Classifieds | Place a class ad | PDF Edition | Home Delivery
By SAM ALLEN
Daily News Staff Writer
Battling weather and equipment failures, Ketchikan Public Utilities has reported three power outages in two consecutive weekends, affecting different parts of Revillagigedo Island.
The most recent of the three outages occurred on Saturday at about 8:30 a.m., originating at the Tyee Lake hydro facility, southwest of Wrangell.
"Operators were investigating a transformer alarm and through their investigation they wound up tripping one of their (generators)," said Andy Donato, KPU Electric Division manager.
When the generator went offline, it tripped generators throughout KPU's system.
"So, everything is running around initially at 60 hertz. All a sudden that generator trips offline, now the frequency starts to drop," said Donato. "Ketchikan has a load-shed scheme so, as the frequency decays, we shed load quickly and aggressively until we match the current generator. And we have that set up in stages and in areas."
It's set up to protect the core of the town — the commerce areas would be the last to be affected, if at all, he said.
For example: "You’re a railroad engine pulling a stream of cars for a load, and you’re going uphill," said Donato. "And frequency is the same (as the) speed of the train, so as the train slows down, in order to keep it from stalling you start dropping off railroad cars. And you keep dropping off railroad cars to the point where it can still maintain its original speed."
KPU workers were told to wait until workers at Tyee got their generator back up before restoring theirs. Since the systems are tied together, allowing the Tyee side to start first enabled the communities of Wrangell and Petersburg to avoid using diesel generation.
"We were already running diesel; we’re running diesel right now," said Donato. "So, we went into load shed, the diesels were still running, that equalized load and generation. As far as we know the northern communities did not trip off. They did not lose power, they didn’t have any outages."
Affected areas in Ketchikan were restored in less than an hour.
The previous weekend, at around 7 p.m. on Jan. 25, a conductor, called a jumper, on the cross arm of a utility pole burned and opened up. A crew sent in for repairs restored power within two hours.
The next morning, high winds pushed a tree on the lines, knocking out power for nearly two hours as a Ketchikan Public Utilities crew responded by cutting a tree off the line near Point Higgins. The outage occurred at 3:17 a.m. on Jan. 26.