Key events surrounding Super Bowl blackout

The company that supplied electricity to the Super Bowl says the blackout that halted the big game was caused by a device it installed specially to prevent a power failure. A look at key events surrounding the blackout:

— May 19, 2009 — New Orleans is awarded the 2013 Super Bowl, beating out Miami and Glendale, Ariz. It will be the 10th time the city has hosted the game and the first since thousands of people took refuge in the heavily damaged Superdome after Hurricane Katrina in 2005.

— 2011 — The main electric utility for New Orleans, Entergy New Orleans, begins considering possible upgrades at the Superdome in anticipation of the championship game.

— July 2012 — Most of the work on the Entergy upgrades is done, but the final touches and the switch to the new equipment won't take place until December, weeks ahead of the big game.

— Oct. 15, 2012 — While Entergy is working on the upgrades, concerns arise about the Superdome's electrical equipment. A memo to the Louisiana Stadium and Exposition District describes decay in the electrical feeders that connect the stadium to the power grid, creating "a chance of failure." The district authorizes nearly $1 million for Superdome improvements, including more than $600,000 to upgrade the feeder system.

— December 2012 — Entergy completes the upgrades, and the new equipment is energized.

— Jan. 2, 2013 — The Superdome is showcased on primetime television as Louisville upsets Florida in the Sugar Bowl — the third event since the upgrades. No problems reported.

— Feb. 3, 2013 — Less than two minutes into the third quarter of the Super Bowl, power is lost to half the Superdome, dimming lights and forcing suspension of the game. It takes 34 minutes to restore power. The game is completed, but the outage takes some of the sheen off what many praised as a flawless hosting effort by the city.

— Feb. 8, 2013 — Entergy announces that a relay device that was specifically designed to prevent a power failure caused the blackout. But the utility stops short of taking all the blame and says it's looking into whether the electrical relay at fault had a design flaw or a manufacturing defect.

The manufacturer of the relay, S&C Electric Co. of Chicago, says in a statement that the blackout occurred because system operators put the device's so-called trip setting too low.