Sistemas para dedição de correntes de descargas atmosféricas: desenvolvimentos e resultados preliminares

• Ano de defesa: 2010
• Autor(a) principal: André Matias Nunes Teixeira
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Engenharia Elétrica; Engenharia elétrica
• Link de acesso: http://hdl.handle.net/1843/BUOS-8F9HSC

The return current is the main source of the lightning effects and of electromagnetic disturbance caused by such event. In the past, this was the main reason to justify the investigation of this current and related parameters. Recently, the possibility to infer information about the formation of the final stage of lightning discharges from the current measured at the channel bottom close to the ground has been explored.Most of the available information about lightning current is derived frommeasurements performed in temperate regions of Europe and North America. It has been verified that the parameters of such currents present important differences in relation to those obtained from currents measured in tropical areas, including in Brazil. This work is part of a research intended to contribute to the characterization of lightning, mainly in Brazil. The focus of this work is different from the traditional approaches that are dedicated to the evaluation of the impulsive phase of lightning current, the return current, considered the main source of lightning damages. This dissertation developed a more fundamental and general approach related to the investigation of the whole lightning current, comprising those components, such as the continuing current and the phase preceding the return current, that are poorly known. In order to perform such investigation, two measuring systems were developed, the first one being installed at the Morro do Cachimbo Station (MCS). The other one was installed in a two-span experimental transmission line placed at the top of a hill nearby MCS. Several flashes were measured since the installation of these systems and relevant, high-quality and original results were obtained. According to the literature, the phase preceding the return current of natural lightning, consisting in a set of well defined current pulses developed in response to the leader approaching the ground, was measured for the first time. This phase was measured in the base of the MCS tower. The behavior of this phase of lightning current is discussed in details in this work.