Outage Of HVDC Link

Media release 28 April 2009

Outage Of HVDC Link

A fault occurred within a converting transformer at Benmore at 10.40pm last night causing Pole 2 of the HVDC link to trip.

Investigations indicate that the fault is associated with a component within the transformer. Spare parts are on site and Transpower staff are working to repair the fault. Repairs are anticipated to take between two and seven days, depending on the exact cause of the fault.

Electricity can not be transported on the HVDC link until the repair work is completed, although Pole 1 remains available on a limited basis.

“It takes time to make repairs on transformers,” said Transpower CEO, Dr Patrick Strange.

“Given the good amount of generation available in both islands, we don’t anticipate an issue with security of supply while the work is underway.

“But of course, we are working to get Pole 2 back into service as quickly as possible.

“The major inflows the southern hydro lakes have experienced this week indicate we’re a long way away from dry winter issues.” The inter-island High Voltage Direct Current (HVDC) link includes two pairs of converter stations (Pole 1 and Pole 2), which convert the power from AC to DC at Benmore and back to AC at Haywards – or the reverse for the increasingly common southward flow.

The first pole, Pole 1, was commissioned in 1965. Pole 2, on which the outage occurred, was added to the system in 1991.

ENDS

Transpower New Zealand Limited is the State-Owned Enterprise that plans, builds, maintains and operates New Zealand’s high voltage electricity transmission network – the National Grid. The Grid links electricity generators to distribution (lines) companies and major industrial users. Transpower has approximately 12,000 km of overhead transmission lines and 178 substations and switchyards throughout New Zealand. For more information, please click on the link to read A Guide to Transpower.