Analysis of Coordination between Surge Protection Devices in Low Voltage ‎Electric Networks

Low voltage Surge Protection devices (SPDs) are one of the most important electrical equipments to protect the electric networks against transient destructive electrical waves. Using only one SPD, in general, is not enough due to either large distances between SPDs and electric loads or high sensitivity of the electric networks’ apparatuses. In practice, to make conditions better, several SPDs are used simultaneously and in due order. In this case, right technical selection of each of the SPDs and the electrical distance between each pair play an important role to achieve an effective protection system to keep the electrical equipments safe; this is specifically important since having not taken into account the SPDs specifications and the distance between each pair would lead into destructions of electric equipments and even SPDs themselves. In this paper, though modeling and simulation of a complete low voltage network, coordination's between a two-stage protection systems will be analyzed; modeling and studies have been implemented in EMTP-RV software package and results extracted and investigated. The outcomes of this study have pointed out that when SPDs are selected technically rightfully, an increase in the cable between two SPDs would increase the absorbed energy and current discharge in the upstream SPD and decrease the voltage of the SPD near to the load.