(Reuters) - U.S. power company Entergy Corp said Friday it has traced the cause of Sunday's Super Bowl power outage to an electrical relay device.

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.

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, causing a partial power outage in the building.

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

With more than 108 million Americans watching along with television viewers in 180 countries, about half the stadium lights went dark early in the second half of the National Football League championship game, in which the Baltimore Ravens defeated the San Francisco 49ers, 34-31.

The disruption lasted about 35 minutes.

"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.