Level, Class, and Prospected Safety Performance of a Lightning Protection System for a Complex of Structures (LPCS)
The Standard IEC 62305 provides advanced information for the design of lightning protection of structures (LPS). In determining the position of the air-termination system, two methods are generally suggested: the protective angle method and the rolling sphere method. Adopting a 3-D graphical simulation, the “rolling sphere” method allows one: to analyze the protected volume at the building roof inside of the rolling ply surface; to verify the behavior of the designed air-termination system; to evaluate the contribution of the surrounding structures in limiting the lightning current flowing in the down-conductors. This current affects the probability of dangerous sparking and the separation distance for the protection of internal installations. This paper presents this approach by a case study of a building in a complex of structures: it highlights particularly the worst cases of the lightning impact related to the designed air-termination system.
Controllability Intelligence of Lightning Protection System due to 110kV Transmission line
A lightning protection system (LPS) of an urban 110 kV substation is designed and analysed according to NFPA 780 and IEC 62305–3 standards. The analysis of the LPS is based on the value of risk assessment. The total area of the plant is described by one soil layer with uniform resistivity. This study aims to improve the understanding of unexpected attitude of the grounding grid system under lightning strike currents by explaining the basic notion of the lightning protection level. The program is integrated with the CDEGS software, which provides effective geometrical modeling with object and result visualization. Furthermore, module and automated fast Fourier fransform is implemented in this study to simulate electromagnetic fields in the period and frequency scope. These current values are compared to the desired protection levels within the standards. The study results show that for the improved protection of the system against lightning, the total power grid must be considered as a source of improvement for studying shielding influence and the protection levels provided inside this substation.
Lightning hazard of structures and protection system efficiency
A probabilistic method for assessing the lightning hazard of structures and a simplification of this method for practical purposes is proposed and discussed. The risk of structural damage is evaluated as a function of the efficiency of the lightning protection system, the probability of damage due to a single flash, and the frequency with which lightning flashes strike the structure. Simplifications of this method are introduced; the damage probabilities are replaced by a weighting coefficient corresponding to different properties of the structure but without respect to economical factors, which should be considered on the background of local particularities. These considerations are illustrated by practical examples.<<ETX>>