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By Dan Rudy 

Unusual buildup causes tri-borough power outage

 


Many residents in Wrangell woke up Thursday to discover a power outage, following damage caused by a storm to Ketchikan’s Bailey Substation the previous evening. Power across the entire transmission system was down, affecting Ketchikan and Petersburg for most of the morning as well.

A storm the previous evening featured winds between 43 and 61 miles per hour by 7 p.m. Gusts topping 90 mph were also reported at Ketchikan International Airport.

“We started getting calls in,” recounted Andy Donato, electric division director of Ketchikan Public Utilities (KPU). By 9 p.m. there were six small outages around Ketchikan.

“We had crews out through the night,” he said, explaining that everything was just about repaired when the failure happened at the central Bailey Substation.

The storm and subsequently dry conditions Thursday combined to create an electrical situation unusual to Southeast Alaska, called corona. Strong winds had picked up ocean salt and blown it onto nearby lines and pole-mounted devices held into place by condensation.

Because the storm was followed by comparatively dry conditions on Thursday, the salt was not rinsed from the lines as it normally would be. This salty condensation then acted as a conductor, overcoming the wires’ insulation and triggering a power failure by around 5:30 a.m.

“Corona is a high-voltage phenomena,” Donato explained, which can also be seen when conditions are right. During the night, people reported seeing blueish sparks and arcs emanating from the affected wires.

“You can hear it crackling,” he added. From his back porch that morning Donato said the telltale crackle from nearby lines had first clued him in to the problem.

Donato has had experience with a similar problem caused by road salt in the winter at his previous utilities position in Detroit, Mich. KPU identified the issue early and called out the local fire department to help hose down the affected infrastructure once the power was turned off.

“By 8:30 we were done,” Donato said. Technicians closed the first breaker, hydroelectric power generated by Southeast Alaska Power Authority at Tyee Lake went back online, and regular service resumed by 11 a.m. In the Ketchikan area, Donato estimated about 4,500 homes had been affected by the lapse in service.

“We get about a dozen system outages a year,” he said. “This one was unusual.” Asking around, he said none of those employed at KPU could remember such a situation before in Ketchikan. “That was a first.”

In Petersburg and Wrangell, local utilities returned power to their communities in stages with the aid of diesel

generators. A series of switches allow different coverage areas to be powered on without overburdening the generators.

“During a power outage all the switches have to be turned off then turned on again,” explained Brook Williams,

temporary electrical secretary at Wrangell Light and Power. Wrangell uses 11 switches

during the winter, with an additional one used during the summer to service Trident Seafoods.

The generators in Wrangell began operating by 8 a.m.,

and the island was fully switched back on within the hour. When Tyee was back online by 10:45 a.m., the borough was simply able to switch back to hydroelectric before powering down its diesel generators.

“People might not even notice during the switch,” said Williams.

Other islands in the south-southeast also experienced power troubles and minor damage during the storm but not systemwide failure.

 

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