Influence of line routing and terminations on transient overvoltages in LV power installations

IEC 62305-4 gives the rules for the selection and the installation of surge protective devices (SPDs), where the maximum enhancement factor is considered to be equal to 2 in the worst case of open-circuit condition. The objective of the present paper is to check this relation for equipment connected to low-voltage (LV) power system. The LV power system is considered as TN-S system with different routings in three- and six-storey buildings. The terminals of apparatus are substituted by a variety of different loads, namely, resistances, inductances, and capacitances. All Maxwell's equations are solved by the method of moments (MoM) and the voltage is calculated at the apparatus terminals. The SPD itself is simulated by a voltage source at the ground floor. The results reveal that the voltage at the apparatus terminals may overshoot the SPD protection level by a factor of 3 irrespective of the number of floors and loops.