
207Transients on Overhead Lines
In Equations 2.22 and 2.23, the damping factor exp(–αt) is neglected. If this
is included, the oscillating term in Equation 2.23 will die out for t → ∞. Then,
the equation becomes the steady-state voltage during the phase a-to-ground
fault. For example, if k = 0.4, the maximum phase b voltage is given as
t
b ma
148puat1ms
2
≒
0
2.5.3 Lightning Surge
2.5.3.1 Tower-Top Voltage
The transient voltage at a tower top, at which lightning strikes, is easily cal-
culated by applying traveling wave theory. An example has been explained
in Section 1.7 (see Problem 1.19).
)
–E
a
(c)
–E
a
L
s
L
s
L
bb
L
aa
R
bb
Z
0
C
bb
L
s
x
1
P
x
2
b
E
b
FIGURE ...