This is an excerpt from EERE Network News, a weekly electronic newsletter.
Real-World Test of Superconductor Cable Delayed
A test of a high-temperature superconductor (HTS) cable at a Detroit Edison substation has been delayed indefinitely. According to American Superconductor Corporation, which made the HTS wires for the cables, a problem with the vacuum insulating system used to help keep the cables cool is preventing Detroit Edison from placing the HTS cables into service. The company says the HTS wires met all their performance requirements, and the vacuum insulating technology is a proven technology that would not be expected to hinder the future use of HTS cables. Pirelli Energy Cables and Systems, the cable manufacturer, is expected to issue a revised timetable for the demonstration project in spring.
The Detroit Edison substation is the site of the first installation and demonstration of an underground HTS cable in a U.S. utility network. The utility installed three 400-foot cables inside 4-inch-diameter underground ducts during the summer of 2001. All other cable components, including the cryogenic cooling and vacuum insulating systems, were completed in the fall.
American Superconductor does have some good news, though: its 5,000-horsepower HTS motor prototype, which uses HTS wires in its rotor winding (the part of the motor that rotates), was successfully tested at full load early this month. The motor also successfully carried a peak load of 7,000 horsepower while running at its rated speed. Both the HTS rotor coils and the refrigeration system met or exceeded their performance goals, and the system as a whole operated at an efficiency of 97.2 percent. The company claims it also identified potential changes to the stator (the part of the motor that stays still, or static) that could boost the efficiency of the motor to 97.7 percent. See the American Superconductor press releases.