Managing the Risk of Line Conductor Failure

On 1 November 2022, ElectraNet published a Project Specification Consultation Report (PSCR) which identified the need to replace line conductors on seven transmission lines as the most efficient solution to manage the risk of failure of these assets based on their assessed condition.

Line conductors are essential to the task of transmitting electricity. Without them, no power can be transmitted between generators and customers. The line conductors in question for this PSCR are in poor condition and pose a risk to public safety and continuity of customer supply.

The ‘identified need’ is to efficiently manage the risk of asset failure.

The identified need for this project is to continue to provide electricity transmission services in South Australia at a prudent and efficient cost. Specifically, the identified need for this Regulatory Investment Test for Transmission (RIT-T) is to efficiently manage the risk of failure of line conductors across seven 132 kV transmission lines that are in poor condition and have reached the end of their useful lives. It also allows us to continue to meet the reliability standards of the Electricity Transmission Code at the relevant connection points on the network.

We classified this RIT-T as a ‘market benefits’ driven RIT-T as the economic assessment is not being progressed specifically to meet a mandatory reliability standard, but rather to deliver positive net benefits to customers.

A full cost benefit assessment has been undertaken, comparing the risk cost reduction benefits of line conductor replacement with the cost of a base case ‘do nothing’ option, together with options considered but not being progressed.

Line conductor replacement is the only credible option.

The analysis has identified that there is only one economically feasible option, which is to replace the end-of-life line conductors on the identified transmission lines. The estimated capital cost of this option is approximately $25.6 million.

There is no feasible role for network support solutions in addressing the identified need for this RIT-T.

Network support solutions cannot credibly meet the identified need for this RIT-T. This is due to the unique and specific role that the line conductors play in transmitting electricity. Nevertheless, for completeness and consistent with the requirements of the RIT-T this PSCR sets out the required technical characteristics a network support option would have to meet.

On 1 June 2023, ElectraNet published the Project Assessment Conclusions Report (PACR) which can be downloaded from the RIT-T tab on this project page.

The PACR maintains the initial conclusion that replacing the identified line conductor on the seven 132 kV transmission lines within the 2024-2028 regulatory period is the preferred option.

The preferred option that has been identified is Option 1, which is to replace the line conductors on the seven 132 kV transmission lines between 2023 and 2026. The estimated capital cost of this replacement is $25.6m.

We have undertaken a thorough sensitivity testing exercise to investigate the robustness of the RIT-T assessment to underlying assumptions about each of the key variables. For all sensitivity tests undertaken, the preferred option remains replacing the line conductors by the end of 2026.

The preferred option is defined as the option that maximises net benefits under the RIT-T framework.

ElectraNet intends to commence work on replacing the line conductors on the seven 132 kV transmission lines in 2023 and to have all conductors replaced by the end of 2026. Further details in relation to this project can be obtained from consultation@electranet.com.au