Multiconductor System Research Articles

Coupling of external electromagnetic fields to underground multiconductor cable transmission systems

In this paper, a general model for voltage and currents induced by the primary and secondary field couplings in a multiconductor cable system buried in lossy earth, and illuminated by an external electromagnetic field is presented. Generalized form of equivalent transmission line equations (ETLEs) obtained from this model are presented, which could analyze many of the associated problems, involving the field couplings in underground transmission systems. These equations are then used to derive general solutions for the currents and potentials induced by the external fields along the underground conductors.

Spectral domain analysis of conductor losses in a multiconductor system via the incremental inductance rule

Spectral domain analysis is adapted to analyse the conductor losses of a multiconductor system embedded in a multilayered medium using a quasi-TEM approach and assuming a strong skin effect. After adapting the incremental rule to a multiconductor system, the conductor losses are computed in terms of the derivative of the inductance matrix.

Calculation of the partial capacitance in a system of conductors within the calculable resistor

A method for calculating the partial capacitance (PC) in a multiconductor system (a system of conductors) consisting of n conductors parallel to the shield axis inside earthed cylindrical shields is discussed. Formulas for the PC in SI units are given. The PC is defined as the conductor-to-conductor capacitance and conductor-to-shield capacitance. These methods and formulas are suitable for calculating the PC of Gibbings' resistors with a calculable ac/dc resistance ratio.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

電力線のインピーダンス周波数特性および誘導電圧の解析

Line impedances were measured for frequencies from 1 to 500KHz. The high resistive-impedance distorted the propagation wave, and the distortion generated sine wave oscillation. The sine waves were superposed on transient voltages of the propagation wave on a multi-conductor system. The voltage waves by the proposed method in the paper showed a good agreement with the measured results.

Frequency-dependent impedance of vertical conductors and a multiconductor tower model

The paper proposes a frequency-dependent characteristic impedance of a vertical multiconductor system above an imperfectly conducting earth and a multiconductor multistair model with a number of legs between tower arms to represent an actual tower for a lightning surge analysis. Surge impedances calculated by the proposed formula and model show a satisfactory accuracy compared with a number of experimental and field test results of vertical conductors and actual towers. It is observed that an imperfectly conducting earth causes no significant effect on the characteristic impedance of a tower, and the wave propagation velocity is nearly the light velocity in free space in the entire frequency range.

Digital simulation of electromagnetic wave propagation in a multiconductor transmission system using the superposition principle and Hartley transform

A method of calculation of electromagnetic transients in a multiconductor transmission system using the superposition principle and Hartley transform is developed. The method takes into account all frequency dependent parameters of the transmission system. In the method, the impulse responses of a transmission system are first obtained in the actual phase domain using a Hartley transform method. Then, the impulse responses are included in a transient calculation using the superposition principle. The properties and advantages of the Hartley transform are considered in comparison with more usual approaches using the other transform methods. The new method is applied on different transmission systems (underground power cables and power overhead lines). The results are compared with those calculated by using conventional methods and field tests. The accuracy of the method is found to be good.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Transient analysis of dispersive VLSI interconnects terminated in nonlinear loads

An algorithm for computing the transient response of a coupled, dispersive multiconductor system terminated in nonlinear loads is presented. The characterization of the multiconductor system is based on full-wave analysis using the spectral domain approach, rather than the usual TEM approximation. To compute the transient response of such a system, a bilevel waveform relaxation method is used. Waveform relaxation is applied to compute a time-domain solution at the input and output interfaces. The waveforms are then transformed into the frequency domain to compute the updates induced by the multiconductor system and are transformed back to the time domain for the next set of relaxation at the interfaces. Techniques for convergence are discussed. Examples of ECL, CMOS, and GaAs circuits connected by coupled lines are given for illustration. >

Approximate method for calculating the impedances of multiconductors with cross sections of arbitrary shapes

AbstractThis paper proposes an approximate impedance formula of a conductor with an arbitrary cross section, and also a method of approximating the conductor by an equivalent circular conductor. Thus, a multiconductor system consisting of arbitrary cross section conductors is represented by circular cross section conductors, the impedance of admittance of which are evaluated by the existing impedance and admittance formulas.The calculated results by the proposed method agree satisfactorily with measured results and numerical results by a finite‐element method which is, at present, the only way of calculating such impedance, but requires a large computation time and large memory. The proposed method might be very useful in evaluating the impedance and admittance of a multiconductor system consisting of arbitrary cross section conductors.

Radio-frequency analysis of carrier channels on multiconductor distribution cable networks

The frequency-domain analysis of carrier channels on distribution cable networks is performed by means of an efficient procedure based on the nodal approach and modal theory. The multiconductor system may represent any configuration with multiple discontinuity points. The use of equivalent two-port PI-circuits allows the nodal admittance matrix to be defined in a new form. Very accurate frequency-dependent analytical models are developed to simulate systems of single-core cables or multiple-core pipe-type cables, buried or above a ground plane. >

A circuit model of a system of VLSI interconnects for time response computation

A novel computational model based on the spectral-domain approach for the characterization of a dispersive multiconductor system is developed for time response computation. The model consists of two identical impedance networks and equivalent voltage-controlled voltage sources, and it is particularly suitable for timing analysis. Since the model is constructed based on full-wave analysis, the hybrid nature of the VLSI interconnects is taken care of, and thus the model is valid at high frequencies when the longitudinal field components are no longer negligible. Signal distortions due to the dispersive nature of a multiconductor system are demonstrated by an example. >

Perturbed-TEM analysis of transmission lines with imperfect conductors

A perturbed-transverse electromagnetic (TEM) approach to studying the detailed current distribution and the propagation constant of a multiconductor transmission line system with imperfect conductors is discussed. The perturbed fields are derived assuming that the fields outside the conductors are TEM waves of the corresponding lossless system and those inside the conductors satisfy the transverse magnetic (TM) modal equations. These fields are then inserted into a perturbational formula to obtain the propagation constant of the lossy system. The current distribution and the propagation constant (which clearly illustrates the loss mechanism due to the skin effect and the proximity effect) of a lossy two-wire system are presented as an example.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Lightning overvoltage protection of the Paddock 362-145 kV gas-insulated substation

Backflashovers close to the Paddock 362-145 kV gas-insulated substation (GIS) have been analyzed with the electromagnetic transient program (EMPT) using a frequency-dependent multiconductor system. The severities of the lightning stroke currents were based on recent recordings in the eastern United States. The effects of corona attenuation and distortion were accounted for using a shunt linear model approach. Turn-up effects of both line insulator flashover voltages and surge arrester protective characteristics were based on manufacturer's volt-time curves. Wave-shaping effects of substation capacitances were modeling details in determining the overvoltages inside the GIS due to close backflashovers, which are caused by lightning strokes with varying intensity. These results are aimed at better evaluation of lighting protection requirements for GIS protected by metal-oxide surge arresters.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A quasi-TEM analysis for curved and straight planar multiconductor systems

A quasi-TEM (transverse electromagnetic) analysis for straight and weakly curved planar multiconductor transmission lines is presented. This transverse field of a weakly curved planar multiconductor system is described by the static electric and magnetic solutions of the corresponding axially symmetrical structure. The capacitance and inductance matrices of this system of concentric microstrip rings are calculated using the method of lines. A two-port network consisting of circularly curved transmission lines is calculated and the results are compared with measured values. It is concluded that the proposed method of approximation is suited for analysis of microwave components as well as for high-speed digital circuits with interconnections consisting of curved striplines instead of straight lines with discontinuities.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Variational method for multiconductor coupled striplines with stratified anisotropic media

Numerical examples are presented for the propagation constants as well as the characteristic impedances of various types of multicoupled striplines. Numerical computations are performed very accurately to provide sufficient precision even for tight coupling between strips of the multiconductor system. The basis functions used in the calculation are increased up to ten. Accurate numerical results reveal the mode coupling in the multimode propagation. >

A finite-element method for transient skin effect in 2-D loaded multiconductor systems

Two approaches for analyzing steady-state skin effect phenomena in multiconductor systems are well established. In one method, the scalar potential gradient, the so-called source term of the partial differential equation, is treated as an extra unknown; in the other this term is replaced by the total current of the conductor. It is shown that in handling real-life transient problems the first approach is superior, since, in general, neither the potential gradient nor the total current of conductors are given explicitly, but only active electrical networks that terminate both ends of the multiconductor system. The geometry of that problem is assumed to be two-dimensional, neglecting effects due to the finite length of the conductors. For sake of brevity, material characteristics are treated as linear and isotropic, although nonlinearities are admissible. >

Magneto-thermal coupled finite element calculations in multiconductor systems

In this paper we present, the calculation of temperature transients in devices where the electromagnetic and heat, transfer processes are coupled. We have extended the finite element electromagnetic code (WEMAP) in such a manner that the calculated power loss densities in a multiconductor system are used as the heat, sources for a transient thermal solution in subregions of the original problem geometry. These subregions are enclosed by surfaces on which either temperature, or a convection boundary condition is known. The implementation of this capability will be shown by way of an example.

Analysis and modeling of multilevel parallel and crossing interconnection lines

Analytical and numerical techniques to study the pulse propagation characteristics such as delay, distortion, and crosstalk in multilevel interconnections associated with high-speed digital IC's including VLSI chips are presented. The parallel and crossing interconnections at various levels are modeled as lossy coupled lumped distributed parameter systems, which are analyzed for their time domain characteristics. The characterizing electrical parameters of the structures are computed by utilizing the network analog method that has been formulated to solve for the lossy line constants and parasitic coupling associated with a three-dimensional multiconductor system in a layered lossy medium. It is shown that the time domain response of the multiport structures can be computed by using standard CAD programs such as SPICE by utilizing compatible circuit models developed from the solution of such systems. Examples of the step and pulse response of typical systems are included to demonstrate the versatility, usefulness, and accuracy of the techniques presented in the paper.

Crosstalk noise analysis of wiring on the printed circuit board

AbstractRecently, progress in the high‐density wiring technique on a printed circuit board (PCB) has been remarkable. Thus the problem of malfunctions due to crosstalk noise occurring on the signal line must be addressed. The authors have been developing the noise estimation system for PCB named NESSY and a program to calculate the capacitance of multiconductor system (CALCAP). In NESSY, the wiring pattern is divided into small segments, which comprise the equivalent element circuit. The partial capacitance of the printed pattern is calculated by solving the integral equation and using the image method in CALCAP. The crosstalk analysis of equivalent circuit was made by the circuit simulation program.Among the results of this analysis, crosstalk noise using the partial element equivalent circuit (PEEC) agrees quite well with the measurement. The crosstalk noise should be anticipated by the close coupling theory in the case of frequently used wiring (both the width of signal line and line spacing are less than 1 mm). The crosstalk noise voltage was relatively large in the case of impedance mismatching. The far end crosstalk noise, previously neglected in most cases, becomes especially large.

斜行導体系インピーダンスおよびアドミタンスの導出

斜行導体系インピーダンスおよびアドミタンスの導出

Extension of the Chowdhuri-Gross Model for Lightning Induced Voltage on Overhead Lines

This paper presents a corrected expression of the Chowdhuri-Gross model for the induced voltage on an overhead line, which is derived in an analytical form for a linearly rising ramp stroke current waveform. Based on certain corrections, it is shown that the induced voltage on a conductor of a multiconductor system is the same as that of a single conductor occupying t e same position. A new expression which is of an analytical form for the induced voltage due to a rising ramp wave is also presented. This expression can predict both bipolar and unipolar induced voltage waves. Comparisons of calculated induced voltage waveforms of several models with the published simultaneous lightning current/induced voltage field result of Yokoyama are also presented.