Parasitic currents

The electric field produced by the current-carrying conductors of each phase also links the metallic bus enclosure, its mounting supports, and structures existing in the vicinity, parallel and around the axis of the current-carrying conductors. It causes induced (parasitic) currents in such structures and leads to the following ... 

As discussed later, the enclosure of an IPB may carry induced currents up to 95% of the current through the main conductors. Accordingly, the enclosure is designed to carry longitudinal parasitic currents up to 90-95% of the rated current of the main busbars. The cross-sectional area of the enclosure is therefore maintained almost equal to and even more than the main conductors to account for the dissipation of heat of the main conductors through the enclosure only, unless an additional forced cooling system is also adopted. The outdoors part of the enclosure exposed to atmospheric conditions is also subjected to solar radiation. Provision must be made to dissipate this additional heat, from the enclosure. 

When applied on a macro scale — samples of 1 - 5 millimoles — generation rates of 100-500 milliamps are required parasitic currents may be induced in the indicator electrodes at currents in excess of about 10-20 mA consequently precise location of the equivalence point by amperometric methods is not trustworthy. 

The MCFC has also been tested as a true concentrator, with electric power supplied instead of H2 [32], With inlet C02 at 0.25% (in air), the outlet could be brought as low as 75 ppm, albeit with the rather low current efficiency of 40% (based on 1 mol CO2/2 F). The parasitic current is due to transport of oxyanions (Of " or 02) which are discharged as molecular oxygen at the anode. For lower C02 utilization, say below 80%, the polarization is quite acceptable, as seen in Fig. 23. Application to manned spacecraft, however, is handicapped by the high temperatures needed (> 500 °C). 

The problems connected with the TeClt (C) and C1(C) cells are low capacity and parasitic currents, and of the S, Se and CI2 cells corrosion of the seals and insulators. All these cells were (in 1973) in the early stages of development. The cells have ED of about 200 Wh/kg (70). 

Ersfeld, K. (2003) Genomes and genome projects of protozoan parasites. Current Issues in Molecular Biology 5, 61-74. 

James, S.L. and Nacy, C. (1993) Effector functions of activated macrophages against parasites. Current Opinion in Immunology 5, 518-523. 

Using impedance spectroscopy we measured transistors with solution processed pentacene as the semiconductor. Fabrication details are discussed in Section 13.3.1. We have made use of a ring-type transistor, in which the source electrode forms a closed ring around the transistor channel and the drain electrode, at which the current is monitored. Using this geometry, the measurements are insensitive to parasitic currents that may flow outside the transistor area [29]. 

Since the electrical resistance of the effiuent and parasitic currents are minimal at high level of impurities, specihc interest in electrically assisted membrane processes could increase due to more strict laws and legislation around effluents. The depletion of freshwater resources and the necessity to process brackish or seawater to produce potable water could promote the use of electrically assisted membrane processes in the future. Electrodialysis will have to compete with pressure-driven membrane processes such as reverse osmosis. The growing awareness of the unique cleaning ability of electrically ionized water (EIW) [47], a byproduct of electrodialysis, may be a factor to consider in the choice between ED and RO systems. NMR relaxation measurements were used to determine the water cluster size of electrically ionized water EIW. It is known that the water cluster size of EIW is signihcantly smaller than that of tap water. The smaller water cluster size is believed to enhance the penetration and extractive properties of EIW. Recently, EIW has been produced and used in several cleaning processes [47] in industry. 

Resistance among endoparasites and ectoparasites, such as those that cause malaria and schistosomiasis in humans, or for animal nematodes, is a well-recognized problem. In veterinary medicine, integrated parasite control and rotation of different parasiticides has been used to slow development of resistance. For many parasites, current agents are very effective. Due to host specificity, there has been little problem with zoonotic human disease caused by resistant animal parasites. 

The regulation noise induces, through the electrochemical cell impedance, a parasitic current fluctuation /reg(0 that can be calculated from... 

Another source of inefficiency are the shunt currents arising in all series-connected systems with a common electrolyte. In the EDA system, these parasitic currents are minimized to some (model computed) 5% power loss by maximizing the hydraulic resistance. 

The problem of ohmic drops by diaphragms has been studied for a long time. A laboratory scale diaphragm-less water electrolyzer was developed for hydrogen production at large pressures of up to 140 kPa by electrolysis in an alkaline solution. Porous electrodes with a nickel catalyst and a copper cover layer serve as cathodes, whereas nickel sheets are used as anodes. Modular construction of the electrolyzer permits simple combination of its cells into larger units. Thus, up to 20 cells with diskshaped electrodes of 7 cm in diameter were connected in series and provided with electrolyte manifolds, automatic pressure, and electrolyte level control devices. The dimensions of the electrolyte manifolds were optimized based on the calculations of parasitic currents [50],... 

Vehicle on-board electronics consume small maintenance currents that will reduce SoC over time. This parasitic current is normally on the order of 20-30mA at 12V. Should the battery deeply discharge (say, during an extended airport park), there is a chance that the battery will not be of high enough SoC to crank the engine. 

A comparison of the i>E response for the three fuels investigated is illustrated in Fig 1.45. Since both trimethoxymethane and dimethoxymethane behave in a similar manner to concentrated solutions of methanol, the comparison of fuels was made using less concentrated solution of the formates compared with the standard 1.0 M methanol solution, in addition, since the permeation of energetic fuels such as trimethoxymethane and dimethoxymethane to the cathode result in greater parasitic current densities compared to methanol, the lower concentrations were found desirable due to the lower crossover rates. As shown in Fig. 1.45, dimethoxymethane performed almost identically at low current densities (>150 mA/cm 90 0) with methanol. At higher current densities, the methanol shows the best... 

However, when the crossover rates are compared for the various fuels in terms of the parasitic current density experienced at the cathode, the values observed for TMM are more than double than that of methanol when comparing equimolar solutions under open circuit conditions. The observed crossover current densities at the cathode for different concentrations of TMM is illustrated... 

The steady state crossover rates for trimethoxymethane and methanol have been determined by measuring the carbon dioxide content in the cathode stream. The crossover rates for both fuels were found to decrease with increasing current density, and also increase with temperature. When the crossover rates of TMM are compared with those of methanol in terms of the amount of moles per second, TMM was observed to have lower crossover at low current densities. This observation can be explained as being due to the physically larger size of a TMM molecule compared with methanol. However, when the crossover rate is expressed as a parasitic current density, the value... 

Steam turbine used for the generation of electricity Turbine overspeeding [load disconnection suddenly] /[trip throttle valve stuck] /control valve fault//[extrac-tion valve fault]. Bearings damaged" [turbine overspeeding] /[lube oil] /exces-sive vibration/no lube oil/bearing temperature too hot/insuffident oil because of dogged lines/flow of parasitic currents. 

Jamet D, Torres D, Brackbill JU (2002) On the theory and computation of surface tension the elimination of parasitic currents through energy conservation in the second-gradient method. J Comput Phys 182 262-276... 

The basic idea behind the VOF method is to discretize the equations for conservation of volume in either conservative flux or equivalent form resulting in near-perfect volume conservation except for small overshoot and undershoot. The main disadvantage of the VOF method, however, is that it suffers from the numerical errors typical of Eulerian schemes such as the level set method. The imposition of a volume preservation constraint does not eliminate these errors, but instead changes their symptoms replacing mass loss with inaccurate mass motion leading to small pieces of fluid non-physically being ejected as flotsam or jetsam, artificial surface tension forces that cause parasitic currents, and an inability to calculate accurately geometric information such as normal vector and curvature. Due to this deficiency, most VOF methods are not well suited for surface tension-driven flows unless some improvements are made [19]. 

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