Author: He, Anni
Title: Simulative study of indoor electromagnetic environment of isolated house struck by lightning with FDTD method
Advisors: Chen, Mingli (BSE)
Degree: M.Eng.
Year: 2021
Subject: Lightning protection
Hong Kong Polytechnic University -- Dissertations
Department: Department of Building Services Engineering
Pages: xii, 78 pages : color illustrations
Language: English
Abstract: With the pursuit of quality of life, the number of small independent houses in the construction market is gradually increasing, and there are more electrical leads and equipment inside the buildings. At the same time, it is known that household weak current equipment is sensitive to lightning electromagnetic radiation. In the past, people usually paid more attention to the lightning protection safety of structural buildings, and the focus was mainly on preventing buildings from being struck by lightning or avoiding casualties. For this kind of problem, it is necessary to use lightning protection system (LPS) to divert the lightning away and prevent it from directly hitting the house. However, due to the popularization and application of modern equipment, weak current equipment is very sensitive to the electromagnetic radiation of strong electricity such as lightning, that is, secondary radiation. In such cases, it is not only need to lead the lightning, but also to greatly reduce the secondary radiation caused by lightning within a certain range. For this purpose, in this study, the optimal wiring scheme of the building LPS was investigated based on computer simulations and suggestions of the household function area division were put forward in reference to the simulation results.
Specifically, for a given specially designed small building, the finite difference time domain method (FDTD) was used for the simulations. After the building structure was established by Auto CAD, it was imported into the software to simulate and analyze in three cases. The first case was to set up an independent single down conductor (DC) for a building LPS, and the second was to bind a single DC of a LPS to the steel reinforcement inside the building. The third was to set two DCs for a LPS symmetrically distributed on both sides of the house when case 2 could not be used in the building. According to the simulation results, it was found that in the DC mode of case 2, the electromagnetic field intensity at different testing points in the building was the smallest among the three cases, which means that it had the best lightning protection effect. Therefore, it was suggested that the LPS should be bound to the building reinforcement structure where applicable for the stand-along small houses in lightning prone areas. At the same time, it was also recommended not to place household equipment in areas close to the load-bearing walls of buildings or close to DCs, and to set these areas as utility rooms and other places where residents do not often move.
Rights: All rights reserved
Access: restricted access

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