Small blips in power throughout Sitka over the last week have the city scrambling to fix the problem.
Bryan Bertacchi, the city’s electric utility director, says his department is investigating the cause of several sporadic and short power outages. Since Tuesday, lights have been flickering across town.
“We’ve got crews over at Japonski island isolating pieces at a time to try and identify the root of this intermittent fault including we’ve isolated the coast guard and put them back on,” he said. “Right now we’re in the process of isolating the sewage treatment plant temporarily and so we keep doing that to identify what part of the island it’s coming from.”
In power system speak, a fault is any abnormal electric current. Power outages can occur from all sorts of things such as heavy storms and fallen trees. However, Bertacchi says, the cause of Sitka’s power hiccups hasn’t been that obvious.
“It’s an intermittent fault which is small and it’s a very short duration it’s on the order of 10 to 15 to 30 milliseconds,” he said. “It’s not like a traditional fault where a tree has fallen over a circuit. It’s something way more complicated than that.
And that complicated thing is what Bertacchi is trying to figure out.
In the meantime, he says the city has temporarily reconfigured the electrical system to service downtown and Japonski Island through transformers on Jarvis Street. That area is usually powered by the Marine Street substation but its backup transformer is being repaired
“We did that in order to protect the Marine Street transformers from these short duration intermittent faults,” he said.
He says the spare transformer for Marine Street was sent to a repair facility in South Dakota. It is expected to return to Sitka in April or May.
