The models of lightning strike are analytical
tools for making studies about protection from lightning strike in pylons
and air transmission lines. The main use of these models is for making studies
about protection of electric-power lines or easily affected installations
(gas installations for example) from direct strike. They are also in use
for determining the places for setting and dimensioning lightning rod for
protection of high buildings.
Why do we use these models?
The reason is simple: Physical characteristics of lightning strike are
very complicated and still partly unexplored and are difficult to describe
mathematically. Even when we could take in consider all characteristics
we would get the model, which would be very complicated for practical
use. That is the reason for making some simplifications and that is how
different models were created.
How do we use these models?
Usually these models define a mathematical term for "last permeable
distance" or "pull radius" and these terms are used similarly.
Using geometrical construction we are
trying to determine such place and dimensions of lightning rod to achieve
an adequate protection. The adequate protection is achieved when the descending
leader can not reach the place with distance from the object smaller than
the pull radius and distance from the lightning rod greater than the pull
radius in the same time.