ElectraNet has published a Project Assessment Conclusions Report (PACR) as the final stage of an investigation of the most economic option to manage the risk of transformer bushing failure on the South Australian transmission network. This concludes the Regulatory Investment Test for Transmission (RIT-T) for this replacement expenditure (‘Repex’) assessment, as required by the National Electricity Rules clause 5.16.
There is a need to replace over 100 transformer bushings fitted on 18 power transformers across the transmission network based on their assessed condition. The bushings are located at 10 metropolitan and rural substations which are now reaching, or past, the end of their technical lives.
ElectraNet applies a risk-based approach and assesses the condition and required timing of replacement of transformer bushings as part of its ongoing asset management processes. If the identified bushings are not replaced, there is an increased likelihood that a number of these assets will fail within the next 10 years.
The PACR confirms the conclusion of the Project Specification Consultation Report issued in August 2018 that replacing the identified bushings in the next three years is the preferred option. This estimated cost of this work is $6.86 million ($2017-18).
ElectraNet has undertaken rigorous sensitivity analysis to investigate the robustness of the RIT-T assessment to the key assumptions. The preferred option was demonstrated to deliver positive net market benefits for customers and to be robust across all sensitivity tests undertaken.
ElectraNet will now commence work on replacing the identified bushings in January 2019. The PACR is available for download at www.electranet.com.au.