Conventional Cables Research Articles

Design of Wireless Power Transfer System for Charging of Electronic Gadgets

Wireless charging of gadgets is one of the new emerging technologies in the world at present moment. The most common method used is wireless power transfer is by using the method of inductive coupling. Wireless power transfer is one of the simplest and inexpensive ways of charging as it eliminates the use of conventional copper cables and current carrying wires. The inductive coupling technique is used since currently it is the easiest method of wireless power transfer because of high efficiency and large amount of the energy transferred. Its versatility and range of applications the power transferred will be used to charge a battery with the aid of additional circuitry. This research work focuses on the study of wireless power transfer for the purpose of transferring energy at maximum efficiency within a small range or in the near field region. The motivation to this proposed design model is contact less mobile device charging about 5cm-100cm distance range, which can be used to charge the mobile electronic devices like mobile phones, laptops, smart phones wirelessly. This proposed design is very helpful in the pandemic situation to charge electronic gadgets contactless as well wirelessly in the hospitals, public transports like metro stations, educational institutions, and in office communication systems.

Techno-Economic Assessment of Three-Layered Coating-Based Resistive Heating Systems and Conventional Heat Tracing Cables for Industry Pipes

Techno-Economic Assessment of Three-Layered Coating-Based Resistive Heating Systems and Conventional Heat Tracing Cables for Industry Pipes

Design of high-performance dual-polarized rectenna for microwave wireless power transmission

This paper presents a 5.8 GHz high-efficiency dual-polarized rectenna for microwave wireless power transmission. The rectenna consists of a 5.8 GHz dual-polarized receiving antenna and a 5.8 GHz class-F rectifier. A metallic probe is used to integrate the receiving antenna and the rectifier. The receiving antenna is a 2×2 microstrip array antenna and the metal ring loading technology is adopted to improve the rectenna’s impedance bandwidth and robustness. The metal probe instead of the conventional microwave connector and cable is utilized to realize the integration of receiving antenna and rectifier circuit, thus simplifying the structure and reducing the weight, loss and cost of the rectifier antenna. A prototype of the dual-polarized rectenna is fabricated and its rectifying efficiency is measured and compared with the linear-polarized rectenna with the same aperture area. The measured results show that the maximum conversion efficiency of the dual-polarized rectifying antenna reaches 76.8% under the optimum incident power density of 1.47 mW·cm−2. Compared to the linear-polarized rectenna, when the polarization direction of the incident wave varies from 0° to 90°, the conversion efficiency of the rectenna antenna is always above 62% with stable DC output and the rectenna antenna exhibits excellent all-polarization receiving rectification performance.

A proposal for a lightweight, large current superconducting cable for aviation

More Electric Aircraft (MEA) is one of the most important subjects for designing the next generation of aircraft. Since we cannot ground the electric power systems of a flying aircraft and the air insulation voltage is lower at high altitude, a low voltage, direct current (DC) aircraft electrical system is preferable for a MEA. Since the current must be high to supply high power, we consider high temperature superconducting (HTS) technology because it handles large currents well. We propose a new HTS cable in this paper. The cable uses a stacked conductor, with oppositely directed current in each HTS tape, a structure that has already been shown to be feasible for low voltage cables. It enhances the critical current compared to a single tape conductor, especially for Bi2223 tape. In order to avoid a current imbalance in the stacked conductor, we use the current lead resistance rather than a Roebel conductor design. Then the critical current remains high, and this is confirmed by measurements. The cryogenic pipe will be made of magnesium-lithium alloy, one of the lightest metals available at the present time. We estimate the weight-to-current ratio per unit length to be less than 0.5 kg/A/km at the liquid nitrogen operational temperature of 77 K, lighter than conventional copper cable. If instead we use liquid hydrogen at 20 K, we expect a value less than 0.1 kg/A/km, which is one of the lowest presently achievable values and satisfies the requirements for MEA.

Distributed Acoustic Sensing With Sensitivity-Enhanced Optical Cable

Fiber-optic distributed acoustic sensing (DAS) technology has many outstanding advantages, such as long sensing range, high detection efficiency, wide frequency response, low operation cost, long working lifetime, et al. It can be anticipated that DAS has great potential to become a next generation technology of long-distance vibration and acoustic wave detection in the future. However, despite the rapid development of DAS technology, the sensitivity of optical cable is still a main limitation in terms of the applications of DAS technology. In this paper, we propose and demonstrate a sensitivity-enhanced optical cable with smaller diameter, lighter weight, and greater flexibility than conventional cables. This novel cable is experimentally tested both in lab and field. The results show that the acoustic sensitivity of the cable has been significantly improved by ~10 times, comparing with a rigid cable that has much higher reflection and attenuation of acoustic waves. Hence, such a sensitivity-enhanced cable could be one of the best candidates for DAS applications as a general sensing cable. In addition, we found that the experimental results are in agreement with our theoretical analysis, providing a guidance for design of sensitivity-enhanced cables. Finally, this cable has been successfully demonstrated in the field test of borehole vertical seismic profiling (VSP), and good performances have been achieved. The perfect combination of sensitivity-enhanced cables and high-performance DAS systems would provide a powerful tool for many DAS applications.

Investigation of HTS cable impact on turbo‐electric aircraft performance

With significant interest in the use of high-temperature superconducting (HTS) components in electric aircraft, there is a need for novel modelling techniques that allow architecture-level studies of the electrical systems including HTS components. In this study, a simple electric network architecture, as proposed in the literature has been considered, which includes generators, dynamic propulsion load and cables. This electric network has been modelled considering conventional technology and using HTS cables by replacing the conventional copper cables, to evaluate the variations in the network performance. The network performance has been studied for the dynamically varying propulsion load, which is nearly equivalent to the aircraft load over the entire flight duration. Following this, electric faults have been applied at various locations, and the impact of HTS cables on the network fault levels has been evaluated. The fault current levels are compared using both conventional and HTS cables, due to the fault current limiting properties of the HTS cables, they are observed to offer lowered fault current values.

Influence of thermohydraulic irreversibilities on the efficiency of high temperature superconducting (HTS) cables

High Temperature Superconducting (HTS) cables are emerging as the alternate to the conventional cables for power transmission and distribution due to their higher efficiency with fewer losses and robustness in handling large current densities with lower cross sectional area of the conductor. However, these cables encounter the AC losses due to Joules heating while carrying the transport current. In addition, these cables receive the heat loads from the ambient through the cable shield as heat intrusions. Hence, these cables are internally cooled with forced flow of LN2 to maintain the temperature of the superconductor below to its critical temperature. Due to the forced circulation of LN2 and heat loads, thermal and velocity gradients are developed in the HTS cables which accounts to entropy generation rate. The heat loads, frictional losses due to turbulent flow of LN2 in the corrugated former and entropy generation rate rises the temperature of LN2 above to its saturation temperature and boiling takes place. Hence, the current carrying capability of HTS tapes and the ability of electrical insulation of insulating layers in HTS cable will be reduced. To operate such cable efficiently for long length requires larger pump work for circulating LN2 between the terminations. Further, the losses in the pump work due to frictional entropy generation and losses in the heat transfer rate due to thermal entropy generation leads to quenching of HTS tapes and higher energy consumption thereby reduction in the efficiency of the HTS cable which is not advisable. Motivated by the challenges in reducing the pump work with higher cooling capacity, in this present work a novel method is proposed to estimate the loss contribution in thermohydraulic characteristics in HTS cables during the forced convective cooling at different heat loads.A computational domain is modeled, meshed and analyzed using commercial software ANSYS®. The analysis is carried out with time averaged Reynolds averaged Navier-Stokes (RANS) equations which are solved using Finite Volume Method (FVM) of discretization with κ−εturbulent scheme. In the present analysis, temperature dependent thermophysical properties of LN2 are considered at an operating temperature of 77 K and pressure of 2.7 bar. Further, the flow rates ranging from 11–20 L/min and the heat loads ranging from 1–3 W/m are considered to estimate the entropy generation rate and exergy destruction due to losses. The results obtained from the computational investigation are validated with the experimental results that are available in the literature. From the analysis, it is identified that higher the heat loads higher will be the entropy generation and exergy destruction. Further, the minimum exergy destruction is identified due to contributions of thermal and frictional losses. Furthermore, the exergy efficiency and irreversibility distribution ratio are estimated to identify the influence of thermal losses at different heat loads. It is observed that increase in the heat loads increases the thermal losses thereby contributing to lower efficiency of HTS cable.

Numerical study on the CRLD cable–rock interaction under static pull-out loading using coupled DEM–FDM method

As an effective energy-absorbing cable, constant resistance large deformation (CRLD) cables have been widely applied in rock engineering projects; however, to the best of our knowledge, its interaction mechanism with the surrounding rock has never been studied. According to previous practical projects, the CRLD cable–rock interaction differs from that of conventional cables because of the tubular expansion during the CRLD process, and it influences the performance of the cable reinforcement system. Therefore, an attempt was made to investigate the characteristics of the CRLD cable–rock interaction under static pull-out loading by using a coupled numerical method. The structure of the CRLD cable was modelled via the finite-difference method, and the surrounding rock was modelled via the discrete-element method. The micro-parameters of the surrounding rock were carefully calibrated, and the macro-parameters of the CRLD cable were verified by comparing them with a corresponding experimental test in the laboratory. The numerical results were carefully analysed. The constant resistance forces of a single CRLD cable and a CRLD cable reinforcement system were compared. The distribution of the normal and shearing stresses on the cable–rock interface was obtained, and the evolution mode of the pull-out strength was examined. In addition, the failure mode of the grouting material and surrounding rock was studied on a micro-scale. The findings describe the interaction of the CRLD cable against the surrounding rock, reveal its special anchorage mechanism, and can be used to predict and improve the performance of the CRLD cable reinforcement system.

General Analytic Solution of the Telegrapher’s Equations and the Resulting Consequences for Electrically Short Transmission Lines

Based on classical circuit theory, this article develops a general analytic solution of the telegrapher’s equations, in which the length of the cable is explicitly contained as a freely adjustable parameter. For this reason, the solution is also applicable to electrically short cables. Such a model has become indispensable because a few months ago, it was experimentally shown that voltage fluctuations in ordinary but electrically short copper lines move at signal velocities that are significantly higher than the speed of light in a vacuum. This finding contradicts the statements of the special theory of relativity but not, as is shown here, the fundamental principles of electrical engineering. Based on the general transfer function of a transmission line, the article shows mathematically that an unterminated, electrically short cable has the characteristics of an ideal delay element, meaning that an input signal appears at the output with a slight delay but remains otherwise unchanged. Even for conventional cables, the time constants can be so small that the corresponding signal velocities can significantly exceed the speed of light in a vacuum. The article also analyses the technical means with which this effect can be conveyed to very long cables.

Feasibility study of high temperature superconducting cables for distribution power grids in metropolises

High temperature superconducting (HTS) cables have numerous advantages compared with conventional power cables, such as high power density and low power losses, therefore they have great potential to enhance the transmission capacity and improve the quality of power grids. In this work, we studied various cases to evaluate the feasibility of replacing conventional cables with HTS cables in metropolitan distribution networks. These cases represent three principal strategies. The first, HTS cables are applied at the same or lower voltage levels with the same transmission capacity, named ‘equal capacity replacement’. The second, considering increasing power demands we demonstrate how HTS cables can benefit power grids by providing expanded capacity (expanded capacity replacement). For the third, we consider the case of unequal routes from the perspective of saving land resources (unequal routing replacement). In this paper, we introduce the methods and results of this study and give some preliminary conclusive remarks.

Study of wireless power transmission

Wireless charging of gadgets is one of the new emerging technologies in the world at the moment. The most common method used at the moment is wireless power transfer by inductive coupling. Wireless power transfer is one of the simplest and inexpensive ways of charging as it eliminate the use of conventional copper cables and current carrying wires. In this paper, write up, a methodology and principle of operation are devised for wireless power transfer through inductive coupling, and a feasible design is modeled accordingly. The inductive coupling technique is used since currently, it is the easiest method of wireless power transfer because of high efficiency and large amount of the energy transferred. In this paper, results of experiments done to check wireless working is shown. Also to further show its versatility and range of applications the power transferred is used to charge a battery with the aid of additional circuitry. We also study the effect of placing hurdles between the transmitter and receiver so as to establish if it is an alternative in the medical industry for charging pace makers etc. This research work focuses on the study of wireless power transfer for the purpose of transferring energy at maximum efficiency within a small range or in the near field region.

Design and analysis of composite belt for high rise elevators

Abstract This paper describes and evaluates the mechanical properties of glass and carbon fiber composites for high-rise applications by theoretically comparing and experimentally replacing conventional steel cables. The tensile and bending strength to weight ration of these fibers are extremely high such that the self-weight of the hoisting mechanism is reduced to a larger quantity, which enables to travel twice that of the present travel limitations. Both Unidirectional and bidirectional glass and carbon fibers have been analyzed with different combinations to compare mechanical properties. Significant increases in mechanical properties were absorbed in both fiber combinations.

Entropy Generation Minimization (EGM) in High Temperature Superconducting (HTS) cables for optimization of thermohydraulic performance

High Temperature Superconducting (HTS) cables have potential merits of large current carrying capacity and compactness with reduced transmission losses and Right-of-Way (RoW) compared to conventional transmission power cables. However, internal forced convective cooling is necessary to cool HTS cables using cryogenic coolant such as liquid nitrogen (LN2) to retain the superconductivity for efficient power transmission. Due to forced convective cooling, inevitable pressure drop occurs in these cables and result in development of temperature and velocity gradients. Further, the accounted temperature and velocity gradients in HTS cables lead to volumetric entropy generation which causes reduction in thermohydraulic performance.The present work focuses at investigating the volumetric entropy generation rate in HTS cable. Further, Entropy Generation Minimization (EGM) technique is used as an optimization tool to estimate the minimum volumetric entropy generation rate to optimize thermohydraulic performance in HTS cables. Furthermore, pumping power and cooling capacity at minimum entropy generation rate are calculated. Computational Fluid Dynamics (CFD) is used to analyze the pressure drop and heat transfer rate for different flow rates to estimate the friction factor, pumping power and cooling capacity with flow of LN2 in corrugated former in HTS cable. A 3D computational geometry is developed using commercial software ANSYS®. Relevant boundary conditions are imposed on the computational geometry to reflect the practical operating conditions of HTS cable. Finite Volume Method (FVM) of discretization is used to solve the governing equations in order to obtain pressure drop and heat transfer rate in HTS cables. The simulated results are validated with the results available in literature. From the analysis, it is identified that at a heat load of 2.1 W/m and at an inlet temperature of 77 K, optimum cooling capacity and pumping power with minimum entropy generation rate are possible at a flow rate of 14 L/min.

Recent Progress and Design of Three-Phase Coaxial HTS Power Cable in Korea

High-temperature superconducting (HTS) power cables were developed recently and have several advantages over conventional cables. For high current capacity, two or more layers are required in one phase of the HTS cable. Differences in the radii between each phase and layer cause inherent imbalance and non-uniform current distribution of three-phase currents. These outcomes must be minimized by properly designing the pitches of multi-layer three-phase coaxial HTS cables. In this paper, the authors design the conduction layers of a multi-layer three-phase coaxial HTS cable and analyze the characteristics of the designed cable based on the proposed PSCAD/EMTDC component and simulation method. A 23 kV/60 MVA multi-layer three-phase coaxial HTS power cable is considered. The conceptual design of a multi-layer three-phase coaxial HTS cable includes the radii of each layer, the number of layers in each phase, and the pitch design of each layer of the cable. Using an impedance matching program, current imbalance can be minimized and current distribution can be made uniform in all layers of the phase by adjusting the pitch length and winding direction. The characteristics of HTS cables using the proposed PSCAD/EMTDC component are analyzed. In this component, the dynamic resistance of current- and temperature-dependent HTS cables is added to the HTS model. AC losses are calculated using the some equation. Induced current loss is calculated based on the material properties of the shield layer. A transient simulation is performed for a three-phase fault of the three-phase coaxial HTS cable using a PSCAD/EMTDC-based simulation method.

Dynamic Performance Analysis of Long-distance Power Transmission System with DC Superconducting Cable from Large Photovoltaic Generation

This paper proposes a new long-distance power transmission system with superconducting cable from large-scale photovoltaic (PV) power generation along with the dynamic performance analysis. The advantage of the proposed system is the reduction in the ac/dc conversion steps compared with the conventional one. As is well known, long-distance power transmission requires a dc system, and conventional dc power transmission system requires high dc voltage with low current to reduce losses. Such a high voltage has been achieved by dc/ac conversion with a boost chopper and an inverter from PV, and ac/dc conversion by a rectifier to dc cable. On the other hand, superconducting cable can transmit power with a lower voltage and higher current compared with conventional cable. This enables us to convert the dc voltage from PV plant to dc voltage to superconducting cable directly. Furthermore, the capacitance of the superconducting cable could be used for stable dc operation. In this paper, the system configuration, operation steps, controls, and characteristics verified by computer simulation are presented; eXpandable Transient Analysis Program (XTAP) is used for the simulation.

A novel radial cable for restraining tensile failure in steep fill—rock interfaces

It is quite common for fill slopes such as embankments and airport foundations to be constructed in mountainous areas. Steep fill—rock interfaces in such areas undergo tensile failure owing to differences in the stiffness values and tensile strengths of the soil and hard rock. In this study, a new anchor system, termed “radial cable,” is proposed to increase the pullout capacity of cables in the fill; this in turn helps control tensile deformation in the fill slope along the interface. In a radial cable, the steel ropes of a conventional cable are equally and symmetrically separated into three sub-cables (a central sub-cable and two branch sub-cables) with a radial distribution starting from the position of the interface. Moreover, each of the sub-cables is fixed in the fill using short U-shaped rigid rods along the cable length and a rigid baffle at its end to further increase pullout resistance. Experimental and numerical uplift tests were conducted to analyze the pullout capacity and anchoring behavior of the radial cables in soil to study the effect of branching. The reinforcement effect of the radial cables was also examined using a case study.

Thermohydraulic analysis of cold dielectric high temperature superconducting cable with counter-flow cooling

High temperature superconducting (HTS) cables cooled with liquid nitrogen (LN2) have been found to be most promising alternative to conventional cables for meeting the ever-rising energy demand across the world. The heat accommodated by the LN2 flowing in HTS cable has various major sources such as AC loss in the superconductor, dielectric loss in dielectric material, and heat influx through the cryogenic enclosure wall from ambient temperature. Thus, in order to operate long length HTS cables, the thermal and hydraulic analysis of LN2 flowing in the HTS cable is essential. However, the LN2 flow is more complex when flowing through stainless steel corrugated pipes with counter-flow cooling arrangement. In the present work, counter-flow cooling system is considered for the analysis to reduce the highest temperature attained in the HTS cable. Moreover, the influence of various heat fluxes and heat generations on the pressure drop and heat transfer is carried out using computational fluid dynamics (CFD) approach. The two-equation turbulence model k-epsilon (k-ϵ) is used to analyze the thermohydraulic behavior of LN2, where the thermophysical properties of LN2 are considered to be temperature dependent. The obtained pressure drop is compared with the experimental data of a parallel flow HTS system, fabricated in NEDO project. Consequently, the friction factor for counter flow HTS system is found to be quite larger than the parallel flow HTS system.

Fully Distributed Optical Fiber Strain Sensor With 10−12 ϵ/√Hz Sensitivity

Advanced optical fiber reflectometry techniques enable spatially distributed measurements of true relative deformations over the length of a conventional optical fiber cable. This methodology is attractive for many applications ranging from intrusion monitoring to seismology. However, accurate quantification of the applied stimulus in general implies sophisticated implementations with poor sensitivity performance. Coherent reflectometry using chirped pulses is an appealing solution, as it provides fast dynamic strain measurements with a simple experimental deployment. Here, we analyze for the first time to our knowledge the lower performance bounds of this technique as a function of the signal-to-noise ratio of the acquired optical signal. We demonstrate that implementations realized so far have been limited by the temporal sampling used instead of the optical signal quality. Through post-processing interpolation approaches, we reach the performance limit for a given set of signal parameters, attaining unprecedented strain sensitivities (10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-12</sup> ε/√Hz) for km-length distributed sensors in conventional single-mode fibers.

Effects of Cross-Sectional Size and Shape on the Longitudinal Tensile and Anchoring Properties of CFRP Cables

AbstractCarbon fiber–reinforced polymer (CFRP) is very suitable for use as a prestressed cable and can replace conventional steel cables in cable roofs. In engineering practice, the anchoring lengt...

Insulation Design and Simulation for Three-Phase Concentric High-Temperature Superconducting Cable Under 10-kV Power System

Compared with conventional cables, the high-temperature superconducting cables have advantages in a small volume, large capacity, high current density, low losses, and environmental friendship, which brings a new power electricity transmission method for the future power grid. With the development of the important researches in high-temperature superconducting materials, many projects with superconducting cables have been applied in the power system. This paper introduced a main insulation design for three-phase concentric high-temperature superconducting cable under 10-kV power system. AC puncturing test under power frequency and lighting puncture test have been achieved.