The purpose of this research was to obtain new methods for decreasing alternating-current (AC) losses when transport currents pass through high critical-temperature superconducting power cables. The cables used in this study were composed of (RE)Ba 2 Cu 3 O x (REBCO) superconducting tapes. The AC losses in monolayer and double-layer REBCO cables were calculated by a two-dimensional finite-element method (2D FEM). The cable parameters were those specified for the REBCO cables manufactured by

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... kawa Electric Co. Ltd. In the monolayer cable, the loss in one tape of the cable was drastically decreased by increasing the tape number N from 25 to 100 (maintaining a constant critical current I C of 1,140 A in the cables). The loss in the monolayer cable also decreased as the tape width w decreased from 4 mm to 1 mm. When calculating the loss in the double-layer cable, N in the first and second layers (N 1 and N 2 , respectively) were the same as N 1 = N 2 = 16, and the layer currents were assumed equal. It was observed that the loss drastically decreased as the relative tape-position angle between the layers increased, becoming minimized at a relative angle of 0.5. This reduction was caused by the cancelation of the vertical field between the first and second layers. At this relative angle, the opposite edges of the tapes in the two layers were minimally separated, and the vertical fields were cancelled out.