where I0 is the peak magnitude of the current, i0(t) is the
instantaneous lightning current, α is the wave-front attenuation
quotient of the lightning current, β is the wave-tail attenuation
quotient of the lightning current and k is the current waveform
correction index. The coefficient values of α, β and k were set as
8.66 × 104
, 1.732 × 105 and 4, respectively, while the current was
fixed at 10 kA. The waveform was chosen as it is normally used
in carrying out tests to determine the capability of low-impedance
device such as surge arresters to withstand the currents associated
with lightning discharges [16].