1) The number of lightning trip outs caused by
shielding failure is up to 80, accounting for 96.4%. It's
obvious that shielding failure is the main reason which
leads to lightning outage of 500kV transmission lines.
2) Figure 2 shows the geographical distribution and
topographic statistics of the lightning failure in southern
China during the year 2010 to 2012. Among the 83
lightning trip outs, 61 happened in mountain area,
accounting for 73%. It shows that towers in the
mountains are more likely to be struke by lightning
because of the complex terrain.