American Superconductor Corp. (AMSC; Westborough, Massachusetts, U.S.) announced that a collaborative effort by four Chinese research and industrial institutions has successfully demonstrated a 75-m (246-ft), three-phase high-temperature superconductor (HTS) power cable in a live distribution grid in northwest China. The cable used HTS wire manufactured by AMSC.

The Institute of Electrical Engineering (IEE), the Chinese Academy of Science (CAS; Beijing, China) and the CAS's Technical Institute of Physics and Chemistry (TIPC; Beijing) collaborated on the project with the Changtong Power Cable Co. Ltd. (Baiyin, Gansu, China), who has operated the cable since December 2004 to supply power to its factories in Baiyin.

The cable operates at a distribution voltage of 6.6 kV. A warm dielectric design, the cable is cooled internally with liquid nitrogen at 77°K (-321°F). In preliminary tests, the cable's rated voltage was up to 10.5 kV, and it has conducted up to 1600 A (at 400 V) of alternating electrical current — limited only by the load available at the factory. Tested by engineers at the CAS, the cable's critical current was found to be as high as 5300 A dc and up to 3500 A ac. The plan is to operate the cable on a continuous basis for the remainder of 2005, after which the cable system will undergo internal examination of all its components to learn more about their operating characteristics and capabilities.

Power consumption in China is growing at double-digit rates in major urban centers, such as Beijing and Shanghai. The country's capacity to generate electricity has been increasing at a rate of about 7% per year, while the capacity of its T&D system has been growing at a lower annual rate.

“There is clearly an increasing demand in China for ever-larger amounts of electricity to run factories, homes and businesses,” said Greg Yurek, chief executive of AMSC. “There is also a growing recognition that the transmission and distribution system in China needs to expand significantly over the next several decades. We are delighted with the success of the Changtong cable project — a project we believe will lead to larger demonstration projects and commercial deployment of high-capacity HTS cable solutions in China during the remainder of this decade and beyond.”

Other demonstrations that utilize AMSC's wire include a transmission-level power cable for the grid of Long Island Power Authority in East Garden City (Long Island, New York, U.S.). Two other distribution-level power cable projects that utilize AMSC's wire are being carried out by LS Cable Co. in the District of Gyeongbuk in South Korea and by Condumex Cable Co. in Queretaro, Mexico.