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Electrical Contacts (Holm), 2011 IEEE 57th Holm Conference on

Date 11-14 Sept. 2011

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  • HOLM 2011 - Title Page

    Publication Year: 2011 , Page(s): i
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  • HOLM 2011 [Copyright page]

    Publication Year: 2011 , Page(s): i
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  • HOLM 2011 Conference Supporters

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  • HOLM 2011 Steering Committee

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  • HOLM 2011 Conference Officers

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  • HOLM 2011 Table of contents

    Publication Year: 2011 , Page(s): i - v
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  • HOLM 2011 Foreword

    Publication Year: 2011 , Page(s): i
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  • HOLM 2011 In Memoriam

    Publication Year: 2011 , Page(s): i - ii
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  • HOLM 2011 Morton Antler Lecture

    Publication Year: 2011 , Page(s): i
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  • HOLM 2011 Erle Shobert Prize Paper

    Publication Year: 2011 , Page(s): i - ii
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  • HOLM 2011 Armington Recognition Award

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  • HOLM 2011 Author Index

    Publication Year: 2011 , Page(s): i - ii
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  • Low-Voltage Arc Simulation with Out-Gassing Polymers

    Publication Year: 2011 , Page(s): 1 - 8
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1568 KB) |  | HTML iconHTML  

    Polymer walls and inserts are an important design criterion in low-voltage switching devices. Besides their good insulation properties they are used to influence the switching arc. An important part of the energy dissipated in the arc is absorbed by the walls of the arc chamber. This leads to degradation and evaporation of the polymer and subsequent impact on and interaction with the switching arc. This contribution explains the enhancements of an existing simulation model for the interaction between the low-voltage switching arc and walls composed of polyamide PA 66. This includes a model of plastic ablation, the influence of the plastic vapor on the transport properties of the arc as well as on its radiation. Calculations and comparisons with experimental results show the applicability of the model in arc chambers that are close to reality. View full abstract»

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  • Experimental Investigation of the Interaction of Interrupting Arcs and Gassing Polymer Walls

    Publication Year: 2011 , Page(s): 1 - 8
    Cited by:  Papers (4)
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    Gassing polymer walls are used in circuit breakers to improve their interrupting and current limiting performance. The energy of the arc will be partially absorbed by the polymer walls, causing chemical degradation and evaporation. The evaporated gas reaches the arc plasma changing its composition and influencing its burning conditions. The resulting increase on pressure and arc voltage contributes to current limiting and reduction of arcing time. This paper deals with experimental results of the investigation of the interaction between the arc and gassing polymer walls. The simultaneous detection of pressure in the arc chamber, of arc current and voltage and the use of high speed photography and SEM analysis contribute to the characterisation of the influence of the polymer gases on the arc behaviour. The results of the experiments are used to verify numerical models. View full abstract»

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  • Influence of Voltage and Current on Arc Duration and Energy of DC Electromagnetic Contactor

    Publication Year: 2011 , Page(s): 1 - 5
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    In this paper, experimental results were described for a general DC electromagnetic contactor switching under a permanent magnet for arc extinguishing. The experiment circuit was a series circuit of source voltage E, resistive load R and DC electromagnetic contactor. The closed contact current Io was adjusted by R. The influence of E and Io on arc duration ta and arc energy Ea of break arc were experimented. The E had been changed within range of 50 - 500V DC and Io was set from 5 to 30A at each voltage E. Arc voltage and current waveforms were measured with a digital oscilloscope. When E was high, arc duration ta became long. However, in 300V or more, ta shortens when Io is increased. In 200V, influence of Io on ta was not seen and arc duration became almost constant. In 50V, ta became long along with Io, it is clarified that permanent magnets doesn't influence for arc. However, shortening of the arc duration with permanent magnet was seen in 100V or more. We think that effect of Lorentz's force on the arc was different according to E and Io. In addition, when E and Io are high, it was found that arc energy Ea became large. View full abstract»

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  • A Preliminary Investigation of Graphite, Graphene and Carbon Nanotubes (CNT's) as Solid State Lubricants

    Publication Year: 2011 , Page(s): 1 - 9
    Cited by:  Papers (2)
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    Graphite is well known and has been extensively characterized in its performance as a solid state lubricant, but has not typically been successfully implemented for low voltage/current electrical contacts. Recent advances have shown that both graphene and carbon nanotubes (CNT) exhibit novel properties and could find potential use as solid state lubricants. A comparison of various properties including contact resistance and friction behavior on Au, Ag, and Sn surface finishes has been undertaken to explore the similarities and differences in these different forms of carbon. View full abstract»

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  • Contact Resistance with Dissimilar Materials: Bulk Contacts and Thin Film Contacts

    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (2)
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    Contact resistance is important to integrated circuits and thin film devices, carbon nanotube based cathodes and interconnects, field emitters, wire-array z-pinches, metal-insulator-vacuum junctions, and high power microwave sources, etc. In other applications, the electrical contacts are formed by thin film structures of a few microns thickness, such as in micro-electromechanical system (MEMS) relays and microconnector systems. This paper summarizes the recent modeling efforts at the University of Michigan, addressing the effect of dissimilar materials and of finite dimensions on the contact resistance of both bulk contacts and thin film contacts. The Cartesian and cylindrical geometries are analyzed. Accurate analytical scaling laws are constructed for the contact resistance of both bulk contacts and thin film contacts over a large range of aspect ratios and resistivity ratios. These were validated against known limiting cases and spot-checks with numerical simulations. View full abstract»

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  • Arc Fault Model of Conductance. Application to the UL1699 Tests Modeling

    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (4)
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    Differents types of arc faults can be responsible for the start of an electrical fire. Depending on the power system and the application (photovoltaic, vehicule, aircraft, residential wiring) the arc fault may involve contact or non-contact arcing with eventually semi-conductive materials in the vicinity. Other characteristics such as the gap distance or the electrode material and geometry may also strongly differ. An electrical model was developed to fit with the arc fault scenarios described in the standard for AFCI UL1699. The contact arcing copper-graphite electrodes produced by the arc generator and the non-contact arcing on carbonized track produced with the arc clearing time tester were observed and their electrical characteristics (restrike and burning voltage, time constant and stability) could be verified thanks to the electrical model with a very good agreement. A qualitative study showing the various parameters used for fitting shows that the model is applicable regardless of the arc ignition principle. View full abstract»

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  • High Current Arc Erosion on Copper Electrodes in Air

    Publication Year: 2011 , Page(s): 1 - 6
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    An arc fault inside metal enclosed switchgear will cause the pressure to rise and vaporization of electrode material may contribute to the pressure rise. An experimental study of high current arc erosion on copper electrodes in air has been performed, with an evaluation of fraction lost by gross melting and vaporization. All experiments were performed at NEFI High Voltage Laboratory in Skien, Norway. The measured mass loss from vaporization in our experiments seems to be negligible compared to erosion by gross melting. View full abstract»

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  • Whisker Growth under Controlled Humidity Exposure

    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (1)
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    Studies of Sn whiskers under controlled, calibrated humidity conditions shows that the highest whisker densities occur for ~85% RH. The whisker specimens were 1500 Å Sn films sputtered under compressive stress conditions on silicon and electrochemically polished brass. Subsequently, the samples were exposed to a series of saturated aqueous salt solutions (which generated calibrated relative humidity values of 33, 43, 70, 76, 85, 98% RH) for ~140 days at room temperature. The Sn on brass case at 85% RH produced 6X greater whisker densities than Sn on brass exposed to pure O2, which in turn produced 9X greater whisker densities than Sn on brass exposed to ambient room temperature/humidity. The longest average whisker lengths (6.1 μm for Sn on brass and 9.3 μm for Sn on Si) occurred for 70% RH on both substrates. Corrosion features were observed on all samples, but the 98% RH samples experienced excessive corrosion. Generally, we find a dramatic increase in whisker density at >; 60% RH and especially around 85% RH, in agreement with batch processed whisker experiments involving humidity [H. Reynolds et. al., IEEE Trans. Electron. Packag. Manuf. 33 (2010) and P. Oberndorff et. al., IEEE Electronic Comp. and Tech. Conference (2005) 429]. View full abstract»

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  • The Effects of Current Density Variations in Power Contact Interfaces

    Publication Year: 2011 , Page(s): 1 - 7
    Cited by:  Papers (2)
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    Greenwood's approach to interaction between current carrying contact spots was used to analyze the degradation of single spots. The degradation is assumed to occur from electro-migration which causes a non-uniform increase in the effective resistivity across each contact spot. The latter results were used to evaluate the degradation of a simulated multi-spot interface to demonstrate the cascade failure mode believed to occur in power contacts. In addition, factors such as spot size, position and interaction with nearby spots were assessed in their impact on current density variation across the contact region. View full abstract»

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  • Direct Observation of Current Density Distribution in Contact Area by Using Light Emission Diode Wafer

    Publication Year: 2011 , Page(s): 1 - 7
    Cited by:  Papers (1)
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    Theoretically the Laplace equation can be used to calculate the current constriction behavior in electrical contacts. On the actual behavior of current constriction, although there are many reports on the contact resistance measurement, not many reports on the detailed behavior of current density distribution in the contact area experimentally. Therefore, we attempted to observe the behavior of the current density distribution in the contact by using semiconductor wafers in this study. As a result, it was confirmed that electric current is uniformly distributed over the contact area covered by an oxide film, while it is concentrated at the periphery of the contact if there is no oxide film. These results qualitatively agree with the results of the earlier theory and electric field analysis. View full abstract»

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  • Effect of Contact Parameters on Current Density Distribution in a Contact Interface

    Publication Year: 2011 , Page(s): 1 - 9
    Cited by:  Papers (3)
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    The distribution of individual current paths within a smooth mated surface contact interface results in the areas of highest current density being located at the outer rim of the contact interface. As contact surface roughness increases, the areas of highest current density become more evenly distributed across the contact interface, though still biased toward the outer rim. This effect can be predicted using a 3-dimensional simulation visualization technique and validated experimentally. The technique used for experimental validation involves using thermal camera technology to directly view the thermal response of the material within a contact interface. This is done as a volt-age/current pulse is applied across a plated electrical contact surface mated to an appropriate probe surface. These results are then used to visualize the resulting effect on the current density distribution. This work focuses on the further development and application of the simulation tool and thermal observation tech-nique to be able to better quantify contact interface thermal per-formance with respect to multiple contact parameters. View full abstract»

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  • Fretting Behavior of Nickel Coatings for Electrical Contact Applications

    Publication Year: 2011 , Page(s): 1 - 8
    Cited by:  Papers (4)
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    Fretting remains a major cause of connector failure and can impair reliability in complex systems. Oxidizable metals such as tin, copper and nickel are particularly prone to fretting degradation. We report here the first results of an investigation on fretting of nickel contacts with two types of deposits. Sulfate nickel layers are electrodeposited in different conditions and show very different behaviours during fretting tests. The characteristics of the layers are analyzed and show different compositions and microstructures. The compositions are measured by X-Ray Photoelectron Spectroscopy (XPS) which allows determining the chemical nature of the compounds formed during exposure to air. Topography is measured by AFM and the roughness and grain characteristics are assessed. Electrical properties at the micro/nanoscale are measured with the CP-AFM technique. Various loads are applied to the cantilever beam; the electrical characterization is performed versus the load. The results of fretting experiments are analyzed in terms of fretting regimes. The fretting regimes occurring during the test of the matte layers involve partial slip which delays the occurrence of contact resistance (Rc) increase. Gross slip in the interface is shown to create very poorly conducting wear debris leading to drastic increase of Rc. This study is part of a larger one aiming at tailoring coatings allowing the best tribological and electrical behaviors during fretting of nickel contacts. View full abstract»

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  • Research on Fretting Resistance and Fretting Wear Property of Ni-Au Contact Pair

    Publication Year: 2011 , Page(s): 1 - 6
    Cited by:  Papers (1)
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    Au-Au plated contact pairs have long been the most frequently used in electrical and telecommunication system due to their outstanding electrical, physical and chemical properties. However, the increasingly high cost of gold plated connectors forces the manufacturers to seek some inexpensive substitution due to serious global competition. Ni and/or Ni alloy are naturally chosen to make Ni-Au contact pairs. In this paper, Ni-Au contact pairs, that is, Ni is used as probe and gold plating as coupon, are done fretting researches. Fretting tests are finished at the condition of fretting amplitude 200 μm, fretting speed 400μm/s, 3 various normal forces and 5 different number of fretting cycles, 3 repeat times for every fretting conditions. Contact resistance is recorded by capture card with speed 14 data/fretting cycle and measured at constant DC current 100mA and limited voltage IV. Morphology and element composition of fretting wear track are observed and analyzed to study the fretting process and mechanism of Ni-Au contact pairs. View full abstract»

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