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Telephone interference caused by harmonics and unbalance in power lines

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.
Date12 September 2012
CreatorsPaul, Mariam
Source SetsSouth African National ETD Portal
Detected LanguageEnglish

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