A head for heights was a must for Transgrid workers who carried out a vertigo-inducing high-wire job for transmission line repairs on a clifftop near Kangaroo Valley.
The network has been carrying out upgrades to extend the life of a 330kV transmission line which runs through farmland and rugged National Park between Kangaroo Valley and Dapto.
Related article: Transgrid drones take flight to inspect transmission lines
Transgrid executive general manager of delivery Craig Stallan said, “Our network spans more than 13,000km and takes in all kinds of terrain. This is one example of some of the incredibly challenging locations our people work in every day to help keep the system running safely.
“The refurbishment of this line will extend its life by another 35 years which is a great outcome. The team had to overcome many challenges, going above and beyond for the community,” he said.
The transmission line was built in 1963 and spans more than 43km. The refurbishment included strengthening towers and footings and replacing aged insulators and fittings along the line.
One of the most challenging sites was at Tongarra where crews had to work on a clifftop where a 915m span descends into a valley below at 45 degrees. The work included replacing dozens of line spacers, which separate conductors and prevents them from clashing. To do this, a lineworker had to sit in a specially designed trolley suspended from the transmission line, working up to 150 metres above the ground.
Project engineer Katherine Cai said, “When we replace conductor spacers, we de-energise the line, use a winch to lift a trolley up the tower and hook the trolley onto the line. A lucky linesperson then gets to sit in the trolley and ride the trolley down the transmission line.”
The challenging project was completed safely thanks to substantial planning to manage the risks.
Related article: Massive synchronous condensers arrive for EnergyConnect
“The conductor trolley travelled at a controlled speed using a winch to lower it. We had a rescue plan in place with backup trolleys and we also kept a close eye on wind speed and weather conditions.
“Once the lineworker in the trolley arrived at each conductor spacer, they replaced them by hand and once they were done, they were off to the next one, so it was a little bit of a rollercoaster ride,” she said.