AusNet Services PACR: Maintaining safety and supply reliability, transmission lines multiple circuits

Market Network Service Provider
StageProject Assessment Conclusions Report
ConvenorAEMO NSP
Accepting submissions?No

AusNet owns and operates the electricity transmission network in Victoria, which transports electricity from large coal, gas and renewable generators across Victoria and interstate, to terminal stations that supply large customers and the distribution networks.

Electricity is transported by overhead bare conductors that are insulated by the surrounding air, with the insulator strings preventing the conduction of electrical current to the steel structure that supports the transmission wire. Most insulator strings comprise several linked discs made from either porcelain or glass with steel pins to form a continuous string. Over time the condition of these assets deteriorates due to the environmental conditions that cause corrosion and mechanical loading.

The Regulatory Investment Test for transmission (RIT-T) is an economic cost-benefit test used to assess and rank potential investments capable of meeting an ‘identified need’. The purpose of the RIT-T is to identify the credible option that maximises the present value of net economic benefit to all those who produce, consume and transport electricity in the National Electricity Market (the preferred option).
This Project Assessment Conclusions Report (PACR) is the final stage of the RIT-T process, which follows the publication of:

  • the Project Specification Consultation Report (PSCR), which explained the need for the insulator replacement program and our provisional assessment of the preferred option; and
  • the Project Assessment Draft Report (PADR), which set out the cost benefit analysis and identified the preferred option.

We did not receive any submissions in response to the PADR.

The analysis presented in the PACR explains that the preferred option is to replace to 773 insulator strings from 107 transmission tower-circuits in the transmission network, including the installation of approximately 3,000 vibration dampers on the phase conductors.

This option addresses the identified need and provides an efficient, targeted replacement. At this stage, we propose to commence the works in December 2023 for completion in December 2024. The analysis presented in this PACR complies with the AER’s RIT-T guidelines.

Any questions about this report should be directed to: or contact Francis Lirios on (03) 9695 6000.

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