Cable Materials Research Articles

Experimental and numerical study of corrugated anchors for CFRP plates

Carbon fibre reinforced polymer (CFRP) plates are promising materials for cables and prestress tendons in structural engineering for the excellent tensile performance, light in weight and anti-corrosion character. Anchoring has always been the main challenge of this high-performance material due to its anisotropy and brittleness. Corrugated anchors are high-efficiency friction-based anchorage devices. Nevertheless, premature failure of the CFRP plates can still be observed with this type of anchors, and the anchor efficiency for the corrugated anchors needs further improvement. This paper proposes a novel configuration of corrugated anchors. Experimental tests are then carried out to investigate the influence of the pre-tensioning bolt load and adhesive layer. Consequently, numerical analysis is conducted to reveal the anchoring mechanism. The results indicate the traditional corrugated anchors lead to non-uniform stress distribution in the CFRP plate, and with the proposed configuration the anchor efficiency can be increased up to 100%.

Improving the distribution system capability by incorporating ZnO nanoparticles into high-density polyethylene cable materials

This paper introduces a novel insulated cable designed to enhance the distribution system’s capabilities. Accordingly, high-density polyethylene loaded with varying concentrations of zinc oxide (ZnO) nanoparticles (NPs) ranging from 0.0 to 5 wt% was prepared using the melt-blending technique. Zinc oxide (NPs) is synthesized by using sol–gel technique and their microstructure was examined by X-ray diffraction. The new insulated cable, HDPE nanocomposite loaded with 1 wt% of ZnO, demonstrates a 43% reduction in the relative dielectric constant and a 16.5% improvement in breakdown strength compared to pure HDPE. The observed changes in both the dielectric constant and breakdown strength offer several advantages in electrical applications. These benefits include a decrease in feeder current at the same loading level, mitigation of inrush transients during load switching, and a reduction in earth fault current values, particularly in unearthed distribution networks with ungrounded cables. A comparative study is conducted between the conventional insulating cable based on the original material (HDPE) and the new insulated cable incorporating ZnO nanomaterial at a ratio of 1.0 wt% of the total cable mass per unit length. This comparison utilizes data from two actual medium-voltage distribution feeders. Both actual feeders are simulated using the EMTP/ATP package. The obtained results prove the efficacy of the developed material cable (polymer doped with ZnO NPs) compared to the base material. The peak and duration of inrush current can be cut to 77.3% and 67% of their original values, respectively. The earth fault current can be reduced to 56.5% in ungrounded networks, while substation current under the normal operation can be cut to 84.3% with the same load currents.

Recyclable Polymeric Cable Insulation Materials: A Comprehensive Review

Recyclable Polymeric Cable Insulation Materials: A Comprehensive Review

Research progress on high-temperature properties of carbon fiber reinforced polymer composites for cables

Carbon fiber reinforced polymer composites (CFRP) cable has advantages of lightweight, high strength, and excellent durability, providing a new materials for cables and bringing out potential breakthrough in spanning capacity of structures. At present, CFRP cable has already been applied in some engineering bridges. The fire resistance performance of CFRP cable is critical for ensuring structure safety when suffering accidental fire disaster, and clarifying mechanical performance deterioration and failure mechanism of CFRP cable at elevated temperature is fundamental for research of its fire resistance. This paper summarizes current research progress on high-temperature properties of CFRP cable from two levels, including epoxy resin matrix and CFRP composites. Firstly, at resin matrix level, mechanical properties of epoxy resin and its degradation at elevated temperatures are reviewed and analysed, and potential ways to improve high-temperature performance of epoxy resin are suggested. Secondly, at CFRP composites level, high-temperature properties test methods and mechanical performance of CFRP composites in longitudinal direction and transverse direction at elevated temperatures are summarized and discussed. In addition, research shortage of high-temperature properties of CFRP cable is summarized, and corresponding further research is recommended.

Surface Microstructure Study on Corona Discharge-Treated Polyethylene Using Positron Annihilation Spectroscopy.

The microstructure and chemical properties of the corona discharge process could provide an effective method for predicting the performance of high-voltage cable insulation materials. In this work, the depth profile of the microstructure and chemical characteristics of corona discharge-treated PE were extensively investigated using Doppler broadening of position annihilation spectroscopy accompanied with positron annihilation lifetime spectroscopy, attenuated total reflectance Fourier transform infrared spectra, Raman spectra and contact angle measurement. By increasing corona discharge duration, the oxygen-containing polar groups, including hydroxyl, carbonyl and ester groups, strongly contribute to the deterioration of hydrophobicity and the enhancement of hydrophilicity. And the mean free volume size, with a broadening distribution, decreases slightly. The line shape S parameter decreases because of the decrease in free volume elements and the appearance of oxygen-containing groups. Also, the thickness of the degradation layer, determined from the S parameter with positron injection depth, increases and diffuses into the PE matrix. A linear S-W plot within the degradation layer of different corona treatment duration samples indicates the defect type does not change. The S parameter decreases and the W parameter increases with an increasing corona duration. Using a slow positron beam, the nondestructive probe can be used to profile the microstructure and chemical environment across the corona discharge damage depth, which is beneficial for investigating the surface and interfacial insulation materials.

Based on experiment and quantum chemical calculations: a study of the co-pyrolysis mechanism of polyesterimide enameled wires with polyvinyl chloride and the catalytic effect of endogenous metal Cu

Pyrolysis technology is a green and efficient method for recycling enameled wires. However, since waste enameled wires are typically recovered from electronic waste, they often contain small amounts of wires and cables. Therefore, during the pyrolysis process of waste enameled wires, it is inevitable for the paint film and the cable sheath to undergo co-pyrolysis. Polyesterimide enameled wires (EPEsI) and polyvinyl chloride (PVC) were chosen as represent enameled wires and cable sheath materials, respectively. Using thermogravimetric analysis with various pyrolysis kinetic analysis methods, the pyrolysis characteristics and kinetics of EPEsI and Mixture (mixture of EPEsI and PVC) were studied. Through synergy analysis and pyrolysis-gas chromatography/mass spectrometry analysis, the influence of PVC on the pyrolysis of EPEsI was elucidated from aspects such as pyrolysis characteristics and product distribution. Based on density functional theory calculations and wave function analysis, the role of endogenous metal Cu in EPEsI on the pyrolysis processes of PEsI and PVC, as well as the mechanism of HCl from PVC on the pyrolysis of PEsI, were clarified.

Cyclic tensile response and crack closure performance of novel superelastic Ni-Ti SMA cable grid-reinforced engineered cementitious composites

To further improve the tensile and self-healing properties of engineered cementitious composites (ECCs) for their special uses such as harsh environments, plastic hinge regions, and old members strengthening, an innovative high-performance superelastic Ni-Ti shape memory alloy (SMA) cable grid-reinforced ECC (SMACG-ECC) was first proposed and tested in this study. The effects of water-binder ratio, cable grid material, and reinforcement ratio on the cyclic tensile properties and crack closure performance of the proposed SMACG-ECC were systematically examined. Test results revealed that the tensile strength, initial crack strength, ultimate tensile strain, dense crack, crack closure, and self-healing properties of the traditional ECC were obviously improved by being reinforced with the SMACG. Compared with the ordinary steel cable grid-reinforced ECC (SCG-ECC), the proposed SMACG-ECC exhibited approximately 50 % lower first crack strength, similar tensile strength and deformation ductility, but a 53.7 %-75.1 % greater energy dissipation, 75.8 %-80.2 % lower residual strain, and 80.4 %-83.4 % smaller maximum residual crack width. The tensile properties, cracking performance, and self-healing ability improved with the incorporation of SMACG as well as the increase in reinforcement ratio. Notably, most specimens showed satisfactory composite operation with no cable ends slipping during the entire cyclic loading process, with a maximum tensile strain amplitude of 8 %.

Study on preparation and performance of cable trench fire separation material for converter station (transforming station)

Study on preparation and performance of cable trench fire separation material for converter station (transforming station)

Degradation effects in FRNC jackets of optical fiber cables

AbstractIn large scale manufacturing, polymeric materials for cable jackets are subjected to high temperature and shear, what can induce degradation processes. In result, changes in structure of polymer materials can occur what is critical for their applications. Permanent market pressure on increase of productivity and product reliability as well as rigorous administrative regulations in telecommunication industry are the driving forces for development and introduction of new advanced Flame Retardant Non-corrosive jacketing materials. Despite many studies, their behavior is still neither well characterized nor understood in large-scale production. The object of studies was characterization of a relationship between processing conditions and effects of degradation of FRNC cable materials. The main goal was to find the processing factors limiting the production speed. Materials taken into consideration were two commercially available thermoplastic FRNC compounds dedicated to fiber optic cables, based on linear low-density polyethylene/ethylene–vinyl acetate composites with high loading of aluminum trihydroxide and magnesium dihydroxide fillers. Thermal degradation of cable materials was studied with use of thermogravimetry and rheometry. The series of jacket samples under different processing conditions were produced. Material processing behavior was characterized, and tensile and heat aging performance of cable jacket were tested. The results showed that the primary limiting factors for line speed increase were the melt pressure and jacket tensile performance, but neither the shrinkage nor extruder motor load. The result and general approach to the FRNC investigation can be successfully used in cable industry or in other industries involving the extrusion of FRNC materials.

Preparation and mechanical properties of the 2.5D carbon glass hybrid woven composite materials

Abstract The 2.5D carbon glass hybrid woven composite (CGHWC) is currently being utilized as a protective material for the external cables of solid rockets due to its extensive advantages in terms of structural load-bearing and integrated thermal insulation. This study reveals that 2.5D hybrid woven composites, prepared using T300 and T800, exhibit improved compression and tensile properties, respectively. T300 and T800 carbon fibers are preferred for the preparation of 2.5D CGHWC, with a volume fraction of carbon fibers along the weft yarn ranging from 20 to 60%. As the proportion of carbon fibers increases, the weft tensile and compressive strength of the composite material progressively improve, resulting in a maximum increase of 67% in tensile strength and 52% in compressive strength. The optimal volume fraction of carbon fibers was found to be 40%. The performance retention of low-cost hybrid composite materials was investigated, and it was found that even when the cost of carbon fibers decreased by 87.5%, the mechanical properties could still be maintained at above 85%. This article has expanded the mechanical performance database of hybrid composite materials, providing data support and theoretical foundation for the large-scale engineering application of composite materials.

Comprehensive investigation of bond properties of CFRP cables with concrete and mortar

This study investigated the bond properties of carbon fiber reinforced polymer (CFRP) cables with concrete and mortar. Analyses focused on the bond-slip behavior considering various factors, such as CFRP cable types (e.g., CFRP rod and strand), surface treatments, fixed end materials (e.g., concrete and mortar). Remarkably, the material type and compressive strength at the fixed end were found to have no discernible impact on bond-slip behavior. Conversely, the type of CFRP cable and its surface treatment emerged as pivotal factors influencing bonding strength outcomes. Employing the modified Bertero-Popov-Eligehanusen (BPE) model, a comparative evaluation was performed between experimental results and theoretical estimation of bond-slip behavior. Furthermore, image processing analysis revealed a similar bonding strength of CFRP cables with both concrete and mortar. This similarity can be attributed to the sparser distribution of coarse aggregates around cables in concrete samples, implying that the cementitious phase primarily governed the bond properties, resulting in consistent bonding strengths across different fixed end materials. Overall, this study sheds light on the intricate interplay between CFRP cable types, surface treatments, and material compositions, ultimately contributing to a deeper understanding of bond properties and their implications for various structural applications.

Breaking the strength-conductivity paradigm in hypoeutectic Al–Si alloy via annealing-induced Si nanoprecipitation

Hypoeutectic Al–Si alloys are increasingly recognized as promising materials for aluminum conductor cables owing to their remarkable combination of high strength and castability. However, the widespread industrial application of these alloys is limited by their moderate electrical conductivities (ECs). In this study, we explored the effects of direct annealing on the EC, mechanical properties, and microstructure of AA4043 rods fabricated via Properzi continuous casting. The AA4043 rods were annealed at different temperatures (200, 250, 300, and 350 °C) for 4 and 24 h. Direct annealing resulted in a significant improvement in the EC of the rods, with all samples exhibiting an EC improvement from 50 to 58% IACS. However, the mechanical strength of the rods was considerably reduced. The sample annealed at 250 °C for 4 h exhibited the best combination of EC (58.8% IACS), microhardness (43 HV), and ultimate tensile strength (141 MPa) among all the as-prepared samples. The sample annealed at 350 °C for 24 h showed the lowest microhardness (31.8 HV) and ultimate tensile strength (113 MPa), with EC of 58.05% IACS. Electron backscatter diffraction (EBSD) results revealed retained fibrous grains structure with partial recrystallization at a lower annealing temperature of 250 °C, whereas a higher annealing temperature of 350 °C resulted in complete recrystallization leading to coarse equiaxed grains. Transmission electron microscopy (TEM) analysis revealed the formation of nano-Si precipitates in the annealed samples. To understand the diverse contributions of the resistivity mechanisms and microstructural characteristics to EC improvement, a constitutive resistivity model was employed. These findings offer valuable insights into improving the EC and maintaining a delicate balance between the EC and strength of novel Al–Si conductor alloys.

Temperature Evaluation Considering Gradient Distribution for MV Cable XLPE Insulation Based on Wave Velocity

Temperature is an important factor for the service life of cable insulation. To ensure safety, the operating temperature of cables must be monitored. Since optical fiber temperature measurement technology is difficult to be used widely in medium voltage (MV) cables due to cost, this paper proposes a temperature evaluation method based on wave velocity. Firstly, the dielectric constant of cross-linked polyethylene (XLPE) cable insulation under different temperature is obtained through experiment. Based on the result, the relationship curve between wave velocity and temperature is established. The asymmetry effect due to temperature gradient in the cable insulation is discussed via finite element simulation. The effectiveness of obtaining the average insulation temperature of the cable based on wave velocity is validated. In addition, the mechanism of the temperature influence on the cable insulation material’s dielectric constant is analyzed by molecular dynamics simulation, which further deepens understanding of the characteristics of cable insulation materials.

Designing the Extruding Process of LLDPE/HDPE-Alumina Blends using Two-Level Factorial Method for Conductivity Level Optimizing HVDC Cable Insulation Material

Designing the Extruding Process of LLDPE/HDPE-Alumina Blends using Two-Level Factorial Method for Conductivity Level Optimizing HVDC Cable Insulation Material

Enhancement of the underground cable current capacity by using nano‐dielectrics

AbstractIn most underground power cables, cross‐linked polyethylene (XLPE) is utilized as the main insulating material, while polyvinyl chloride (PVC) is usually used as a nonmetallic sheath or jacketing for the cable. Accordingly, improving the electrical and thermal characteristics of these materials leads to an increase in cable dielectric strength, besides a rise in the current capacity of the underground power cables. Thus, enhancing the thermal characteristics of cable insulation is the goal of many research studies. In this regard, increasing the current capacity of underground power cables is an essential topic for electrical distribution and transmission networks. This usually occurs by increasing the cross‐sectional area of the cable conductor, which means raising the cost of transmitting electrical energy. Another proposed alternative may be to improve the thermal properties of the dielectric material using nanotechnology to allow better dissipation of heat resulting from the cable losses. This article proposes the use of nano‐composite dielectrics to increase the current capacities of underground power cables. Nano‐fillers are used to enhance the thermal and electrical characteristics of XLPE and PVC, which represent cable dielectric materials. Accordingly, in this paper, many experiments are conducted on various nano‐dielectric materials to choose the most appropriate nano‐dielectrics for improving both the thermal and electrical properties. Hence, measurements are performed on the thermal and electrical properties of dielectric nano‐materials manufactured in the laboratory. Further, calculations of the cable's current capacities by the use of the measured properties of nano‐dielectrics are done considering several backfill soils. From the obtained measurements and calculations carried out on cable capacities, it is concluded that the use of XLPE/ZnO 5 wt.% as the insulation and PVC/ZnO 5 wt.% as the jacket material increased the cable current capacity by 6.2% for a cable of 33 kV rating, 9.2% for 66 kV cable, and 15.7% for 220 kV cable when wet clay is used as backfill soil. From the calculations carried out it is found that the use of nano‐composite dielectrics reduces the temperature of the cable components by significant values. For example, the core temperature of the 33 kV cable is reduced by 15.6°C, while for the 66 kV cable, the cable core temperature is decreased by 12.6°C, and for 220 kV the conductor temperature is reduced from 71.3°C to 58.3°C when each cable is loaded by its rating.

High-performance cable materials for maglev trains prepared by the multiple synergistic regulation effects of the functionalized ionic liquids on EVA-based composites

High-performance cable materials for maglev trains prepared by the multiple synergistic regulation effects of the functionalized ionic liquids on EVA-based composites

Extra-Low Frequency Dielectric Relaxation in HVDC Cable Insulation Material Caused by Cross-Linking Byproduct

Extra-Low Frequency Dielectric Relaxation in HVDC Cable Insulation Material Caused by Cross-Linking Byproduct

Structure-performance relationship of polypropylene/elastomer/carbon black composites as high voltage cable shielding layer

As polypropylene (PP) is a competitive insulating material for next generation high-voltage cable, the corresponding PP based cable semi-conductive shielding layer material needs to be developed. This paper developed an excellent material prescription and proposed an analytical method of structure-performance relationship for the application and the evaluation of PP-based cable shielding layer. First, PP/POE/CB and PP/SEBS/CB composites with different carbon black (CB) loading were prepared and their electrical and mechanical properties were compared. Through thermal analysis technique, crystalline property and thermal stability of the composites were studied in detail. And the synchrotron radiation X-ray scattering techniques were employed to analyze the distribution of carbon black in the blend semi-quantitatively. The analysis result turns out the enrichment of carbon black in POE phase and its instability at high temperature limits its application under cable operation conditions. In contrast, PP/SEBS/CB30phr is recommended for lower thermal deformation, lower PTC effect and better mechanical parameters.

Catalytic Pyrolysis of Polypropylene for Cable Semiconductive Buffer Layers.

With the progress of the power grid system, the coverage area of cables is widening, and the problem of cable faults is gradually coming to affect people's daily lives. While the vast majority of cable faults are caused by the ablation of the cable buffer layer, polypropylene (PP), as a common cable buffer material, has pyrolysis properties that critically impact cable faults. Studying the semiconductive buffer layer of polypropylene (PP) and its pyrolysis properties allows us to obtain a clearer picture of the pyrolysis products formed during PP ablation. This understanding aids in the accurate diagnosis of cable faults and the identification of ablation events. In this study, the effects of temperature and catalyst (H-Zeolite Standard Oil Corporation Of New York (Socony) Mobil-Five (HZSM-5)) content on the PP thermolysis product distribution were studied by using an online tubular pyrolysis furnace-mass spectrometry (MS) experimental platform. The results showed that PP/40% HZSM-5 presented the highest thermolytic efficiency and relative yield of the main products at 400 °C.

Effect of Ethylene-Propylene-Diene Monomer Blending on the Dielectric Properties of Polypropylene for Power Cable Insulation

Thermoplastic materials such as polypropylene (PP) are ideal candidates to be used as power cable insulation materials. However, the mechanical properties of PP, which is brittle and stiff, need to be modified to meet the requirements of power cable insulation applications. To overcome this, ethylene-propylene-diene monomer (EPDM) can be melt blended with PP to improve PP’s mechanical properties. In the current work, the effect of blending different contents of EPDM with PP was investigated in terms of the morphology, chemical structure, dielectric response, electrical, and mechanical properties. The results show that the EPDM blended well with the PP as the EPDM dispersed in the PP structure. Meanwhile, the chemical structure and dielectric response of the EPDM and PP blend became slightly different with high contents of EPDM, which subsequently affected the breakdown strength and mechanical properties. Nevertheless, it is worth noting that PP blended with low contents of EPDM has the potential to be used as recyclable power cable insulation materials.