Mechanism of Orientation and Parameters of Lightning in Context of Lightning Protection
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MA DIAGNOSTICS
Mechanism of Orientation and Parameters of Lightning in Context of Lightning Protection E. M. Bazelyan* Krzhizhanovskii Power Engineering Institute, Moscow, 117927 Russia *e-mail: [email protected] Received August 21, 2018; revised September 20, 2018; accepted September 20, 2018
Abstract—Details of the process of lightning formation and orientation of the downward leader required to solve applied problems in the field of lightning protection are considered. It is shown that it is necessary to take into account the mechanism of the bipolar leader formation in the thundercloud electric field, according to which the thunderstorm cell cannot be regarded as a conducting charged electrode, the potential carried by the downward leader channel is determined by the start point and path of the lightning, and the effect of the thunderstorm cell charge reveals itself to a much less degree. An algorithm is proposed for calculating the orientation height, charge per unit channel length, and attraction radius of lightning from the value of the return stroke current. It is stated that lightning current measurements currently used at tall structures cannot serve as a basis to estimate the frequency of dangerous lightning strikes to structures of ordinary height. A scheme of the field research of lightning is proposed that allows the required statistics of lightning currents to be accumulated for a foreseeable time period at admissible material costs. The need to study the mechanism of the competing development of counter discharges from ground-based electrodes is proven, and the relevant technique is offered. DOI: 10.1134/S1063780X19020041
1. INTRODUCTION In gas-discharge physics, there are not so much problems that have not been solved reliably for almost one century of research. Estimation of the reliability of protection against lightning strokes is one of them. The beginning was optimistic. When lightning was found to be nothing else as a very long spark, it seemed natural to organize model laboratory experiments by decreasing the scale of lightning rods and protected objects in accordance with dimensions of the used laboratory discharge gap. Something similar has been done up to date [1, 2], although the fundamental violation of similarity laws in several-meter-long spark discharges has long been established [3]. Results of experiments turned out to depend on the gap length, the polarity of the voltage pulse, and its time parameters. In the best case, it could be hoped to determine qualitative regularities of the lightning orientation process, but in no way to quantitatively estimate the reliability of lightning rod operation, which is needed in practice. Experience in using different lightning protection systems also has delivered not so much. A few reliable data were obtained only for air high-voltage power transmission lines; however, regretfully, the range of their heights is rather limited and organization of systematic observations of lumped structures of different height has failed for the present. Thu
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