For the second time in as many days, a power blackout put many Whitehorse customers in the dark and cold for several hours on Wednesday night.
Around 4,000 customers were affected by Wednesday’s blackout, said YEC spokesperson Laura Carlson.
The power went out about 6:50 p.m.
Most people had their electricity restored by 7:20 p.m. But a pocket of Porter Creek customers had to wait for almost three more hours before their lights came back on.
On Tuesday a blown transformer at the sternwheeler substation blacked out most of downtown for almost two hours.
But what caused that transformer to fail is still a mystery, said Carlson.
“We’re going to have to do an analysis on that transformer to find out what exactly happened,” she said.
While repairs were underway, Yukon Electric had to reroute the power around the substation.
“We had to shift the load around to the rest of the city to manage it,” said Carlson.
But on Wednesday night, when electricity use peaked in the evening, it overloaded the system and blew some of the breakers.
“It was basically a huge overload draw,” said Carlson. “The system is set up to operate safely and when it goes beyond those safe limits it trips off.”
When it tripped, it caused a blackout that stretched from the Canada Games Centre all the way to the Hot Springs Road.
The cold temperatures didn’t help, said Carlson.
“It’s been very, very cold and that certainly has had an impact on the amount of power that’s drawn on the system,” she said.
Winter is the peak time for electricity use in the Yukon, said Janet Patterson, spokesperson for Yukon Energy.
“The colder the temperature, the higher the energy demand,” she said.
Unfortunately the winter is also the worst time for the Whitehorse dam.
With the river half frozen, the water level drops. That means the dam is only able to produce a little more than half of its 40-megawatt capacity.
Over the winter, Yukon Energy relies heavily on the Aishihik hydro plant, said Patterson.
A third turbine was recently installed at Aishihik bringing its capacity up to 37.5 megawatts.
In addition, the Mayo B hydro plant was put online. However, because of flooding concerns, it’s not yet operating at full tilt, she said.
With these three plants, and a little bit of help from some diesel generators, Yukon Energy was able to produce more than 82 megawatts on Monday.
“We haven’t seen those kinds of numbers since the Faro mine was in production in the late 1990s,” said Patterson.
Repairs to Yukon Electric substation have already been completed, said Carlson.
The cold weather is also expected to break by Sunday, but according to Environment Canada the frigid temperatures will be back by next weekend.
While cold weather does create more demand for electricity, that doesn’t necessarily mean there will be more issues with the grid, said Patterson.
“You can’t really draw that correlation,” she said.
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