Behavior Of Conductors Research Articles

A Wind Tunnel Study on the Aerodynamic Characteristics of Ice-Accreted Twin Bundled Conductors

Galloping of twin bundled overhead conductors accreted by ice is a frequent phenomenon during freezing weather, which may damage the operation of transmission lines. To analyze the galloping behavior of iced conductors, their aerodynamic characteristics must be studied. In this study, models with two different outlines were designed and tested to determine a more suitable ice-accreted conductor testing model. Subsequently, the influences of the conductor type, ice thickness, wind turbulence intensity, and wake effect of the windward conductor on the aerodynamic coefficients of the conductors with crescent-shape ice are investigated. The results show that the strand outline of overhead conductors must be considered to improve the accuracy of aerodynamic tests. With increasing ice thickness, the aerodynamic stability becomes rapidly deteriorated. Under the wind turbulence intensity of 4%, the aerodynamic stability gets the most enhancement. Moreover, different conductor types have little impact on the aerodynamic coefficients. The wake caused by the windward conductor is the leading cause for the twin bundled iced conductors to have weaker aerodynamic stability than a single conductor. The aerodynamic coefficients determined in this study are essential for predicting the galloping amplitudes of ice-accreted twin bundled overhead conductors under different weather conditions.

A Highly Robust Ionotronic Fiber with Unprecedented Mechanomodulation of Ionic Conduction.

Stretchable ionic conductors are appealing for tissue-like soft electronics, yet suffer from a tardy mechanoelectric response due to their poor modulation of ionic conduction arising from intrinsic homogeneous soft chain network. Here, a highly robust ionotronic fiber is designed by synergizing ionic liquid and liquid crystal elastomer with alternate rigid mesogen units and soft chain spacers, which shows an unprecedented strain-induced ionic conductivity boost (≈103 times enhanced as stretched to 2000% strain). Such a surprisingly high enhancement is attributed to the formation of microphase-separated low-tortuosity ion-conducting nanochannels guided by strain-induced emergence of aligned smectic mesophases, thus allowing for ultrafast ion transport that resembles the role of "swimming lanes." Intriguingly, the boosting conductivity even reverses Pouillet's Law-dictated resistance increase at certain strains, leading to unique waveform-discernible strain sensing. Moreover, the fiber retains thermal actuation properties with a maximum of 70% strain changes upon heating, and enables integrated self-perception and actuation. The findings offer a promising molecular engineering route to mechanically modulate the ion transport behavior of ionic conductors toward advanced ionotronic applications.

On the Euler-Lagrange formalism to compute power line bundle conductors subject to aeolian vibrations

Analytical models of aeolian vibrations for both twin and quad bundle conductors are summarized in this paper. These analytical models are defined by equations of motion and developed using the Euler-Lagrange formalism. They describe the behavior of bundle conductors under combined effects. The generated swinging, and flexural and torsional motion are addressed. To simplify the complexity of the calculus during the development of the analytical models, several assumptions are made: (i) aeolian vibrations remain in the range of small oscillations; (ii) acceleration is constant at each frequency; and (iii) the Kelvin-Voight rheological model is considered for the vertical and horizontal stiffness in the spacer-damper. These analytical models are compared and validated by means of numerical simulations using the results from indoor experiments on an overhead transmission line-span with quad-bundle conductors. This has only one spacer-damper attached at its mid-span. The comparisons show good agreement between experiments and numerical simulations in the rigid mode, and an insignificant discrepancy in the damping mode. Finally, the performance of twin spacer-dampers in terms of dissipating wind-induced power in transmission line twin-bundled conductors is assessed and compared with quad bundles through developed analytical models, and the physical significance are highlighted.

Vibration behavior of an overhead conductor under updraft winds

At present, the wind-induced response analysis of an overhead conductor is mainly based on the action of horizontal normal wind. However, for crossing hillsides or extremely strong winds, such a conductor will bear the action of updraft wind, which will change the geometry of the conductor and make its structural dynamic characteristics nonlinear to some extent. In this work, the in-plane and out-of-plane two-dimensional nonlinear equations were established under the action of self-weight and updraft wind. Furthermore, the improved equations of conductor tension and sag were obtained, and the wind-induced vibration response was further investigated. The results showed that the updraft wind caused the nonlinearity of the tension and sag of the overhead conductor, and the nonlinear geometric change significantly affected its resonance response, which exceeded 25% if the wind speed was 50 m/s. In addition, because the proportion of the resonance response in the total wind-induced response was different, the influence of the wind attack angle calculated using the gust response factor method on the gust response factor was slightly larger than that calculated using the the American society of civil engineers method.

The crystallization phenomenon on a modified phosphate glass interpreted through the correlation between the a.c. electrical behaviour and the non isothermal nucleation

The electrical behavior of a bismuth-phosphate glass lithium ion conductor is studied in a very wide temperature range, from 39 K to 843 K, encompassing the glassy state, passing through the glass transition temperature, and reaching devitrification. The relationship between the structural changes caused by the thermal treatment and the resulting electrical response is interpreted through the dc conductivity and ac permittivity. An isothermal and a non-isothermal treatment allows to propose a simple analysis of the energy distribution and atoms rearrangement times involved in devitrification, using a Gaussian approximation method considering the fundamental elements in the M. Avrami’s generalized theory.

Resistance to fracture in the glassy solid electrolyte Lipon

We report on the mechanical behavior of a solid Li-ion conductor, lithium phosphorous oxynitride (Lipon), for solid-state batteries. In particular, the purpose of this investigation was to quantify the resistance to cracking (fracture toughness) of this material by nanoindentation. We observed surprising ductility and the ability to recover in Lipon. We were unsuccessful in inducing cracks in Lipon and observed accommodation of stress via pile-up and densification rather than by cracking at various strain rates. Simulations demonstrate that both deformation and densification depend on the alkali content. Densification appears to be recoverable at room temperature. We discuss the findings in comparison with nanoindentation-induced cracking in other inorganic solid electrolyte materials and provide possible explanations for high resistance of Lipon to Li filament propagation.

Surrogate Model for Torsional Behavior of Bundle Conductors and its Application

By means of numerical models for torsional behavior of bundle conductors under distributed torque, parameter study of torsional behavior under various structural parameters, including conductor type, bundle number, bundle spacing, span length, height difference, initial tension in sub-conductors, spacer number and arrangement of spacers, is carried out. With the over twenty thousand numerically simulated samples a dataset is set up. A surrogate model for the prediction of torsional behavior of bundle conductor lines is constructed by means of the BP neural network, in which the structural parameters are set as the input variables and the collapse torque and torsional stiffness the output. The dataset is divided into two subsets, the training dataset and the testing one. High prediction precision of the surrogate model is achieved through training with the training dataset and verified by the testing dataset. Combining the surrogate model and the particle swarm optimization (PSO) method, optimizations of spacer arrangement to obtain maximum collapse torque and torsional stiffness of bundle conductor lines are carried out.

Estimating fatigue behavior of a family of aluminum overhead conductors using ANNs

AbstractThis study aimed to create an artificial neural network (ANN) architecture capable of estimating the fatigue behavior of aluminum overhead conductors, considering specific weight (W) and bending stiffness (EI) as parameters of influence. ANN training and testing is conducted by using a dataset obtained from fatigue tests carried out in a 50 m resonant bench at the University of Brasilia (UnB). ANNs are used to construct constant life diagrams for this family of conductors, and to compare the results obtained experimentally. Our findings show that for the architectures analyzed, it is possible to accurately estimate the fatigue behavior of this family of aluminum conductors.

Multi-Layer Transient Heat Conduction Involving Perfectly-Conducting Solids

Boundary conditions of high kinds (fourth and sixth kind) as defined by Carslaw and Jaeger are used in this work to model the thermal behavior of perfect conductors when involved in multi-layer transient heat conduction problems. In detail, two- and three-layer configurations are analyzed. In the former, a thin layer modeled as a lumped body is subject to a surface heat flux on the front side while it is in perfect (fourth kind) or in imperfect (sixth kind) thermal contact with a semi-infinite or finite body on the back side. When dealing with a semi-infinite body in imperfect contact, the temperature solution is derived by means of the Laplace transform method. Green’s function approach is also used but for solving the companion case of a finite body in perfect contact with the thin film. In the latter, a thin layer with internal heat generation is located between two semi-infinite or finite bodies in perfect/imperfect contact. For the sake of thermal symmetry, such a three-layer structure reduces to a two-layer configuration. Results are given in both tabular and graphical forms and show the effect of heat capacity and thermal resistance on the temperature distribution of conductive layers.

Partial Discharge of Polyurethane/ Organoclay Composite Coated on Aluminum Conductor Overhead Lines

Aluminum conductor have been used worldwide as the primary conductive materials for high voltage electrical transmission lines. The partial discharge behavior of the aluminum conductor have been obeserved during operation due to the transmission line's performance to serve electricity. The partial discharge of aluminum alloy coated by polyurethane/organoclay (PClay) composite material was studied. PClay composites were prepared by adding organoclay with different content in polyurethane as a matrix then coated on an aluminum conductor sample. A partial discharge test was conducted to obtain the behavior of partial discharge versus voltage. It was found that an escalation of organoclay content in the polyurethane reduce partial discharge appears.

Thermopower of ionic conductors and ionic capacitors

We theoretically study the thermoelectric response of ionic conductors to an applied temperaturegradient. As a main result we find that open and closed systems with respect to charge exchange,result in different expressions for the thermopower which may even take opposite signs. For theexperimentally most relevant zero-current steady state, we show that the thermopower of ionic conductorsdoes not depend on the mobilities, contrary to what is known for metals and semiconductors.The different behavior of ionic and electronic conductors is traced back to the unlike conservationlaws for ionic carriers and electron-hole pairs.

Corrosion behavior of oxide ion conductors for high‐temperature direct electrochemical metal oxide reduction

AbstractThe corrosion behaviors of high oxide ion conductors using solid oxide membrane (SOM) electrolysis were investigated in practical operating conditions (current load or molten CaF2‐NaF‐CaO eutectic salt). In previous researches, yttria‐stabilized zirconia (YSZ), which is widely used in SOM electrolysis due to its good mechanical properties and ionic conductivity at high temperature, has several problems including phase transition due to yttrium ion dissolution, which results in decreased current efficiency and severe fracture of SOM tube. Thus, we introduced oxide ion conductors with a higher ionic conductivity than that of YSZ to exploit its excellent current efficiency and long‐term stability. In this study, we investigated the phase stability of Sr‐ and Mg‐doped lanthanum gallate (LSGM), Sc‐doped zirconia (ScSZ) and Gd‐doped ceria (GDC) using the structural analysis methods. Phase transition of LSGM and ScSZ easily occurred than that of GDC. GDC showed fairly tolerable stability; the molten salt ions were found only 10 μm deep on the surface, and the ions hardly penetrated the interior of bulk. However, LSGM (~40 μm) and ScSZ (~100 μm) showed a deep cation ion infiltration depth from the surface and severe surface corrosion was observed on the surface of LSGM and ScSZ.

Numerical Investigation Into Torsional Behavior of Quad Bundle Conductors

A numerical modeling method to investigate the torsional behavior of bundle conductors under distributed torque is presented. The distributed torque is applied to the bundle conductors by means of a user-defined subroutine in the ABAQUS finite element software. The method is verified by the torsional instability and self-restoring process of quad and twin bundle conductors tested by other authors. By means of the numerical method, parameter study of torsional behavior of quad bundle conductors under different parameters, including initial tension in sub-conductors, unbalanced tension in sub-conductors, spacer clamping forms, spacer arrangements, and sub-conductor spacing is carried out, and the effect of electromagnetic force between sub-conductors on the torsional behavior is also numerically investigated. Based on the numerical simulation results, some suggestions for the anti-rolling design of quad bundle conductor lines are proposed.

Reliability of screen-printed conductors and resistors during fatigue cycling on flexible substrate

Abstract Scalable printing of conductor and resistor components has revolutionized the field of flexible electronics by enabling a myriad of low cost highly conformable devices. Flexible electronic devices need to exhibit reliable performance under strenuous mechanical deformations to be adopted in applications such as human and asset monitoring. The reliability of the devices is in turn affected by the microstructure of the materials, manufacturing processes, and conditions of use. In this research, the mechanical behavior and microstructural properties of stretchable silver conductor and stretchable carbon conductor inks on flexible substrate are studied. The test vehicles (such as 4- point probe structures are screen printed on thermoplastic polyurethane (TPU) and cured in a convection oven. The quality of the printed traces including the resolution and thickness profile are measured by Confocal Laser Scanning microscope. The microstructure of the sample including particle/nanoparticles morphology is studied by Scanning Electron Microscopy (SEM). The electrical resistance is measured by 4-point probes method and the sheet resistance of the printed samples is calculated. The mechanical and electrical reliability of the samples are investigated by fatigue-cycling and in-situ measuring of the electrical resistance. In terms of electrical conductivity, the silver printed traces show different behavior compared to the carbon printed samples when exposed to fatigue cycling. The electrical resistance of the printed silver trace increases during the fatigue cycling. Higher extension rate along with higher strain magnitude accelerate the rate of increase in the electrical resistance. The relative electrical resistance of the carbon trace initially drops to 0.7 after 40 cycles and remains constant for the rest of the cycles. The extension rate does not considerably change the electrical resistance of carbon trace. The stability in electrical resistance is crucial in applications where electrical shielding is concerned.

Temperature calculation of overhead power line conductors based on CIGRE Technical Brochure 601 in Slovakia

An overhead power line is a structure used in the electric power system to transmit electrical energy. The performance of overhead power lines depends on their parameters. An important parameter of the power line in the power system is its thermal limit. This article deals with the temperature calculation of overhead power line ACSR conductors according to the methodology stated in CIGRE Technical Brochure 601: Guide for thermal rating calculations of overhead lines. The calculated temperature is also compared with the measurement under laboratory conditions and also on a real power line in the Slovakia power system. At the end of the article, the dynamic thermal rating of ACSR conductors depending on climatic conditions is also calculated. Obtained results are compared with ampacity limits for summer and winter season used by Slovak transmission system operators. The article also compares the CIGRE Technical Brochure 601 with its older version CIGRE Technical Brochure 207: Thermal behavior of overhead conductors.

A “Thermal-conductive Simplified Model” for the Actual Temperature of Overloaded Cables

Thermal-conductive models are relatively new, and have allowed the study and thermal characterization of electrical wires in overload state. Unlike the models of resistivity, or “Joule type models”, which form the basis of energy losses in wires based only on the properties of the conductors at given temperatures, the thermal-conductive models consider the behavioral characteristics of electromagnetic energy in the form stipulated by Maxwell's equations (electromagnetic model), as well as the behavioral characteristics of energy in form of heat, stipulated by the governing equations of conduction, convection and radiation. The ambient that surrounds the wire becomes very important, as well as the shape of the electromagnetic wave that is conducted in the material. Recent work has given unexpected results in the behavior of electrical conductors under states of overload. The usual models of Joule effect, were not able to predict these effects in overload, and have been used the new thermal-conductive models, with very high levels of accuracy in the predictions of global warming. Experimentally the tests have demonstrated that in overload the heat dissipation can be more than 50% higher than what is predicted by Joule type models, and theoretically, thermal-conductive models can achieve accuracy with less than 0.01% of total error (energy and temperature). But these thermal-conductive models currently require the use of a large amount of mechanical and electromagnetic equations, apart from a large amount of data (for ambient), which are highly variable, leading to the use of extensive modeling programs work for a long time for the characterization of a single wire in a particular state. In this paper we show a simplified thermal-conductive model, not only with sufficient precision for use in calculations of effective thermal dissipation, but also with sufficient simplicity, for use even in manually way.

The winding mechanical behavior of conductor on round core cables

In the process of the HTS cable structure cabling, the HTS tape is subjected to the combined deformation caused by tension, bending, and torsion. The electro-mechanical behaviors and the degradation mechanism of HTS cable are remain elusive. In the present paper, a numerical model is built in ABAQUS software to analyze the winding mechanical behavior of the CORC cable. Then, the critical current degradation is calculated and the effects of the tape width, substrate thickness, pre-stress, winding pitch and helix angle are investigated. The results show that it should be avoid selecting a roller with a much small radius to produce a large strain. The critical current degradation of the cable is minimal when the helix angle equals to 45°, which is the best choice to winding the tape to form the CORC cable. A smaller winding radius can be choose when the thickness of the substrate is in the small strain region of 10–20 µm. This study helps understand the deformation of the HTS tape during the winding process and provides a winding optimization for the CORC cable.

Synthesis and conductivity behaviour of Mo-doped La2Ce2O7 proton conductors

Mo-doped La2Ce2O7 with varied concentrations are prepared by the traditional citrate-nitrate combustion method. The effects of the phase structure of Mo-doped La2Ce2O7 are investigated by X-ray diffraction, scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and conductivity measurements. X-ray diffraction patterns reveal that all La2-xMoxCe2O7+δ samples have a cubic structure. Neverly, hole can be found on the surface of the samples from scanning electron microscopy. Raman spectra show that the different vibrating structures of pellets can be changed by introducing Mo into La2Ce2O7. Detailed X-ray photoelectron spectroscopy studies on the oxidation states of La2Ce2O7 and La1.85Mo0.15Ce2O7+δ indicate ratios of OC to OT (OT = OC + OL) are between 32.21% and 46.24%. The conduction behaviour of Mo doped La2Ce2O7 electrolyte is seriously researched under air and 5%H2-95%Ar conditions at 350–700 °C, and the highest conductivity of 7.36 × 10−3 and 1.65 × 10−2 Scm−1, respectively, are obtained with La1.85Mo0.15Ce2O7+δ pellets at 700 °C. The highest power density of single cells with the La1.85Mo0.15Ce2O7+δ electrolyte is approximately 0.643 Wcm−2 at 700 °C, suggesting that Mo-doped La2Ce2O7 can be used to substantially improve the electrochemical performance of low-temperature solid oxide fuel cells.

Transient behaviour of grounding electrodes in uniform and in vertically stratified soil using state space representation

This investigation is devoted to study, in time domain, the transient behaviour of vertical and horizontal grounding conductors submitted to impulse current using state space representation-based transmission line method. This study has been carried out with and without incorporating soil ionisation and mutual coupling between conductor elements for soils of low and high resistivities. The results are focused on the time-domain solution of the electrode's transient potential rise and its impulse performance parameters. The results show the importance of including the mutual coupling between segments of the same electrode and soil ionisation. The results are compared with both published theoretical approaches and experimental measurements, and show acceptable agreement. This method has been applied to compute the transient potential of horizontal electrodes buried in vertically stratified soil, a situation which can occur where long horizontal counterpoise is buried in a highly contrasting soil along its length.

Design of a textile antenna with artificial magnetic conductor for wearable applications

AbstractWith the development of modern wireless technologies and the miniaturization of antennas and electrical systems, the use of antennas on the human body for Wi‐Fi applications has become important. However, integrating the antenna near the body immediately raises the question about the protection of the body and the radiation effectiveness of the antenna. One solution that has recently attracted great attention is the use of high impedance surfaces (HIS), which is studied here for the antennas integrated on clothes. Indeed, the HIS greatly reduces the radiation back face of the antenna, thus reducing the value of the specific absorption rate in the presence of the body. In this article, we present a dual‐band antenna placed above an artificial magnetic conductor (AMC). The AMC used has the smallest dimensions and makes it possible to obtain the behavior of a perfect magnetic conductor at 2.45 and 5.8 GHz.