The last culprit to take out Sitka’s main transmission line was this Honda sedan, in May 2016. (Sitka Electric Dept. photo)
All of Sitka lost power for nearly an hour Friday night (12-30-16), after a tree shorted out the main transmission line. A partial outage earlier in the evening, though, was due to elderly equipment.
During stormy weather Friday night a tree “swiped” the main transmission line near the Alaska Raptor Rehabilitation Center, creating a fault and sending the entire system offline.
Utility director Bryan Bertacchi says that the tree cleared itself, but crews had to scour the length of the system looking for the fault.
“Yeah we’ve got fairly sophisticated relay protection, as all utilities do, and it gives us an indication of what occurred. But still that 69kV transmission line goes all the way from Green Lake power plant as everybody knows way south of town to the Blue Lake switchyard, then all the way into town to Marine Street. So we knew that trip was somewhere on that 69kV line, but finding exactly where was pretty difficult from the indication we had.”
It took a half-dozen electric department staff to fix the problem, and restart equipment at Blue Lake. The outage lasted nearly an hour, from 11:45 PM to 12:37 AM Saturday.
The outage Friday afternoon was a different story. Sitka has been running its backup diesel generators during repairs at the Green Lake hydro plant. While one of the big diesel turbines is brand new, a couple of others are starting to show signs of age. One of them more or less turned itself off.
“What happened there was, we were running one of the old diesel machines — that are very old. And the vibration on that machine, one of the switches on the control panel just vibrated to the wrong position and tripped that machine off.”
The problem shut down power to customers from the Hames Center out Sawmill Creek Road, from 4:15 to 4:50 PM.
Bertacchi blames old infrastructure for this outage — and for several recent others. Now that the Blue Lake Hydro expansion is complete, he says the department is refocusing its attention on bringing the system up to date.
“Our new slogan is It Was Brand New in ‘82. So we’re really trying to fix the big stuff that’s really old — and we need to do it as a community. We don’t sweat the small stuff because we can’t afford to do that. We’re trying to fix all the big stuff that would cause long outages and be very costly. Se we’re spending the money that we do have on fixing the big stuff.”
And on a bright note: Bertacchi says extended repairs are wrapping up at Green Lake. The hydro plant should be back in service by the end of the week.
