1,721,089 research outputs found
A brief history of Maxwell's equations
No full textMaxwell's equations explain all phenomena of classical electrodynamics, magnetism, and optics the way Newton's equaMaxwelltions of motion describe classical mechanics. Maxwell introduced the theoretical description of electromagnetic waves and fostered a deeper understanding of the behavior of light
Insulation resistance and failures of a high-power grid-connected photovoltaic installation. A case study
No full textIn this article, the authors discuss the crucial aspects of the insulation resistance testing of photovoltaic (PV) installations. This test verifies the integrity of the wiring systems and can be used to detect or prevent damages to wiring as well as ground faults. The insulation resistance test measures the resistance between the ungrounded circuits and the ground under the application of high voltage. The baseline insulation resistance can be compared to measurements over time to assess the degradation of PV arrays or conductors. This test is accepted worldwide as a crucial element of commissioning and acceptance, and it is governed by several technical standards
Joint meeting of the 17th edition of the IEEE international conference on environment and electrical engineering (EEEIC) and the 1st edition of the IEEE industrial and commercial power systems Europe (I&CPS Europe)
No full textThe 17th edition of the IEEE International Conference on Environment and Electrical Engineering (EEEIC) and the 1st edition of IEEE Industrial and Commercial Power Systems Europe (I&CPS Europe) held a joint meeting in Milan, Italy from 6 to 9 June 2017
A brief history of electromagnetism
No full textHans Christian?ersted (Figure 1) was a professor of physics at the University of Copenhagen (1777-1851). When he learned of the invention of the electric battery in 1799 from Alessandro Volta, he began to experiment with electric currents
Computation, properties, and realizability of the characteristic immittance matrices of nonuniform multiconductor transmission lines
No full textPower lines are longitudinally nonuniform, nonsymmetrical systems, where ordinary modal analysis, originally conceived for uniform multiconductor transmission lines (MTL), can be utilized only as a zeroth-order approximation. In this paper, we present an accurate analysis of nonuniform MTLs based on the frequency-domain transmission-matrix formalism for 2n-port systems, where two unequal characteristic immittance matrices need to be defined, one for forward propagation and another for backward propagation. This paper, focused on the characteristic (or surge) immittance matrices, shows how they can be computed, describes their general properties, and reveals, for the first time, that in some cases they may not be physically realizable, meaning that a matched termination made of purely passive lumped components may not exist. The matrix theory developed in the paper is illustrated with simulation results concerning three-phase power line configurations where resonance phenomena take place at certain critical frequencies
On the measuring methods of the soil electrical resistivity
No full textThe design of grounding systems must guarantee the electrical safety of installations and be based on the actual conditions of the site. The electrical resistivity of the soil is the most significant parameter upon which the design should be based and should allow a multi-layer modelling. In this paper, the authors illustrate the major techniques and configurations for soil electrical resistivity measurement, and discuss advantages and drawbacks of each. The convention to be adopted to correctly identify the depth of investigation for vertical electrical soundings associated with the electrode arrangement, independently of the measurement technique, is also discussed. The data inversion, a mathematical procedure by which the measured values of apparent resistivity are processed to determine the true values of soil resistivity, is presented. This paper is meant to be a reference for practitioner engineers, who must perform soil electrical resistivity surveying to produce reliable results for a proper grounding electrode design
A rigorous matrix procedure for calculating the line constants and wave parameters of uniform MTLs using SMT/PMU
Full text linkReal-time monitoring of the operation state of wide-area transmission line links has become possible with the help of phasor meter units. Synchronized information acquired by phasor meter units needs to be adequately processed to permit the accurate estimation of the line constants of the transmission link. In this paper, a novel general rigorous compact procedure for correctly processing the measured voltage and current phasors of uniform multiconductor transmission line systems is proposed. The procedure based on the ABCD matrix and on modal analysis techniques applies to transposed or untransposed multiconductor transmission lines, with arbitrary geometry, number of conductors, and length. The proposed algorithm, adequate for multiport structures, avoids the approximations usually required by ordinary methods mostly focused on lumped parameters and on 2-port approaches. The proposed matrix procedure is illustrated and validated using simulation results
Finite-difference time-domain study on the influence of the conductor catenary in the simulation of lightning surges
No full textWhen accounting for the catenary shape, overhead power lines are non-uniform structures. Usually, the impact caused by the catenary on the transmission properties of the line is neglected. Hence, the line is simulated as uniform considering a constant equivalent height. In this paper, we investigate the impact of the catenary on induced overvoltages caused by direct and indirect lightning strokes. Employing a recently proposed implicit finite-difference time-domain code, we assess that the catenary may have a severe impact on the correct computation of the overvoltages. Finally, we outline the accuracy limits of the EMTP-RV software in conjunction with the LIOV module through an in-depth comparison
A survey on analytical solutions and tools for lightning-induced voltages calculations
No full textIn this paper, that is an extended version of a work [1] presented at the 2019 International Symposium on Lightning Protection (XV SIPDA), a survey of analytical solutions available in the literature for the evaluation of the lightning-induced voltages in case of both step and linearly rising channel-base currents is presented. Two tools, CiLIV and LIV, based on some of the above mentioned analytical solutions are also presented. Finally, a validation of both analytical solutions and tools is presented
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