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Voltage Drop (voltage + drop)
Selected AbstractsRelationship between Contact Voltage Drop and Frictional Coefficient under High-current Sliding ContactIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 4 2010Takahiro Ueno Member Abstract Large DC motors are used in various industrial applications. These motors repeatedly generate arcs between the brush and commutator, because the load change is intense and the current value is also large. In particular, for the case in which the current is concentrated on a part of the brush, brush burnout may occur as a result of overcurrent. Therefore, excellent brushes to withstand arc generation and with good electrical properties are required. In the present paper, we discuss the relation between contact voltage drop and frictional wear for electrical sliding contacts when high currents flow to the brush. Specifically, we investigate the means by which to prevent brush burnout when high-current flows to the brush. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Computation of locational and hourly maximum output of a distributed generator connected to a distribution feederELECTRICAL ENGINEERING IN JAPAN, Issue 2 2009Yasuhiro Hayashi Abstract Recently, the total number of distributed generation such as photovoltaic generation systems and wind turbine generation systems connected to a distribution network has drastically increased. Distributed generation using renewable energy can reduce the distribution loss and emission of CO2. However, the distribution network with the distributed generators must be operated while maintaining the reliability of the power supply and power quality. In this paper, the authors propose a computational method to determine the maximum output of a distributed generator under operational constraints [(1) voltage limit, (2) line current capacity, and (3) no reverse flow to bank] at arbitrary connection points and hourly periods. In the proposed method, a three-phase iterative load flow calculation is applied to evaluate the above operational constraints. The three-phase iterative load flow calculation has two simple procedures: (Procedure 1) addition of load currents from the terminal node of the feeder to root one, and (Procedure 2) subtraction of voltage drop from the root node of the feeder to terminal one. In order to check the validity of the proposed method, numerical simulations are performed for a distribution system model. Furthermore, the characteristics of locational and hourly maximum output of a distributed generator connected to a distribution feeder are analyzed using several numerical examples. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(2): 38,47, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20610 [source] Preparation of Nanogapped Gold Nanoparticle Array for DNA DetectionELECTROANALYSIS, Issue 4 2008Shiho Tokonami Abstract A novel DNA detection technique using a gold nanoparticle array film electrode has been reported here. The gold nanoparticles molecularly linked with binder molecule (1,10-decanedithiol) were separated 1.3,nm from each other, and the DNA conductivity change from single to double strand was measured by monitoring a voltage drop across the particles, between which a probe of a 12-mer oligonucleotide was immobilized. In adding a complementary oligonucleotide on the nanoparticle film chip, an immediate decrease in the film resistance (ca. 1.4 ,) due to a hybridization event occurred in a reproducible manner with this simple setup. In the paper, we have an interest in the primary sensing properties; effect of the film resistance on the sensor response, dependence of the resistance change on the DNA concentration, and the performance of the system for DNA detection including single nucleotide polymorphisms were described. [source] About the role of the park imaginary power on the three-phase line voltage dropEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 5 2000A. Ferrero In this paper the line voltage drop concept is investigated and extended to non-sinusoidal conditions. The results are applied to the three-phase configuration. In this approach the presence of harmonic and sequence components is taken into account. The formal invariance of the obtained results with respect to the original single-phase relationships is ensured by means of the three-phase rms concept. The Park transformation is used as well, so that the three-phase relationships are reduced to a simpler formal single-phase approach: the simultaneous contributions of harmonic and sequence components are unified in a single formulation. Therefore the Park imaginary power role results as a natural extension of the usual single-phase reactive power concept. [source] Experimental Analysis on Performance and Durability of SOFC Demonstration UnitFUEL CELLS, Issue 3 2010M. Halinen Abstract A technical description and experimental analysis of a SOFC demonstration unit is presented. The unit contains most of the primary BoP-components of a complete SOFC system, except of air and fuel recirculation equipment or fuel system compressor. Natural gas is used as the fuel and electricity is supplied to the electric grid. A 5,kW power class planar SOFC stack from Research Centre Jülich is assembled to the demo unit and a long-term experiment is conducted to assess the characteristic performance and durability of different components of the unit (e.g. the SOFC stack, the fuel pre-reformer and air heat exchangers). The evolution of absolute voltage drop of the stack over time is found to be of the same magnitude when compared to short stack experiments. Thus, other system components are not observed to cause an increase in the characteristic voltage drop of the stack. Two BoP-components, the afterburner and the power conversion unit failed to operate as designed. The performance of other BoP-components i.e. fuel pre-reformer and heat exchangers were satisfactory during the test run, and no significant performance loss could be measured. [source] Relationship between Contact Voltage Drop and Frictional Coefficient under High-current Sliding ContactIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 4 2010Takahiro Ueno Member Abstract Large DC motors are used in various industrial applications. These motors repeatedly generate arcs between the brush and commutator, because the load change is intense and the current value is also large. In particular, for the case in which the current is concentrated on a part of the brush, brush burnout may occur as a result of overcurrent. Therefore, excellent brushes to withstand arc generation and with good electrical properties are required. In the present paper, we discuss the relation between contact voltage drop and frictional wear for electrical sliding contacts when high currents flow to the brush. Specifically, we investigate the means by which to prevent brush burnout when high-current flows to the brush. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Integrated method of determining transmission and distribution loss-minimum network configurationsIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 3 2006Yasuhiro Hayashi Senior Member Abstract In Japan, the secondary transmission system (66 kV, 77 kV) and distribution system (6.6 kV) with loop structures are operated using the radial configuration. The transmission and distribution network configurations must be determined so as to keep the radial configuration and satisfy the operational constraints such as line capacity, voltage drop, and so on. However, the configuration candidates are too many, and it is not easy to determine transmission and distribution loss-minimum network configurations comprehensively. In this paper, the authors propose an integrated method of determining the transmission and distribution loss-minimum network configurations under the operational constraints within practical computation time. In order to check the validity of the proposed method of determination, numerical simulations using the proposed method are carried out for a real-scale Japanese transmission and distribution network model with 22098 configuration candidates. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Kinetics of Electrophoretic Deposition for Nanocrystalline Zinc Oxide CoatingsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2004Yuan-Chung Wang An integrated process combining the preparation of ZnO nanoparticles and the formation of ZnO coatings using electrophoretic deposition (EPD) is reported. The work focuses on the deposition kinetics of nanocrystalline ZnO coatings on copper electrodes during EPD by direct measurement of the thickness of the deposited layer. The experimental results show that the EPD process is a powerful route to fabricate uniform coatings with desired thickness and excellent surface smoothness, which might be attributed to small particle size and narrow size distribution. On the other hand, the deposition kinetics changes with applied voltage and deposition time. The deposition thickness increases with increasing applied voltage and deposition time. In a short deposition time, the deviation of deposition rate between the theoretical and experimental values is caused by voltage drops during deposition, and the discrepancy increases with the applied voltage. Moreover, the increasing voltage drop and depletion of the suspension lead to decreasing current and lower deposition rate after longer deposition time. The critical transition time of deposition kinetics is found to exponentially decrease with increasing applied voltage. [source] Influence of adsorbates on the piezoresponse of KNbO3PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2006F. Peter Abstract We report on the reduction of piezoresponse in KNbO3 originating from a surface layer. An analysis with surface sensitive measurements shows that this layer consists of chemisorbates and physisorbates. Heating the sample under ultra high vacuum conditions removes the surface layer on the perovskite to a large extend. This treatment has a drastic effect on the piezoresponse as the potential difference applied to the sample is no longer reduced by a voltage drop across the adsorbate layer, leading to a higher electric field compared to the case with an adsorbate layer. Experiments and simulations are presented confirming this postulation on KNbO3. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Influence from front contact sheet resistance on extracted diode parameters in CIGS solar cellsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 2 2008Ulf Malm Abstract The extraction of one-diode model parameters from a current,voltage (J,V) curve is problematic, since the model is one-dimensional while real devices are indeed three-dimensional. The parameters obtained by fitting the model curve to experimental data depend on how the current is collected, and more specifically the geometry of the contact. This is due to the non-uniform lateral current flow in the window layers, which leads to different parts of the device experiencing different front contact voltage drop, and hence different operating points on the ideal J,V curve. In this work, finite element simulations of three-dimensional contact structures are performed and compared to experimental data on Cu(In,Ga)Se2 -based solar cell devices. It is concluded that the lateral current flow can influence the extracted parameters from the one-diode model significantly if the resistivity of the front contact material is high, or if there is no current collecting grid structure. These types of situations may appear in damp heat-treated cells and module type cells, respectively. Copyright © 2007 John Wiley & Sons, Ltd. [source] Mathematical Modelling and Simulation of Polymer Electrolyte Membrane Fuel Cells.FUEL CELLS, Issue 2 2002Part I: Model Structures, Solving an Isothermal One-Cell Model Abstract Amongst the various types of fuel cells, the polymer electrolyte membrane fuel cell (PEM-FC) can be used favourably in vehicles and for in house energy supply. The focus of the development of these cells is not only to provide cost-effective membranes and electrodes, but also to optimise the process engineering for single cells and to design multi-cell systems (cell stacks). This is a field in which we have successfully applied the methods of mathematical modelling and simulation. Initially, in this work, a partial model of a single membrane-electrode unit was developed in which the normal reaction technology fields (concentration, temperature, and flow-speed distributions) were calculated, but also the electrical potential and current density distribution in order to develop model structures for technically interesting PEM-FC. This allows the simulation of the effects that the geometric parameters (electrode and membrane data and the dimensions of the material feed and outlet channels) and the educt and coolant intake data have on the electrical and thermal output data of the cell. When complete, cell stacks consisting of a number of single cells, most of which have bipolar switching, are modelled the distribution of the gas flows over the single cells and the specific conditions of heat dissipation must also be taken into consideration. In addition to the distributions mentioned above, this simulation also produces characteristic current-voltage and power-voltage curves for each application that can be compared with the individual process variations and cell types, thus making it possible to evaluate them both technically and economically. The results of the simulation of characteristic process conditions of a PEM-FC operated on a semi-technical scale are presented, which have been determined by means of a three-dimensional model. The distributions of the electrical current density and all component voltage drops that are important for optimising the conditions of the process are determined and also the water concentration in the membrane as an important factor that influences the cell's momentary output and the PEM-FC's long-term stability. [source] Kinetics of Electrophoretic Deposition for Nanocrystalline Zinc Oxide CoatingsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2004Yuan-Chung Wang An integrated process combining the preparation of ZnO nanoparticles and the formation of ZnO coatings using electrophoretic deposition (EPD) is reported. The work focuses on the deposition kinetics of nanocrystalline ZnO coatings on copper electrodes during EPD by direct measurement of the thickness of the deposited layer. The experimental results show that the EPD process is a powerful route to fabricate uniform coatings with desired thickness and excellent surface smoothness, which might be attributed to small particle size and narrow size distribution. On the other hand, the deposition kinetics changes with applied voltage and deposition time. The deposition thickness increases with increasing applied voltage and deposition time. In a short deposition time, the deviation of deposition rate between the theoretical and experimental values is caused by voltage drops during deposition, and the discrepancy increases with the applied voltage. Moreover, the increasing voltage drop and depletion of the suspension lead to decreasing current and lower deposition rate after longer deposition time. The critical transition time of deposition kinetics is found to exponentially decrease with increasing applied voltage. [source] Luminescence imaging for the detection of shunts on silicon solar cellsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 4 2008M. Kasemann Abstract Luminescence imaging is a non-destructive, fast, and versatile imaging method for spatially resolved solar cell and material characterization. In this paper, we investigate its ability to detect shunts on silicon solar cells. We give a detailed description of the relation between local junction voltage and local luminescence signal. This relation is important because shunts drain majority currents causing voltage drops across the surrounding series resistances and that way affect luminescence images. To investigate effects related to majority currents, we describe and apply a simulation model that allows the simulation of lateral voltage distributions on solar cells. This model, and a comparison to illuminated lock-in thermography, helps to discuss some practical aspects about shunt detection by luminescence imaging. We will discuss a procedure to distinguish between ohmic and diode-like shunts and finally present simulations and measurements showing that luminescence imaging is only weakly sensitive to shunts under the metallization. However, we also show its high sensitivity for remote shunts and propose a possible application where this high sensitivity could be especially helpful. Copyright © 2008 John Wiley & Sons, Ltd. [source] | |||||||||||||