Cable Materials Research Articles

Research on the Application of Plastic Modification Technology in the Production of Wire and Cable Materials

Research on the Application of Plastic Modification Technology in the Production of Wire and Cable Materials

Reaction to fire of polymethylmethacrylate and polyvinylchloride under reduced oxygen concentrations in a controlled-atmospherecone calorimeter

Electrical cable sheaths are the most abundant fire load in nuclear power plants, mainly in rooms that are kept in under slight pressure. This configuration leads fires to grow in under-ventilated and vitiated conditions. Assessing fire threat involves characterizing the heat released, responsible for fire growth, and the smoke evolved, which may interact with sensitive components in the area. For that purpose, a revisited controlled-atmosphere cone calorimeter has been designed, set up, and coupled to a Fourier transformed infrared spectrometer and an electrical low-pressure impactor to measure simultaneously the evolved gases and aerosols, respectively. This bench-scale apparatus has been first qualified with polymethylmethacrylate. It has second been used to characterize polyvinylchloride cable sheath representative material reaction to fire in under-ventilated and vitiated conditions. It appeared that vitiation in under-ventilated fires lowers the heat release rate and the fuel mass loss rate.

Life-Cycle Cost Analysis of Long-Span CFRP Cable-Stayed Bridges

With the advantages of high strength, light weight, high corrosion and fatigue resistance, and low relaxation, carbon-fiber-reinforced polymer (CFRP) is an excellent cable material for cable-stayed bridges. However, the relatively high unit price of CFRP compared to that of steel may hinder the large-scale application of CFRP stay cables. This paper presents the economic comparison between long-span cable-stayed bridges using CFRP cables and the corresponding steel cable-stayed bridges through life-cycle cost analysis (LCCA). Three CFRP cable-stayed bridges with a main span of 600 m, 1200 m, and 1800 m, respectively, along with their steel counterparts, were designed, and their life-cycle costs (LCCs) were calculated. The comparison of LCCs was not only between the CFRP and steel cable-stayed bridges with the same span, but also between the cable-stayed bridges with different spans. Furthermore, the different unit prices of CFRP cables and different replacement frequencies of steel cables were also investigated. The results show that the initial design and construction cost of the long-span CFRP cable-stayed bridge is higher than that of the corresponding steel cable-stayed bridge, although using CFRP cables can reduce the materials used, primarily due to the higher unit price of the CFRP cable. Despite the higher initial cost, the long-span CFRP cable-stayed bridge can still achieve lower LCC than the steel cable-stayed bridge, because it has significantly lower rehabilitation cost and user cost, as well as slightly lower vulnerability cost. Furthermore, with the increase in the main span and the decrease in the unit price of CFRP cables, the LCC advantage of the long-span CFRP cable-stayed bridge becomes more obvious.

Nonsingular fast terminal sliding mode-based robust adaptive structural reliable position-mooring control with uncertainty estimation

This paper addresses a novel robust structural reliable position mooring scheme for a turret-moored floating production storage and offloading (FPSO) vessel subject to system uncertainties, environmental disturbances and unmeasurable velocity. A realistic mooring tension model considering buoys and different cable materials that can improve the capacity of the mooring system is derived. A sigmoid tracking differentiator (STD) is employed as a state observer to estimate the unmeasurable velocity. A structural reliability index is introduced to design a position mooring control law so that an FPSO vessel adequately uses a mooring system on the premise of safety to maintain position in an allowable region. It provides strong robustness and a fast transient response and suppresses chattering by merits of a backstepping method and an integral nonsingular fast terminal sliding mode surface (INFTSMS). An adaptive estimator is proposed to address the required unknown uncertainties and disturbances. Theoretical analysis proves the globally asymptotic stability of the whole system. Finally, comparative simulations on an FPSO vessel are conducted to illustrate the effectiveness and superiority of the proposed position mooring control scheme.

Analysis of Plasticizer Evaporation from Locally Available Poly(vinyl chloride) Cable Insulations

AbstractPoly(vinyl chloride) (PVC) is one of the most popular and widely used materials for electrical cables that offers insulation and sheathing. It is considered agile and durable as it easily exceeds 25–30 years while being used for household wiring. PVC provides insulation, strength, and protection at a wide range of operating temperatures. During cable manufacturing, plastics are exposed to heat that leads to degradation. Although degradation cannot be eliminated, it must be held to a minimum to keep the quality of the final products high. In this work, locally available single strand plasticized PVC insulations that are used for domestic electrical wiring and lighting purposes are investigated for their initial plasticizer content. The thermal‐induced degradation process is a moderate process that would take years to estimate the lifetime of a cable under ordinary ambient conditions. Thus, the study is carried out in accelerated conditions.

Superconductivity 2022

Superconductivity in metals and alloys, i.e., conventional superconductivity, has seen many new developments in recent years, leading to a renewed interest in the principles of superconductivity and the search for new materials. The most striking discoveries include the near-room-temperature superconductivity in metal hydrides (LaH10) under pressure, the extreme stability of superconductivity in NbTi up to 261 GPa pressure, the discovery of high-entropy alloy (HEA) superconductor materials, and the machine learning prediction of new superconducting materials. Other interesting research concerns the properties of 2D superconductors, topological superconductors, e.g., in hybrid systems, and the use of nanotechnology to create nanowires and nanostructures with new properties. Furthermore, and most importantly, the drive from new accelerator and fusion reactors for stronger superconducting magnets has lead to improved cable materials, showing the highest critical current densities ever. Thus, this Special Issue aims to bring together a collection of papers reflecting the present activity in this field.

Analysis of the Effect of Air Gaps on the Electric Field in the Insulation Material of High Voltage Transmission Cables

High voltage (HV) cables are widely used in the transmission and distribution of electrical energy. The design and manufacture of these cables with great precision are of great importance for power systems. Mistakes made during the manufacturing phase and defects that may occur in the structure of the cable material can cause premature aging and continuous malfunctions in the cables. Factors such as air gaps, foreign substances, and moisture in the insulating material may cause punctures and insulation problems in high voltage cables. In this study, the effects of air gaps left as manufacturing defects on the electric field distribution in the insulation of high voltage cables used in power systems were investigated. The effects of 154 kV high voltage cable, the air gap in different coordinates, and diameters in the insulating layer on the electric field distribution in the cable have been investigated. For this analysis, the Finite Element Method (FEM) and ANSYS@Workbench program which realizes a solution based on this method were used. It has been found that the diameter and location of the air gap significantly affect the electric field distribution of the high voltage cable.

An integrated approach for electromagnetic compatible commercial aircraft engine cable harnessing

Signal transmission reliability of cable harnesses is essential to commercial aircraft engine performance and flight safety as a commercial aircraft operates in growingly complex electromagnetic (EM) environments. Investigating EM responses of aircraft engine cable harnesses under high-intensity radiated field (HIRF) excitations enables optimization of cable harness configurations, and ensures satisfaction of airworthiness requirements of electromagnetic compatibility (EMC). Comprehending EM responses of aircraft engine cable harnesses also significantly improves robustness of the engine control system against EM disturbances. In alignment with industrial information integration engineering (IIIE), this work develops an integrated EM compatible cable harnessing model consisting sub-models accounting for disciplinary concerns of engine system performance, cable materials, cable structures, EM interferences, electric loadings, control robustness, etc. Then, this work verifies and validates the proposed cable harnessing models by conducting numerical experiments on a given cable harness subject to a number of EM wave interferences. The cable harnessing models and the tandem numerical analysis approaches developed in this work appreciably overcomes deficiencies appeared in relevant previous studies, and substantially support developments of a commercial aircraft engine.

Effects of electrical aging on the structural and physicochemical properties of crosslinked polyethylene (XLPE) cable insulation material

The aim of this work is to highlight the evolution of physico-chemical properties of peroxide crosslinked polyethylene (XLPE) insulation material exposed to electrical aging. Specific analysis and characterization studies were carried out to determine the effect of electrical aging on different samples at micro and macro levels. Based on the analytical investigations, it was shown that electrical aging yielded significant changes in the chemical and thermal characteristics of XLPE. It was also showed that property loss increased with the aging time.

Analysis on Fire-Retardant Performance of non-Class 1E Cables Depending on the Ambient Temperature Condition Surrounding the Facilities for Flame Test of Cables

Electrical cables are extensively used in nuclear power plants. Therefore, the fire-retardant performance of electrical cables is generally verified according to the Institute of Electrical and Electronics Engineers (IEEE) 383 standard, which describes the requirements for flame testing of cables. However, the IEEE 383 standard only stipulates one requirement for the minimum ambient temperature (5°C) surrounding the facilities for the flame test. To analyze the influence of the ambient temperature on the fire-retardant performance of 5cables, flame test experiments were conducted on two types of non-Class 1E cables under several conditions with respect to the seasonal ambient temperatures surrounding the experimental facilities. According to the results, the burning lengths of the cables did not increase in proportion to the increase in the ambient temperature. The longest burning lengths of the cables were obtained from experiments conducted in the autumn season, and not the summer season (with the highest ambient temperature). To investigate these experimental trends, we analyzed the influence of the ambient temperature on the flammability of the cables in terms of the consumption rate of the propane fuel used for the flame tests and the evaporation rate of volatile cable materials. Consequently, it was found that the highest flammability of the cables was observed under autumn conditions, similar to the standard temperature conditions in accordance with the IEEE 1202 standard and in which the volatile materials in the cables did not evaporate more than in the summer condition.

Crosslinking-modulated direct-current conductivity of XLPE-PS composite via charge trap characteristics

Low direct-current (DC) conductivity is one of the most desired characteristics for crosslinked polyethylene (XLPE) as a high-voltage DC cable insulation material. In this Letter, a correlation between the DC conductivity and cross-linking characteristics of XLPE-polystyrene (PS) composites at 50 °C was studied. Experimental results show that by adjusting the cross-linking structure, different trap distribution characteristics for XLPE-PS composites were realized. With the increase in the cross-linking agent content, DC conductivities of XLPE-PS composites tend to decrease, and the introduced average trap depth increases correspondingly. An increase of 0.07 eV for average charge trap depth in XLPE-PS composites could be acquired in the test range. It is considered that the increase in the average trap depth reduces the carrier mobility, contributing to the reduction of DC conductivity for XLPE-PS composites. Thus, the DC conductivity and average trap depth of XLPE composites show a strong relevance. The results suggest that the interaction between PS particles and the matrix introduced by cross-linking plays a dominant role in determining the charge conduction for XLPE-PS composites.

New Graphene Composites for Power Engineering.

Intensive research is underway worldwide to develop new conductive materials for applications in the power industry. Such tests aim to increase the electrical conductivity of materials for conductors and cables, thus increasing the current carrying capacity of the line and reducing the loss of electricity transmission. The scientific discovery of recent years, graphene, one of the allotropic types of carbon with very high electrical and thermal conductivity and mechanical strength, creates great opportunities for designing and producing new materials with above-standard operational properties. This project concentrates on developing technology for manufacturing aluminum-graphene and copper-graphene composites intended to be used to produce a new generation of power engineering conductors. In particular, we present the results of the research on the mechanical synthesis of aluminum-graphene and copper -graphene composites, as well as the results of the electric, mechanical, and structural properties of rods obtained after the extrusion process and wires after the drawing process.

Mechanical properties and space charge behavior of thermally aged polypropylene/elastomer blends

Polypropylene has excellent potential as a thermoplastic insulation material for HVDC cable, while its mechanical property and aging problem limit its engineering application. In this work, isotactic polypropylene (iPP) was blended with the polyolefin elastomer (POE), and the blends were thermally aged at 130 °C for various periods (up to 200 h). Taking pure iPP for a reference, the elongation at break of iPP/POE increased by 54.8%, the elastic modulus decreased by 42.5%, and the low-temperature brittleness decreased from −5 °C to −32 °C. During the 60 min polarization process of −100 kV/mm, the electric field distortion of pure iPP changed from 2.5% to 11.3% after thermal aging for 200 h, while that of iPP/POE just changed from 2.2% to 6.2%. The carrier mobility of both iPP and iPP/POE increased after thermal aging, and the carrier mobility of the latter increased by about two orders of magnitude. Combined with the results of thermally stimulated discharge current, iPP/POE was found to bring in more trapping center due to the newly generated interface between POE and iPP, which contributes to a smaller conduction current. This work provides insight into the thermal aging effects of polypropylene composite insulation for HVDC power cables.

Invariant electrical conductivity upon thermal ageing of a crosslinked copolymer blend for high voltage insulation

Click chemistry type reactions between polyethylene-based copolymers are a promising and by-product free alternative to peroxide crosslinking of low-density polyethylene, which is widely used as an insulation material for high-voltage power cables.

Study on Storage Activity of Cross-linkable Polyethylene material used for High Voltage Cables

Cross-linked polyethylene (XLPE) is widely used as insulation material in high-voltage cables. Impurities, moisture, microvoids, extrusion technology, and other factors all have an effect on insulation properties. However, the primary of this article focus is the self-decomposition characteristic of the cross-linking agent in the cross-linkable polyethylene during the storage process. In general, cross-linkable polyethylene used for 220-kV power cables must be manufactured to cable within one year. However, no studies have been conducted on the performance and stability of cross-linkable polyethylene and its usability during the long-term storage process. As a result, an accelerated storage experiment is carried out in this article to simulate the long-term storage of the cross-linkable polyethylene at room temperature. The electrical and mechanical properties of XLPE samples made from the cross-linkable polyethylene with different equivalent storage times are then measured. The storage activity refers to the activity of dicumyl peroxide (DCP) acting on the properties of the cross-linkable polyethylene after long-term storage because the DCP will be decomposing slowly over time. The result shows that, as storage time increases, the storage activity of the cross-linkable polyethylene decreases due to the gradual decomposition of cross-linking agents in granules. When the XLPE is made from cross-linkable polyethylene stored for an extended period, the cross-linking degrees decrease, and mechanical properties deteriorate significantly. Long-term storage, on the other hand, aids in the improvement of crystal structures and, to some extent, increases ac breakdown strength. The final XLPE properties still meet the Chinese National Standard after one-year storage of the cross-linkable polyethylene. After two years, the thermal extension property, i.e., the elongation under load, is close to the requirements of the Chinese National Standard. However, after five years, the thermal elongation property has degraded to the point where it is no longer acceptable.

Fundamental study on a diagnostic technology for degradations of cable insulation materials due to radiation exposure and aging

Fundamental study on a diagnostic technology for degradations of cable insulation materials due to radiation exposure and aging

Technology Topic Identification and Trend Prediction of New Energy Vehicle Using LDA Modeling

As new energy vehicle (NEV) is the future of automobile development, it is of great significance to dig deeper into the technical topics and development trends of new energy vehicles for accurately understanding the technical trends of the new energy vehicle industry, grasping development opportunities, and scientifically formulating strategic plans. This paper takes the patent texts in the field of new energy vehicles from 2000 to 2020 in the patent database of CNKI as the data source, identifies 25 technical topics implied in the patent texts by using the LDA (Latent Dirichlet Allocation) topic model, analyzes the evolution trend of the 25 technical topics in terms of importance and popularity, and predicts the popularity and development trend of each technical topic in new energy vehicles from 2021 to 2025 by constructing the ARIMA model. The popularity and development trend of each technology topic of new energy vehicles in China from 2021 to 2025 are predicted by constructing ARIMA model. Drawing on quantitative evidence, the study found that there are top five technical topics in terms of importance in this field, namely, Topic 8 (Installation and Fixation), Topic 5 (Heat Dissipation), Topic 14 (Vehicle Data Monitoring), Topic 9 (Charging Pile), and Topic 15 (Damping). From 2014 to 2020, the importances of Topic 5 (Heat Dissipation), Topic 8 (Installation and Fixation), Topic 6 (Electric Drive System), Topic 9 (Charging Pile), and Topic 15 (Damping) are gradually rising. In terms of popularity of technical topics, from 2014 to 2020, the first to fifth topics are Topic 20 (Safety), Topic 8 (Installation and Fixation), Topic 3 (Cable Insulation Materials), Topic 15 (Damping), and Topic 10 (Pump Cooling). Based on the prediction of ARIMA model, it is found that the popularity of these five technical topics is steadily increasing from 2021 to 2025, among which the popularity of Topic 20 (Safety) will increase from 63.58 to 113.07, the largest increase in popularity among all technical topics. The paper provides implications for countries dedicated to developing the new energy vehicle industry.

Modeling the formulation of the PVC cable composition

Increasing the fire-retardant characteristics of polymeric cable materials has attracted the close attention of experts all over the world for many years, since fires are often associated with the ignition of cable products, followed by the spread of fire through cable communications. In this regard, the development of new modern formulations of fireproof compositions with improved performance properties is especially relevant for the production of PVC cable composites. The article describes the production of a new phosphorus-containing flame retardant phenyldixylol phosphate and investigated its physicochemical properties. The new flame retardant was tested in an industrial formulation of a PVC cable composition using dibutoxyethyl adipate as a plasticizer. Using the methods of correlation-regression analysis and optimization, the optimal ratio of the resulting additive and tricresyl phosphate was selected, which provides the best technological and operational parameters of the PVC composite.

Communication Distance Estimation for Power Line Communication Using Various Differently Constituted Power Cables

The use of PLC (power line communication) is growing as the adoption of IoT technology becomes more widespread. However, the maximum communication distance between PLC modems cannot yet be clearly defined since the communication characteristics of the power lines used for PLC are not formally specified. In this paper, the propagation characteristics in the high‐speed PLC communication band of 2–30 MHz were investigated when equipment is not connected to the power line except both ends. The line constants for five typical types of cables used as single‐phase and two‐wire power lines were measured. Our results showed that different cables have markedly different transmission characteristics. The attenuation constant varied up to fourfold depending on the cable insulator material. We also derived a method of estimating the communication distance for different cables for application of the HD‐PLC system, which is the most commonly used type of high‐speed PLC. The measurement result by using VCT cable was almost agreed with the estimated value. By comparing the estimated distance with the experimental results, we show that the transmission distance can be estimated with sufficient accuracy for practical use. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Composite Micro-Nanoarchitectonics of MMT-SiO2: Space Charge Characteristics under Tensile State.

Low density polyethylene (LDPE) is a good insulating material which is widely used in cable materials due to its excellent insulation and processability. However, in the DC high voltage environment, pure polyethylene materials still face many problems, the most serious of which is space charge accumulation. The cable will inevitably be subjected to tensile stress during production, installation and operation. Therefore, it is of great significance to study the effect of stretching on the microstructure and space charge characteristics for polymers and their composites. In this paper, MMT/LDPE micro-composites, SiO2/LDPE nano-composites and MMT-SiO2/LDPE micro-nano-composites were prepared by melt blending. Mechanical stretching was carried out on pure LDPE materials and the above three kinds of composite materials. Each material was stretched according to four stretching ratios, which are 0%, 5%, 10% and 20%. The crystal morphology was observed by polarizing microscope (PLM), the crystallization perfection was tested by differential scanning calorimetry (DSC), and the space charge distribution inside each sample was measured by pulsed electro-acoustic (PEA) method. At the same time, the average charge density and apparent charge mobility for samples during depolarization were calculated and analyzed. The experimental results show that when the pure low density polyethylene sample is not stretched, its crystal structure is loose. Tensile stress can make the loose molecular chains align in LDPE and improve its crystalline structure, which is helpful to restrain the accumulation of space charge inside the sample. For MMT/LDPE, SiO2/LDPE and MMT-SiO2/LDPE composites, their internal crystal structure is compact. Stretching will destroy their original crystal structure at first, and then disorder molecular chains inside the three composite materials. With the increase of stretching ratio, the molecular chains begin to orient along the direction of force, the crystallization tends to be perfect gradually, and the space charge accumulation in samples also decreases. From the calculation results of apparent charge mobility for each sample, with the increase of stretching ratio, the trap depth and trap density inside samples firstly increased and then decreased.