Large-scale electricity cuts that have hit Invercargill three times since December have put a black mark against PowerNet in the network operator's annual report.
The report for the year ended March 31 says that the SAIDI index, which measures the average duration of an interruption, for Electricity Invercargill's network was 63.63 minutes. This is more than double forecasts.
PowerNet had planned for it to be only 31.54 minutes and the Commerce Commission reliability target was 45.65 minutes.
The SAIDI index takes the total amount of minutes of supply lost and averages it across the customer base.
The Power Company network area, which includes most of rural Southland, also failed to reach its SAIDI target of 162.57 minutes, recording 238.09 minutes.
The report blames the figures on storms in May, October, November and January, as well as increasing work to control vegetation.
Chief executive Jason Franklin said the company was focused on improving the SAIDI for both Electricity Invercargill Ltd and The Power Company.
"We had a couple of unfortunate incidents we have addressed and the plan is they won't be repeated."
However, he said EIL still compared well to other networks.
"We need to step back and realise EIL is one of the top two most reliable networks in all of New Zealand," he said. "The Commerce Commission thresholds are based on historic averages and are not relative to the industry."
The Doon St substation next to the Invercargill water tower could be moved because of earthquake risk. Mr Franklin said PowerNet had assessed all its substations to ensure they could survive a large earthquake and the Doon St substation, one of the oldest in the network, was vulnerable.
More than $1 million has been spent replacing the two substation transformers in the past year, but Mr Franklin said they could be moved to a new site at minimal cost. The rural network continued to expand as dairying increased.
PowerNet had bought new transformers worth more than $1m for distribution points in Awarua, Kennington and Hedgehope, while an upgrade of the substation in Ohai cost more than $500,000.
This year, an upgrade to lines in Hedgehope and Athol was planned, while the line from Athol to Mossburn was also being upgraded at a cost of more than $1m to provide for future growth. New TPC customer connections, including 42 dairy sites, and reticulation of new subdivisions cost more than $3m in the past year.
In the OtagoNet joint venture network, the SAIDI was within the planned 327.85 minutes.
PowerNet made a $28,000 surplus after taxation, with operating revenue of $87,368,00.
- © Fairfax NZ News
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