On the Performance of Grounding, Bonding, and Shielding Systems for Direct and Indirect Lightning Strikes

A full-wave solution method of Maxwell's equations is adopted for the analysis of the performance of grounding, bonding, and shielding systems of a metallic enclosure subjected to direct and indirect lightning strikes. The method is based on a numerical solution of the electric field integral equation by the method of moments. An array of conducting wires and metallic surfaces is used to represent the lightning channel and structures in its proximity. An improved antenna theory model approach based on the concept of the distributed source is adopted for the electromagnetic analysis of indirect lightning. The methodology enables an efficient electromagnetic compatibility analysis of a combined network of metallic plates, wires, and cables exposed to direct and indirect lightning strikes. The effectiveness of most common protective schemes-namely grounding, shielding, and bonding-is examined for cables located inside a metallic enclosure with apertures. A safety assessment analysis is performed for the case of indirect lightning and is compared to the case where the lightning current is injected directly into the top of the enclosure.