Simplified Approach for Protection of Apparatus Powered by an HV/LV Transformer Against Lightning Strokes to the Structure

The paper deals with the probability of damage of apparatus connected to an overhead HV power line through an HV/LV transformer due to direct lightning to a structure protected by a Lightning Protection System (LPS) where such apparatus are installed. An approach is proposed to evaluate such probability and guidance is given for dimensioning a surge protective device (SPD) system able to protect internal apparatus against lightning surges with a given probability and then to improve the LV power systems availability.