Discussion on Statistical approach to thermal rating of overhead lines for power transmission and distribution

In the past, current ratings of a transmission line have been calculated by assuming a minimum wind speed, a maximum solar radiation and the maximum ambient temperature all occurring together. For many years, I have believed that the current ratings obtained by making these assumptions are conservative, because, in practice, the probability of these three meteorological factors occurring at the same time is extremely low. It is interesting to note that the authors have confirmed my views and, by their efforts, have revised the thinking behind current rating technique calculation to produce a more realistic approach to the problem. It is also encouraging to note that the CEGB have now adopted the new approach, and, in my view, this technique can be recommended to other developed countries where reliable meteorological data is easily obtained, or where there are resources available to collect any additional data needed to apply the method.