(Reuters) - U.S. power company Entergy Corp has discovered the cause of the power outage seen around the world, blaming the sudden darkness at the Super Bowl last Sunday on an electrical relay device.

With over 108 million Americans watching a game which was televised in more than 180 countries worldwide, about half the stadium lights went dark early in the second half of the National Football League's championship game, in which the Baltimore Ravens defeated the San Francisco 49ers, 34-31.

Baltimore led 28-6 when the lights went out and some say the disruption at the New Orleans Superdome, which lasted about 35 minutes, was a momentum changer that allowed the 49ers to get back in the game.

The device was specifically installed to protect the Superdome's equipment in the event of a cable failure between the switchgear and the stadium, Entergy said on Friday.

The relay had functioned without issue during a number of other events, including the New Orleans Bowl, the New Orleans Saints-Carolina Panthers game, and the Sugar Bowl.

But during Super Bowl XLVII on Sunday, the relay device triggered, signaling a switch to open when it should not have, which caused a partial power outage in the building.

Entergy said the device has since been removed from service and new replacement equipment was being evaluated.

"While some further analysis remains, we believe we have identified and remedied the cause of the power outage and regret the interruption that occurred during what was a showcase event for the city and state," Charles Rice, president and chief executive officer of Entergy New Orleans, said in a statement.

Entergy New Orleans, a unit of Entergy Corp, provides electricity to more than 160,000 customers and natural gas to more than 100,000 customers in Orleans Parish in Louisiana.

(Reporting by Scott DiSavino; editing by Daniel Trotta, desking by G Crosse)