A first-of-its-kind cyberattack on the U.S. grid created blind spots at a grid control center and several small power generation sites in the western United States, according to a document posted yesterday from the North American Electric Reliability Corp.

The unprecedented cyber disruption this spring did not cause any blackouts, and none of the signal outages at the “low-impact” control center lasted for longer than five minutes, NERC said in the “Lesson Learned” document posted to the grid regulator’s website.

But the March 5 event was significant enough to spur the victim utility to report it to the Department of Energy, marking the first disruptive “cyber event” on record for the U.S. power grid (Energywire, April 30).