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Whitehorse neighbourhoods hit by mini blackouts

Almost two weeks to the day after a massive blackout swept southeastern Yukon, two Whitehorse neighbourhoods lost power again.At 11:11 p.m.

Almost two weeks to the day after a massive blackout swept southeastern Yukon, two Whitehorse neighbourhoods lost power again.

At 11:11 p.m. Sunday, the number four generator at the Whitehorse dam failed, according to Yukon Energy.

 This generator, called the fourth wheel, is by far the most powerful turbine at the Whitehorse plant, capable of generating 20 megawatts of power, according to the Yukon Energy website.

When it tripped the grid, residents in Riverdale and Porter Creek North, which includes Crestview and the Mayo Road, lost power, said Yukon Energy spokesperson Janet Patterson.

Riverdale was in the dark for 14 minutes and Porter Creek North for 16.

Crews were dispatched immediately, said Patterson.

“They were here most of the night,” she added.

While the fourth wheel was being repaired, other turbines were able to pick up the load, keeping homes lit and heated.

After crews finished working on the fourth turbine, however, it failed again at around 4:30 a.m. Monday, said Patterson.

“They started up number 4 again, and again it just didn’t do what it was supposed to do,” she said.

In the early morning, Riverdale lost electricity for 36 minutes and Porter Creek North for 41.

“They finally got it back on … and it worked fine this time and appears to be working fine now.” said Patterson.

It is not known why the specific piece of the generator broke, she said, noting that Yukon Energy is discussing the problem with the designer.

The piece that broke, the bus bar, is a conductor that moves energy from the turbine to the breaker.

The breaker works like a valve, or switch, and controls how much energy flows from the generator into the station, said Patterson.

After energy passes through the breaker into the station, it can then be fed into the Whitehorse-Aishihik-Faro electric grid.

So, overall, that energy was not travelling from the generator into the grid.

This is not the first time the fourth wheel has crashed, either.

During the major power outage on January 29, workers were unable to put the generator back into use for hours, according to reports from Yukon Energy at the time.

This is one of the reasons it took up to nine hours to get power back on in some communities.

When workers went to fire up the fourth wheel, they heard a strange sound, said Patterson.

It wasn’t until around 4 p.m. that they were able to set the turbine’s wheels in motion for generating power.

This was approximately two-and-a-half hours after generators at both the Aishihik and Whitehorse dams collapsed.

When asked if there was a link between the current trouble with the generator and the sounds it was making two weeks ago, Patterson said she didn’t know. (CO)

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