The effects of lightning induced overvoltages on low voltage power networks

The issue of lightning induced overvoltages in distribution networks has been treated in numerous works. Approaching of various models and accepting simplified assumptions allowed the calculation of their parameters and comparison with experimental data. Thus, about the amplitude and shape of induced overvoltages a relative consensus exists although research is still far to be completed. The paper discusses only how the overvoltages induced by lightning in distribution networks can affect the end user, connected to a low voltage network, after having traveled along an overhead line and passed through step-down transformers. It studies a real network configuration case and analyses the opportunity of arresters disposal both on the low voltage transformer terminals and to the end user connection point and also the necessity of own user ground. The conclusion is that these combined measures ensure the protection of the user, regardless of the distance at which it is situated relating to the point where induced overvoltages were injected.