An engineering consortium led by Purdue University and the University of Missouri has taken a most important step toward replacing the century-old technology behind the numerous, oil-filled power transformers that hang like icons from utility poles in residential neighborhoods.

The consortium developed a new class of transformers that will smooth out the irregular voltages that plague today's grid and prematurely age electrical hardware ranging from light bulbs to motors to power supplies in electronic equipment. They are designed with so-called "solid state" technology, meaning they rely mainly on semiconductor components such as transistors and integrated circuits instead of the heavy copper coils and iron cores of conventional transformers.

The work is sponsored by Asea Brown Boveri, an engineering and technology company with head office in Zurich, Switzerland. A copyright recently was issued for the solid-state transformer, which over the next decade is expected to begin replacing existing technology, says Scott Sudhoff, an associate professor in the Purdue School of electrical and Computer Engineering.

Transformers are fundamental elements of the power grid; they convert the high-voltage electricity delivered by power lines to the 120-volt supply needed for consumers. Normally, one transformer supplies power to several homes. They arrived in three varieties: the pole-mounted canisters; ground-level metal boxes normally painted green or blue; and, rarely, underground transformers.

Though the solid-state transformers may not look very different on the outside, they promise major advantages, most importantly in an area referred to as power quality, which is profoundly influenced by users of the grid.