Lightning Protection Improvement and Economic Evaluation of Thailand’s 24 kV Distribution Line Based on Difference in Grounding Distance of Overhead Ground Wire

Table 1

Lightning-current parameters in this study.

First negative stroke
If (kA)	30	40	50
tf, front time (μs)	3.66	4.12	4.52
Tail time (μs)	77.5
Sm (kA/μs)	23.35	26.01	28.29

t_f and S_m are calculated using equations (5) and (6).