ABB (Zurich, Switzerland) has successfully tested a new type of transformer that is a key component of power superhighways, or power links that can deliver vast amounts of electricity over very long distances.

ABB developed the 800-kV transformer within one year of winning a major order to equip the ultrahigh-voltage direct current (UHVDC) transmission corridor from the Xiangjiaba hydropower plant in western China to Shanghai, 2000 km (1242 miles) to the east. It is the world's highest-voltage power link and will have a record capacity of 6400 MW, capable of supplying about 31 million people.

The transformer is the first of several ordered by the State Grid Corporation of China and is a critical element of the systems that ABB is supplying to convert ac current to dc and back, and to alter the voltage at each end. Among other challenges, raising the voltage to as much as 800 kV increases the technical requirements on a transformer's insulation and on the design of critical parts such as bushings.

Power transmission at ultrahigh voltage has considerable advantages for the environment, because it reduces the power losses and requires a smaller transmission corridor than conventional technologies. UHVDC technology is particularly suitable for large countries such as China, where the centers of power consumption are often far from the power sources.