Simulations of induced voltage on a nonsymmetrical transmission line inside a building with experimental results

The paper presents a study of the behavior of the electromagnetic field inside a shielded structure (shielded enclosure) and on overhead lines, when it is submitted to a transient electric current. The shielded structure is used in electrical protection systems by annulling the electromagnetic field in its interior. A closed structure, made up of a considerable number of interconnected cables, can be a good approach for a Faraday cage. Based on this approach, simulations of the transient electric current in the structure were made using a numerical technique, TLM (transmission line modelling), (Christopoulos, C., "The Transmission-Line Modeling Method TLM", p.54, IEEE Press, 1995). Connected to this was a current source at one of its borders, with its base plane grounded. Through the transient current obtained, and by applying an expression adequately developed for this end, the electromagnetic field in the time domain was simulated.