model we have other, more complex, which considered either some specifications
for protection of certain object kinds or tried to take into calculations
most of familiar lightning strike influences.
We can mention two models:
- model of leader in general (Rizko's model),
- model of leader movement
MODEL OF LEADER IN GENERAL (Rizko's model)
This model is made after detail considering appearance positive leader
under negative leader as their later movement. This model is advisable
for configurations where the voltage of corona appearance smaller than
voltage of positive leader appearance. That is the cause that he finds
use in considering chances above overground lines. The final expressions
for calculation of radius of attraction are:
where Rac is radius of attraction for horizontal lines,
h is height of line above ground, I is lightning current and Rat (I, 40)
is radius of attraction for pylons height 40 meters. In formulas we need
to insert currents in kiloampers and height and radius in meters.
MODEL OF LEADER MOVEMENT
In creation of this model, beginning was at the determining of resultant
electric field in negative leader to simulate the charge in cloud. Result
is model that doesn't have a formula for radius of attraction but he has
maximal horizontal distance (LD) and maximal protective distance on the
ground level (PDg).
Using this model we can see series of relations for LD and PDg and different
structures of dimensions even on the different configurations of field.