ing waveforms when lightning strikes point P2 are depicted in
Figs. 3(b), 4(b), and 5(b). Consider Fig. 3(a) and (b). In this
figure, curve 1 is the voltage calculated when the ground is
perfectly conducting; curve 2 is the voltage calculated over
finitely conducting ground, and curve 3 is the voltage calculated
by using wavetilt approximation. First, note the influence
of the ground conductivity on the calculated induced voltages.
The finite conductivity of the ground changes the polarity,
the shape, and the amplitude of the induced overvoltages.
Note also that as far as the peak of the induced voltage
is concerned, the wavetilt approximation does not introduce
significant errors. However, the wavetilt approximation may
lead to significant errors in the tail part of the induced
overvoltages. This point is important in cases where it is
necessary to quantify the amount of energy dissipation in
protective devices.