Impact of Bird Streamers on Quality of Supply on Transmission Lines: A Case Study

J. Smallie and C. van Rooyen (South Africa)


Bird streamer, eagle, bird guard, quality of supply,


Eskom, the South African national electricity provider, experienced unusually high levels of bird related faulting on the Hydra-Droërivier 1 & 2 400kV transmission lines from 2000 to 2003. The Endangered Wildlife Trust (EWT) carried out a risk assessment to identify sections of the line that should be fitted with anti-perching devices (bird guards) to reduce faulting levels, and recommend any other relevant management measures. Bird streamers, predominantly caused by large eagles, were identified as the dominant cause of bird related faulting. There was a slight peak in faults on the eastern phase. Most faults occurred on towers of the “VVV” design. Streamer faults were spatially associated with eagle nests. Whilst these faults may have been attributed to nests/nest material previously, EWT concludes they are as a result of the bird activity associated with breeding. However, even though the likelihood of a nest being the source of a fault is relatively small, the consequences, should a fault occur, can be significant. Most streamer-induced faulting occurred on towers situated on ridges. EWT recommended fitting bird guards to all 3 phases of all towers within 10 towers of eagle nests and all towers on ridge areas.

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