Surge protective devices for low voltage systems: practical approach for the protection distance evaluation

The evaluation of the protection distance of an SPD is a main step for assessment of effective reduction of the failure probability of an electrical and electronic system within a structure. The evaluation of this distance is performed taking into account the traveling and induction phenomena in the circuit formed by SPD and apparatus to be protected. By means of computer simulation the conditions for which the phenomena could cause hazardous situation for the internal systems are investigated. As a result, simple relations and diagrams are given in order to help in the estimation of the proper SPD protection distance.