Volume 3 nr 1 / 2011 - Academia Oamenilor de Stiinta din Romania

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122 Alexandru Ionuț Chiuță, Liviu Mihai Sima, Nicoleta Doriana Secăreanug) Because of the rapid changes in the current when the subway train starts, itcauses the magnetic field variation and voltage dips, the electric fieldharmonics at dispatcher were recorded and power electric laboratory, as well.It was found a similarity between the form of variation sizes and recordedones;h) During the start-up process, the voltage, current, active power, distorting powerand apparent power were recorded simultaneously to see the influence ofswitching phenomena;i) All such records have imposed the need for a data bank on industrial equipmentapplications - giving real-time behaviour. It appears the need to improve therunway insulation - which was carried out carelessly - and, as well,determination by an effective method of behaviour of electric powerinstallations in a new section put into service:- features of voltage - current in the subway train;- voltage harmonics;- variable potential along the tunnel;- graph recording of disturbances submitted to telecommunication cables.1.5. Behavior of switching equipmenta) Following the short-circuit test near and far in the IMGB substation, it wasfound that the high- speed circuit breakers behave normally and switching overvoltages do not occur. Not exceed 18 kA < 30 kA – present value of guaranteedshort-circuit;b) After the short-circuit test near and far (stations Piata Sudului, AparatoriiPatriei) it was found that the high-speed breakers behave normally, but shortcircuitcurrents of 29 kA appear, as well as switching over voltage of1260 V > 850 V;c) From the test of disconnecting and connecting the rectifier on DC and AC sidewhen there is no train or train to start - it is found that the switching equipmentbehaves normally;d) Recording DC voltage shows the presence of harmonic of 300 Hz produced bythe hex phase rectifier.Copyright © Editura Academiei Oamenilor de Știință din România, 2011Watermark Protected
Disturbances in The Power Supply Network of Bucharest Subway System 1231.6. Behaviour of Closed Circuit TV (CCTV) equipmenta) Electromagnetic disturbances of frequencies between 50 Hz-50 MHz penetrateall equipment of the subway system;b) The strongest penetration is observed through the CCTV cable (double shieldedcable) - because along the tunnel there are variable potentials and the cables donot meet the terms of the level of insulation - since it takes over as the variationof variable potentials along the tunnel;c) In the CCTV cable, insulation breakthrough occurs, changes in insulationresistance and electrical resistance, as well;d) Inductive coupling of screen with wire inside creates low impedance for thereturn current through the screen (the disruptive route);e) Connecting the screen to earth (tunnel - with variable potentials) forces thedisruptive current returns from the central wire through the screen.1.7. Preliminary ConclusionsUsing Fluke devices, in the work we have established new measurementmethodologies, we checked them and realized measurement result analysis. Theyled to the following conclusions:- Have established the precise conditions of operation of upgraded tractionrectifier RSTM - 0825M;- Have set the effect of electric traction substations of the electrical company’spower system. To define solutions for admission to the technical norms, therewere determined the short-circuit currents and characteristics of the electricalcompany’s 110 kV / MV power network;- Have defined technical solutions to framing into technical regulations foroperation under deforming system and load shock throughout the SubwayLine II;- Have established the causes and nature of disturbances that occur in the closedcircuit television system at the central dispatch of the Unirii 1 station. Todiminishing that, the runway insulation needs to be improved, subway frameoptimized and properly maintained as well.Copyright © Editura Academiei Oamenilor de Știință din România, 2011Watermark Protected
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3FOREWORDBased on a rich scientific
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Annals of the Academy of Romanian S
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The remanufacturing of an articulat
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Influence of Vibrations and Dynamic
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Products recovery opportunities at
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Products recovery opportunities at
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Recycling and Remanufacturing -Two
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Recycling and Remanufacturing -Two
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The Study of Heavy Metal from Envir
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mg/kg d.wThe Study of Heavy Metal f
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ConclusionsThe Study of Heavy Metal
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Analytical Evaluation of Crack Prop
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Y d Notations:Analytical Evaluation
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General Considerations Regardingthe
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Intelligent Networks, Smart Grids C
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Volume 3 nr 1 / 2011 - Academia Oamenilor de Stiinta din Romania

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