Transend - Appendix 5 Renewal capital expenditure - Australian ...

1 BACKGROUND
0BInvestment Evaluation Summary
TNM-GS-809-0720
New Norfolk Substation was commissioned in 1987. The substation is a critical part of the transmission network in
southern Tasmania because it provides key connections to generation sources located in the Upper Derwent area of
Tasmania. It supplies Boyer paper mill and Aurora Energy’s customers via two 110/22 kV transformers. It also provides
110 kV connections to Chapel Street, Creek Road and Meadowbank substations and Tarraleah Switching Station. The
substation also has one 30 MVAr 110 kV capacitor bank installed. A power circuit one line diagram for New Norfolk
Substation is provided as Attachment 3.
The secondary assets that will be replaced in this project will be 27 years old when decommissioned and will have
exceeded their assigned class life of 15 years as defined by Sinclair Knight Merz in its ‘Assessment of Economic Lives
for Transend Regulatory Asset Classes’ report prepared in April 2008.
2 PROJECT OVERVIEW
The New Norfolk Substation 110 kV Protection Replacements project replaces obsolete, unreliable and difficult to
maintain protection and control devices that are in service at New Norfolk Substation. The majority of the protection and
control devices at New Norfolk Substation are of the static type. Across the transmission network, static devices,
including those in service at New Norfolk Substation are starting to fail regularly, typically requiring card replacements
to maintain good working order.
Spare parts are no longer available from manufacturers for static devices of the types in service at New Norfolk
Substation; hence it is important that a prioritised replacement program be established to enable spares to be made
available from the de-commissioned units. By replacing all of the static relays at New Norfolk Substation, Transend will
be able to support the remaining in-service schemes at other substations until their scheduled replacement. Spares
holdings for a certain devices at New Norfolk Substation are at critically low levels.
The project includes the replacement of the following protection schemes at New Norfolk Substation:
� 110 kV bus bar protection scheme;
� Meadowbank–New Norfolk 110 kV transmission line protection scheme;
� New Norfolk–Creek Road 110 kV transmission line protection scheme;
� New Norfolk–Chapel Street 110 kV transmission line protection scheme; and
� Tarraleah–New Norfolk 110 kV transmission line protection scheme.
3 INVESTMENT TIMING
The New Norfolk Substation 110 kV Protection Replacement project has been programmed to be completed in 2014.
Where practicable, planned outages will be coordinated with other planned works, particularly planned protection
scheme replacements at the remote ends of the connecting transmission lines.
4 INVESTMENT NEED
This project is required to achieve the following capital expenditure objectives identified in clause 6A.6.7(a) of the
National Electricity Rules (Rules):
� maintain the quality, reliability and security of supply of prescribed transmission services; and
� maintain the reliability, safety and security of the transmission system through the supply of prescribed
transmission services.
© Transend Networks Pty Ltd Page 3 of 6