Engineering and validating electronic switching systems to withstand the effects of lightning strikes

The effects of direct and indirect lightning strikes on the performance of electronic switching systems (ESS) are always a major concern to network operators. Protection against discharge events and their effects are employed in ESS in the form of surge protective devices (SPD) at the AC mains and primary protectors installed into each subscriber line at the main distributing frame. In many cases the topology and integrity of the grounding system permit discharges introduced into the ESS to be safely carried to earth. While SPDs and grounding systems provide a level of assurance that there will be minimal detrimental effects to switch performance in the presence of lightning, nevertheless, undetected potential problems can still occur. This paper presents the benefits and limitations of SPDs and industry accepted grounding systems topologies. It also presents and describes testing methods that uncover potential problems and to be made that preclude degradation of switch performance.