height of which is drawn from telescopically connected to the joint cone sections inserted with a given force by the narrow part of one section into the wide part of another section; the length of the joint l of the _{joint of} each joint of the joined sections of the support is selected from the ratio (1.75 ÷ 1.85) × d of the _{joint of the section} , the taper of the joined sections is within (0.015 ÷ 0.035), while the force N from the preliminary compression of the telescopic joint of the joined sections is calculated by the formula N = 5.0 × Q × l of the _junction / d of the _{junction of the section} , where Q is the shear force in kgf, l of the _junction is the length of the joint in cm, d of the _{junction of the section} is the average value of the cross-sectional diameter of the connected sections in the joint zone in cm.

The invention is illustrated by drawings, in which figure 1 is a General view of a support pillar made in accordance with the present invention; figure 2 is a General view of one separate section, from which the full height of the pillar of the support in figure 1; figure 3 is a section along arrows 1-1 in figure 2; figure 4 - scan section in figure 2; figure 5 is a General view of a single-column support in figure 1; 6 is a diagram of the installation of two sections in a multifaceted module, from which the support strut is assembled.

The proposed pillar 1 of the support consists of several (for example, five) sections 2 assembled into multifaceted modules, of which freestanding single-column 3, two-column and portal (not shown) metal supports of various heights are mounted. Traverses 4 for these supports 3 are made and mounted in the same way as they are made and mounted for widely known unified, for example, reinforced concrete supports. The sections 2 from which the strut 1 of the support 3 is assembled are conical with a polyhedron in their cross section (for example, ten faces 5, see Fig. 3), and they are inserted one with the calculated and experimentally selected force during the mounting of the rack 1 of the support 3 to the other until the strut 1 of the support 3 reaches a predetermined height, while the strut 1 of the support 3 is assembled as a result with constant taper. The foundation part of such supports 1 can, for example, be made in the form of a reinforced concrete centrifuged cylindrical rack with a cone in the upper part and has two to three standard sizes, depending on the diameter of the sections to be joined.

The equal strength of telescopic joints with the bearing capacity of racks 1 supports 3 in the proposed embodiment is achieved due to the optimal choice of parameters such as the joint length l of the _joint and taper or run - the ratio of the diameter D ^{1 of the} wide part of the section 2 ¹ to the diameter d ^{2 of the} narrow part of the section 2 ² on the length of the joint l of the _{junction of the} connected sections 2 of the rack 1 of the support 3 (see Fig.6). In this case, the calculated force N for preliminary compression of the telescopic joint of the connected sections 2 is calculated by the following formula: N = 5.0 × Q × l of the _joint / d of the _{joint of the section} , where Q is the shear force in kgf, l of the _joint is the length of the joint in cm, d _{section junction} , is the average value of the diameter of the cross section of the connected sections in the zone of their junction in cm; in each case, the force N is determined depending on the length and diameter of the joint, as well as on the magnitude of the calculated shear force. The optimal value of the length of the junction of the connected sections is selected from the following ratio: l of the _joint = (1.75 ÷ 1.85) × d of the _{junction of the section} , and the taper of the connected sections is in the range (0.015-0.035).

Racks 1 of free-standing supports 3 are assembled from separate sections 2 of a multifaceted module. Traverses 4 for these supports 3 can be made of a corner profile and round steel and are fixed on the rack 1 pivotally, for example, using a through bolt (kingpin) or clamps (not shown).

The connection of section 2 can be performed both in horizontal and vertical position. In the horizontal position, one section 2 ^{1 of the} rack 1 is fixed on the pads, and the other section 2 ^{'of the} rack 1 is hung by a crane. Using the longitudinal force generated by the crane, section 2 ² is introduced into the adjacent section 2 ¹ (see FIG. 6). Then the stops 6 are installed and with the help of two hydraulic jacks 7 driven from the pumping station 8, the sections 2 are coupled using intermediate links 9, fixed to the connected sections 2 through bolts 10. The coupler forces for each jack and movements in the joints should be no less than the values given in the following table:

Minimum joint movement in mm Minimum jacking force in kgf Maximum jacking force in kgf 65 14000 18000 80 16000 19500 95 18000 21000

The application of the proposed support structure based on a unified rack mounted by telescoping the conical sections allows you to:

- to provide a significant increase in the operational reliability of supports of this class by increasing the mechanical strength of the joints of the telescopic sections to be joined, from which the specified support height is gained (the strength of the joints in this design option is equal to or even higher than the mechanical strength of the support itself due to preliminary compression, since the joints are a single monolithic assembly with the entire support structure);

- significantly reduce the time for repair and restoration work on overhead power lines, since such poles are easily delivered and assembled from finished sections right at the place of replacement of damaged poles and do not require the construction of expensive foundations;

- exclude the costs associated with the temporary installation of supports, since the declared supports are designed for full load and are installed in continuous operation;

- to ensure a reduction in the area of warehouses of the stock volume of emergency reserve of supports for overhead power transmission lines with a voltage of 35 ÷ 750 kV in any power system, since from such telescopically connected sections a support of any configuration can be obtained instead of the existing one.

Information sources

1. US patent No. 3865498, class 403/292 (ЕНН 12/08), published June 16, 1975

2. US patent No. 3270480, class 52-726 (Е04Н 12/08), published September 6, 1966

Claims (1)

A support for suspension of wires of an overhead power transmission line, comprising a free-standing at least one rack with traverses mounted on it, the height of which is drawn from cone sections telescopically connected to the joint, inserted with a given force by a narrow part of one section into a wide part of another section, characterized in that the length l of each butt _joint sections joined support is selected from the relation (1,75 ÷ 1,85) · d _{joint section} connected taper sections is within the range (0,015 ÷ 0,035), with the force N on the preliminary of zhatiyu telescopic joint connected sections is calculated by the formula N = 5.0 · Q · l of the _junction / d of the _{junction of the section} , where Q is the cutting force in kgf, l of the _joint is the length of the joint in cm, d of the _{joint of the section} is the average value of the diameter of the cross section of the connected sections in the zone of their joint in cm.

Images