The equipment was owned and installed by Entergy New Orleans.
"If higher settings had been applied, the equipment would not have disconnected the power," said Michael J.S. Edmonds, vice president of strategic solutions for S&C.
In a follow-up statement, Entergy said that tests conducted by S&C and Entergy on the two relays at the Superdome showed that one worked as expected, the other did not.
Entergy spokesman Mike Burns said both relays had the same trip setting.
Entergy's announcement came shortly before company officials were to answer questions from a committee of the City Council, which is the regulatory body for the company.
During the committee hearing, council member Susan Guidry asked Entergy executives whether they were "fairly certain" that the relay was faulty.
"That is correct," Dawsey said.
However, when asked if the outage was caused by the design or a defect in a part of the equipment, Entergy New Orleans CEO Charles Rice said that had not been determined.
"The equipment did not function properly," Rice said. "At this particular time, based upon our analysis, we cannot say definitively that there was a defect in design. What we do know is that the equipment for some unknown reason, at this particular time, did not react the way that it should have."
Asked if Entergy and SMG still plan to hire a third-party investigator to get to the bottom of the cause, Rice said that possibility remains open.
"We'll work closely with SMG, and if there is a need for a third-party investigation, we will do that," Rice said, adding that Entergy was also working with the relay manufacturer.
Shabab Mehraeen, an assistant professor of electrical engineering at Louisiana State University, said relays are common electrical fixtures in businesses and massive facilities such as the Superdome.