OVERHEAD DISTRIBUTION LINES - SOME REFLECTIONS ON DESIGN

Recent events, when many networks suffered damage in Europe, have highlighted the need for a critical review of design practices. It is argued that, provided some statistical data on meteorological phenomena are available, attempts could be made to design overhead lines to suit subsequent performance requirements. The ultimate load design concept is favoured, in which an anticipated load with a quantified probability of occurrence is compared with the strength of a component having a selected probability of being achieved. It is suggested that, by the use of suitable coefficients, a preconceived coordination of strengths of the components can be obtained. Due to electrical constraints, there is a limit on conductor sizes, beyond which there is no measurable improvement in electrical performance. There is obviously an economic impact which must be appreciated. For a rapid assessment of a suitable voltage and conductor size the technique of kVA-km is a handy design tool.