Models are proposed for two major components of the coupling eddy currents, induced in RTD- HTSC power transmission cables by a time varying transverse magnetic field. We consider multi-layer, multi-tape cable designs in which the winding direction alternates with each layer. By assuming unsaturated operation in the tapes we calculate resistive losses for a wide range of possible inter-tape contact resistances. Specific results are given for two hypothetical tape models corresponding to multi-filamentary OPIT (Oxyde-Powder In Tube) and thin film IBAD (Ion Beam Assisted Deposition) elaboration processes. Conclusions are made on the constraints that the results may take place on the future designs: particularly, on the decision whether or not to insulate the winding layers.