Electrical Bus Bars Research Articles

Preliminary design of the cold mass supports for the EU DEMO feeders

The Cold Mass Support (CMS) is a basic structural component of the feeder system of the EU DEMO tokamak. The function of this structural element is not only to provide support to the containment duct – wiring the cryogenic lines, electrical bus bars and instrumentation to the magnets – in terms of both gravity loads and Lorentz forces, but also to isolate the low-temperature elements from the ambient, minimising the (conductive and radiative) heat loads. In this work, we describe a simulation and optimisation procedure adopted for the preliminary design of the EU DEMO CMS, which makes use of finite-element analyses and a shape parameterisation based on Radial Basis Functions (RBF). Structural and thermal numerical grids are morphed from a baseline configuration, and complex shape variations are achieved by means of an advanced meshless procedure based on CAD parametric surfaces, respecting the given geometrical constraints. A response surface-based optimisation is finally performed, in order to obtain a preliminary CMS candidate able to fulfil both structural and thermal targets.

Role of traversing speed and axial load on the properties of friction stir welded dissimilar AA6101-T6 AND AA1350 aluminium alloys

ABSTRACT Traditionally, AA6101-T6 and AA1350 aluminum alloys find prominent place in many industrial applications like electrical bus bar utilities for the sake of better conductivity. Friction Stir Welding is a non-traditional solid-state welding technique that was invented and developed by The Welding Institute. In this analysis, AA6101-T6 and AA1350 alloys have been put on experimentation with friction stir welding by varying axial load (5 kN to 9 kN) and traversing speed (60 mm/min to 120 mm/min). In order to examine the weld quality, properties such as tensile, wear and microstructural analyses have been carried out. From the results, it was observed that the weldment made with 7 kN axial load and 90 mm/min traversing speed exhibited better joint properties. Similarly, the weldment made with 5 kN axial load and 120 mm/min traversing speed exhibited poor joint properties. This has been attained due to the variations in heat input, metals softening and grain coarsening at weld nugget. Taguchi L9 orthogonal array with ANOVA and Signal to Noise ratio have been adopted to understand the contribution of axial load and traversing speed on the properties of weldments. Results reveal that traversing speed is statistically significant on the properties of weldment, when compared to axial load.

Effects of tool pin profile on tensile and wear behaviour of friction stir welded AA6101-T6 and AA1350 alloys

In Friction Stir Welding (FSW) technique, hard rotating tool with specially profiled pin is plunged into base metals and traversed along the interface of the plates, generating the frictional heat and plasticizing the base metals. This leads to flow of materials and makes solid state joint. AA6101-T6 and AA1350 alloys are widely applied in electrical bus bars, because of their high electrical conductivity. In this present work, these two alloys are joined by varying the pin profile of the tools as circular, triangular, square and hexagonal. Of these four joints, the joint fabricated by circular pin profiled tool exhibits poor tensile and wear properties whereas hexagonal pin profiled tool exhibits better tensile and wear properties. This is due to the volume defects and grain refinement at stirred zone.

Multiphysical characterization of FSW of aluminum electrical busbars with copper ends

This work investigates the benefits of having an aluminum (Al) busbar with welded copper (Cu) ends, and evaluates the force relaxation phenomena of a pre-loaded bolt joint on Cu versus Al, under cyclic thermal loading. The results show a force relaxation rate 50% lower in the Cu-bolted joint compared with the one in Al. The core of this research is the weldability analysis of Al-Cu butt joints made by friction stir welding (FSW). The materials are AA1050 H14/24 and Cu OF 04 with thickness of 6 mm. Temperature monitoring during the FSW cycle emphasize how heat generation depends mostly on local internal viscoplastic deformation. Tensile, bending, and microhardness tests were used to establish the mechanical properties. Optical microscope and scanning electron microscopy were used to characterize the microstructure. Joining mechanisms in the weld were investigated using energy-dispersive X-ray spectroscopy. The FSW resulted in 85% tensile strength efficiency compared to the Al base material, and 97% electrical conductivity efficiency compared to an ideal bimetallic component made of the same materials with no contact resistance. Electrical resistance of the FSW is 200 times lower than the electrical contact resistance between the Al-Cu materials while under high compressive force.

Property Evaluation of Friction Stir Welded Dissimilar Metals : AA6101-T6 and AA1350 Aluminium Alloys

Next to copper, aluminium alloys are widely used in electrical industries, because of their high electrical conductivity. AA6101-T6 and AA1350 aluminium alloys are widely used in electrical bus bars. As these alloys are joined by mechanical fasteners in electrical bus bars, the conductive area has been reduced. To avoid this problem, they should be joined without removal of metal as well as their properties. Friction stir welding technique is mainly invented for joining similar and dissimilar aluminium alloys. In this investigation, friction stir welding of AA6101-T6 and AA1350 aluminium alloys was done by varying tool traversing speed, rotational speed and tilt angle with hexagonal pin profiled tool. The analysis of variance was employed to study the effect of above parameters on mechanical properties of welded joints. From the experimental results, it is observed that welded joint with the combination of 1070 rpm rotating speed, 78 mm/min traversing speed and 2° tilt angle provides better mechanical properties. Analysis of variance shows that most significant impact on tensile strength is made by variation in tool rotating speed while tool tilt angle makes the most significant impact on elongation and bending strength.DOI: http://dx.doi.org/10.5755/j01.ms.23.1.14132

Ultra-Portable Smartphone Controlled Integrated Digital Microfluidic System in a 3D-Printed Modular Assembly

Portable sensors and biomedical devices are influenced by the recent advances in microfluidics technologies, compact fabrication techniques, improved detection limits and enhanced analysis capabilities. This paper reports the development of an integrated ultraportable, low-cost, and modular digital microfluidic (DMF) system and its successful integration with a smartphone used as a high-level controller and post processing station. Low power and cost effective electronic circuits are designed to generate the high voltages required for DMF operations in both open and closed configurations (from 100 to 800 V). The smartphone in turn commands a microcontroller that manipulate the voltage signals required for droplet actuation in the DMF chip and communicates wirelessly with the microcontroller via Bluetooth module. Moreover, the smartphone acts as a detection and image analysis station with an attached microscopic lens. The holder assembly is fabricated using three-dimensional (3D) printing technology to facilitate rapid prototyping. The holder features a modular design that enables convenient attachment/detachment of a variety of DMF chips to/from an electrical busbar. The electrical circuits, controller and communication system are designed to minimize the power consumption in order to run the device on small lithium ion batteries. Successful controlled DMF operations and a basic colorimetric assay using the smartphone are demonstrated.

A three-dimensional multi-physics model for a Li-ion battery

A multi-geometry and multi-physics model is developed for a Li-ion battery module which includes three cells connected in series by electrical busbars. The model can be used to predict the 3D profiles of the electrical potentials and temperature in the battery. The physics-based porous electrode (P2D) model is used to predict the electrochemical behavior of the cells, and the coupling between the P2D model and the electrical/thermal equations is simplified through a linear approximation method. This approximation is useful at rates of at least 5C and reduces the computation time significantly. The anisotropic conductive properties for the regions where conductors are separately arrayed are discussed in detail, and the model predictions are presented and discussed.

대용량 HVDC 컨버터의 Busbar 설계

This paper studies a busbar design of high power HVDC converter. In order to design a electrical busbar, we need to consider electrical, mechanical and environmental condition. In this papre, we focus on the electrical design in terms of temperaure and currnet. Busbar conductor can be damaged to burn due to the temperature and fault current of busbar. In this paper, Busbar design of Jindo-Jeju HVDC #2 System that will start operate in 2012 is considered.

The U.S. NHMFL 100 Tesla multi-shot magnet

The design, analysis and fabrication progress of the 100 T Multi-Shot Magnet is described. The description includes the structural analysis of the outer coil set, the fabrication of the 100 T prototype coil 1, the fabrication of a coil 1 test shell, and the analysis of the electrical busbar assembly. Fabrication issues and their solutions are presented. This magnet will be installed as part of the user facility research equipment at the U.S. National High Magnetic Field Laboratory (NHMFL) Pulsed Field Facility at Los Alamos National Laboratory.

Optimum reduction of self field effects in a Bi-2223 stacked superconducting busbar

High T/sub c/ superconductors, such as Bi-2223, have been promising candidates for an electrical busbar because the busbar has a relatively low self magnetic field. It has been found that the critical current of Bi-2223 stacked tapes is much less than the total summation of critical currents of each tape, which is mainly attributed to the self magnetic fields. Furthermore, since the critical current degradation of Bi-2223 tape is greater in the normal magnetic field (to the tape surface) than in the parallel one, detailed magnetic field configurations are required to reduce the self-field effects. Conceptually, by rearranging each stacked tape properly, the self field effects could be minimized. In this paper, we calculate the self field effects of a stacked conductor, defining self field factors of normal and parallel magnetic fields to the tape surface. We propose an optimum shape of octagonal structured busbar which has minimum self field effects.

Heating of damaged conductors

The heating of damaged electrical conductors and bus bars is examined from both a theoretical and experimental point of view. It is shown that the damage has a negligible effect on the heating because of the high thermal conductivity of all electrical conductors.