Lightning Protection; Lightning Theorie - Siemens GPS1000 2XV9450-1AR82 User Manual

User Manual SICLOCK GPS1000

3. Lightning Protection

When exterior antennae are used in industrial areas, a reliable lightning protection is of the utmost importance for operating
the system safely.
The installation of a lightning protection unit alone is not sufficient. The antenna and antenna cable must be installed in such
a way that a direct stroke of lightning or flashover in these parts is not possible. Otherwise it would not be possible to prevent
the destruction of parts of the unit.

3.1. Lightning Theorie

Recordings made with high speed cameras have shown that lightning does not cover the distance between the storm cloud
and the point of striking at a continuous and constant speed but travels intermittently at intervals on average of 20 to 40 meter
in length. Between these lightning advancing distances there are holding points of a few microseconds, during which time
further energy is built up (see Fig. 6).
The possible locations of the subsequent holding points lie within a sphere (here called ball of lightning) around the previous
holding point with 20 to 40 meter radius. Upon reaching the last holding point before striking, parts of the earth's surface lie
within the ball of lightning and accordingly also elevated parts lying on earth potential which stand out (e. g. parts of build-
ings). Lightning then strikes exactly at the point with the shortest distance from the last holding point.
Fig 6: The course of a lightning stroke
10 Version 1.0 Order number 2XV9450-1AR82-BA