Transgrid PACR: Maintaining compliance with performance standards applicable to Lower Tumut substation secondary systems

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

Transgrid has published the Project Assessment Conclusions Report (PACR) for Maintaining compliance with performance standards applicable to secondary systems at Lower Tumut substation. The PACR is the final step in the Regulatory Investment Test for Transmission (RIT-T) process and follows the Project Specification Consultation Report (PSCR) published in February 2024.

The secondary systems assets are subject to technological obsolescence. This means that the technology is no longer being manufactured or supported. Reactive replacement of failed secondary systems components is not sustainable and impacts our ability to meet the requirements of the National Electricity Rules (NER).

Secondary systems assets at Lower Tumut substation are facing technological obsolescence, increasing the time to reactively rectify faults and increasing the risk that primary assets at the substation may not be able to reliably operate.

Redundant protection schemes are required to ensure the transmission system is adequately protected as outlined in the Network Performance Requirement under Schedule 5.1 of the National Electricity Rules (NER), therefore the condition issues affecting the identified protection relays on the ACT and NSW transmission network must be addressed.

If the failure to provide functional secondary systems due to technology obsolescence is not addressed by a technically and commercially feasible credible option in sufficient time (by 2027/28), the likelihood of not recovering from secondary systems faults and not maintaining compliance with NER performance requirements will increase. The proposed investment will enable Transgrid to continue to meet the standards for secondary systems availability set out in the NER, and to avoid the impacts of taking primary assets out of service.

Transgrid published a Project Specification Consultation Report (PSCR) for maintaining compliance with performance standards applicable to Lower Tumut substation secondary systems in February 2024. In the PSCR Transgrid presented two credible network options that would meet the identified need from a technical, commercial, and project delivery perspective.

No submissions were received in response to the PSCR during the consultation period which closed in May 2024 and no additional credible options have been identified.

The assessment in this PACR finds that Option 2 (complete replacement with Secondary Systems Buildings) is the preferred option to meet the identified need at this stage of the RIT-T.

In accordance with the requirements of the 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

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