Maintenance work on the HVDC transmission line underway

7 December 2010

Transpower has now started maintenance work on replacing the conductors (wires) on sections of the HVDC overhead transmission line that runs between Oteranga Bay (on the South Coast) and Haywards substation.

The $26 million maintenance project is required to replace some sections of the line where the conductors (most over 45 years old) are reaching the end of their life. Given the importance of the HVDC link to New Zealand’s power supply, some of the work involves building temporary bypass line sections (comprising wooden poles) to allow the work to be undertaken on the existing line without impacting on the availability of the link.

Stage 1 of the project which started on site in late November involves the first 12km of towers from Haywards through the Belmont Regional Park and is expected to be complete by mid-2011. This section of the line will involve a temporary bypass line, which is presently being erected to the west of the existing line.

Transpower’s General Manager Grid Performance, Garth Dibley said that the maintenance work is important to ensure the HVDC link continues to provide a reliable service to New Zealand. "While we have a major project underway to install new converter stations at each end of the HVDC link, we still have to maintain the line, including periodic replacement of its conductors. Conductors generally have lives up to about 60-70 years, but this can be shortened significantly in environments close to the coast like this line or near sources of industrial pollution."

Stages 2 and 3 of the project (from Oteranga Bay to Makara, and Makara to the back of Johnsonville) will take place over 2011 and the first quarter of 2012.

For more information:
Rebecca Wilson | Communications Manager | 04 498 2695 | 021 578608