PACR Managing increased fault levels in southern NSW

Transgrid has recently published a Project Assessment Conclusions Report (PACR) for managing increased fault levels in southern New South Wales. The PACR is the final step in the Regulatory Investment Test for Transmission (RIT-T) process and follows the Project Assessment Draft Report (PADR) published in December 2024.

The expected commissioning of three actionable ISP projects in southern NSW in coming years (Project EnergyConnect, HumeLink and VNI West), as well as full commercial operation of Snowy 2.0 in December 2028, is expected to result in fault levels that exceed the existing fault level ratings of existing transmission assets at four Transgrid substations in southern NSW if action is not taken. Without action, (i.e., under the base case), this would cause equipment failure and likely significant unserved energy to end consumers in the NEM.

The four affected substations are:
• Lower Tumut 330 kV substation;
• Upper Tumut 330 kV substation;
• Murray 330 kV substation; and
• Wagga 330 kV substation.

Transgrid has therefore commenced this RIT-T to assess the options available for managing the expected increased fault levels to avoid these consequences and continue to maintain compliance with the relevant standards.
We published a PADR on 19 December 2024 and invited written submissions on the material presented within the document. No submissions were received in response to the PADR and no additional credible options were identified.

Consistent with the PADR, this PACR finds that Option 1 is the preferred option to manage the expected increased fault levels at the four affected substations and to continue to maintain compliance with the relevant equipment standards. Option 1 involves upgrading certain existing substation switchgear and earth grid at the four affected substations to meet the increased fault levels in the network.

The estimated capital cost of this option is approximately $52.1 million +/- 25 per cent. Transgrid is the proponent of the proposed network project.
In accordance with the requirements of the National Electricity Rules, a summary of the PACR is made available on the AEMO website. A copy of the PACR can be obtained from Transgrid’s website or by emailing regulatory.consultation@transgrid.com.au