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National Environmental Standards for Electricity Transmission Activities: technical (6 of 9)
The technical pages provide background and explanations of:
Maintenance and upgrading
Optimising the ability of the existing network to meet demand
There is a statutory commitment to maintain and upgrade the transmission network in order to meet the community's needs. A number of variables influence how the transmission network is planned and developed. The main drivers are growth in demand and investment in new generation sources.
Projections of electricity demand in relation to existing transmission capacity allows assessment of options and development of infrastructure to meet demand.
Transpower assesses the potential capacity of the existing infrastructure. Upgrading existing infrastructure is generally considered preferable to building new infrastructure, because it is usually more cost-effective.
Delays in achieving upgrades or routine maintenance works will also influence grid planning and performance. The integrated nature of the network means that changes to demand or capacity on one line, at one particular location may affect capacity along a different line, at a distant location. Therefore if works need to be undertaken to meet capacity in one place, this may mean capacity at a different location is affected. The implications of delayed or stalled upgrades can be significant. Measures may include the need for deliberate reductions in load to industry or towns to preserve the overall security of the electricity supply.
Upgrades to existing infrastructure are an important means of meeting increased capacity needs on the network. Upgrades on an existing line may include:
- undertaking tower extensions and related measures to allow increases in current carrying capacity, while maintaining minimum safe clearance distances between conductors and the ground
- adding circuits
- adding sub-conductors or re-conductoring.
Last updated: 18 January 2010
On this 'technical' page: Maintenance and upgrading
Optimising the ability of the existing network to meet demand
