Cable Radius Research Articles

Enhancing the performance of optoelectronic potential of CuO/Al nanoplats in a PVC for medium voltage cables applications

This study investigates the potential of incorporating CuO and Al nanoplates into a polyvinyl chloride (PVC) matrix to enhance the performance of medium voltage cables. The incorporation of nanoparticles into the PVC insulation material aims to improve the electrical, dielectric, and optical properties of the cable. The nanocomposite films were synthesized by dissolving PVC in tetrahydrofuran (THF) solvent and adding a mixture of 5 wt% CuO and Al nanoparticles. Fourier-transform infrared spectroscopy (FTIR) analysis confirmed the successful incorporation of the nanoparticles into the PVC matrix. The optical properties of the PVC/AlNPs and PVC/CuONPs + AlNPs nanocomposite films were characterized, revealing a decrease in band gap energy (4.35 eV) and Urbach tail energy (0.3702 eV) for the PVC/CuONPs + AlNPs film compared to the PVC/AlNPs film (4.5 eV and 0.41816 eV, respectively). Additionally, the PVC/CuONPs + AlNPs film exhibited higher absorption coefficients and increased electron delocalization and conjugation (carbon cluster value of 62.53). The dielectric properties of the CuONPs + AlNPs nanocomposites were investigated, with the sample containing 1.5% AlNPs demonstrating the highest AC conductivity (2.029 × 10−3 S/m), dielectric constant, and dielectric loss across the frequency range. Simulations of electric field distribution revealed that the PVC/CuONPs+1.5% AlNPs nanocomposite cable exhibited a more uniform electric field distribution compared to the PVC market cable, contributing to a reduction in electrostatic tension and a relative permittivity increase from 2.25 to 2.35. The electric potential distribution along the cable radius remained similar for both cable samples. These findings demonstrate the potential of nanocomposite insulation materials in enhancing the performance of medium voltage cables, paving the way for improved reliability, longevity, and efficiency.

Pretension Design and Analysis of Deployable Mesh Antenna considering the Effect of Gravity

The difference between the space and the earth environment has significantly influenced the shape accuracy of the antenna reflector surface. With the increasing demand for the aperture of the antenna reflector, gravity has become one of the main factors that restrict the accuracy. In this paper, a new method for pretension design considering the effect of gravity is proposed. The design surface can be well restored to the ideal surface in orbit. Meanwhile, this method can avoid flipping antenna reflectors or extensive experiments for modification during ground adjustment. Then, the feasibility and effectiveness of the design method are validated by several numerical simulations. Moreover, the results are compared with the previous method and the differences have been discussed in detail. Finally, the effects of cable radius, cable length, and elastic modulus of the mesh reflector have been researched, respectively.

POWER CABLE INSULATION PRODUCTION LINE CONTROL

The paper considers the problem of control the cable insulation continuous vulcanization line. The axisymmetric mathematical model of the power cable rubber insulation vulcanization technological process has been developed. The model describes the heat transfer process inside the vulcanization pipe and the vulcanization process kinetics inside the insulation. The mathematical model is based on the energy conservation equation and it is presented in the form of a differential equations system closed by boundary conditions The mathematical model makes it possible to estimate the influence of various technological and design parameters on the temperature distribution along the radius and length of the cable. Based on the temperature distribution curves, the cable insulation vulcanization degree is calculated The study of the raw rubber compositions vulcanization properties was carried out by rotary rheometer, where the samples of the material were subjected to an oscillating load at different temperatures. As a result of the experiment, the curves family of the torque dependence on the curing time at different temperatures was obtained. To describe the vulcanization process kinetics, a parametric expression is used based on the experimentally obtained torque dependences. The obtained temperature dependence of the parametric expression coefficients makes it possible to describe the vulcanization process taking into account the uneven temperature distribution along the cable radius and length. The developed model makes it possible to calculate the speed at which the vulcanization degree reaches a given value. Algorithms for calculating and correcting line speed and extruder flow rate are proposed on the basis of a mathematical model. It allows us to determine the speed and flow rate of the extruder for various: cable designs, insulation materials, abnormal operating conditions of the production line. The results can be used at enterprises engaged in the production of cable and wire products with cross linked insulation. In cases where it is required to quickly calculate a new technological mode, make changes to the cable design, change the insulation material, and also take into account possible pressure drops inside the vulcanization pipe and deviations in the cable properties during the production process.

A mechanical model to interpret distributed fiber optic strain measurement at displacement discontinuities

Distributed fiber optic (strain) sensing, which provides the unique advantage of sensing damage (e.g. cracking) at locations that are not known a priori, has been increasingly used in civil engineering. Quantitative crack measurement requires the translation of a discontinuous displacement field at the crack to a continuous strain deformation in the fiber. The main purpose of this article is to develop a mechanical model to explain the fiber deformation in the presence of a displacement discontinuity. The proposed mechanical model is validated with experimental results from cable calibration tests and concrete cracking tests. The model is extended to simulate the effects of multiple closely spaced cracks on fiber optic strain measurement, and this model is used to create an algorithm to automatically distinguish multiple cracks in distributed fiber optic (strain) sensing strain distributions. Using the model and two shape parameters, kurtosis and standard variation, the effects of cable properties (i.e. shear stiffness between cable and fiber, cable radius, elastic modulus, and interface cohesion) on the shape of fiber optic strain distributions across cracks are also quantified. The results provide an indication of beneficial cable properties for various measurement objectives.

Analysis and design procedure of hybrid long-span cable-stayed bridge using advanced composite material

An innovative solution is proposed in this paper by introducing a hybrid-type cable stayed bridge as a competent system to safely bridge very long spans. The new system leads into huge reduction in deck weight and its critical stresses in the pylon zones by using hybrid advanced composite deck. It also reduces the stiffness losses of the stay-cables due to the catenary’s action by using carbon fiber reinforced polymer cables. The paper proposes a proper consistent and systematic analysis and design procedure that optimize and precisely simulate the proposed bridge system. It recognizes the changes in structural behavior of the cable-stayed system, accordingly it clearly defines the ultimate and serviceability limit states for such new structural system in consistence with the limit state design philosophy. The design steps of the ADP represent a multi-scale design technique while the analysis steps characterize a multi-scale modeling technique. They represent the material design in the micro/macro-level, and accurate homogenization of the advanced composite components properties and evaluation of the resulting anisotropic characteristics and then, three-dimensionally simulate the hybrid bridge system involving all its nonlinearities. This paper investigates the performance of a new hybrid long-span cable-stayed bridge, which engages the use of advanced composite materials for the deck and the stay-cables, applying the analysis and design procedure. This design is scaled to match the general geometrical shapes, structural and aerodynamic characteristics of three of the world-longest cable-stayed bridges. What’s more, four advanced composite deck section models are proposed in this research. In order to study the performance of the referenced bridges, such as the natural frequencies, the deck top surface maximum vertical displacement, maximum Tsai-Hill failure function and the critical flutter velocity, three sets of parameters are investigated. The parameters include: (i) the micro level parameters-fiber fraction, (ii) the macro level parameters-Laminas Dominant Fiber Alignment and Laminate Thickness and (iii) the structure level parameters- cable radius.

The statistical enlargement law for HVDC cable lines part 2: application to the enlargement over cable radius

This paper is the second part of an investigation on the new enlargement law for HVDC cables developed by the authors. The previous Part 1 has illustrated the theoretical derivation of this law and its application to enlargements over cable length. The present Part 2 is dedicated to the enlargement over cable radius and to its noteworthy aspects, that are essentially associated with the complicated function HDC. These aspects are mainly relevant to the role played by cable conductor losses, or equivalently by conductor temperature. They are deeply investigated here via a series of three radial enlargements for HVDC extruded cables, that involve conductor cross-section and insulation thickness only: this enables focusing the attention on the H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DC</sub> function, that includes the dependence of the enlargement law on the radial cable geometry.

The statistical enlargement law for HVDC cable lines part 1: theory and application to the enlargement in length

In this investigation the innovative enlargement law for HVDC cables, developed by the authors, is illustrated and applied extensively. In the present Part 1 of the investigation, the theoretical approach to the derivation of the enlargement law for HVDC cables is reported, with a broader and more rigorous formulation and a deeper insight compared to the first proposals by the same authors. Later on, the theoretical approach is applied to different volume enlargements relevant to mass impregnated and extruded cables, focusing mainly on cable line length. These are typical examples of the enlargements that designers may be asked to consider in practice when dealing with R&D activities that have a particular HVDC cable line project as their ultimate goal. Such examples also lead to single out some important aspects relevant to the complex function HDC, associated with the enlargement over cable radius. This latter enlargement is deeply analyzed via several case-studies in paper Part 2 of this study.

Multiphase transport processes of droplet impact and ice accretion on surfaces

In this paper, transport phenomena are examined for multiphase heat transfer with incoming supercooled droplets and icing of heated curved surfaces. The processes of rime ice, transition and combined rime/glaze ice conditions are investigated. Heat conduction equations in the ice and unfrozen water layers are solved simultaneously with the mass balance. Energy input from the heated boundary (due to electrical heat generation) affects the growth of the glaze film thickness and associated liquid runback along the ice surface. Validation of the predictive model is carried out through comparisons with experimental data involving ice buildup on heated, non-rotating circular conductors. Close agreement is achieved between the predicted ice growth and the measured data. Physical effects of cable radius, surface heating rate and surface curvature are presented. The heat transfer model approaches the dry growth limit, based on mass conservation alone, under appropriate thermal conditions when the surface heating rate is diminished sufficiently. By examining all of the relevant physical processes leading to ice accretion on the surface, a single formulation is developed to cover the entire range of rime, transition and combined rime/glaze ice conditions, including the simultaneous growth of unfrozen water and ice layers.

Semi-quantitative analysis of photoluminescence in thermoelectrically aged cables: II-analysis of a population of cables

A set of thermo-electrically aged cross-linked polyethylene-insulated HVAC cables has been characterized by photoluminescence measurements. The photoluminescence spectra have been decomposed into a set of seven bands representing the response of three contributions to the emission: bulk cross-linked polyethylene emission, fluorescence of the antioxidant used in the semi-conducting screens of the cables, peaking at 400 nm, and an emission at 540 nm that has been correlated to the yellowing of the cables observed during thermal ageing. From the analysis of the cable radius dependence of these emissions, it is shown that traces of the antioxidant can be found in the 14 mm-thick insulation after less than 5000 h of ageing at 90 degC. The emissions related to the antioxidant and to yellowing appear dependent on the cable manufacturing process.

Modelling method for critical current of YBCO tapes in cable use

Superconducting YBCO cables are suitable to transfer large amounts of energy due to their small space requirements and low losses. The large energy transfer capacity is achieved by connecting several coated conductor (CC) tapes in parallel. The critical currents of the tapes will be changed when they are placed from self-field to the magnetic field of the cable. In this paper, the change was determined from the cable geometry and intrinsic Jc(B)-dependence with fast and robust integral element method exploiting thin elements. The critical current distribution and the magnetic fields of 1kA cable were computed. The so-called gap effect causes the critical current of the individual tapes to rise from 86.5 to 88.8A when they are moved from the self-field to the cable field. The gap effect was studied as a function of width of the superconducting layers, cable radius and the number of the tapes. It was shown that the cable critical current can be given as a function of the tape number and the layer fill factor defined in this paper. In addition, the gap effect was studied as a function of zero field critical current density. The results suggest that up to 16% rise can be obtained with a cable of 25 tapes with critical current per tape width 500Acm−1.

A Novel Non-contact Capacitive Probe for Common-Mode Voltage Measurement

This paper describes a capacitive voltage probe (CVP) that can measure a common-mode voltage on a cable without touching its conductor. This CVP has two coaxial electrodes: the inner electrode works as a voltage pickup and the outer one shields the inner electrode. These electrodes separate into two parts for clamping to the cable. Using a high input impedance circuit, this probe measures the common-mode voltage by detecting the voltage difference between the two electrodes. The probe characteristics are evaluated by measuring its linearity and frequency response. The results show that this probe has a dynamic range of 100dB and flat frequency response from 10 kHz to 30MHz. Deviations in sensitivity due to the position of the clamped cable in the inner electrode and to differences in the cable radius are evaluated theoretically and experimentally. The results indicate that the influence of the cable position can be calibrated. Finally, measured data obtained using both an impedance stabilizing network (ISN) and a CVP are compared to confirm the validity of the CVP. The results show that data measured by the CVP closely agreed with that obtained by the ISN. Therefore, the CVP is useful for EMC measurements to evaluate common-mode disturbances.

Coupled liquid film and solidified layer growth with impinging supercooled droplets and Joule heating

Phase change heat transfer with incoming supercooled droplets on heated curved surfaces is examined. The processes of rime ice, transition and combined rime/glaze ice conditions are modelled. In the analysis, heat conduction equations in the ice and unfrozen water layers are solved simultaneously with the mass balance, including incoming droplets. Energy input from the heated boundary (due to electrical heat generation) affects the growth of the glaze film thickness and associated liquid runback along the ice surface. Validation of the predictive model is carried out through comparisons with experimental data [Lu et al., A semi-empirical icing model for an energized power line, Internal Report, Department of Mechanical and Industrial Engineering, University of Manitoba, Winnipeg, Canada, 1999; Mass of ice accretion from freezing rain simulations, Proceedings, 8th IWAIS, Reykjavik, Iceland, 1998] involving ice buildup on heated, non-rotating circular conductors. Close agreement is achieved between the predicted ice growth and the measured data. Additional effects of cable radius, Joule heating rate and surface curvature are presented. The heat transfer model is shown to correctly approach the dry growth limit, based on mass conservation alone, under appropriate thermal conditions when the surface heating rate is diminished sufficiently. As a result, a single formulation is provided over the entire range of rime, transition and combined rime/glaze ice conditions, including the simultaneous growth of unfrozen water and ice layers.

Effects of cable scattering on underwater acoustic measurements

In many situations, cable scattering can be a major contribution to errors in underwater acoustic measurements, far exceeding the errors due to electronic sources. When a cable passes near a hydrophone, the cable generates a scattered wave, which can add to the incident signal to create a standing wave pattern. The amount of deviation of pressure from free-field values depends on frequency, separation distance, and the impedance of the cable. In this work, a computer model of an infinite rigid or soft cylinder has been developed, which provides a contour map of the sound field around the cylinder. The calculations are nondimensionalized in terms of ka and r/a, where a is the cable radius, k is the wave number, and r is the distance of a field point from the cable center. These results are compared with measurements on common types of real hydrophone cables and strength members. In general, the comparisons show that real cables have an effect that is somewhat greater than theoretical values for a rigid cylinder. Guidelines are provided for designing measurement arrays with a specified maximum measurement error. [Work supported by DARPA.]

Action potential collision in heart tissue--computer simulations and tissue experiments.

The electrical effects of action potential collision were studied using a computer simulation of one-dimensional action potential propagation and tissue experiments from isolated cardiac Purkinje strands and papillary muscles. The effects of collision, when compared to normal one-way propagation, included quantitative changes in all of the measured indexes of action potential upstroke and repolarization. These changes can be attributed to spatiotemporal changes in the net membrane current. Parameter sensitivity and analytic techniques identified five factors which determine the collision-induced decrease in action potential area: conduction velocity, action potential height, cable radius, specific intracellular resistivity, and the specific membrane resistance during action potential repolarization. The simulations demonstrated that collision effects were independent of inhomogeneity in action potential duration, the spatial extent of the collision effects was greater than the passive space constant, and certain simulated abnormal conditions (e. g., discontinuous propagation, ischemic tissue) increased the magnitude of the collision effects. The tissue experiments supported the simulations regarding the changes in action potential configuration directly at and on each side of the collision site. Elevated [K+]0 increased the changes in action potential duration in both tissue preparations. In papillary muscles, collision effects in the transverse direction were confined to a narrower region than collision effects in the longitudinal direction with no difference in the peak magnitude of the changes. Action potential collision is a common occurrence in the heart.

External thermal resistance of two buried cables. Restricted application of superposition

New formulas are derived for the external thermal resistance of one of two equally loaded identical cables laid direct in the ground at the same depth. The formulas are based on a restricted application of the principle of superposition, and remain valid when the cables are close or touching. Two assumptions made are that the depth of the buried cables is much greater than the cable radius, and that the cable surfaces are isothermal at a common temperature. The former assumption is justified as the cable depth is generally equal to at least ten times the cable radius. The latter assumption is recognised to be an approximation, but the present approach may prove to be more acceptable than alternative techniques. Comparison is made with previously published formulas.