1,721,014 research outputs found
EMP-coupling to twisted-wire cables
No full textAn EMP (electromagnetic pulse) coupling to twisted-wire pair (TWP) cables above a ground reference plane is considered. The high-altitude EMP is represented by a plane wave. TWP cable is simulated in the frequency domain as a multiconductor uniform line excited by non-uniform electromagnetic fields. EMP-induced effects are computed by using an efficient matrix procedure based on the transmission line model (TLM). The transient waveforms for any terminal load conditions are obtained by an inverse discrete Fourier transformation. The theoretical procedure is applied for evaluating the EMP-induced effects on a TWP cable for different electric and geometric configurations. The results obtained by the procedure are compared with those computed for a parallel wire-line. The transient wire-to-ground voltages are very similar for TWP and parallel wire configurations. The wire-to-wire voltages and wire currents depend on the polarization and the incidence angles of the EMP plane-wave
FD-TD analysis of nonuniform multiconductor lossy lines
No full textTransients in lossy multiconductor lines are analyzed by the Transmission Line Model (TLM) assuming a quasi-TEM propagation. Voltage and current waves propagation is described by integrodifferential equations with variable coefficients, where a convolution integral between the transient impedance and the time derivative of the current is used to model the skin effect in the conductors.The resulting equations system is solved by the Finite Difference-Time Domain (FD-TD) method. A new algorithm for the recursive calculation of the convolution integrals is proposed. Distributed nonuniformities, due to line parameters variation, and lumped nonuniformities, due to loads, junctions and discontinuities are considered
3-D analysis of shielding effectiveness of planar sheets against the power lines magnetic field
No full textBEST SYMPOSIUM PAPER AWARD
ANALYSIS OF FAST TRANSIENT ELECTROMAGNETIC-FIELDS - A FREQUENCY-DEPENDENT 2-D PROCEDURE
No full textAn automatic procedure for the analysis of two-dimensional fast transient electromagnetic fields is presented. The fields are analyzed in the frequency domain by means of a node-based finite element procedure and the transients are derived by the application of Fourier transforms. The FEM mesh is generated through an algorithm which selects the element size as a function of the wavelength. The conductive regions are automatically removed from the FEM region when the value of the penetration depth is very small, and impedance boundary conditions (IBC) or perfect electric conductor (PEC) approximations are imposed. Open boundary conditions are applied at a distance varying with the frequency where the mesh is truncated. The FEM implementation of the proposed procedure is discussed
TRANSIENT SCATTERING PROBLEMS SOLUTION BY SURFACE EQUIVALENT SOURCES
No full textA numerical study is developed to evaluate the response of a system excited by a transient incident field. A new formulation is introduced in order to apply surface impedance boundary conditions (SIBC) while adopting the scattering formulation. The elimination of conductive regions requires the imposition of appropriate interface conditions, which are represented by equivalent current sources depending on the incident field. In the time domain the equivalent sources are described by a convolution integral in which appears the transient surface impedance derived analytically by the inverse Laplace transform. The resulting equations system is solved by applying the finite element method (FEM) in space and the Crank-Nicolson scheme in time
FEM COMPUTATION OF INDUCED EFFECTS IN MULTICONDUCTOR LINES
No full textA numerical procedure based on a two-dimensional finite element formulation is presented to evaluate the induced effects on a multiconductor line excited by an external electromagnetic field. The field incident to the cable is simulated by a plane wave and the line is considered in free space. The coupling problem is described by the homogeneous Helmholtz equation which is solved in the frequency domain. Appropriate open boundary condition techniques are implemented. An accurate investigation is performed to analyze the validity of the Impedance Boundary Conditions (IBC) applied to the conductor surfaces. Some applications are presented to illustrate the validity of the proposed procedure
TIME-DOMAIN FINITE-ELEMENT SIMULATION OF CONDUCTIVE REGIONS
No full textTransient magnetic fields are analyzed in the time domain by utilizing the finite element method (FEM) in space and the finite difference (FD) method in time. Conductive regions are eliminated from the domain under examination by imposing impedance boundary conditions on the surfaces separating conductive and non-conductive regions. In the time domain the impedance boundary conditions are represented by a convolution integral in which appears the transient surface admittance whose expression can be obtained analytically by the inverse Laplace transform. A 2-D numerical procedure is presented for solution of the integral equation deriving from application of surface impedance boundary conditions (SIBC)
TIME-DOMAIN SOLUTION OF FIELD-EXCITED MULTICONDUCTOR TRANSMISSION-LINE EQUATIONS
No full textAnalytical solution of lossless field-excited multiconductor transmission lines is presented, The equivalent circuit of a multiconductor transmission line with distributed sources is reduced to a simple lumped parameter circuit with independent voltage sources at both the ends of the transmission line, The transient source waveforms are analytically estimated for exponential time dependence of the external field, as EMP, ESD, and lightning, The method is suitable for a direct implementation in computer-aided circuit analysis codes and enables a very fast analysis for any load condition, Some numerical results are presented for single conductor and multiconductor lines excited by an EMP plane-wave field
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