Aluminum Conductor Steel Reinforced Research Articles

산불에 노출된 강심알루미늄연선 송전선 알루미늄 선재의 기계적 및 전기적 특성 거동

Forest fire can cause a serious damage to overhead conductors. Therefore, detailed investigation on the changes of mechanical and electrical properties of damaged conductors should be carried out to understand the effect of forest fires on conductors. This is of critical importance in maintaining transmission line safely. This paper examines the changes of mechanical and electrical properties of flame exposed conductor. Tensile strength (TS) decreased according to increase of forest fire temperature and conductivity changed according to forest fire temperature. Specimens were aluminum conductors of aluminium conductor steel reinforced (ACSR) 410, 240, 480 <TEX>$mm^2$</TEX>. In this paper, the electrical and mechanical characteristics of forest fires exposed overhead conductors depending on the diameter of aluminum conductors are presented. It was possible to estimate the degree of deterioration caused by forest fires. The detailed results are given in the paper.

A Performance Analysis of Reconductoring an Overhead Line Structure

A holistic computational methodology is employed in this paper to present an analysis of the widely used aluminum alloy conductors (AAAC) performance on a 33-kV wood pole structure. This analysis highlights the basic system properties that influence its mechanical and electrical performance. A comprehensive comparison of the performance of the common AAAC and aluminum conductor steel reinforced (ACSR) conductors erected on the structure is presented, including the study of the increase in operating temperature on the losses, ampacity and sag, in order to identify the most appropriate conductor for the pre-specified structure. Some recently developed high temperature low sag (HTLS) composite conductors are also studied in terms of power transfer uprating on distribution overhead lines. Their performance is examined at normal temperatures instead of the high operating temperatures for which they are specifically designed for, in order to evaluate the benefits they may offer at distribution level voltages.

Detection of wire element breakage in power transmission line using HTS-SQUID

We have proposed the application of nondestructive evaluation (NDE) using HTS-SQUID gradiometer to detect wire breakage in compressive conductor joints in overhead transmission line. In this study, we prepare an aluminum conductor steel reinforced (ACSR) transmission line with a broken wire. The ends of the ACSR cable were compressed with Al sleeves. An AC current was injected toward into the cable axis by applying AC voltage across the both ends of the sleeves. Then the two-dimensional distribution of magnetic field gradient above the cable was measured by a HTS-SQUID gradiometer. In the case of the compressed ACSR with a wire breakage, the field gradient changed periodically along the spiral of the broken wire. In contrast, such changes did not appear above the ACSR cable without defects. These results suggested the possibility to detect the wire breakage in the compressive conductor joints by this method. We also conducted electromagnetic field simulation to verify the experimental results.

Investigation of mechanical properties of single layer ACSR based on an Integrated Model

The design, selection and improvement for overhead aluminum conductor steel reinforced (ACSR) require intensive understanding of the cable characteristics. Until now, the analytical model for single layer ACSR is not satisfactory because of an unacceptable error between the analytical value and the experimental value. This paper presents a newly developed Integrated Model designed and performed on single layer conductors to investigate their electromagnetic, thermal and mechanical properties based on the Unified Model which was initially designed for three-layer ACSR. Carefully designed physical experiments to obtain conductor electromagnetic properties were used to validate the Integrated Model for various composite single layer ACSR: Guinea, Penguin, and Raven, popularly used in North America. An analysis of the electrical losses is also reported, and mechanical properties of odd-layer ACSR conductors are studied through case examples.

A Composite Core Conductor for Low Sag at High Temperatures

A new type of overhead conductor with a polymer composite core is evaluated in terms of the mechanical properties and operating characteristics. The conductor is composed of trapezoidal O'-tempered aluminum wires helically wound around a hybrid glass/carbon composite core produced by pultrusion. The conductor is intended for electrical power transmission, and is designated ACCC/TW, for aluminum conductor composite core/trapezoidal wire. Measurements of core properties and conductor sag at high temperatures were compared to conventional ACSR (aluminum conductor, steel-reinforced) of the same diameter. The tensile strength of the ACCC/TW was /spl sim/1.5 times greater than conventional ACSR of the same outer diameter. The CTE of the composite core was approximately 4 times lower than the steel core in ACSR. The ACCC/TW conductor exhibited a six-fold reduction in high-temperature sag compared with conventional ACSR (Drake) when operated at the same current. The ACCC/TW conductor also exhibited greater ampacity than ACSR conductor at all operating temperatures.

Unifying calculation of vortex-induced vibrations of overhead conductors

This paper deals with a unified way for calculating vortex-induced vibrations (Aeolian vibrations in transmission line parlance) of undamped single overhead conductors. The main objective of the paper is to identify reduced parameters which would unify the predicted vibration response to the largest possible extent. This is actually done by means of a simple mathematical transformation resulting, for a given terrain (associated to a given wind turbulence intensity), into a single, unified response curve that is applicable to any single multi-layered aluminium conductor. In order to further validate the above process, the predicted, unified response curve is compared with measured response curves drawn from tests run on a full-scale test line using several aluminium-conductor-steel-reinforced (ACSR), all-alloy-aluminium-conductor (AAAC) and aluminium-conductor-alloy-reinforced (ACAR) conductors strung at different tensions. On account of the expected scatter in the results from such field tests, the agreement is shown to be good. The final results are expressed by means of only four different curves pertaining to four different terrain characteristics. These curves may then be used to assess the vibration response of any undamped single, multi-layer aluminium conductor of any diameter, strung at any practical tension.

An approach for analysis in refurbishment of existing conventional HV–ACSR transmission lines with AAAC

In this study, Turkish National Interconnected Network System (TNINS) has been considered as a case. TNINS’s HV-overhead lines have initially installed with conventional aluminium conductor steel reinforced (ACSR), and economical service life of the conductors has been completed. The approach has been applied at the stage of refurbishment of transmission lines with the condition that available steel towers should be kept up. The best comparing way to find out the equivalence of the conventional ACSR among the types of all aluminium alloy conductor (AAAC), conductors have been appreciated with a computer program based on Turkish outdoor installation regulation conditions. Results were summarised and author hopes that a similar approach can be applied for other countries at the same stage as well.

Analysis of Traditional Suspension Strings With GTACSR Conductors

The technological development experienced by industrialized countries has brought about a huge increase of demand for electric power. As a result, the utilities in charge of electric power transmission and distribution have noticed that the high-voltage overhead lines are reaching critical values of ampacity and sag. In order to tackle this issue, we have undertaken the analysis of the eventual replacement of traditional aluminum conductor steel reinforced (ACSR) conductors with other conductors of better thermal properties. In the present paper, we report on the results obtained about how well the suspension strings of the ACSR conductors perform with the gap-type aluminum conductor steel reinforced (GTACSR) conductors. This study has been achieved using a multipurpose finite-element analysis (FEM) software package for both design and simulation.

On Mechanical Waves Along Aluminum Conductor Steel Reinforced (ACSR) Power Lines

The propagation of elastic waves along composite wire rope is considered. The rope is modeled as co-axial layers of cylindrically anisotropic material. Simple kinematical assumptions lead to a “rod theory” for the wire rope, consisting of three coupled one-dimensional wave equations. Solutions of these equations are found. Results for a particular aluminum conductor steel reinforced (ACSR) conductor are described in detail. The slowest mode is found to be mainly torsional and mainly nondispersive in character. The other two modes are dispersive and have small torsional components.

Some effects of mill practice on the stress strain behavior of ACSR

Operating temperatures of overhead lines have risen. Tests have indicated that conventional sag tension calculations may underestimate sags that occur at the higher temperatures in ACSR (aluminum conductor steel reinforced) spans. Search for the source of the disparities has identified two effects associated with the manner in which conductors are manufactured. One effect involves residual stresses, resulting from stranding practice, in the finished conductor. The other is caused by the ability of the aluminum part of ACSR to bear axial compression. Analysis of these effects appears to explain the disparity in at least one of the test programs that revealed it.

Effect of magnetic induction in a steel-cored conductor on current distribution, resistance and power loss

The presence of a steel core in the commonly used aluminum conductor, steel reinforced (ACSR) on overhead transmission lines causes an increase in the AC resistance of the conductor, as a result of the magnetic induction in the core. This induction, which is higher with an odd number of aluminum layers, causes hysteresis and eddy current power losses in the steel, and a redistribution of current in the layers of aluminum wires. The effects of the total current in the conductor and the temperature of the steel core on the current distribution, the AC/DC resistance ratio and the power loss are determined for a Grackle conductor with three layers of aluminum wires. It is shown that the resistance ratio and the power loss can be significantly reduced at higher currents by careful design of the lay length (pitch) of each layer of aluminum wires.

96/05069 A recursive Newton type algorithm for digital frequency relaying

This chapter focuses on the components that make up the modern power system. This chapter also focuses on the transmission of electric power and how to optimize its power transfer capability. Generators are the starting point in a power system where electricity is generated. The most commonly used type of generator is the synchronous generator, driven by a prime mover. The bulk transfer of electrical energy from generating power plants to substations located near population centers is achieved through high-voltage transmission lines. Interconnected transmission lines are referred to as high-voltage transmission networks. Electric utility companies have utilized aluminum conductor steel-reinforced (ACSR) as a common choice of conductor in transmission lines for many years. ACSR is used extensively on long spans as both ground and phase conductors because of its high mechanical strength-to-weight ratio and good current-carrying capacity. Due to this reason, the conductor temperature is normally influenced by weather condition as well as the electrical current loading of the conductor.

Similarity laws of the internal damping of stranded cables in transverse vibrations

Similarity laws governing the internal damping of stranded cables in transverse vibrations are based on the assumption of hysteretic loss factor associated with the flexural rigidity of the cable and the assumption that this loss factor is the same for all cables of the same construction. These laws are derived from the basic cable differential equation. The proportionality factors, the exponents of the various parameters in the laws, are obtained from the experimental results of a typical member of a family of similar cables. The same set of laws has been found to apply very well to ACSR (aluminum conductor steel reinforced) conductors having the same number of strands and fairly well to all ACSR conductors. Other families of cables, such as ACAR (aluminum conductors aluminum reinforced), steel cables, etc., could each have their own set of similarity laws, which would all look alike. >

Aged ACSR conductors. I. Testing procedures for conductors and line items

Field and laboratory tests of aluminum conductor steel reinforced (ACSR) conductors and related line items from many of Ontario Hydro's older transmission lines are described. A nondestructive corrosion detector was modified for live line measurement of the loss of galvanizing from the steel cores of the ACSR conductors. Samples of conductors tested in the field have also undergone laboratory metallurgical investigation, and tests of fatigue, tensile strength, torsional ductility and electrical performance. Extensive environmental studies have identified corrosion products of ACSR conductors, the atmospheric factors responsible for corrosion, and the mechanisms by which corrosion takes place. It is concluded that the corrosion detector serves as a useful indicator of impending end of conductor life while the torsional ductility tests serve as a more precise condition indicator and can provide a guide for scheduling conductor replacement. >

The effect of frequency on the resistance and internal inductance of bare ACSR conductors

An experimental investigation of the effects of varying the frequency on the electrical characteristics of a 54/19 ACSR (aluminum conductor, steel reinforced) conductor is described. Current from a sine wave alternator with precise voltage and frequency controls in the range 25 to 60 Hz was supplied to a pair of parallel tensioned lengths of the conductor, forming a loop within a nonmagnetic enclosure. The DC and AC resistances, the internal inductive reactance, the axial magnetic flux, the surface current density, and the temperature of the conductor were found. The AC-to-DC with resistance ratio was found to increase with increasing current and increasing frequency. The surface current density decreased with increasing current and increasing frequency. All these variations can be attributed to the transformer effect, resulting from the presence of the steel core and the spiraling of the layer currents, and the increase of magnetic power loss. >

Computational comparison of efficacies of aeolian vibration damping devices for multiconductor overhead power lines

Aeolian vibration in multiconductor overhead power transmission lines is usually controlled by one of two techniques, namely by a combination of rigid spacing elements and end point Stockbridge dampers, or suitably positioned spacer dampers. In this paper, a comparison based on theory and computation is provided. It is concluded, consistent with observations over many years, that both philosophies suffice when the conductors are moderately tensioned ACSRs (aluminium conductor steel reinforced). When the conductors are moderately/highly tensioned AAACs (all aluminium alloy conductors), neither philosophy is totally adequate. If the two philosophies are combined, good vibration control will result in many circumstances.

Probabilistic Approach to Aeolian Fatigue Design of Overhead Conductors

Research to develop a probabilistic model and methodology for aeolian fatigue design of overhead conductors that makes use of S‐N and “Load”‐N design curves is described. The probability‐based design equations and methodology use the mean and variance data of the S‐N and “Load”‐N curves to evaluate the reliability of overhead conductors subjected to aeolian fatigue. Even though the developed equations do not provide exact reliability levels, the values obtained allow rational decisions to be made on the basis of comparison with known safe levels of reliability. Using data available for 12 Drake Aluminum Conductor Steel‐reinforced (ACSR) Georgia Power Company lines, the simplified probabilistic design approach yielded probabilities of fatigue failure from 0.006% to 30%. Hence, the probabilistic model did predict aeolian fatigue problems for some of the lines using a 1% acceptable probability of failure.

Experimental Evaluation of S‐N Curves for Drake ACSR Conductor

This paper reports on an experimental effort to generate S-N (dynamic stress-fatigue life) curves for a Drake ACSR (aluminum conductor steel reinforced) conductor. In the testing, aeolian vibrations were simulated by mechanical means in a controlled laboratory environment for one set of line conditions. Fatigue data for the first five strand breaks were evaluated, and S-N curves for the first through fifth strand breaks were fit to the data using linear regression analyses. A minimum of four duplicative tests at each stress level tested were conducted to allow an evaluation of the statistical parameters and to provide statistical credibility to the results. A pseudo endurance limit of 21.31 MPa (3.09 ksi) was estimated from the S-N data. The S-N curves generated in this study provide much needed information for transmission line designers on the fatigue characteristics of Drake ACSR conductors. It is recommended that the S-N curves be used in conjunction with a probabilistic approach in designing transmission lines for aeolian fatigue.

Theoretical Estimation of the Response of Helically Armored Cables to Tension, Torsion, and Bending

This paper concerns the mechanical behavior of ACSR (aluminum conductor steel-reinforced) conductors under static-loading conditions, which may comprise any combination of tension, torsion, and bending. The model described is quite general and can be applied to other types of helically armored cables. A stiffness matrix is developed and relations are given for axial, torsional, and flexural rigidities and for coupling parameters. For small curvatures, the flexural rigidity is comparable to the upper limit accepted in current practice by ACSR users. As the curvature increases, however, frictional forces develop between the outer layers and sliding of wires may occur, with the result that the flexural rigidity decreases. The tension level also influences the flexural rigidity of the conductor. Actually the model does not consider the flexural rigidity of the system as a fixed entity but as directly influenced by local compressive forces and internal radial and tensile forces. The analysis can also apply to situations where a given number of initial constituent wires have failed and the load is transferred to neighboring wires, leaving the conductor unbalanced; it will be seen how internal arrangements manage to accommodate the local perturbation.

A model to predict the coupled axial torsion properties of ACSR electrical conductors

The modeling of ACSR (aluminum-conductor steel-reinforced) electrical conductors for dynamic analysis requires some knowledge of the mechanical properties of the conductor. It was found both experimentally and theoretically, using a simple strength of materials approach, that the axial-torsional behavior of ACSR conductors is highly coupled; i.e., axial motion causes torsional motion and vice versa. Although wind-induced oscillation of ACSR power lines has been observed for years, the importance of axial-torsional coupling has not been generally recognized, nor studied. A simplified mathematical model correlated well with experimental measurements for this type of coupled mechanical behavior. It is hoped that being able to control the amount of coupling through cable design may lead to better control of wind-induced oscillations.