New results in the analysis of the electromagnetic field near the lightning channel

Abstract

Nowadays one of the most important areas of the lightning researches is in the centre of the interest, the protection of different low voltage systems, against the overvoltages caused by the lightening. The so-called secondary lightning protection system protects against overvoltages caused by the lightening. To plan this system, we have to investigate the electromagnetic field of the lightning strikes and the manner in which it causes damages. The published lightning electromagnetic field models suppose that the so-called static component is negligible, because it decreases proportionally with the third power of the distances. The results presented in this publication prove that this assumption is not acceptable in the case of close lightning strikes. It means that a lightning can cause larger electric fieldstrength in a few hundred meters distance than it was supposed. The electric fieldstrength can reach the amplitude that causes breakdowns, corona discharges, or damages of electronic parts. It can cause dangerous voltages even on a small metallic part, that behaves like an aerial. These facts have to be considered during the planning of the secondary lightning protection systems.