Parts of Central were without power again today - the third time in two weeks.

The outages occurred in parts of Alexandra, Omakau and Moa Creek just as an electrical storm was passing over the district, with some customers remaining without power for up to seven hours.  

According to the Aurora Energy website, there were 228 customers in Omakau who were without power from 10.40am. It was estimated to come back on at 5pm. 

While it did return, it was short lived before going off again and not returning until about 8.30pm.

In Moa Creek the power went out at about 1.15pm affecting 302 customers. It was estimated to come back on at 6pm.

Parts of Alexandra also lost power at 2.20pm, affecting 853 customers. It was estimated to return at 6pm. 

Many of those customers were also left without power on January 19 and 23, when a widespread outage affected almost 8000 customers extending from Clyde to Ettrick and Lauder Flat.

While Aurora Energy could not provide a likely cause for today’s outage, it has been investigating the earlier incidents, which it suspects could have been caused by a tree or animal.

At the time of the outage on January 19, one of the two lines that feed the Central Otago network from the Clyde grid exit point was out of service to enable Trustpower to undertake essential maintenance on their grid assets.

The third power outage in two weeks affected customers in Alexandra, Moa Creek and Omakau today. IMAGE: The Central App

Aurora Energy general manager for network operations Matt Settle said it meant electricity was being supplied to the region via a single line.

“Unfortunately, we experienced a fault on this line, at a location on the line where it had the most impact - cutting supply to all customers.”

He said, under normal operating conditions, if the two lines were operating, the fault would not have been noticed as the second line would have taken over supply.

The cause of the fault has not been identified. 

“Having patrolled the line, we do know that there were no visible faults with the line itself and at this stage we suspect an outside interference such as a tree, or animal contact.”

He said both of the lines were in service when the second outage occurred on January 23.

However, this time a fault occurred on the Aurora Energy line that had been out of service on January 19, Matt said.

“When we have two lines in service, a fault on one line should not cause an outage to customers because ‘protection systems’ switch the load onto the in-service line.”

He said the January 23 outage happened when the primary protection system didn’t operate as planned, which caused a trip to both lines and loss of supply to all customers.

“It is important to note that there was no heightened ‘safety risk’ at the time, but the protection didn’t manage the fault and load transfer as intended. We have since corrected and tested the protection settings.”

He said although Aurora Energy didn’t find the direct causes of the two outages, it planned to do a specialist acoustic inspection to ensure it didn’t miss anything.

That work is planned for mid-February.

It also plans to review the animal protection mitigations that are in place, such as possum guards.

Stay as up to date as possible via Aurora Energy under reports, power outages in The Central App.

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