Lifetime Estimation of Transmission Line Based on Health Index and Normal Distribution Technique

Lifetime of HV transmission line by using practical health index (HI) and normal distribution approach is proposed in this paper. The HI of transmission lines is evaluated by using actual technical data, practical testing results and visual inspection. The weighting-scoring method and analytical hierarchy process are applied to this assessment. The %HIs are used to determine %HI-curve by applying normal distribution technique while the aging-curve is determined by using Gompertz–Makeham law of mortality. These curves are matched to estimate age or lifetime according to %HI at a particular probability of failure. Forty HV transmission lines in 115 kV, 230 kV, and 500 kV networks in Thailand with actual data are performed in the assessment resulting in a proper maintenance planning and risk mitigation.