Transpower repairs high voltage line

Media release

19 May 2009

Transpower repairs high voltage direct current link to avoid outage

At 3am this Tuesday, 19 May, Transpower removed Pole 2 of the High Voltage Direct Current Link (HVDC link between the North and South Island) from service in order to effect repairs. The line is expected to be back in service later today.

The problem is in a rural area between Otorohanga Bay and Haywards in the Wellington region. A limited number of joins in the line have become overheated, preventing the proper flow of current and increasing heat and stress on the line.

Only the overhead portion of the line is involved; there are no issues with the undersea Cook Strait cables or the converter stations themselves.

Checks on the Pole 2 lines have been increased leading up to winter, particularly as the HVDC is integral to New Zealand’s power system. Transpower uses thermovisioning technology to inspect the joints, with a helicopter flying along the line. Thermovision measures the temperature of the line with potentially faulty components showing white on the monitor.

“The outage has no impact on consumers, said Transpower’s Chief Executive Patrick Strange. “Further, it can be fixed relatively quickly. However, it does create issues for generators in the South Island, unable to supply power to the North Island until Pole 2 is restored to service.”

ENDS

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