Formulas giving the impedance and admittance matrices of a system consisting of three underground singlecore cables have already been proposed. By applying now clasdcal methods, we deduce the wavepropagation modes in this system.The present paper differs from its predecessors in proposing:-a simplified method for working out propagation parameters (problem reduced to 2 dimensions instead of 6 ) ;-a definition of modes in the form of a "generalized concordia matrix" similar to what is done for overhead lines and having the advantage of greatly simplifying the calculation of the transient response of cables; -a defiition and a method for calculating the impedances that characterize the modes.Furthermore, full-size tests, the results of which are given in the second part of this paper, have made it possible to check the validity of the hypothesis on which this study is based.
-INTRODUCTION -The advantage of modal decomposition for studying the transient response of multi-conductor systems no longer needs to be proved. This method has, in fact, been used successfully for many years in solving problems of wave-propagation on overhead lines. In the case of highvoltage cables, the problem becomes complicated because of the presence of 6 modes of propagation, the system being made up of 7 conductors (one core and one metalsheath for each single-core cable, and the soil). Close calculation, such as has already been presented in papers on the subject, shows in addition a variation with the frequency in the matrix defining the modes. Our main concern has thus been to simplify the problem so as to reach practical methods for calculation of the transient response of cables.On the one hand, it has been possible to reduce calculation of the propagation parameters to a problem with two dimensions, thanks to a particularly well choosen hypothesis.On the other hand, from this we can deduce in a frequency domain sufficiently wide in practice, a modal transformation matrix independent of the frequency and quite simple in aspect (generalized concordia modes). If the use of this matrix is valid only for calculating the pmpagation of rapid transient phenomena (hghtning strokes), the determination of modal parameters (velocity, attenuation, impedance) by solving a system of two equations naturally remains exact at any frequency and, in particular, at the power frequency.To check the hypothesis this study is based on, measurements were made of the response to step injections on a cable section of a link in course of construction on the network. For this type of simals, the high-frequency approximation of the modes proved most satisfactory.Also noted was the almost complete independence of the different phases subjected to coaxial excitation.Within the limits of evaluation of these parameters, the values measured of wave-propagation velocities, of impedances and attenuations proved to be in good agreement with the theory. Conductors Committee of the IEEE Power Enpeerin Society for presentation at F 76 481.2. A paper recommended and approv...
In the present work, damage produced by a crack in a statically loaded beam is first evaluated. Subsequently, an attempt is made to repair the effect of the crack by attaching a piezoelectric patch to the beam as an actuator. Static analysis of PZT patched cracked beam along with rotational spring is performed using Ritz method. Subsequently, a finite element analysis is performed by using ABAQUS 6.12 to collate the analytical results. It is shown in the study that when PZT patch is subjected to external electric field, it yields a local reactive moment, which counters the crack effects. An equation is procured in order to compute the required actuation voltage for repairing of cracks. A parametric study is performed for various boundary conditions and loading patterns. It is distinctly noticed that the technique nullifies the discontinuity in slope curve which develops due to a crack.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.