Lightning protection of medium voltage lines

n this chapter we attempt presenting a more modern approach to the problem, which makes use not only of simple analytical formulas, but also of advanced models and computer codes. Due to the complexity of the problem, it is indeed almost impossible to achieve sound results without the use of adequate modeling and relevant software. In general, the community dealing with lightning protection is prepared to use EMTP-like computer codes mostly for the calculation of the lightning-response of high voltage transmission lines, while for distribution networks, due to the inherent larger complexity of both topology and configuration, the use of advanced computer codes has not been very popular so far. This is probably due to the fact that, besides the mentioned complexity of the system to be studied, also the phenomena involved are in general more complex for distribution lines than for transmission lines. Think for instance of the electromagnetic coupling between the lightning electromagnetic pulse (LEMP) radiated by a nearby return stroke and the conductors of an overhead distribution network. It is reasonable to imagine that in the future the use of “coupling-transient” codes will progressively enhance its importance with larger benefits for the power quality and reliability of power distribution networks. After all the use of sophisticated computer codes for the calculation of the power flow and of the stability of power network is nowadays representing a common practice nobody can do without.