AC losses of a tri-axial superconducting cable with balanced three-phase current distributions

High Temperature Superconducting (HTS) cables have been studied because of low loss and compactness, compared with conventional copper cables. Three-phase cables are usually composed of three single-phase concentric cables. Recently, a tri-axial cable composed of three concentric phases, has been intensively developed, because it has advantages such as reduced amount of HTS tapes, low leakage fields, low heat in leak and compactness, compared with the three single-phase cables. We analyzed the three-phase balanced current distributions in the tri-axial cable as functions of winding pitches of three concentric phase layers. We formulated the general form of AC losses in the case of the transport current and the field in different phase. We analyze AC losses of a tri-axial cable with balanced three-phase current distributions