Communities in southern Southeast Alaska lost power for a few hours Thursday afternoon, due to a failure along the power grid in Ketchikan. Wrangell, Ketchikan, and Petersburg all lost power around noon on April 25.
Jeremy Bynum, the electrical division manager for Ketchikan Public Utilities said the outage was caused by a failed part on a power pole near the Landing Hotel in Ketchikan, which caused a fire to spark. The failed part was an insulator, which protects the power poles from electrical current. Wood conducts electricity, so electrical wires are connected to the wooden poles that hold them by insulators – silicone or porcelain gadgets that look like discs stacked on top of each other.
Ketchikan, Wrangell, and Petersburg receive most of their electricity from hydropower. Dam projects at Swan Lake near Ketchikan and Tyee Lake near Wrangell feed power to the communities through a massive intertie. Those hydropower projects are managed by the Southeast Alaska Power Agency (SEAPA), a utilities coalition serving the three communities.
“It was a complete system collapse due to that pole fire,” explained Robert Siedman, CEO of SEAPA. He said that when they contained the fire in Ketchikan, it took down the whole system. “That pole fire, when it was isolated, it caused Tyee generators to go offline, Swann generators to go offline, Petersburg to go offline, Wrangell to go offline, and Ketchikan to go offline.”
Siedman said the regional outage started at the Tyee Lake generator. I have compared it to a train. The generator is the engine and hauls the heavy part of the power load. When Ketchikan Public Utilities cut power to isolate the pole fire, they removed a heavy portion of the load from the system. But the brakes on the speeding train were calibrated for more.
“Tyee Lake had to try and slow down and it ended up going negative in megawatts instead of producing megawatts,” said Siedman. “It went negative, because it had to slow down that train because it was over-speeding. And then it tripped.”
Siedman said that Swan Lake was on emergency power and the next steps were to get Tyee and Swan hydro plants back online. As of 2 pm Thursday, power in Wrangell and Petersburg was restored. When SEAPA got word from Ketchikan Public Utilities that their workers had repaired the pole, they were able to bring Ketchikan back onto the grid. As of 3pm Thursday, KPU reported that power had been restored to all of Ketchikan except North Point Higgins.
