Advanced requirements on SPDs protecting sensitive equipment

Nowadays SPDs are of essential importance to protect highly sensitive, electronic devices installed closely to electric distribution systems and switchgear installations. The increasing numbers of applications require that not only the different stages of SPDs, installed e.g. at the building entrance and in electric distribution systems, are well coordinated, but that they are also coordinated with the equipment to be protected. In these cases, the protective function of the SPDs has to be coordinated with the individual immunity of the equipment against energetic, conductive impulse voltages and impulse currents. It can be shown that the coordination behavior depends on the technology used as a protective component in the SPD. Current SPD standards [I], [2], electric installation standards [3] [4] and equipment EMC-standards [5] give requirements and test procedures that have to be fulfilled by the SPDs and have to be withstood by the equipment. In order to verify the immunity against partial lightning currents of the complete system laboratory tests on a system level are a suitable approach. The proposed test schemes for complete systems have been successfully performed on various applications. Examples will be presented.