Power mostly restored after massive blackout in Argentina, but questions remain

BUENOS AIRES (Reuters) - Power returned to much of Argentina and two neighboring countries following a massive blackout that left tens of millions in the dark on Sunday, but Argentine President Mauricio Macri said the cause of the “unprecedented” outage was still unclear.

Argentina’s grid “collapsed” around 7 a.m. (1100 GMT), leaving the entire country without power, Argentina’s Energy Secretariat said. The outage also cut electricity to much of neighboring Uruguay and swaths of Paraguay, and shut down YPF SA’s La Plata refinery, Argentina’s largest.

Power had returned to nearly 90 percent of Argentina by early on Sunday evening and to virtually all of Uruguay and Paraguay, officials in each country said.

Macri´s energy secretary, Gustavo Lopetegui, told reporters earlier in the day that the blackout started with a failure in the country´s “interconnection system,” known as SADI, but said the root cause of the outage remained unknown and that results of a full investigation would not be available for 10 to 15 days.

“There was a failure in the system, the kind that happens regularly in Argentina and other countries,” said Lopetegui, adding that “a chain of events that took place later ... caused a total disruption.”

“This case is unprecedented and will be deeply investigated,” Macri said on social media.