The choice of optimum cross section for overhead line by economic intervals' method

2011 ◽  
Vol 28 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Svetlana Guseva ◽  
Lubov Petrichenko
Keyword(s):  
Cross Section ◽  
Current Density ◽  
Uncertain Information ◽  
Overhead Line ◽  
Market Conditions ◽  
Overhead Lines ◽  
Mathcad Software

The choice of optimum cross section for overhead line by economic intervals' methodIn this paper an approach to choosing the optimum cross section for overhead line in conditions of incomplete and uncertain information is considered. The two methods of such choice are presented: method of economic current density and economic intervals' method. The correction of the economic intervals method is offered under market conditions of costs. As example 20 kV and 110 kV overhead lines with aluminum, copper and ferroaluminum wires are selected. Universal nomograms with different standard cross section are calculated and constructed. The graphics using Mathcad software are offered.

scholarly journals Transient Current Density in a Pair of Long Parallel Conductors

2021 ◽  
Vol 11 (15) ◽  
pp. 6920
Author(s):  
Oldřich Coufal
Keyword(s):  
Steady State ◽  
Cross Section ◽  
Current Density ◽  
Circular Cross Section ◽  
Transient Current ◽  
Constant Current ◽  
Voltage Source ◽  
Sinusoidal Voltage ◽  
Steady State Current ◽  
Maximum Current

Two infinitely long parallel conductors of arbitrary cross section connected to a voltage source form a loop. If the source voltage depends on time, then due to induction there is no constant current density in the loop conductors. It is only recently that a method has been published for accurately calculating current density in a group of long parallel conductors. The method has thus far been applied to the calculation of steady-state current density in a loop connected to a sinusoidal voltage source. In the present article, the method is used for an accurate calculation of transient current using transient current density. The transient current is analysed when connecting and short-circuiting the sources of sinusoidal, constant and sawtooth voltages. For circular cross section conductors, the dependences of maximum current density, maximum current and the time of achieving steady state on the source frequency, the distance of the conductors and their resistivity when connecting the source of sinusoidal voltage are examined.

Case Analysis on PTH Fracture Caused by Twin Copper

2014 ◽  
Vol 1061-1062 ◽  
pp. 431-435
Author(s):  
Xiao He
Keyword(s):  
Thermal Analysis ◽  
Thermal Stress ◽  
Theoretical Analysis ◽  
Cross Section ◽  
Current Density ◽  
Case Analysis ◽  
Actual Case ◽  
Soldering Process ◽  
Root Cause ◽  
Section Analysis

An actual case of PTH fracture after soldering process was studied. By means of cross section analysis using metallography microscope and SEM, together with thermal analysis results, root cause of PTH fracture was concluded that a high density of twin copper weakened the mechanical strength so seriously that PTHs could not undergo thermal stress from soldering process, and higher CTE was attributed to an accelerative factor. Moreover, it is recommended to enhance current density properly and make sure the effectiveness of electroplating additives to prevent twin copper by theoretical analysis.

Study on Reasons of the Falling of the Overhead Line Based on Fault Tree Analysis

2013 ◽  
Vol 325-326 ◽  
pp. 590-593
Author(s):  
Fei Xiang Wei ◽  
Yang Song ◽  
Xiao Xu Ma ◽  
Ying Qian
Keyword(s):  
Power System ◽  
System Reliability ◽  
Fault Tree ◽  
Fault Tree Analysis ◽  
Power System Reliability ◽  
Overhead Line ◽  
Qualitative And Quantitative Analysis ◽  
Tree Analysis ◽  
Overhead Lines ◽  
Qualitative And Quantitative

The transmission line is an important part of the power system, its reliability will directly affect the reliability of the power system. The reliability of the overhead line plays a crucial role for the power system reliability. This paper analyze the reasons of the falling of the overhead lines, establish a fault tree, and make qualitative and quantitative analysis of the fault tree.

scholarly journals The Way of Reducing Current Values in Optical Ground Wires at Asymmetrical Faults on Overhead Transmission Lines

2016 ◽  
Vol 11 (1) ◽  
pp. 13-20
Author(s):  
Georgiy Egamnazarov
Keyword(s):  
Cross Section ◽  
Transmission Lines ◽  
Conclusive Evidence ◽  
Fault Current ◽  
Overhead Lines ◽  
Optical Cable ◽  
Electric Power Grid ◽  
Three Phase ◽  
Wire Steel ◽  
Wire System

Abstract Given the fact that the installing costs of an optical ground wire on overhead lines directly depend on its cross-section, which in turn depends on the level of fault current it should withstand, in order to reduce these current values in the optical ground wire, I suggested performing its isolated descents from the end towers of the line with its transition to an optical cable. The research was carried out on the example of a 500 kV overhead line in the National Electric Power Grid. The Method of Symmetrical Components for calculating asymmetrical fault currents was not used; therefore, calculations were carried out on the base of presenting the line as a multi-wire system for the considered case as a five-wire system (optical ground wire, steel ground wire, and three phase wires). Such approach allows taking into account the initial asymmetry of the line parameters and modeling any kind of asymmetrical faults. The analyses of calculated results were performed. The conclusive evidence that the optical ground wire isolated descents from the end towers of the line give the possibility of reducing the level of maximal fault current distribution values in it and therefore its cross section, is presented.

scholarly journals Radar Cross-Section Formulation of a Shell-Shaped Projectile Using Modified PO Analysis

2012 ◽  
Vol 2012 ◽  
pp. 1-9
Author(s):  
Mohammad Asif Zaman ◽  
Md. Abdul Matin
Keyword(s):  
Differential Geometry ◽  
Cross Section ◽  
Current Density ◽  
Surface Current ◽  
Radar Cross Section ◽  
Analysis Procedure ◽  
Physical Optics ◽  
Surface Current Density ◽  
Filtering Method ◽  
Good Agreement

A physical optics based method is presented for calculation of monostatic Radar Cross-Section (RCS) of a shell-shaped projectile. The projectile is modeled using differential geometry. The paper presents a detailed analysis procedure for RCS formulation using physical optics (PO) method. The shortcomings of the PO method in predicting accurate surface current density near the shadow boundaries are highlighted. A Fourier transform-based filtering method is proposed to remove the discontinuities in the approximated surface current density. The modified current density is used to formulate the scattered field and RCS. Numerical results are presented comparing the proposed method with conventional PO method. The results are also compared with published results of similar objects and found to be in good agreement.

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