On the shielding effectiveness of MV/LV substation walls in the presence of IEMI sources

The assessment of the electromagnetic shielding performance of shielded components or apparatus placed inside a shielded enclosure may represent a complex task especially when the external enclosure exhibits several apertures and a potentially resonant behavior. In this work, the transient intentional electromagnetic interference incident onto a medium voltage/low voltage substation is investigated in order to evaluate the susceptibility of shielded devices installed inside the reinforced concrete enclosure. The field inside the substation is strongly non-uniform because of the asymmetrical position of the apertures, mainly for access and ventilation purposes. The considered victim is a commercial mini computer unit installed for the remote control of the substation and to store relevant data.