On Sunday16 June a catastrophic blackout cut power to all of mainland Argentina and Uruguay for most of a day, affecting tens of millions of people in an electrical failure that officials called ‘unprecedented’ in its scope. By late Sunday, when power had been largely restored to both countries, the root cause was still under investigation.
Much of Argentina was hit by heavy rainfall over the weekend, and Uruguay’s state-owned utility, UTE, said some systems had been damaged by the recent rain and still needed to be repaired.
“This is the first time something like this has happened across the entire country,” said Alejandra Martínez, a spokeswoman for Edesur, an electricity company in Argentina that serves parts of Buenos Aires and its suburbs.
“There was a failure in the system, the type of failure that takes place regularly in Argentina and in other countries,” Argentina’s energy secretary, Gustavo Lopetegui, said at a news conference. But then, he said, “there was a chain of events that happened later that caused a total disconnection.”
In Buenos Aires, a city of almost 15 million people, cars slowed to a crawl as traffic lights went dark, and trains stopped dead on their tracks.
The Argentine water company AySA asked customers to ration water because its distribution system had been shut down.
The Secretariat of Energy said that an electrical grid that serves both nations “collapsed” at 7:07 am cutting electricity in all of Argentina and Uruguay as well.
A spokesman for Edesur, the electrical distribution company, announced at 7:50 am that a “massive failure in the electrical interconnection system left all of Argentina and Uruguay without power. This was an extraordinary event that should not have occurred,” he said, saying that Argentina’s electrical grid was “robust with excess capacity in both generation and transportation.”
“Generally, though, these things happen not because of a lack of robustness in the system but rather a lack of co-ordination,” he said. “Failures in lines can happen, but what cannot happen is for this failure to then propagate to the whole system.”
ABC News reported that experts claimed the blackout should have been limited. It appears that a power surge on a transmission line and touched off a widespread tripping cascade. The experts said that power companies should have spotted the problem and taken action to limit the outage. They pointed to the safeguards put in place after the huge Northeast USA blackout in 2003, which would likely have stopped the Argentinian event.
Argentina's energy secretary said that the power surge was caused somewhere along the transmission line between two hydroelectric plants, when the line was damaged or couldn't handle the electric load. The plants did not trip immediately which caused an overload, which then tripped the generators. Even though it was a period of low demand, other generators didn't have enough capacity to pick up the slack, tripping protection circuits on the rest of the power plants and bringing down the entire grid.
It is believed that a tree limb bringing down a power line, or a lightning strike damaging equipment, could have been the original cause. But Argentina's system apparently did not react fast enough. "If the automatic system had worked correctly, we would not be talking about this," said former Argentine Energy Secretary Daniel Montamat.