Has anyone been following this story? It's an interesting coincidence that it happened (Tuesday evening - Wednesday morning, Nov. 10-11) just two days after "60 Minutes" reported that previous major blackouts in Brazil had been the result of cyber attacks on the power grid.

According to a press release from Brazil's national system operator, the immediate cause was the failure of three 750 KV [AC] transmission lines plus one DC line originating at the huge Itaipu hydro plant. All of these lines head east toward major cities in the eastern and central regions.

Itaipu is the second largest hydro development in the world, after Three Gorges in China (Grand Coulee in the U.S. is third). It is jointly owned by Brazil and neighboring Paraguay, with half of its units generating 60Hz for Brazil and the other half generating 50Hz for Paraguay. It provides about 19 percent of Brazil's power and an amazing 90 percent of Paraguay's.

Initial reports attributed the outage to a failure at Itaipu, but later it was reported that the cause was the transmission lines, probably due to severe weather.

The entire country of Paraguay was out for about 15 minutes. It's not clear to me why that happened, since they're served by separate generators at a different frequency, and thus by separate lines.

Last edited by Albert; 11/14/09 10:34 PM.