The extreme cold temperatures experienced by a large part of the United States this month have highlighted the vulnerability of power systems equipment in such extreme weather. This week’s snowstorm led to power outages in the Northeast, but cold weather alone can be enough to cause problems: The Tennessee Valley Authority, which serves 9 million people in the Southeast, urged customers Thursday to conserve energy to prevent a cold-weather outage. The average person might ask, why would my power go out when it’s just cold outside?

The electric system consists of thousands of components that are mostly electromechanical, with lots of moving parts. Like your car, these systems work best when they operate in the middle of the temperature