Aluminum Cables Research Articles

Emergency-Temperature Testing on MV Jacketed Reduced-Wall TRXLPE Aluminum Cable Systems in Duct Bank

Two MV reduced-wall TRXLPE-insulated 500-kcmil aluminum-conductor cables with encapsulated XLPE jacket were designed as replacements for the 350-kcmil copper-conductor cables with bare concentric neutral. The objective was to realize substantial cost savings on the purchase of the expensive copper-conductor cables. However, it would require an appropriate reduction of the insulation thickness of the aluminum cables in order to have the same ampacity as well as to fit into the existing 90-mm (3½″) PVC conduit. An emergency temperature test to be carried out in a duct bank containing 90° bends was chosen to evaluate the overall performance of the new cable systems. Thermal, mechanical, and electrical measurements were made in the testing. The test results were compared to those obtained previously on the 350-kcmil copper-conductor cables.

Application of the Feature Selective Validation Method and Kolmogorov-Smirnov Test to Evaluate Handling Effects on Crosstalk of Ethernet Cables

The use of Ethernet cables in internet of things (IoT) infrastructure continues to grow due to high demand as the reach of the IoT itself expands. Crosstalk is a major limiting factor in communications systems that need to be taken into consideration when selecting cables for deployment. In typical installations, these cables require a certain degree of manipulation that involves repeated coiling and uncoiling of a few meters which can adversely affect performance. It is thought that this is especially true with counterfeit or copper clad aluminum (CCA) cables often disguised as compliant Ethernet cables. In this paper, four unshielded twisted pair cables of which one of them is a CCA cable were subjected to three rounds of coiling and uncoiling tests representing installation manual handling. Given the visually complex measurements that are a feature of the Ethernet infrastructure, an approach to quantifying chances is needed that is particularly sensitive and nondiscriminatory. The Feature Selective Validation (FSV) method and Kolmogorov-Smirnov test is proposed as an appropriate method to use to assess crosstalk variations between the cables when subjected to this manipulation. The paper shows that the methods do allow quantified measurement of the variations between the tests which can lead to objective decision on the part of the cable installer.

Comparative cradle-to-grave life cycle assessment of traditional grid-connected and solar stand-alone street light systems: A case study for rural areas in Lebanon

Abstract Nocturnal lighting systems account for 20% of the total global electricity consumption. The aim of this paper is to investigate and compare the following two street lighting technologies in Lebanon from an environmental perspective: i) traditional grid-connected system and ii) solar stand-alone system. Life Cycle Assessment (LCA) is the methodology used to assess and compare the potential environmental impacts of the two systems from cradle-to-grave, i.e. from the raw material extraction until the end-of-life product stages. Two end-of-life scenarios are modeled: landfilling and recycling. The SimaPro software is used for modeling the Life Cycle Inventory and the IMPACT 2002 + method is used for the Life Cycle Impact Assessment. The traditional system includes a steel pole, a High-Pressure Sodium lamp, and aluminum cables. The stand-alone solar system includes a steel pole, a Light Emitting Diode lamp, a photovoltaic panel, a valve regulated acid battery, a controller, a dimmer, and copper cables. Results show that the traditional system has less environmental impacts than the solar stand-alone system when considering the life cycle stages from the raw material extraction to the production phase only. This is mainly due to the important environmental impacts of the lead and electronics used in the solar system. However, this difference is compensated during the entire life cycle from the raw material extraction to the end-of-life because the traditional system consumes a significant amount of energy from the Lebanese electricity grid during the use phase. The grid mostly relies on thermal power plants, imported fuel, and diesel generators. The results show that the solar system has less overall environmental impacts than the traditional system for both landfilling and recycling scenarios. In particular, it is shown that the recycling scenario for the solar system results in positive impacts on the environment.

A thermomechanical analysis of interfaces between the mating parts in ultrasonic wire bonding

AbstractUltrasonic welding (USW) is an alternative solution for the bonding process especially in automotive industry. Ultrasonic welding of metals is a joining technique as a combination of applying pressure and frictional vibrations within the range of ultrasonic frequencies. In automotive industry, ultrasonic welding is often used for wired connections. As an alternative for crimping technology of multi‐strand aluminum cables in wire bonding, ultrasonic welding is used. This work presents a thermomechanical analysis of the interface between two mating parts in USW. For this reason, the temperature distribution at bonding locations inside a wire bundle due to frictional vibrations and pressure is investigated using the finite element method (FEM). The obvious difference in microsections from different welding samples, which originates from different local temperature rises, was the motivation for this study to further investigate the thermomechanical aspects of the USW by use of finite element simulations. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Aluminium cables recycling process: Environmental impacts identification and reduction

Life cycle impact of European generic primary and secondary aluminium are well defined. However specific end-of-Life scenario for aluminium products are not available in the literature. In this study, the environmental assessment of cable recycling pathway is examined using the Life Cycle Assessment (LCA) methodology. The data comes from a recycling plant (MTB Recycling) in France. MTB Recycling process relies only on mechanical separation and optical sorting steps on shredder cables to obtain a high purity aluminium (above 99.6%). The life cycle assessment results confirm the huge environmental benefits for aluminium recycled in comparison with primary aluminium. In addition, our study demonstrates the gains of product centric recycling pathways for cables. The mechanical separation is a relevant alternative to metal smelting recycling.This work was done firstly to document specific environmental impact of the MTB Recycling processes in comparison with traditional aluminium recycling smelting. Secondly, to provide an environmental overview of the process steps in order to reduce the environmental impact of this recycling pathway. The identified environmental hotspots from the LCA for the MTB recycling pathway provide help for designers to carry on reducing the environmental impact.

Comparative study on life cycle environmental impact assessment of copper and aluminium cables

With the rapid development of industrialization and urbanization in China, domestic demands for copper and aluminium resources increase continuously and the output of copper and aluminium minerals rises steadily. The output of copper in China increased from 0.6 million tons (metal quantity) in 2003 to 1.74 million tons (metal quantity) in 2014, and the output of bauxite increased from 21 million tons in 2006 to 59.21 million tons in 2014. In the meantime, the import of copper and aluminium minerals of China is also on a rise. The import of copper concentrate and bauxite increased from 4.94 million tons and 9.68 million tons in 2006 to 10.08 million tons and 70.75 million tons in 2013 respectively. Copper and aluminium resources are widely applied in fields such as construction, electrical and electronics, machinery manufacturing, and transportation, and serve as important material basis for the national economic and social development of China. Cable industry is a typical industry where copper and aluminium resources are widely used. In this paper, a product assessment model is built from the perspective of product life cycle. Based on CNLCD database, differences in environmental impacts of copper and aluminium cables are analyzed from aspects such as resource acquisition, product production, transportation, utilization, and resource recycling. Furthermore, the advantages and disadvantages of products at different stages with different types of environmental impact are analyzed, so as to provide data support for cable industry in terms of product design and production, etc.

A finite element analysis of effects of ultrasonic welding parameters on the temperature distribution in wire bonding

AbstractWire bonding is an essential process in the automotive industry. Multi‐strand flexible aluminium cables are used for connection of different electronic components and electrical centres in cars. As an alternative for crimping technology in wire bonding, ultrasonic welding (USW) is applied, which is a rapid manufacturing process used to create solid joints between mating materials at low energy consumption compared to the known welding processes, such as oxy‐fuel welding and arc welding. An ultrasonic welding machine consists of different parts, such as pneumatic cylinder, piezoelectric converter, booster, welding sonotrode and anvil. Despite of the simplicity of the USW process, choosing the right machine and process parameters, like pressure of the pneumatic cylinder, welding time as well as vibration amplitude of the piezo‐converter, is a tricky and complicated task for obtaining an adequate bond. Experimental investigations done in this area are extremely time‐consuming and require a lot of effort. Therefore, some new approaches must be developed to understand the process in more detail. The present study focuses on the influence of the ultrasonic welding parameters, such as sonotrode pressure and vibration amplitude, on the temperature distribution at interfaces of two mating pieces in wire bonding [1,2]. Investigations are done by means of FEM simulations as well as by experiments. The results are then extended to thermo‐mechanical analysis of multi‐strand models. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Effects of various Mg/Si ratios on microstructure and performance property of Al-Mg-Si alloy cables

High quality AA6101 aluminum cables are critical to electrical industry to meet the energy consumption requests. In the present work, the influence of Mg/Si ratios on the electrical conductivity and mechanical properties of AA6101 aluminum alloy was investigated. Wheatstone Bridge method and tensile test were employed to characterize the mechanical properties. X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) were used to understand the morphology of the precipitation and the mechanism of age hardening. It is found that excessive Si benefits high strength and high conductivity while excessive Mg plays a negative role in the strength and the conductivity of AA6101 cables. Excessive Si elements promote both the precipitating rate and quantity of β″ phase therefore increase the tensile strength. Excessive Si elements also help with decreasing the lattice distortion, which contributes to the enhancement of the conductivity. Excessive Mg elements lead to more dissolved Mg after aging treatment, therefore increase lattice distortion of the matrix and promote the deposit of coarse Mg-enriched secondary phase.

Very long distance connection of gigawatt‐size offshore wind farms: extra high‐voltage AC versus high‐voltage DC cost comparison

This study presents a cost comparison between commercially available high-voltage DC (HVDC) and extra high-voltage AC shore connection (±320 kV voltage source converter and 420 kV–50 Hz single-core and three-core cables), for a 1 GW offshore wind farm cluster, considering transmission distances up to 400 km. The HVDC system is a point-to-point connection whereas multiple AC intermediate compensating stations are envisaged for AC when needed. Capital costs are evaluated from recently awarded contracts, operating costs include energy losses and missed revenues due to transmission system unavailability, both estimated using North Sea wind production curves. Optimal AC intermediate compensation, if any, and reactive profiles are also taken into account. Resultsshow that HVDC has lower transmission losses at distances in excess of 130 km; however, due to the combined effect of lower AC capital cost and unavailability, using three-core aluminium cables can be more convenient up to 360 km distance.

Internal impedance of steel-reinforced helically stranded conductors at commercial frequency

An original simplified mathematical model is proposed that describes the distribution of a harmonic electromagnetic field at a commercial frequency in steel-reinforced high-voltage cables with helically stranded single-layer winding. In the framework of the idealized physical concepts on which the proposed model is based, stranded conductors are treated as an anisotropic conducting layer. It is shown that taking into account the helical twist of conductors leads to the appearance of an axial magnetic field, the presence of which can significantly influence the level of ac losses. The model has been used to calculate the dependence of the internal impedance on the magnetic permeability of the steel core for commercial AS-70 grade steel-reinforced stranded aluminum cable. The results are compared to those obtained using a hollow cylinder model and full-scale numerical calculations using the finite element method.

Grain Refinement of High-Iron Aluminum Alloy by Inoculation with Al-B Master Alloy

Aluminum cables are playing an increasingly important role in power transmission system, in which the “rare-earth high-iron aluminum alloy power cables were developed in China. In this paper, the effects of B on grain refinement of high-iron aluminum alloy were studied by using OM (optical microscopy), SEM (scanning electron microscopy), EDX (energy dispersive X-Ray spectroscopy) and XRD (X-ray diffraction). And the conductivity of high-iron aluminum alloy was also tested. The results showed that B could take significant effects on grain refinement and promote the increase of conductivity. The refinement may be mainly due to the eutectic reaction in solidification process and the formation of AlB2 particles. The optimal concentration of B was determined as 0.06 wt. %.

Proposed Solution for Random Characteristics of Aluminium Alloy Wire Rods Due to the Natural Aging

In the last 50 years in the worldwide market for power transmission cables, there has been a tendency to replace aluminium cables electrical grade (EC) with steel cables by fully aluminium alloy (AAAC). The advantage in using cable AAAC is mainly economic (least amount of support structures and maintenance), addition to the elimination of the problems of galvanic corrosion and improved abrasion resistance. In order to obtain better mechanical properties, respect to the pure aluminium, aluminium alloyed with magnesium and silicon (AA6XXX series) is used, which by a combination of cold working and heat treatment allows obtaining greater mechanical strength without affecting too much the electrical conductivity. In this development it has worked with AA6101/6101M alloy. The manufacturing of aluminium alloy wire rods for such applications, using the conventional process Properzi, requires heat treatment of solubilized, continuous or discontinuous (batch). During the waiting time of two months or more, the wire coils are exposed to natural aging at room temperature, entering into the wiredrawing machines with different mechanical properties. The wires obtained by the traditional method of manufacture in Argentina, through the wiredrawing, result in significantly higher mechanical properties, not complying with the standards. Furthermore many breaks occur mainly when a high tensile strength wire is processed for wire 2mm in diameter or less. In the proposed method, a part of the initial wiredrawing is replaced by cold rolling and a subsequent partial aging. The results obtained in this study allow us to conclude that in the proposed process better properties and mechanical integrity are achieved than the traditional process, maintaining the electrical conductivity.

Effect of the transmission configuration of wind farms on their capacity factors

This study conducted a feasibility study to analyze and improve the operational performance of two current onshore wind farms on the Changhua coastal area in Taiwan. We selected two adjacent wind farms A and B with similar wind-power density and geographical conditions; whereas, their main differences were the material of cables, the type of transformers, the number of cable branches, and the depth of buried cables. In actual operation states, the wind farm A had greater capacity factor than the wind farm B; therefore, the wind farm A was regarded as a base case, and two new wind farms 1B and 2B, resulting from the changes in the cable materials, transformer types, cable branches, and buried cable depth of the wind farm B, were proposed to assess the feasibility of system improvement. Results showed that the material of cables, the type of transformers, the number of cable branches, and the depth of buried cables were the crucial factors of affecting the efficiency of wind farm B. Shallow cabling increased the temperature of cables, higher temperature causing a decline in cable capacity, and this phenomenon was crucial to aluminum cables rather than copper cables. The results of comparing the wind farms 2B with B indicated that the maximal transmission loss of cables was reduced by 6.4GWh/year, and the maximal annual CO2 emission was reduced by 4.5kt/year. Additionally, the increased cost of transformers and cabling was recovered in 2.12years, when the wind farm B was modified to 2B before construction.

Long Wire Antenna-Like Behavior of Uninsulated Overhead Distribution Cables

Uninsulated overhead distribution cables are evaluated in terms of their propagation and radiation behavior when excited by a partial-discharge (PD) pulse. Low attenuation levels at high frequency and a traveling-wave radiation pattern are observed for a single aluminum cable. The dominant radiated frequency components of surface discharge and dryband arcing are experimentally evaluated, and a high level of activity is observed in the 400-600-MHz and 900-1000-MHz bands. High directivity values at specific angles are also recorded at 400 and 900 MHz for single- and three-cable distribution systems. These findings show that a PD signal will travel for a significant distance along a cable and leak radiation predominantly in a specific direction, thus assisting the design of the RF-based discharge detection and localization system.

Electrical and thermal characterization of a novel high pressure gas cooled DC power cable

High-temperature superconductors (HTS) allow power cables of substantially higher current density than conventional copper or aluminum cables. This is important for applications where a low mass and a low volume are critical such as naval, aeronautical and space applications. The novel type of cable under consideration is cooled by gaseous Helium at elevated pressure. Helium is known for having poor electric breakdown strength; therefore the dielectric capabilities of this type of cable must be tested under conditions similar to the envisaged operation. In order to study the dielectric performance we have designed and built a novel high pressure cryostat rated at 2.17MPa which has been used for testing model cables of lengths of up to 1m. The cryostat is an open system where the gas is not re-circulated. This allows maintaining a high purity of the gas. The target temperature range is between 40K and 70K. This substantially increases the critical current density of the HTS compared to 77K, which is the typical temperature of cables cooled by liquid Nitrogen. The cryostat presented allows for adjusting the temperature and keeping it constant for the time necessary to run a complete dielectric characterization test. We give a detailed description of the cryostat. Measurements of partial discharge inception voltages as well as the temperature distribution along the model cables as a function of time are presented. Tests showed that the thermal insulation characteristics of this cryostat were sufficient for the dielectric tests of up to 1h duration. The partial discharge inception voltage (PDIV) of the high voltage bushing was about 16kV. These values are well within our design requirements.

Fire Hazard Research of Aluminum Cable Joint

On the basis of fire hazard simulation study of aluminum cable joint, it reveals that large contact resistance at cable joint can induce high temperature, and easily ignite combustibles then catch fire. Through macro-examination and metallographic analysis about the melted marks of aluminum cable joint, it clarifies the formation mechanism of the melted marks, and the corresponding preventive measures which can prevent cable fires, provide a practical and reliable scientific basis to guarantee the safe operation of power system.

Laboratory performance tests on aluminum splices for power conductors

AbstractThe paper reviews the results of laboratory testing of compression and bolted splices installed on stranded aluminum power conductors. The tests on compression splices involved connectors of 10 different designs using 240 mm2 stranded aluminum cable. Testing on the bolted splices was performed on connectors of 16 different designs installed on stranded aluminum cable with dimensions of 50 and 240 mm2. Splice performance was assessed on the basis of resistance measurements during short‐circuit tests and thermal cycling as specified by the International Electrotechnical Commission (IEC) 61238‐1 standard, and from inspections of cross‐sectioned connections. Differences in splice performance are related to such factors as physical properties of the materials in contact, splice assembly procedures, number of compression indentations or number of bolts, and other relevant parameters. The influence of conductor deformation on the ability to disrupt aluminum oxide films on the conductor surface during connector installation is addressed. The laboratory data indicate that large mechanical deformations in a splice significantly improve connector performance. For compression splices, relatively soft (annealed) conductors lead to inferior performance than hard‐drawn conductors, unless the soft conductor hardens significantly when it is deformed during installation. The sequence in which the compression indentations are made may influence connector performance. Copyright © 2009 John Wiley & Sons, Ltd.

Ignition of Veld Grass by Hot Aluminium Particles Ejected from Clashing Overhead Transmission Lines

It is common cause that the arcing of high voltage electrical conductors produces a shower of sparks. The flame temperature of aluminium burning in air is reported as having been measured as 3800 K (3527°C) [1]. After ejection from the point of arcing, a globule of aluminium is likely to be at or above its boiling point (2700 K or 2427°C) and surrounded by an aluminium vapour cloud which is promptly ignited and burns with a diffusion flame. If during the luminous period a spark was to fall onto dry veld grass then, provided it had sufficient energy not to be quenched, it would almost certainly cause ignition. Should the flame around a boiling globule be extinguished while it was still of finite size and were such a particle to fall into dry veld grass while its temperature was between 300 and 400°C or above it could cause ignition of the grass. In the present paper, ignition of the veld grass is determined by the temperature-trajectory history of hot particles of different sizes and initial conditions after their projection into a high velocity gusting airstream. This paper complements that of Mills and Xu Hang on trajectories of sparks from arcing aluminum cables [2] and that of Fernandez-Pello and Tse on the flight paths of metal particles and embers generated by power lines in high winds—a potential source of wildland fires [3]. The present study was commissioned in an attempt to establish the likelihood, or otherwise, that the occurrence of a particular veld fire could have been due to hot aluminium particles ejected from the clashing of high voltage overhead transmission lines. From in situ measurements, the fire started some 10.7 m horizontally from the clashing of the overhead conductors. Sets of graphs were obtained by computational experiment with the objective of verifying the starting point of the fire. These sets comprised: Time versus Particle Temperature, Time versus Vertical Penetration, Time versus Horizontal Penetration and Horizontal Penetration versus Vertical Penetration. Not all of the set of graphs satisfied the requirement of starting a fire at the given point. Sets H, I and J provided the definitive clue that the fire would have started by hot aluminium particles. The investigation was done in phases corresponding to the different set of graphs. Two models were subsequently elaborated called herein less rigorous and more rigorous. The effects of downward, upward and negative horizontal ejection velocities were also examined. The aim of the paper was to reconstruct the conditions prevailing on the day of the fire. The results obtained show that the probability the fire having been started by the hot aluminium particles ejected by clashing overhead conductors was high.

Seismic Interaction of Interconnected Electrical Substation Equipment

This paper investigates experimentally the dynamic interaction between components of electrical substation equipment interconnected by rigid bus conductors. Specific tests conducted in this study were (1) quasi-static tests of three different types of rigid bus with spring connectors; (2) quasi-static tests of one rigid bus slider; and (3) shake table tests of five different pairs of generic substation equipment specimens interconnected by three different rigid bus assemblies. All connectors tested exhibit stable hysteretic behavior with various degrees of energy dissipation capacity. The spring connectors dissipate energy through yielding and generated the highest forces among the connector tested and generally caused an amplification of the dynamic response of one of the interconnected equipment components. The bus slider dissipated energy through friction and generated lower forces than those of the spring connectors. Its high damping capacity, however, systematically reduced the dynamic response of interconnected equipment components. Finally, a special seismic connector that incorporates three flexural vertical aluminum cables generated the lowest forces. Its minimal damping capacity, however, resulted in higher equipment dynamic response than with the bus slider.

Atomic absorption spectrophotometric determination of lead in aluminum alloys using direct atomization of solid in a pyrocoated graphite-cup atomizer

A direct solid electrothermal atomization atomic absorption (ETA-AAS) method has been developed for the determination of lead in aluminum alloys using standard reference aluminum alloys as solid and solution calibrants for lead. An acceptable agreement with lead certified values has been achieved. Typical results for lead in two certified aluminum alloys using solid calibrants are: precision varies over the range RSD% 5.10–6.45%. A comparison of the results obtained with those determined by solution standard additions has been made. Accuracy agrees within 3% of the certified values. Limits of detection using 0.110 mg of standard alloy are 26.00 and 22.50 pg g −1; and for 5 μl injected alloy standard solution, limits are 66.00 and 43.20 pg, respectively. Characteristic mass (sensitivity) equals 70.30 pg/0.0044 A s. Beer's law is followed in the range 0.0–25.0 ng. X-ray diffractometry has been employed for identifying lead species possibly deposited within the atomizer. The method has been applied to the determination of lead in aluminium foils, wires, cables, ingots, and bars.