TransGrid has recently published a Project Consultation Specification Report for maintaining a reliable substation at Upper Tumut.
Established in 1959, TransGrid’s Upper Tumut 330 kV substation supports four transmission lines in the southern New South Wales network, connects approximately 616 MW of renewable hydro-electric energy generation, and provides electricity flow paths between the Snowy Mountains, Canberra and Sydney.
Like most substations, Upper Tumut substation contains numerous gantry structures that support high voltage connections between switchbays and busbars. They are mainly used to support the power conductor between the transmission towers closest to the substation and the equipment within the substation. Gantries are connected to concrete footings by concrete plinths, hold down bolts and baseplates. Gantries also support overhead earthwires that protect the substation equipment from direct lightning strikes and are essential for the safe and reliable operation of the substation and the southern NSW network.
A large proportion of the gantries at Upper Tumut substation are affected by corrosion. The corrosion of holding down bolts and structural components ranges from initial development through to loss of thickness (cross-sectional area). Corrosion of holding down bolts is the key corrosion issue at this site and has been accelerated by cracking of concrete base plate plinths resulting from the repeated freezing and thawing of water inside cracks in the concrete.
TransGrid considers that the only feasible option from a technical and project delivery perspective is in-situ steelwork renewal by removing corrosion, painting and replacement of identified components.
The estimated capital cost of the proposed preferred option is $7.99 million.
In accordance with the requirements of the Rules, a summary of the Project Specification Consultation Report is made available on the AEMO website. A copy of the Project Specification Consultation Report can be obtained from TransGrid Website on the RIT-T Consultations page or by emailing RIT-TConsultations@TransGrid.com.au
Submissions in response to this Project Specification Consultation Report are required by the closing date of 25 June 2019.