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

0BInvestment Evaluation Summary
TNM-GS-809-0720
� addresses the asset and safety issues associated with the 110 kV assets identified in section 4, in particular the
110 kV voltage transformers and post insulators;
� addresses other performance, reliability and design issues identified in section 4;
� addresses the NER compliance issues associated with the Meadowbank–New Norfolk 110 kV transmission line
protection scheme;
� enables reduced outage duration and ease of implementation (refer to Appendix A for proposed implementation
sequence); and
� reduces the ongoing maintenance requirements and costs associated with the site.
7.3.3 DRAWBACKS
The option has the following drawbacks:
� higher capital cost than option 2.
7.3.4 CONCLUSION
This option is technically viable.
8 OPTION ESTIMATES
A comparison of the net present value of options is provided in Table 1.
Table 1 - Comparison of options considered
Option Net present value of costs ($M June 2007)
1 Manage existing 110 kV assets and defer replacement -$2.84
2 Replace selected 110 kV assets in-situ -$2.65
3 Replace all 110 kV assets in-situ -$3.37
The economic analysis includes the cost impact to customers in the event of a major circuit breaker failure using a
probabilistic approach based on current and forecast load data for each individual transmission circuit connected to
Meadowbank Substation 110 kV.
9 PREFERRED OPTION
Option 2 (replacement of selected 110 kV assets) is the preferred option because it is the most cost effective solution to
address the identified safety, reliability, condition and design issues at Meadowbank Substation. This approach will also
minimise the number and duration of transmission circuit outages due to reduced frequency and duration of maintenance.
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