Proceedings,
Sag Calculation of Aged Overhead Lines
(August 2005)
Abstract
Due to the changing operation of the
transmission network in Europe caused by the
liberalisation of the energy market condition based
diagnostics get more importance. Based on the large
expansion of the network and the changed stress of the
line components a considerable effort for condition
evaluation is necessary. The Austrian transmission line
system at the level 230kV and 400kV has an important
role for the energy exchange in the centre of Europe and
was built up in 50's to the70's of the last century,
therefore parts of the system are older than 40 years.
Based on this situation this paper focuses on the
operation behaviour of ageing overhead lines with
special regard to the sag calculation of span sections. In
general, the conductor elongates by the permanent
mechanical forces (everyday stress) during its live time.
Additionally to this irreversible elongation, the sag of a
transmission line will increase by the conductor
temperature caused by the electrical load and specific
environmental conditions or other rope forces (e.g. ice
load).
