Overhead line conductor damage from bushfires – ‘an assessment methodology'
Garry Brennan - 23 September 2020
In recent time, Brennan Consultants Australia has had a couple of clients interested in bushfire conductor exposure and longer term conductor serviceability.
The normal ABC of bushfire damaged power line restoration is
A) conductor meets a visible inspection - conductors retension;
B) other line restorations works; and
C) power line returned to service.
Often longer term conductor degradation studies are not carried out and asset managers should be mindful that conductors may be exposure to temperature
excursions for a couple of hours prior to a bushfire passing, many minutes of direct flame contact and after the fire passed several hours of radiant
heat exposure.
The exposed conductors experienced thermal excursions will result in some annealing, for ACSR, loss of grease protecting the Al/Zn interface; melting
of the Zn coating of the steel wires; and in extreme cases, Al may have experienced melting.
Other than the melting of the conductors, the annealing damage, loss of grease and loss of Zn is not visibly detectable. Doubts will remain as to the
longer term serviceability of the conductors and appropriate insurance assessments and future risks.
ABOUT THE SPEAKERS
Garry Brennan
Registered, Chartered Professional Engineer, Fellow Engineers Australia, Masters Engineering Degree (Honours) Mechanical, Bachelors Engineering Degree
(Honours) Electrical and Graduate Diploma Management.
An expert, regularly undertakes forensic investigations and root cause analysis into overhead line failures, bush fires, conductor degradation and
serviceability, electrical equipment failures, fires and electric shocks.
Extensive experience in overhead line planning, optimization, design, construction, assessment and life prediction, maintenance strategies and operation
and spans 500 to 11 kV lines and includes lattice steel towers, concrete, steel and wood poles.Experience in high voltage and high current testing.
15 years’ experience, managing NSW South Coast 132 and 33 kV transmission network including major customers Blue Scope Steel and Tallawarra Power Station.
Currently, Transmission Line and Conductor Specialist consultant and previously Endeavour Energy’s Transmission Manager, worked at TransGrid (ECNSW)
and Ausgrid (SCC) with over 45 years electrical supply industry experience commencing as an apprentice.
Recognized industry expert in bare overhead conductors completing a Masters Degree by thesis on “Methodology for the Assessment of the Serviceability of Aged Transmission Line Conductors” and conductor selection, degradation and serviceability life assessment.
Past Convenor of the CIGRE , Overhead Lines Australian Panel and past Australian CIGRE, International Overhead Lines Study Committee. Awarded CIGRE
Technical Committee Award and Australian National Committee Award of Merit.
Long-standing commitment to continuing education, published 12 part conductors series, 4 part uprating of power lines series, been a post graduate
lecturer at the University of Wollongong and since 2008, presented to over 500 participants Australia and New Zealand wide, a 2 day seminar on
“Fundamentals of Overhead Line Design.”
Member of Standards Australia technical committees on Design of Overhead Power Lines,Conductor and Insulator. In 2006, major industry achievement was
to persuade Standards Australia to develop an overhead lines design Standard which was published in 2010.