Transpower Welcomes Otahuhu Substation Approval

Transpower welcomes Electricity Commission's approval of its Otahuhu substation proposal

Transpower today welcomed the Electricity Commission's approval of its investment plan that will modernise the Otahuhu substation and provide greater security and diversity of electricity supply to Auckland.

The proposal includes building a new physically separate, enclosed, high reliability 220 kV switchyard on the Otahuhu site.

Chief Executive Dr Ralph Craven said that Transpower has responded to concerns about Auckland's heavy reliance on the existing substation equipment at Otahuhu.

"This is a significant investment that addresses historical issues. For many decades Otahuhu substation has been the key link in the network, where electricity comes into Auckland from the south and is then distributed throughout Auckland and Northland. However, the Otahuhu facility is ageing and is in need of some additional equipment."

"The current design of the substation evolved between the 1930s and the 1960s. Currently there are 110 kV and 220 kV outdoor switchyards located side by side and the switchyards are at risk for high impact, low probability events. By providing a separate, new technology switchyard, it will significantly reduce this risk and improve reliability of supplies into Auckland," Dr Craven said.

The power outage of 12 June 2006 occurred when an earthwire fell across one of the busbars. This is an example of a high impact, low probability event.

Dr Craven said that this project is an important step in a long-term strategy to provide much improved diversity of supply into and across Auckland.

"It is also consistent with the objectives of the Government Policy Statement on Electricity. This policy supports investments that provide resilience against the effects of high impact, low probability events and that provide diversity to larger load centres."

Transpower had planned to upgrade the Otahuhu substation by 2011 as part of the proposal to build a new transmission line from Whakamaru to south Auckland. That line is now proposed to terminate at Pakuranga substation, further improving diversity of electricity supply into Auckland.

The Otahuhu substation development proposal was submitted separately for approval to the Electricity Commission. Transpower intends to commission the new facilities at Otahuhu in early 2010.

ENDS

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