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 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 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 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 Accounting for Spacers in the Mechanical Calculation of Flexible Wires for Overhead Lines and Switchgears

2019 ◽  
Vol 62 (3) ◽  
pp. 219-231 ◽  
Author(s):  
Yu. V. Bladyko
Keyword(s):  
Concentrated Loads ◽  
Total Load ◽  
Mechanical Calculation ◽  
Overhead Lines ◽  
Distributed Load ◽  
Ice Loads ◽  
Concentrated Forces ◽  
The Difference

The mechanical calculation of flexible wires of overhead lines and switchgears, in which in-phase or phase-to-phase spacers are installed, is under consideration. Spacers are considered as concentrated loads acting on the split phase. The formulas for determining the sag are given for a different number of spacers as a function of their number and the coefficient of concentrated forces. This takes into account the difference in suspension heights, tension insulators strings, wind and ice loads. These formulas, being presented in a form that is convenient for consumers, can be used for computer execution of the mechanical calculation of flexible wires in different climatic regimes, both in the presence and in the absence of phase splitting. The errors of replacing the spacers with a distributed load are demonstrated. Formulas are proposed that give the smallest error when replacing spacers with a distributed load. The greater the value of the concentrated forces from the tap-off lines and loops, the greater the error in calculating the sag of the switchgears wires. Therefore, it is not possible to replace them with a distributed load obtained by simply dividing the total load by the length of the span in the presence of the tap-off lines and loops.

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 Taking into Account Taps to Electrical Apparatuses

2021 ◽  
Vol 64 (2) ◽  
pp. 109-120
Author(s):  
Y. V. Bladyko ◽  
E. G. Ponomarenko
Keyword(s):  
Vertical Load ◽  
Temperature Changes ◽  
Mechanical Calculation ◽  
Load Factors ◽  
Calculation Results ◽  
Climatic Regime ◽  
Concentrated Forces ◽  
The Given ◽  
Electrical Apparatus ◽  
Good Agreement

A method is proposed for the mechanical calculation of flexible wires of substation in the presence of one tap to an electrical apparatus located in the middle of the span, taking into account its real location. The technique takes into account the presence of tension insulators strings, different heights of the suspension of wires. The loads on the conductor and tap depend on the climatic regime and take into account wind and icy conditions, as well as temperature changes. The transition to another climatic regime is performed by solving the equation of state, taking into account the coefficients of the horizontal and vertical load of the given and initial regimes. Formulas are given for calculating load factors that take into account weight, wind and ice cover loads on wires and insulator strings, as well as the slope of the span. They are calculated for each climatic mode based on the actual location of the tap to the electrical apparatus and the forces from it to the busbar. It is shown that the calculation results are in good agreement with the proposed method and the computer program. Formulas are given for calculating the sag and horizontal deviations of the wires when the tap is located in the middle of the span. A method is proposed for calculating the components of the forces on the busbar from the tap, taking into account its real location in substation. Formulas for calculating these components are given for different variants of the tap orientation. Knowledge of the values of the components of concentrated forces from the tap allows to increase the accuracy of calculating the sag and tension of the substation wires. Formulas are given for calculating the coefficients of increasing the sag, taking into account the components of the forces from the tap.

scholarly journals Wind Load Factors for Use in the Wind Tunnel Procedure

2017 ◽  
Vol 3 (4) ◽  
pp. 04017007 ◽  
Author(s):  
Emil Simiu ◽  
Adam L. Pintar ◽  
Dat Duthinh ◽  
DongHun Yeo
Keyword(s):  
Wind Tunnel ◽  
Wind Load ◽  
Load Factors

Bifurcation of Circular Rings Under Normal Concentrated Loads

1973 ◽  
Vol 40 (1) ◽  
pp. 233-238 ◽  
Author(s):  
P. Seide ◽  
E. D. Albano
Keyword(s):  
Bifurcation Point ◽  
Circular Ring ◽  
Average Pressure ◽  
Uniform Pressure ◽  
Concentrated Loads ◽  
Finite Distortion ◽  
Circular Rings ◽  
Concentrated Forces

The deformation in bending of a circular ring loaded in its plane by concentrated forces is studied. The ring is assumed to be an elastica. The loads are of equal magnitudes and are equally spaced about the ring. Values of loading at which bifurcation of the symmetrical finite distortion shape occurs are determined for forces which remain normal to the ring. It is found that no bifurcation point exists for a ring under three loads. Buckling of a ring under two loads can occur only when the prebuckling configuration is an extremely distorted one. If the number of loads is five or greater, the critical average pressure does not differ greatly from the result for the ring under uniform pressure.

Estimates of extreme wind effects and wind load factors: influence of knowledge uncertainties

2001 ◽  
Vol 16 (4) ◽  
pp. 331-340 ◽  
Author(s):  
Fabio Minciarelli ◽  
Massimiliano Gioffrè ◽  
Mircea Grigoriu ◽  
Emil Simiu
Keyword(s):  
Wind Load ◽  
Wind Effects ◽  
Load Factors ◽  
Extreme Wind
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