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

7.2.3 DRAWBACKS
The option has the following drawbacks:
0BInvestment Evaluation Summary
TNM-GS-809-0720
� high capital cost as the total number of assets replaced is higher than alternative, rationalised arrangements;
� it does not address the operational issues associated with the ring bus arrangement identified in Section 4;
� presents increased risks during implementation working within a constrained, energised site;
� obtaining the required outages to undertake the works will be difficult (in order to allow key equipment to be
decommissioned, civil works including concrete curing, and finally erection and commissioning of the new
equipment);
� long outages will reduce reliability of supply to customers supplied from Creek Road Substation;
� additional temporary works required during implementation to maintain secure and reliable supply at Creek Road
Substation and remote sites; and
� may have implications on future development at the site.
7.2.4 CONCLUSION
This is not the preferred option because it does not address the reliability and performance issues associated with the
110 kV ring bus arrangement at Creek Road Substation. In addition, implementation would be difficult in terms of
obtaining the necessary outages to undertake the works.
7.3 OPTION 3 - STAGED REPLACEMENT OF SELECTED ASSETS IN-SITU
7.3.1 SCOPE
The scope for this option is essentially the same as option 2, but implemented using a staged approach based on
transmission circuit criticality. This option includes:
� initial replacement of assets that have an assigned transmission circuit criticality rating of four or five (13 bays);
� initial replacement of other remaining assets that are known to present a safety risk, including voltage transformers,
current transformers and post insulators in 2014;
� replacement of the underground 110 kV power cable that is in poor condition in 2014; and
� deferred replacement of the remaining 110 kV assets by up to three years (three bays).
The capital cost of this option includes an initial $23.20 million ($June 2007) to replace critical assets and to address
safety issues followed by a deferred capital cost of $4.22 million ($June 2007) to replace remaining 110 kV assets three
years later.
7.3.2 BENEFITS
The benefits for this option are that it:
� allows Transend to achieve the capital expenditure objectives in the mid-term;
� addresses the safety issues associated with the 110 kV assets identified in Section 4 of this document;
� defers capital expenditure associated with lower criticality assets for up to three years;
� addresses the performance issues identified in Section 4 of this document, with the exception of those transmission
circuits that have a criticality less than four; and
� reduces the ongoing maintenance requirements and costs associated with the site.
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