Syncrude, a joint venture majority owned by Suncor Energy Inc , with minority stakes held by Imperial Oil Ltd and others, has shut down the site's upgrader, spokesman Will Gibson said.

The site can produce up to 360,000 barrels per day, upgrading thick bitumen to light oil.

With that production offline, space should open up for Western Canada's oil in limited pipeline capacity, said Phil Skolnick, analyst at Eight Capital.

That relief is likely to reduce the discount that Canada's heavy crude trades at compared to U.S. light oil futures, Skolnick said in a note.

Syncrude is evaluating how a tripped power transformer caused the entire complex to shut down on Wednesday, Gibson said.

"We’re taking our time to ensure it's done right," he said.

No one was hurt as a result of the power outage.

(Reporting by Rod Nickel in Winnipeg, Manitoba; editing by G Crosse and Bill Berkrot)

By Rod Nickel