Transpower to spend millions on upgrade

Transpower yesterday for the first time acknowledged failings in its management of the national grid, as it agreed to resolve shortcomings highlighted by the June power blackout in Auckland.

In a letter to Energy Minister David Parker, Transpower said it would implement changes recommended by the Connell Wagner engineering consultancy company which conducted an independent analysis of the cause of the blackout.

Transpower representative Cynthia Brophy said the Connell Wagner report had highlighted weaknesses, and they would be addressed.

"I think our maintenance has been comprehensive, but there are points to take on board to ensure that risks are managed in critical places," she said.

The measures, likely to cost millions, focus mainly on upgrades to Transpower's Otahuhu substation, the main point through which power comes into Auckland from the south.

But they also include urgent repairs elsewhere on the grid.

The failure of two 40-year-old shackles tethering earth wires that protect substations from lightning strikes caused the blackout.

The wires fell on to the substation and damaged equipment.

Transpower's plans for preventing a repeat include:

* Welding the earth wire connections at the Otahuhu substation and at all other locations. Transpower would also check to ensure that its former policy of welding earth wires at all new installations had been carried out;

* Creating a separate "high reliability" substation at Otahuhu, reducing the reliance on a single entry point for the Auckland isthmus. This plan would include burying the transmission lines that now pass over the substation;

* Improving security of supply standards to ensure other regions do not have a failure like Auckland's.

* Introducing an improved system of inspection at sites where the consequences of a power cut are considered to be especially significant. Transpower may seek Commerce Commission permission to charge customers more to pay for the increased inspections.

This last point is a u-turn on Transpower's position earlier this month,.

It said then: "Our approach has been that we apply the same high standards to all of our locations, as they're all critical to some degree or another."

The plans to bury the lines were already planned as part of the upgrade of lines between Waikato and Auckland.

The other measures were highlighted in the Connell Wagner report as needing attention.

Transpower told Mr Parker it would be able to detail its plans for Auckland's power supply by the end of November.

The development of options for the region had started in May, when it asked for submissions.

Transpower chairman David Gascoigne said in the letter to Mr Parker that the company wanted to take prompt action on any processes and operations that could be improved to reduce the possibility of power cuts.