497Grounding
The above solution involves δ(t) similarly to Equation 7.26 in the case of
Figure 7.26b. That is, v(0) at the measured position becomes very large due to
L′I
0
{δ(0) + β}, although v′(0) at the sending end of the electrode is Z
0
i(0). Again,
this is merely mathematical, because there exists no ideal current source. In
practice, a current source is represented by a voltage source and a large resis-
tance. Also, a lightning channel involves an impedance. Thus, the internal
impedance of a current source representing a lightning current can never be
innite. Thus, the term L′I
0
δ(0) never appears in reality, but v′(0) is roughly
given by βL′ I
0
. This is also true in Figure 7.26b.
In summary, Figure 7.26b gives the same solution as that i ...