Stress to surge protective devices system due to direct flashes to low voltage lines

In the present paper practical recommendations for selection of a surge protective devices (SPD) system with aim to protect electronic and electrical apparatus within a structure against overvoltages coming from the low-voltage power lines are highlighted. The investigation is performed with two standardized lightning currents, namely 200 kA wave shape 10/350 μs for first positive stroke and 50 kA wave shape 0.25/100 μs for subsequent stroke of negative flashes. The analyses are performed by computer simulations at the referring typical basic arrangement consisting of ten poles overhead line terminated on one side by HV/LV transformer and on other side by apparatus to be protected. The results are obtained by means of commercial transient software EMTP-RV. This work is executed in the frame of discussion on recommendation of IEC/EN 62305 [1] for the selection of coordinated SPD system.