NEW ORLEANS - A power company said Friday the cause of the Super Bowl blackout was a faulty device that had been installed to prevent a failure of electric cables leading to the Superdome.

Officials of Entergy New Orleans said the device, called a relay, had been installed to protect the stadium from a cable failure between the company's incoming power line and lines that run into the stadium.

Company officials said the device performed without problem during January's Sugar Bowl and other earlier events.

They said the device has been removed and replacement equipment will be installed.

The power failure cut lights to about half of the stadium for 34 minutes, halting play between the Baltimore ravens and San Francisco 49ers.