Abstract
M.Ing.
Open-wire telecommunications were developed in the 19th and early 20th centuries
without any consideration of the deleterious effects of power lines; compatibility
problems were later caused by the proximity of power lines and telephone lines. The
coexistence of such systems requires careful planning in terms of energy coupled to the
telephone lines; this induction can cause interference, as well as dangerous
overvoltages in telephone circuits, and requires detailed studies of the effects of
coupling between high voltage lines and telephone systems to be done. In terms of
inductive co-ordination in South Africa, the minimum separation distances between
high voltage power lines and communication systems are calculated only for power
frequency and lower order harmonics (up to the 13th). The aim of the study was to
explore the agreement between theory and measurement for frequencies from 50 Hz to
the high order harmonic range of 4 kHz; this makes it possible to extend existing
methods for predicting compatible separations to cases where high order harmonics
(up to the 73rd) are present (balanced and unbalanced) on a 132 kV power line feeding
a large aluminium smelter plant.