Transport current properties of Y-Ba-Cu-O tape above critical current region

YBCO tape is highly promising as a 2nd-stage HTS conductor for power applic ations, and development of long tape is proceeding worldwide. Generally: HT S tape conductors have Dread transition characteristics ranging from the su perconducting state to the normal state, so they rarely quench, just above the critical current defined for a usual electrical field or resistivity: H owever, such characteristics make the stability criteria temples when these tapes are considered for power applications. To estimate the stability criteria of HTS tapes, we prepared YBCO tapes wit h YSZ textured buffers by the IBAD method. The thickness, width and length of the YBCO layer are 1 mum, 10 mm and about 140 mm, respectively, and tape s are coated with Ag of various thicknesses as a stabilizer and protector. Transport current properties are measured in a nide range of current above the critical current defined by 1 mu V/cm. The establishment of criteria to define the stability of HTS tapes will be necessary for their applications in power apparatuses.