scholarly journals Mechanical Calculation of Flexible Wires Loaded with Concentrated Loads

2020 ◽  
Vol 63 (2) ◽  
pp. 103-115 ◽  
Author(s):  
Y. V. Bladyko
Keyword(s):  
Equation Of State ◽  
Horizontal Wind ◽  
Load Factor ◽  
Structural Elements ◽  
Concentrated Force ◽  
Mechanical Calculation ◽  
Combined Action ◽  
Concentrated Forces ◽  
The Wire ◽  
Wire Suspension

Calculating of wires sag and tension under various modes is the task of mechanical calculation. The article derived formulas for the curve of the wire sag under the action of one or several concentrated forces and with various tensioning insulators strings in the span. Formulas for estimating the distance to the maximum sag have been obtained. Based on the length of the system of “first tension insulators string – conductors – second tension insulators string” that depends on the supporting beam reactions and beam lateral forces in the corresponding sections, the system load factor was determined taking into account structural elements for different climatic loads. The formulas to calculate the load factor for solving the equation of state in the case of different insulators strings in span loaded with one or several concentrated forces have been obtained. The resulting expressions can also be applied in case of horizontal wind loads; in this case the equation of state should take this component into account when calculating the resulting reduced load on the wire in an inclined plane. The reliability of the formulas was proved by the coincidence of the results for the particular case of the arrangement of the insulators strings. An algorithm for calculating sag under the combined action of vertical and horizontal loads, as well as in the case of the location of wire suspension points at different heights, is given. A formula has been proposed for estimating the sag increase factor due to the presence of concentrated forces uniformly distributed along the span and various insulator strings in the span. The dependence of the coefficient of increase of the sag on the distance to the concentrated force in the presence of one and two forces in the span is drawn.

scholarly journals Mechanical Calculation of Flexible Wires of Spans with Different Tensioning Insulator Strings

2020 ◽  
Vol 63 (1) ◽  
pp. 55-65 ◽  
Author(s):  
Yu. V. Bladyko
Keyword(s):  
Equation Of State ◽  
Horizontal Wind ◽  
Load Factor ◽  
Inclined Plane ◽  
Load Factors ◽  
Design Activities ◽  
Ice Loads ◽  
The Wire ◽  
The Difference ◽  
Technical Solutions

In design activities, technical solutions are practiced, which provide for the use of different tension strings of insulators in a single span. The present paper considers the calculation of the sag and load factors for a span with two different tensioning insulator strings that are of identical suspension heights. The system of “the first tension insulators string – the wire – the second tension insulators string” was described by the equations of a parabola. A relationship has been established between the sag increase factor and the coefficients that take into account the presence of tensioning insulators strings. The resulting compact formula for sag increase is generally suitable for any combination of strings in a span. The coincidence of the calculation is shown for particular cases known from the literature. The formula for calculating the load factor for the equation of state was derived, taking into account the presence of different strings in the span. The reliability of the formula has been proved by the coincidence of results for particular cases of the arrangement of strings. The obtained expressions can be used both for vertical (weight and ice) loads and for horizontal (wind) ones. In the case of loads in two planes, the equation of state must take into account all the components when calculating the resulting reduced load on the wire along the inclined plane. Calculations were performed for different lengths of spans of switchgear with different wires and strings of insulators. A span with one and two tensioning strings of insulators, with the same suspension heights, in the absence of wind and ice is considered. The curves of the sagging wires to different strings have been plotted. It is demonstrated that when calculating sags and tensions, the difference between strings must not be neglected.

scholarly journals MECHANICAL CALCULATION OF FLEXIBLE WIRES WHEN A CONCENTRATED LOAD IS BEING REPLACED WITH A DISTRIBUTED ONE TAKING INTO ACCOUNT THE STRUCTURAL ELEMENTS Y.V. BLADYKO1)

2018 ◽  
Vol 61 (3) ◽  
pp. 220-234 ◽  
Author(s):  
Y. V. Bladyko
Keyword(s):  
Parametric Method ◽  
Climatic Conditions ◽  
Structural Elements ◽  
Concentrated Loads ◽  
Concentrated Load ◽  
Mechanical Calculation ◽  
Overhead Lines ◽  
Concentrated Forces ◽  
The Wire ◽  
Electrical Apparatus

In the mechanical calculation of the flexible wires of substations and overhead lines, sags and tension are determined in various climatic conditions. Concentrated loads from spacers, barrier balls, stubs, taps to electrical apparatus and other elements are replaced with a load distributed over the span. On the example of a span with tension insulator springs, the action of concentrated loads on the wire is considered, the error is determined when the concentrated forces are replaced with a load one that is uniformly distributed along the span. It is shown that concentrated loads cannot be replaced with distributed ones by simple division of total loads by the span length, since this might result in completely incorrect findings. A relationship is established between the coefficient of the increase of the sag, the coefficient of concentrated forces, the coefficient that takes into account the presence of tension insulator springs, and the angle of inclination of the span. With wind load and the presence of taps to electrical apparatus, the deviations of the wire in two planes may be calculated independently of each other if the forces concentrated in these planes are known. A decrease in the error is shown with an increase in the number of small concentrated forces. The influence of the angle of inclination of the span and the presence of tension insulator springs on calculating the deviations of the wires of substations and overhead lines is assessed. A more accurate calculation of mechanical tensions and sags is possible with the use of a vector-parametric method for calculating the flexible bus of switchgears and wires of overhead lines, where the design model of wires in the form of a flexible elastic thread is used, taking into account the spatial disposition of all structural elements.

scholarly journals Mechanical Calculation of Flexible Wires of Overhead Lines with Barrage Balls

2018 ◽  
Vol 61 (4) ◽  
pp. 299-309 ◽  
Author(s):  
I. I. Sergey ◽  
Y. V. Bladyko
Keyword(s):  
Parametric Method ◽  
Spatial Arrangement ◽  
Total Load ◽  
Mechanical Calculation ◽  
Overhead Lines ◽  
Acceptable Accuracy ◽  
Elastic Thread ◽  
Concentrated Forces ◽  
The Wire ◽  
A Chain

Aerial barrage balls serve for marking high-voltage wires in order to visually warn pilots of civil and military aviation about the presence of overhead lines. The present article deals with the mechanical calculation of flexible overhead wires of overhead lines, in which aerial warning barrage balls are installed. The wire is considered as a homogeneous flexible thread having the outline of a parabola and a chain line. The load from the aerial barrage balls must not be substituted with a distributed one by simple division of the total load into the span length, since it can cause incorrect results. The formulas for determining the sag are given for a different number of aerial barrage balls as a function of their number and the coefficient of concentrated forces. The acceptable accuracy of mechanical calculation is demonstrated when using the model of wire in the form of a parabola adopted in the design practice, provided that the components of concentrated forces are correctly determined. The equation of state is recorded, taking into account the weight and wind loads on the wire, as well as load coefficients in two planes, depending on the number of barrage balls. The performed calculations demonstrate an acceptable accuracy of the determination of the stress at various loadings of the span. For more accurate calculation of mechanical stresses and sag arrows, a vector-parametric method for calculating the flexible wires of overhead lines is suggested, where the calculated model of wires in the form of a flexible elastic thread is put taking into account of the spatial arrangement of all structural elements. The results of mechanical calculation according to the program that had been developed and to the existing methods for a different number of aerial barrier balls moved along the span are presented.

scholarly journals Mechanical Calculation of Flexible Wires in the Presence of Horizontal Concentrated Loads

2020 ◽  
Vol 63 (6) ◽  
pp. 500-514
Author(s):  
Yu. V. Bladyko
Keyword(s):  
Wind Load ◽  
Horizontal Component ◽  
Concentrated Loads ◽  
Mechanical Calculation ◽  
Overhead Lines ◽  
Load Factors ◽  
Linear Load ◽  
Flexible Wire ◽  
Concentrated Forces ◽  
The Wire

The linear wind load on the wires and cables acting perpendicular to the wire depends on the angle between the direction of the wind and the axis of the overhead line. In the methodology of mechanical calculation of wires and cables, it is recommended to take the wind directed at an angle of 90° to the axis of span and it is not specified which side the wind blows from. For spans of air, this is not so much significant as for switchgear spans, where the deviations of the wires depend on the direction of action of the taps to the electrical apparatus. The article discusses various options for the location of taps and their effect on the wire, as well as changing the direction of the wind. An algorithm for calculating the horizontal deviation of a flexible wire and its increase coefficients in the presence of horizontal concentrated loads due to the action of windon spacers, barriers, taps to electrical apparatuses and other structural elements of substations and overhead lines is given. In the absence of wind, horizontal concentrated loads and deviations occur when an arrangement of the taps is non-keel. The formulas for calculating the horizontal component of the load coefficient to solve the equation of state in the presence of horizontal concentrated forces acting in any direction have been derived. The results of the mechanical calculation are obtained for the cases of one and two horizontal concentrated forces, differently oriented with respect to the distributed wind load. In design practice it is recommended to take the wind flow in the direction of the action of horizontal concentrated forces, since in this case the greatest horizontal deviations and load factors are obtained. The reduction in the coefficients of the horizontal load occurs when the current lead is unloaded because of the opposite directions of the wind and horizontal concentrated forces. In the absence of wind, it is proposed to use the formulas for calculating horizontal deviations and load after finding the product of the coefficient of increase in horizontal deviations and the horizontal component of the coefficient of load per linear load.

scholarly journals MECHANICAL CALCULATION OF FLEXIBLE WIRES WHEN THE CONCENTRATED FORCES ARE REPLACED BY A DISTRIBUTED LOAD

2018 ◽  
Vol 61 (2) ◽  
pp. 97-107 ◽  
Author(s):  
Yu. V. Bladyko
Keyword(s):  
Parametric Method ◽  
Climatic Conditions ◽  
Concentrated Loads ◽  
Mechanical Calculation ◽  
Overhead Lines ◽  
Distributed Load ◽  
Uniformly Distributed Load ◽  
Concentrated Forces ◽  
The Wire ◽  
The One

The objective of mechanical calculation of flexible wires of substations and overhead lines is to determine the sag and tension in different climatic conditions. A wire with a uniformly distributed load is considered as a homogeneous flexible thread having the form of a parabola. Concentrated loads from spacers, barrier balls, stubs, taps to electrical apparatus and other elements are replaced with the one distributed over the span. On behalf of a span without tension springs of insulators the action of concentrated loads on the wire is considered, an error is determined when replacing the concentrated forces with the one uniformly distributed along the span by the load. The sag for the equivalent wire is determined with the aid of the ratio of the increase of the sag, due to the presence of concentrated forces. An equation of state has been drawn up which makes it possible to determine the tension after changing the number of concentrated loads, e.g., after installing spacers, hanging the barrier balls, fixing the taps. The dependence of the maximum sag on the number of concentrated forces is given. The definition of the coefficient of concentrated forces as the ratio of the sum of the concentrated loads to the weight of the wire in the span is presented. A relationship between the load factors, the increase of the sag and the coefficient of concentrated forces is established. The formula has been deduced for determining the error in the replacement of concentrated forces by a uniformly distributed load along the span as a function of the number of concentrated forces and the coefficient of concentrated forces. A decrease in the error with an increase in the number of concentrated forces has been demonstrated. A more accurate calculation of mechanical tensions and sag is possible with the use of a vector-parametric method for calculating the flexible busbar of substations and air-line wires, where the design model of wires in the form of a flexible elastic thread is placed, taking into account the spatial disposition of all structural elements.

scholarly journals Geometry and Modeling of the Oval Strand of n0+(2n0+4)+n2 Type

2012 ◽  
Vol 7 (2) ◽  
pp. 33-40 ◽  
Author(s):  
Eva Stanová
Keyword(s):  
Initial Data ◽  
Geometric Modeling ◽  
Geometrical Model ◽  
Wire Rope ◽  
Mathematical Representation ◽  
Structural Elements ◽  
The Core ◽  
Different Shapes ◽  
The Wire ◽  
Wire Strand

Abstract A wire rope is a structure composed of many individual wires. The wires form two major structural elements: the strand core and the layers of the strand. There may be different shapes of strands in the rope depending on the shape of strand core. The paper deals with the mathematical geometric modeling of the oval wire strand created of n0 + (2n0 + 4) + n2 wires. The number and diameter of the core wires are the initial data. The mathematical representation is in form of parametric equations of the wire axes. The equations are implemented in the Pro/Engineer Wildfire V5 software for creating the geometrical model of the strand.

scholarly journals EVALUATION OF THE EFFICIENCY OF THE DEVICE FOR LIMITING TENSION OF THE WIRE IN A SHORT CIRCUIT

2017 ◽  
Vol 60 (4) ◽  
pp. 309-319
Author(s):  
I. I. Sergey ◽  
E. G. Panamarenka ◽  
Ya. A. Potachits
Keyword(s):  
Computer Program ◽  
Short Circuit ◽  
Great Length ◽  
Structural Elements ◽  
Method Of Calculation ◽  
Overhead Lines ◽  
Stage Of Development ◽  
Initial Stage ◽  
The Wire ◽  
Short Circuit Currents

The intensity of the electrodynamic action of currents of a short circuit on the flexible conductors of overhead lines depends on the magnitude of currents of short-circuit. The commis sioning of new capacities is inevitably accompanied by an increase in short circuit currents in the nodes of the grid, so the need to limit peaks of tension arising in a short-circuit can acquire a special relevance at a certain stage of development of the power system. At short circuit currents over 40 kA the mechanical force and displacement of the wires can have a decisive influence on the structural performance of flexible bus as of single wires as well as of split phases. In this regard there is a need for the development and use of new structural elements enhancing electrodynamic stability of flexible busbars of outdoor switchgear. One such element is a tension damper. The damper is installed between the portal and the insulator string and limits the transmission of undesirable forces on the portals in a short circuit. The numerical method of calculation of dynamics of flexible wires of switchgear and overhead lines in a short-circuit taking into account influence of a tension damper has been developed. This method was used for modification of the computer program of calculation of electrodynamic stability. With the aid of the computer program it was demonstrated that the installation of the tension damper makes it possible to cut off peaks of the tension of wire in a short circuit at the initial stage of movement of the conductors. However, in spans of a great length after the actuation of the damper the occurrence of new bursts of tension is possible due to the sudden stop of the wire. 

EQUATION OF STATE OF A WIRE IN THE PARAMETRIC FORM OF A CHAIN LINE

2021 ◽  
pp. 66-72
Author(s):  
V.V. Mishchenko ◽  
Keyword(s):  
Equation Of State ◽  
Nonlinear Equations ◽  
Classical Equation ◽  
Parametric Representation ◽  
System Of Nonlinear Equations ◽  
Parametric Form ◽  
Initial State ◽  
The Wire ◽  
A Chain ◽  
Special Case

Abstract. The "equation of state of the wire" is presented for the parametric representation of a chain line as a system of nonlinear equations. The classical equation of state of a wire is a special case of the presented system of nonlinear equations. The concept of the "initial" state of the wire is introduced, which is used to show the solution of the parametric "equation of state of the wire".

Concentrated Force in an Elastically Embedded Disk

1963 ◽  
Vol 30 (4) ◽  
pp. 568-570 ◽  
Author(s):  
J. Dundurs
Keyword(s):  
Elastic Plane ◽  
Concentrated Force ◽  
Concentrated Forces

This paper deals with the concentrated force in a disk which is embedded in an unbounded elastic plane with different properties. The disk with its edge free of tractions and subjected to concentrated forces and moments is also discussed.

scholarly journals Technical solutions for working elements of machines for efficient compaction of soil

2018 ◽  
Vol 230 ◽  
pp. 01006
Author(s):  
Kazimir Glavatsky ◽  
Volodymyr Cherkudinov ◽  
Olexandr Posmitiuha
Keyword(s):  
Soil Compaction ◽  
Structural Elements ◽  
Initial State ◽  
Modular Units ◽  
Wide Range ◽  
Combined Action ◽  
The Creation ◽  
Technical Solutions ◽  
The Impact ◽  
Light Medium

The modernization of machines for compaction of soil on a modular basis has the following advantages: some of their structural elements (working equipment and working elements) can be performed as unified modular units, from which, depending on the technological requirements, it is possible to assemble the required configuration of the sealing machine; the initial state of the machine does not deteriorate, to which it is easy to return; the nomenclature of structural elements and machines in general decreases, as the machine can be completed with variable modules, which leads to an improvement in their quality. When consolidating the soil massive use static, dynamic and combined action on the soil in the form of rollers, vibro-and ramboards. Machines of the boottype are classified into light, medium and heavy, which determines the order of its application. It is obvious that the reduction of technology for the process of soil compaction is possible due to the creation of machines that can change the intensity of the impact on the soil in a wide range.

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