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In order to qualify the electrical insulation design of future HTS cables installed in the electric grid, a number of high voltage qualification tests are generally performed in the laboratory on either single-phase model cables and/or actual three-phase cable samples. Prior to installation of the 200-rn Triax HTS cable at the American Electric Power Bixby substation near Columbus, Ohio, in September, 2006, such tests were conducted on both singlephase model cables made at ORNL and tri-axial cable sections cut off from cable made on a production run. The three-phase tri-axial design provides some specific testing challenges since the ground shield and three phases are concentric about a central former with each phase separated by dielectric tape insulation immersed in liquid nitrogen. The samples were successfully tested and qualified for partial discharge inception, ac withstand, and lightning impulse where voltage is applied to one phase with the other phases grounded. In addition one of the phase pairs was tested for dc withstand as a "worst case" scenario to simulate the effect of VLF (Very Low Frequency) tests on the actual cable installed at the Bixby site. The model and prototype cables will be described and the high voltage test results summarized. [ABSTRACT FROM AUTHOR]

Ultera has installed a single 200-meter long high temperature superconducting (HTS) 3-phase triaxial design cable at the American Electric Power (AEP) Bixby substation in Columbus, Ohio. The cable connects a 138/13.2 kV transformer to the distribution switchgear serving seven outgoing circuits. It was designed to carry 3000 Arms. Testing of 3- to 5-meter length prototype cables, including a 5-meter prototype with full scale terminations tested at ORNL was conducted prior to the manufacture and installation of the AEP triaxial cable. These prototypes were used to demonstrate the crucial operating conditions including steady state operation at the 3000 Arms design current, high voltage operation, high voltage withstand and 110 kV impulse, and overcurrent fault capability. A summary of the results from the thermal analysis and testing conducted by Ultera and ORNL will be presented. Some analysis of the cable thermal-hydraulic response based on the testing that were used to determine some of the cable Cryogenic system requirements are also presented. [ABSTRACT FROM AUTHOR]