The cause of Sunday's power outage at the Super Bowl in New Orleans has been traced to a newly installed electrical relay device meant to protect Superdome equipment, a power company and the device's manufacturer said Friday.
But the companies appear to be on different pages about whether human error was to blame.
The relay, put online late last year, triggered unexpectedly, causing another device to stop supplying power to part of the building, Entergy New Orleans told city officials Friday.
The partial outage interrupted the game between the Baltimore Ravens and the San Francisco 49ers for about 35 minutes, and city officials have been anxious about whether the outage will impact the city's efforts to attract future big-ticket events.
Entergy told New Orleans City Council members that the company still doesn't know why the device triggered, but the relay has been removed, the the dome's electrical system is ready to go and steps will be taken to ensure a malfunction doesn't happen again.
"Rest assured, the Superdome is fully functional," CEO Charles Rice told the council's utility committee Friday morning.
But the relay's manufacturer, Chicago-based S&C Electric Co., says it believes it knows why the problem happened: The relay, it says, wasn't operated at the proper setting.
System operators essentially put the relay's trip setting too low, S&C vice president Michael Edmonds wrote to CNN in an e-mail. The electrical load exceeded the trip setting, so the relay triggered, he said.
That activated the switch gear, which is designed to cut some power to isolate any problem and prevent system damage and a larger outage.
"Based on the onsite testing, we have determined that if higher settings had been applied, the equipment would not have disconnected the power," Edmonds wrote. "S&C continues to work with all those involved to get the system back online, and our customers can continue to rely on the quality and performance of our products."
Asked whether Entergy agrees with S&C's characterization of the problem, Entergy spokesman Mike Burns responded:
"Tests conducted by S&C and Entergy on the two relays installed at the Superdome shows that one relay functioned as expected and the other relay did not.
"We will continue to do more testing but we believe that we have zeroed in on the device that caused the outage, and we have removed it from service."
S&C was not represented at the council committee meeting in New Orleans.
The company that manages the dome, SMG, told the panel it concurred that the device is linked to the power outage.
But the explanation won't end the issue for some officials, as Councilwoman Jackie Clarkson pressed Rice to allow an independent audit.
Rice didn't commit, instead replying that a third-party inspector will be used if Entergy and SMG determine one is needed.
The relay and switch gear were part of Entergy's 2011-2012 project to improve electrical reliability at the dome, Entergy official Dennis Dawsey told council members.
The relay device wasn't put online until December 21. Between then and the Super Bowl, the device functioned properly during three major events -- the New Orleans Bowl, a Saints-Panthers NFL game, and the Sugar Bowl -- Entergy said.
Rice said the company would work closely with the device's manufacturer to determine what caused the device to trigger when it shouldn't have.
"We are going to do everything humanly possible (to ensure) we do not experience an event like this again," Rice said.
An SMG official emphasized to the panel that the power failure had nothing to do with SMG's recent efforts to replace the cables that feed electricity from Entergy's connection points to the dome.
The Louisiana Stadium and Exposition District, a state agency that oversees the Superdome, had approved spending hundreds of thousands of dollars to replace the feeder cables. The SMG official said Friday that the cables were replaced because they were 15 years old, and that SMG doesn't "see any way (the cables) were involved in this."
The electrical outage at the Superdome set off a storm of social media amusement among viewers and inspired advertising tweets with blackout twists.
Carmaker Audi took a swipe at its competitor, tweeting that it was sending "LED lights" over to the dome, which is officially named the Mercedes-Benz Superdome.