Lightning conductors, their history, nature, and mode of application /

"List of books referred to, or consulted, relating to ... lightning conductors" : p. xi-xv. Appendix, "Bibliography of works bearing upon lightning conductors" : p. [231]-248.

Shipwreck by lightning. Papers relative to Harris lightning conductors.

Mainly a reprint from papers by Sir W. Snow Harris.

Traite des paratonnerres : leur utilite, leur théorie, leur construction /

Mode of access: Internet.

Unterricht vom Blitz und den Blitz- oder Wetter Ableitern : zur Belehrung und Beruhigung sonderlich der Ungelehrten und des gemeinen Mannes : mit einer Kupfertafel /

Signatures: pi1 2pi⁴ A⁸(-A1) B-I⁸ K⁴(-K4).

Instruction sur les paratonnerres /

"Signé, Poisson, Lefèvre-Gineau, Girard, Dulong, Fresnel, et Gay-Lussac, rapporteur"--p. 51.

Numerical Electromagnetic Analysis of Current and Voltage Distribution along Down Conductors and Towers Hit by Direct Lightning

In order to answer the practically important question of whether the down conductors of lightning protection systems to tall towers and buildings can be electrically isolated from the structure itself, this work is conducted. As a first step in this regard, it is presumed that the down conductor placed on metallic tower will be a pessimistic representation of the actual problem. This opinion was based on the fact that the proximity of heavy metallic structure will have a large damping effect. The post-stroke current distributions along the down conductors and towers, which can be quite different from that in the lightning channel, govern the post-stroke near field and the resulting gradient in the soil. Also, for a reliable estimation of the actual stroke current from the measured down conductor currents, it is essential to know the current distribution characteristics along the down conductors. In view of these, the present work attempts to deduce the post-stroke current and voltage distribution along typical down conductors and towers. A solution of the governing field equations on an electromagnetic model of the system is sought for the investigation. Simulation results providing the spatio-temporal distribution of the post-stroke current and voltage has provided very interesting results. It is concluded that it is almost impossible to achieve electrical isolation between the structure and the down conductor. Furthermore, there will be significant induction into the steel matrix of the supporting structure.

On the Influence of Neighboring Conducting Objects on the Induced Currents in Simple Down Conductors Due to Nearby Lightning Strike

A lightning strike in the neighborhood can induce significant currents in tall down conductors. Though the magnitude of induced current in this case is much smaller than that encountered during a direct strike, the probability of occurrence and the frequency content is higher. In view of this, appropriate knowledge on the characteristics of such induced currents is relevant for the scrutiny of the recorded currents and in the evaluation of interference to the electrical and electronic system in the vicinity. Previously, a study was carried out on characteristics of induced currents assuming ideal conditions, that there were no influencing objects in the vicinity of the down conductor and channel. However, some influencing conducting bodies will always be present, such as trees, electricity and communication towers, buildings, and other elevated objects that can affect the induced currents in a down conductor. The present work is carried out to understand the influence of nearby conducting objects on the characteristics of induced currents due to a strike to ground in the vicinity of a tall down conductor. For the study, an electromagnetic model is employed to model the down conductor, channel, and neighboring conducting objects, and Numerical Electromagnetic Code-2 is used for numerical field computations. Neighboring objects of different heights, of different shapes, and at different locations are considered. It is found that the neighboring objects have significant influence on the magnitude and nature of induced currents in a down conductor when the height of the nearby conducting object is comparable to that of the down conductor.

Role of upward leaders in modifying the induced currents in solitary down-conductors during a nearby lightning strike to ground

Electromagnetic field produced by a lightning strike to ground causes significant induction to tall objects in the vicinity. The frequency of occurrence of such nearby ground strikes can be higher than the number of direct strikes. Therefore, a complete knowledge on these induced currents is of practical relevance. However, limited efforts towards the characterisation of such induced currents in tall down-conductors could be seen in the literature. Due to the intensification of the background field caused by the descending stepped leader, tall towers/down-conductors can launch upward leaders of significant length. The nonlinearity in the conductance of upward leader and the surrounding corona sheath can alter the characteristics of the induced currents. Preliminary aspects of this phenomenon have been studied by the author previously and the present work aims to perform a detailed investigation on the role of upward leaders in modifying the characteristics of the induced currents. A consistent model for the upward leader, which covers all the essential electrical aspects of the phenomena, is employed. A first order arc model for representing the conductance of upward leader and a field dependant quadratic conductivity model for the corona sheath is employed. The initial gradient in the upward leader and the field produced by the return stroke forms the excitation. The dynamic electromagnetic response is determined by solving the wave equation using thin-wire time-domain formulation. Simulations are carried out initially to ascertain the role of individual parameters, including the length of the upward leader. Based on the simulation results, it is shown that the upward leader enhances the induced current, and when significant in length, can alter the waveshape of induced current from bipolar oscillatory to unipolar. The duration of the induced current is governed by the length of upward leader, which in turn is dependant on the return stroke current and the effective length of the down-conductor. If the current during the upward leader developmental phase is considered along with that after the stroke termination to ground, it would present a bipolar current pulse. (C) 2015 Elsevier Ltd. All rights reserved.

Basic features of current induced/shared by cables mounted on down conductors/towers during stroke interception

The telecommunication, broadcasting and other instrumented towers carry power and/or signal cables from their ground end to their upper regions. During a direct hit to the tower, significant induction can occur to these mounted cables. In order to provide adequate protection to the equipments connected to them, protection schemes have been evolved in the literature. Development of more effective protection schemes requires a quantitative knowledge on various parameters. However, such quantitative knowledge is difficult to find at present. Amongst several of these aspects, the present work aims to investigate on the two important aspects: (i) what would be the nature of the induced currents and (ii) what will be the current sharing if as per the practice, the sheath of the cable is connected to the down conductor/tower. These aspects will be useful in design of protection schemes and also in analyzing the field structure around instrumented towers.

Modelling Proximity Effects in Transverse Magnetic Mode for Lightning Studies

Lightning strike to instrumented and communication towers can be a source of electromagnetic disturbance to the system connected. Long cables running on these towers can get significant induction to their sheath/core, which would then couple to the connected equipments. For a quantitative analysis of the situation, suitable theoretical analysis is necessary. Due to the dominance of the transverse magnetic mode during the fast rising portion of the stroke current, which is the period of significant induction, a full wave solution based on Maxwell's equations is necessary. Owing to the large geometric aspect ratio of tower lattice elements and for feasibility of a numerical solution, the thin-wire formulation for the electric field integral equation is generally adopted. However, the classical thin-wire formulation is not set for handling non-cylindrical conductors like tower lattice elements and the proximity of other conductors. The present work investigates further into a recently proposed method for handling such a situation and optimizes the numerical solution approach.

Transient behavior of a system composed of conductive thin wire structures excited by harmonic and lightning type signals

The transient response of a system of independent electrodes buried in a semi-infinite conducting medium is studied. Using a simple and versatile numerical scheme written by the authors and based on the Electric Field Integral Equation (EFIE), the effect caused by harmonic signals ranging on frequency from Hz to hundred of MHz, and also by lightning type driving signal striking at a remote point far from the conductors, is extensively studied. The value of the scalar potential appearing on the electrodes as a function of the frequency of the applied signal is one of the variables investigated. Other features such as the input impedance at the injection point of the signal and the Ground Potential Rise (GPR) over the electrode system are also discussed