edison ac and dc transmission...

Topsy the elephant (Edison was a jackass)

http://en.wikipedia.org/wiki/Topsy_the_Elephant

War of current (Fallout with Tesla, Edison was a jackass)

http://en.wikipedia.org/wiki/Thomas_Edison#War_of_Currents_era

High-voltage DC transmission is quite fascinating...

http://en.wikipedia.org/wiki/HVDC

The Pacific Intertie which runs south from Celilo, through eastern oregon is one of the larger dc transmission lines in the US...

http://www.transmission.bpa.gov/cigresc14/Compendium/PACIFIC.htm

The modern AC-DC transformers for these things are actually solid-state silicon semi-conductor devices.

http://en.wikipedia.org/wiki/IGBT