On May 2, 2008, the first extra-high-voltage (EHV) dead-tank-type 800-kV gas circuit breaker was energized at Hanging Rock Substation near Ironton, Ohio, U.S. Japan AE Power Systems Corp. (AE Power; Tokyo, Japan) was the principal design and developer with assistance from American Electric Power (AEP; Columbus, Ohio). Since May, three additional units have been delivered to the same site.

HVB AE, owned by AE Power, supplied technical support and training during the installation and commissioning of the first two units. Both HVB AE and AEP personnel received training by AE Power at Kokubu Works.

Although AEP previously purchased 800-kV units from the only other U.S. supplier, AEP signed a blanket agreement with HVB AE for this product, which could result in the supply of 70 more units.

One 765-kV line can carry as much electricity as six 345-kV single-circuit lines. This makes building new 765-kV lines more economical for U.S. electric utilities.

New 765-kV transmission lines are planned through joint ventures of electric utilities, including AEP in West Virginia, Maryland, Michigan, Kansas, Oklahoma and Texas. HVB AE also will market this product to these joint ventures and a Northeast utility.