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damp (calculation of vibration dampers)

Сalculation of mounting stresses and sag of wires, cords and self-supporting cables of communication and power transmission lines


MS PowerPoint Presentation

LineS, program package for designing overhead power and communication lines (OHL, FOCL OHL, FOCL). The calculating part of the program has been used since 1985 beginning with SM-4 EVM (System of mini-computers developed in USSR in 1970-80s).

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LineMount program is designated for calculating mounting stresses and sag of wires, cords and self-supporting cables of overhead communication and power transmission lines of 0.4, 6, 10, 35, 110, 220, 500 kV and communication lines.

Additionally, the program calculates the lengths of the wires, cords, self-supporting cables in spans considering sag for each sector and the entire project. Provided the large differences in heights of wires’ attachment, useLineCross (LineCrossCad) program for defining the spam lengths.

In case of mounting a fiber optic communication line to an existing overhead line (FOCL OHL) the first program for calculation, provided the cable is selected correctly, will be LineMount (LineMountCad). At the same time the calculation will take into account the existing wire of the overhead line and the communication cable, optical self-supporting cable or optical ground wire cable that is being mounted. (See “Project” page of the site).

The entire behavior of the wire, cord, self-supporting cable is verified by LineMech (LineMechCad), program, which includes, besides the approximate mounting modes, the loading modes (maximum loads, lowest temperatures), the modes necessary for other calculations including that for defining the overall span.

The entire behavior of the wire, cord, self-supporting cable is verified by LineMech (LineMechCad) The theory for calculating mounting stresses and sag “manually” ad explanations for the program are presented on “Theory and Practice” page of the site.
The calculation is based on permissible tension method. The kernel of the program – fill mechanical calculation.

The permissible tension (stress) is justified by LineMech (LineMechCad) program “Mechanical calculation of wires, cords, self-supporting cables”. Climatic conditions, climatic parameters specification and reliability coefficients are implied to be ported from there, from the source data as well.

At the same time, the program gives the values for loads per unit length to be taken into account by the line designer for the load-bearing constructions (supports, portals, etc.) from the stress of wires, cords, self-supporting cables and different influences of climatic conditions.

According to 2.5.185 of EIR, the mechanical calculation of optical ground wire cable, optical phase wire cable, optical self-supporting cable should be performed for reference loads based on permissible tension method following the rest of the requirements for wires and cords of overhead lines, see the section of EIR in “Fiber optic communication lines on overhead lines”.

The clearances with crossed objects and natural obstacles according to EIR are provided by LineCross (LineCrossCad) program – “Claculation of crossings between overhead communication and power transmission lines and engineering objects and natural obstacles”.

The source data of the program reflect the tension (stresses) accepted for the project for all the sectors of the designed line, spur lines
The user is given a warning in case the reliability coefficients to standard loads are used not according to 2.5.11 of EIR-7; in the source data they equal 1 by default.

The program allows performing calculations for new lines as well as for the reconstructing using the requirements of both EIR-7 and earlier versions.

The calculation results for mounters should contain mounting stresses and the spans attested by the sag for all the strain sectors of an overhead line.
The program provides, if necessary, the calculation taking into account the weight of insulator strings for spans with lowered stress. The program could be used for calculating mounting stresses and sag of self-supporting insulated wires for overhead lines of 0.4, 6, 20 kV, as well as self-supporting fiber optic communication cables (FOCL, FOCL OHL).

The calculation (by default) is done inconsiderate of further creep elongation of the wires, cords, cables. The mounting process should take into account the corresponding overdraw.
Given the further creep elongation, mounting stresses and sag are calculated in % from elongation given in reference literature for wires, cords, for cables – in Rules of suspending and mounting self-supporting fiber optic cable.

We do recommend supplying the project with both calculations inconsiderate(settled stress mode) and considerate of the elongation, so that the mounting organization could control the elongation during the mounting process.

To perform calculation, the data from supports-spotting on the line route profile or corresponding constructions with suspension (intermediate) or strain attachment of wires, self-supporting cables.

If a self-supporting cable or optical ground wire is input as “cord”, it is convenient to verify the correlation between the sag of the wire and that of the cable (cord) in the same row of the calculation results.
Any existing wire of the power transmission line could be indicated as “wire”, with the tension defined by the measurements of sag and stress at different temperatures.

The program is applicable for any climatic zone.
Besides the description of the required source data, Help file for the program gives recommendation on the application of calculation results and their place in each particular project.
The calculation results are given in the form of Excel tables. The resulting tables are customary for the customers and mounters.
The tables could be formed into any formed of project documentation accepted by design organizations.
Take into account that self-supporting insulated wires and cables are not mounted at low temperatures.
The calculation results are given in different forms at customers’ requests.
Form 1 of calculation results are presented in the beginning by the tables of stresses in strain sectors, then sag according to classical approach given in manuals and industry materials:

The results of calculation in form 2 submitted by tienimi and arrows of SAG separately for each anchor site:

The program forms the supports-spotting catalog according to the input source data for control and use on the project (for fiber optic communication lines – the catalog of mounting fiber optic cables on supports of an overhead line). If necessary, the supports-spotting catalog could be amplified with the data in the program as well as in Excel table. By default, if no additional data are input in the catalog through the program interface, the supports-spotting catalog is formed based on the data from calculation of stresses and sag.

LineMountCad. Support-by-support plan of the overhead line (FOCL OHL) in AutoCad.

Based on the data of supports-spotting catalog and the calculation results the program now has an option of preparing a new form to be used for future in projects of overhead power transmission lines (OHL) and fiber optic communication lines (FOCL OHL). Support-by-support plan of OHL, FOCL OHL is ported to AutoCad and other graphical packages supporting dxf exchange format.
The received form with results could be gracefully used for projects of overhead lines, for example, when replacing wires, ground wire, vibration dampers according to new requirements in FOCL OHL projects for mounting optical ground wire cables and optical self-supporting cables.
This form could replace the usual tables of mounting stresses and sag due to its visual representation and easy to make.

When inputting the wire with large sectional area as “cord” when replacing an old wire, it is convenient to follow the correlation the sag of the old wire and that of the new wire in one row of the calculation results (or vise versa, input the old wire as “cord” and the new wire as “wire”).
The wire of the existing overhead line could be indicated as “wire” with the tension defined by the measurements of sag and stress at particular  temperatures.

LineMount_damp (LineMountCad_damp) The version of the program with the calculation of vibration dampers

The calculation of vibration dampers is done for wires and cords (including optical ground-wire cables) of the overhead lines of 35 and more kV, as well as for self-supporting communication cables, dielectric (FOCL OHL) and others, not on an overhead line, if it is required in accordance with Organization Standard 34.20.264-2005, Organization Standard 34.20.265-2005. The result of the calculation is the register of vibration dampers.

The catalogs of wires, cords, self-supporting cables are open for additions and editing.
When using non-standard self-supporting cables of fiber optic communication lines, it is necessary to ask their characteristics from the manufacturer for each particular project.

The source data input is supplemented with an option of porting from Excel file.

For more details see the User Guide for the program (Program description. Application.) which could be downloaded along with the demo version.