Multicore Cables Research Articles

Knowledge-assisted differential evolution based non-contact voltage measurement for multiconductor systems in smart grid

Multiconductor systems, such as overhead lines and multicore cables, are widely used in smart grids for their reliable power transmission capabilities. However, measuring the voltage of individual conductors in these systems has been challenging despite their promising applications. This paper proposes a novel framework to address this issue by utilizing a low-cost electric field (EF) sensor array and a knowledge-assisted differential evolution algorithm. The framework involves designing an annular EF sensor array to capture EF information around the multiconductor systems while ensuring its anti-interference capabilities through grounding and balanced electrodes. Furthermore, an optimization problem is formulated to reflect the model accuracy, and a knowledge-assisted differential evolution algorithm is proposed to optimize the voltage values and conductor positions by leveraging knowledge about the conductor positions and EF distribution. The use of this knowledge is expected to generate promising initial solutions for accelerating the optimization process. The proposed framework is experimentally validated, and the results demonstrate the robustness and accuracy of the EF sensor array and algorithm in obtaining the voltage of individual conductors in multiconductor systems.

ДИСИПАЦІЯ ЕНЕРГІЇ НИЗЬКОМОЛЕКУЛЯРНИМИ РЕЧОВИНАМИ ПІД ЧАС ЗОНДУВАННЯ ЕЛЕКТРИЧНИМ ПОЛЕМ БАГАТОЖИЛЬНИХ КАБЕЛІВ АТОМНИХ ЕЛЕКТРИЧНИХ СТАНЦІЙ

A model of the piece-homogeneous interphase space of stranded cables is proposed, taking into account the influence of cracks oriented along the lines of force of the electric field. The cracks are filled with low molecular weight substances. The case of a probing electric field with a significant tangential component is considered.. The equivalent values of the tangent of the dielectric loss angle at various parameters of low molecular weight substances in the cracks of the polyethylene insulation of the conductor with a cross section of 2.5 mm2 were determined. The equivalent tangent of the angle of dielectric loss increases by (3-20) times when the dissipation of electrical energy by low molecular weight substances changes from 10% to 100% in a crack, which is 1% of the thickness of an intact section of polyethylene insulation. The distribution of the electric field for the general case of accumulation of low-molecular products in capillaries formed by slit-like gaps between isolated veins is obtained. A strong electric field in the smaller part of the gap between the insulated cores, which occurs at a core potential of 1 kV, contributes to the capillary absorption of decomposition products of both solid polyethylene insulation and water vapor from the atmosphere in the case of unshielded structures of multi-core cables. The asymmetric configuration of the probing electric field with a significant tangential component makes it possible to detect low-molecular decomposition products of solid polymer insulation, which are a sign of its aging. Differences experimentally observed in the value of tgδ with different schemes of examination of multi-core cables are related, to a greater extent, to the uneven distribution of substances dissipating electrical energy across the cross-section of the cable, and not to a change in the structure of the probing electric field. References 11, figure 5.

Applicability of Standard Cladding Diameter Multi-Core Fiber Cables for Terrestrial Field

Applicability of Standard Cladding Diameter Multi-Core Fiber Cables for Terrestrial Field

Event-Driven Non-Invasive Multi-Core Cable Current Monitoring Based on Sensor Array

Current monitoring of multi-core cables plays an important role in various applications since cables are widely utilized in distribution and transmission systems. However, existing current sensing devices which are mostly designed for the single conductor break the cable jacket to measure conductor currents in multi-core cables. Recently various non-invasive sensing devices with reconstruction algorithms are designed for rapid access to currents in multi-core cables but don't make full use of abundant information during current monitoring. Thus, this paper proposes an event-driven non-invasive multi-core cable current monitoring method using an array of magnetic field sensors. Real-time currents of the multi-core cable are determined by solving conductor localization and current measurement problems. Since the observed changes of the magnetic field around the cable are caused by current or position changes, conductor localization is driven by the events which are classified as electrical events and mechanical events respectively. The key idea is to improve the accuracy of conductor localization through effective electrical events. Then current monitoring is achieved by solving current measurement problems using more accurate conductor positions and the measured magnetic field. This method is utilized in the real cable current monitoring, a sustaining decrease of relative current errors is observed, which is below 1% in long-term monitoring.

Ethernet Over Coaxial (EoC) Cable Telemetry Over High Voltage Dc And High Power Ac For Airborne Sonar Applications


 
 
 We have proposed a new passive component-based coupling scheme to simultaneously transmit high power AC, high voltage DC and high speed data through a long, single core coaxial cable, particularly for Airborne Sonar applications. This method is intended to replace the bulky multicore cables with single core coaxial cables that are compact and effective for transmitting data over long distances. This coupling scheme consists of three couplers to superimpose high power AC, high voltage DC and high speed data at the onboard end of the cable, and three decouplers to separate them at the remote end. The long cable, couplers, decouplers and the acoustic transducer are represented by their corresponding equivalent circuits that are cascaded together to construct the complete network. Power loss in the circuit is minimised by providing impedance matching networks in the form of a T-network transmission line and a tuning coil. The Ethernet over Coaxial (EoC) module can transmit high speed Ethernet data at the rate of 10/100 Mbps for telemetry from onboard to remote units and vice versa. DC voltages up to 300 V are coupled to the single core coaxial cable from the onboard unit and superimposed with high power AC signals and high-speed data. Passive filter-based coupling and decoupling schemes are demonstrated. Network simulation studies and experimental studies are carried out to verify and validate the equivalent circuit model. The transfer functions of each set of couplers and decouplers are determined independently as well as collectively and their effects on the underwater acoustic performance of the system are studied. The model resuls are found to agree with experiments. The proposed system is capable of generating an acoustic Source Level of about 195 dB with the supply of 125 V continuous wave (CW) AC signals, with simultaneous transmission of data at 10 Mbps and DC supply of 260 V from the on-board unit to the remote unit at the end of a coaxial cable of 200 m length. Introduction of impedance matching network is found to increase the source level by about 12 dB.
 
 

Numerical Prediction of Cables Fire Behaviour Using Non-Metallic Components in Cone Calorimeter

ABSTRACT Electrical cables must fulfil the Construction Product Regulation (CPR) by testing them according to EN 50,399. Nevertheless, an unfordable trial and error procedure could stem from the definition of new cables. To achieve a better understanding of fire behavior of cables, researchers have been using techniques such as bench and reduced scale tests and computational fire models result in a way to minimize trial and error process. The present work proposes the combination of bench scale tests, using cone calorimeters and fire simulation modeling. In a first step, the thermal characterization of the cable parts is carried out, and then, in a second step, use these data to model complete cable samples in cone calorimeter tests. The simulations are compared with experimental data of two already rated cables. This process is intended to discard erroneous configurations, which display in bench scale signs of misbehavior compared with rated cables. This would avoid the manufacture of the complete cable if the results do not fulfill the requirements, and eventually, proceed to its production and test in full-scale when they do. This work has been carried out with two multi-core cables and the materials they were made of, and the results showed: a) the inverse modeling process to characterize materials parts obtained a fairly accurate approach, with small inaccuracies in the peaks of the curves; b) two simulation models (simple and detailed) were able to reproduce in general terms the heat release rate curve; however, they released more energy than experimental tests and some discrepancies in the peaks were observed. Despite its simplicity, simple model obtained results fairly close to the experimental curves and took less time to simulate.

Implementation of Unbalanced Thermoelectric Equivalent Circuit for Power Flow and Thermal Rating of Underground LV and MV Cables

This manuscript proposes a time-series temperature-dependent power flow method for unbalanced distribution networks consisting of underground cables. A thermal circuit model for unbalanced three-phase multi-core cables is developed to estimate the conductor temperature and resistance of Medium (MV) and Low Voltage (LV) distribution networks. More specifically, a novel approach is proposed to model and estimate the parameters of the three-phase thermal circuit of 3- or 4-core cables, using the results of Finite Element Method and Particle Swarm Optimization. The proposed approach is generic and can be accurately applied to any kind of 3- or 4-core cables buried in homogeneous or non-homogeneous soil. Furthermore, it is applicable in cases where one or more adjacent cables exist. Using the proposed approach, the conductor temperature of each core can be individually and precisely calculated even under unbalanced loading conditions. The proposed approach is expected to be an important tool for simulating unbalanced distribution networks and estimating the conductor temperatures. The proposed thermal circuit is validated using two 4-core LV and one 3-core MV cables buried in different depths in homogeneous or non-homogeneous soil. Time-series power flow for a whole year is performed in a 25-bus unbalanced LV network consisting of multicore underground cables.

A Coreless Current Probe for Multicore Cables

To measure the current on each conductor in a three-phase three-core cable or a three-phase four-core cable without an armor or the armor that is made of nonmagnetic material, one has to remove its sheath/armor and applies a traditional device, such as a current transformer (CT) to each conductor, which is invasive and inconvenient. In this article, a Coreless current probe, composed of a tunnel-magnetoresistance (TMR)-based magnetic sensor array, is presented to nondestructively achieve current measurement for multicore cables. The conductor positions, incline angles, and current phasors of a multicore cable are simultaneously identified by solving a nonlinear least square (NLLS) problem. The current waveforms are reconstructed in real time through a real-valued matrix multiplication using the measured time-domain TMR sensor voltage signals. Both simulation and experiment are performed to validate the feasibility of the proposed method. The simulation study is first conducted and demonstrates that a maximum relative current amplitude error of less than 5% and a maximum phase error of lower than 4° can be achieved, and three-phase current waveforms with many harmonics are also successfully reconstructed by simulation. A prototype Coreless current probe is designed and fabricated. The experimental study involving fundamental current phasor measurement and current waveform reconstruction is subsequently performed on a three-phase three-core cable. The experimental results indicate that the maximum relative current amplitude error and phase error, respectively, have average values of 5.44% and 2.58°. Meanwhile, three-phase current waveforms with many harmonics generated by three types of appliances are also successfully reconstructed.

Comparison of Shielding Effectiveness of Different Shielding Methods for Multi-Core Cable on Lightning Surge Current

Appropriate shielding methods can reduce the lightning induced voltage and current of cables. In this article, different lightning surge currents (8/20 and 5/320 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> s) are coupled to the tested multi-core cable with single shielding layer and double shielding layers. The shielding effectiveness (SE) on the lightning surge current is compared for different cable shielding methods. The experimental results show that the cable induced current is effectively reduced when the shielding layer, the shielding spare core wire or the metal tube are grounded at two ends. A better shielding effect for the cable with double shielding layers is achieved by grounding both ends of the outer shielding layer and one end of the inner shielding layer, reducing the induced current to about 5% when the shielding layer is not grounded. Moreover, the SE of the spare core wire, used as the shielding wire in the multi-core cable, is better than that of the external shielding wire of the cable. The SE of the metal tube increases more and more slowly with the increase of the tube coverage percentage. Furthermore, the descending order of the SE of shielding methods involved here are grounding both ends of double shielding layers, grounding both ends of single shielding layer, spare core wire shielding and metal tube shielding. Finally, some engineering recommendations are proposed through the comparison between the shielding methods in this article and relevant works.

Verification and Analysis of Lumped-Circuit Approximate Models of Twisted-Stranded Cables for High-Speed Railway Signaling Systems

To evaluate the transmission characteristics, anti-electromagnetic interference performance, and cable channel fault detection of multi-core twisted-stranded cables used in high-speed railway signaling systems, this study established a model for accurate twisted cable physical simulations. With the LEU-BSYYP cable, the finite element method (FME) software constructed a one twisted cycle length model and calculated the per-unit-length (pul) distribution parameters of the cable under high-frequency pulses. The purpose is to simulate long-distance twisted cables physically and analyze the factors affecting the transmission quality and transmission distance of high-frequency signals quantitatively by constructing a lumped equivalent circuit comprising cascaded T-type circuits. Additionally, by analyzing the relationship between the working frequency and the characteristic impedance error, where the characteristic impedance error is the difference in characteristic impedance between a lumped equivalent circuit and a lossy uniform transmission line, the number of T-type cascaded circuits that fulfill the accuracy requirements of the physical simulation is determined. Finally, the model output is compared with the measured waveforms using a 500 m LEU-BSYYP twisted pair cable as an example to verify the correctness of the equivalent modeling of the lumped circuit in the paper.

Power Efficiency Theory and System Parameter Optimization for Multi-Core Fiber-Based Submarine Cables

Power Efficiency Theory and System Parameter Optimization for Multi-Core Fiber-Based Submarine Cables

History and Future of Connecting Broadcast Television Cameras: From Multicore to Native IP

<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Since the early days of broadcast television, there has been an ongoing evolution of the signal transmission between the camera heads and the camera base stations or camera control units (CCUs). In the 1970s, multicore cables were replaced by triax cables and more recently, with the introduction of ultrahigh-definition (UHD-1)/4K standards, SMPTE hybrid fiber cables became the de facto standard for most applications. At the same time, the signals transmitted over camera cables migrated from analog to digital, and now the most advanced broadcast cameras use Internet Protocol (IP). This paper explains the challenges and the potential solutions for a direct integration of a system camera for live broadcast applications into a full IP infrastructure. This next step in the evolution of camera signal transmission and connectivity will establish new workflows and offers more flexibility for cameras</i> .

Fire ignition of NYM cable shield vapor on excessive electric current in multi core cables

People oftenky use electrical appliances exceeds the technical specifications, but if done technically prevention of the manufacture of the cable to prevent the occurrence of fire, the fire risk will be minimized. Under the rules of SNI, heated wires or fed by the overcurrent, to be able to not burn. However, in some ocassions, electrical wires burned and turned into a heat source for fires. NYM cable flame characteristics in the event of overload currents, laminar diffusion flame occurs, the process of liquefaction, pyrolysis, diffusion, and combustion clearly seen. NYM cable flame propagation patterns in the incidence of overload start happening at that point reaches ignition temperature, which occurs due to an electric wire heat reaching the melting temperature of copper. Flame propagates in all directions where their fume and oxygen along the cable and around the cable. In certain circumstances, occur splash / explosion of the fuel to evaporate.

Investigation of cable effects in spectral induced polarization imaging at the field scale using multicore and coaxial cables

The spectral induced polarization (SIP) method has emerged as a well-suited laboratory technique to characterize hydrogeologic and biogeochemical parameters in soil samples. However, field applications of the SIP imaging method are still rare, which can be attributed to the particular care required to minimize the contamination of the data by electromagnetic coupling. To date, field procedures rely on the use of two different cables separating the current and potential dipoles to improve the quality of the SIP readings, although this increases the efforts in the field and might reduce the depth of investigation or the spatial resolution of the data. To overcome these limitations, we have investigated the use of a single coaxial cable, as an alternative to improve data quality and simplify field procedures. We evaluate SIP imaging data collected with the same measuring device using a coaxial cable and a combination of multicore cables of different lengths and manufacturers. Data sets collected with a single coaxial cable reveal a significantly lower number of outliers and a high spatial consistency between the phase-lag readings, even for measurements collected with a coaxial cable five times longer than the length of the profile. Furthermore, the data collected with coaxial cables reveal an improved quality for deeper measurements (with a lower signal-to-noise ratio) in comparison to data sets collected with separate cables. Our results demonstrate that the use of coaxial cables might permit the collection of SIP readings with high quality and similar field procedures to those used in resistivity surveys.

Nonintrusive Current Sensing for Multicore Cables Considering Inclination With Magnetic Field Measurement

Magnetic sensor arrays have been employed to measure currents for multicore cables due to their advantages of compact size, lightweight, low power consumption, and large dynamic range. However, the existing methods are applicable only to cases where the cable must be perpendicular to the sensor array plane due to the lack of capability of the 2-D magnetic field model to consider conductor inclination. To solve this problem, this article presents a method using a circular array of single-axis magnetic sensors to measure magnetic fields along and perpendicular to the sensor array plane. A 3-D magnetic field model that involves conductor incline angles is first derived. On the basis of the derived model, two main steps are performed to realize current sensing. First, an off-site calibration method is used to calibrate magnetic sensor parameters, including sensor position, orientation, gain factor, and phase shift. Second, not only the conductor currents and positions but also the incline angles are simultaneously calculated based on the detected magnetic fields and calibrated sensor parameters. Both steps are formulated as nonlinear least-square problems and solved efficiently. Both simulation and experiment are performed to demonstrate the superiority of the proposed method compared to the existing ones based on the 2-D magnetic field model when inclinations are introduced. The proposed method may have the potential for designing a clamp-on current sensor dedicated to multicore cables similar to hand-held current probes with a relatively large inner diameter for single-conductor systems.

The discovery of the tomb of the Great Army General Iwrhya: A quasi 3D Electrical Resistivity Tomography (ERT), Saqqara, Giza, Egypt

A quasi 3D electrical resistivity (ERT) survey was undertaken at a UNESCO World Heritage site, Saqqara, Giza, Egypt, during a joint archaeological-geophysical mission from Cairo University. The main objective is to detect the locations of the subsurface archaeological tombs/or crypts and to allocate any possible archaeological bodies/features buried underneath the study area. In this survey, SYSCAL Pro system with 24 electrodes and a multi-core cable is used for automatic data acquisition of profiling data. The dipole–dipole array was used to enhance resolution, 14 resistivity lines are conducted during this Survey. The processed data were analysed in order to produce resistivity tomography (ERT) for qualitative and quantitative interpretations. Inversion of the ERT data identified variation of resistivity values and the expected locations of the underground galleries and highlight the presence of regular shape structures probably due to features of archaeological interest. Excavations made accordingly in the study area led to an interesting discovery of a tomb of the Great Army General, Iwrhya. The tomb is approximately 2000 years old as it covers the reigns of both Kings Seth I and Ramesses II. Using the 3D resistivity tomography with such a multi-electrode technique proved its efficiency and applicability for non-invasive archaeo-geophysical prospecting.

Determination of Interaction Force Between Single Core Cable Elements under Deformation

The purpose of this paper is to investigate friction forces in the design of a single-core flexible cable in the deformation zone and the practical applicability of the results obtained for these purposes. The power interaction of the design of a single-core flexible cable during its deformation is considered. For the first time, formulas were obtained for determining the interaction forces between the constituent parts of a single-core cable as a composite multilayer beam. A calculation technique has been developed and shear force values have been determined for some types of single-core flexible cables. The nature of the change in these forces along the length of the cable is investigated. At the beginning of the cable deformation zone, the force value can fluctuate within its constant value. In the remaining part, the shear forces along the section are constant and only at the end of the deformation zone is zero. Practically, the formulas work for the tasks. The resulting expressions for shearing forces allow one to evaluate the tribological interaction of the constituent parts of each cable element and take into account their influence when creating multicore cables. The results of the research can be used to improve the reliability of the design of flexible cables at the design stage.

Enhancing Electrical Contact with a Commercial Polymer for Electrical Resistivity Tomography on Archaeological Sites: A Case Study.

This communication reports an improvement of the quality of the electrical data obtained from the application of electrical resistivity tomography method on archaeological studies. The electrical contact between ground and electrode enhances significantly by using carbomer-based gel during the electrical resistivity tomography measurements. Not only does the gel promote the conservation of the building surface under investigation, but it also virtually eliminates the necessity of conventional spike electrodes, which in many archaeological studies are inadequate or not permitted. Results evidenced an enhancement in the quality of the electrical data obtained in the order of thousands of units compared with those without using the carbomer-based gel. The potential and capabilities of this affordable gel make it appropriate to be applied to other geoelectrical studies beyond archaeological investigations. Moreover, it might solve corrosion issues on conventional spike electrodes, and electrical multicore cables usually provoked for added saltwater attempting to improve the electrical contact.

TECHNICAL APPROACH IN EVALUATING OF THE CHARACTERISTICS OF MULTI-CORE BALANCED NONQUADDED CABLES FOR DIGITAL COMMUNICATION SYSTEMS

The article proposes a variant of the technical approach in evaluating of the characteristics of multi-core balanced nonquadded cables for digital communication systems.&#x0D; The list of modern standards of the International Electrotechnical Commission, and also the National standards of Ukraine and the international standards which are created on their basis is presented. The proposed standards define the general requirements for communication cables, offer verifying methods for the design, structural dimensions, and materials of elements, marking and packaging. In addition, the provisions of these standards define the methods of testing the electrical characteristics, survivability and resistance of the cable to climatic and mechanical factors.&#x0D; A list of proposed cable characteristics, i.e. electrical, survivability and resistance to environmental influences, is sufficient to assess the cable for compliance with the stated requirements. The list of considered characteristics is not exhaustive and can be supplemented or changed depending on requirements of the customer.&#x0D; On the example of using the automatic measuring system AESA 9500 made in Sweden to measure electrical characteristics, the possibilities of optimizing the process of evaluating the characteristics of the cable through the use of modern automatically controlled measuring systems, which will significantly reduce the time and cost of evaluation are considered.&#x0D; The approach presented in the article to the evaluation of the characteristics of multi-core balanced nonquadded cables for digital communication systems can be used during the testing of the cable planned for delivery to the Armed Forces of Ukraine.

Classification of Faults in Multicore Cable via Time–Frequency Domain Reflectometry

Owing to the increasing complexity of electrical systems, diagnostic techniques of cables used for connecting electrical elements are essential for system maintenance in order to prevent a failure that can cause significant impacts on the overall electrical systems. Multicore structures are typically used as control and instrumentation cables in nuclear power plants, and the failure of the control and instrumentation cables can result in a disaster such as a radiation leak. In this paper, a method for the diagnosis of multicore cables is proposed based on the reflectometry. The diagnosis relates to the classification of defective cores in joint, which is one of the weakest parts in cable systems. The reflected signals obtained through reflectometry are converted into images by an advanced image processing algorithm, and the images are classified using artificial neural networks. The proposed method is demonstrated by experimental data using a real-world multicore cable. In the experiment, the faults are emulated similar to real-world defects using a potentiometer. It is expected that the proposed technique will enhance the stability and reliability of multicore cable systems.