For NET application, CEA is developing a 40 kA cable in conduit1 whose fabrication technique is expected to be applicable to both NbTi or Nb3Sn strands. To ensure a good overall mechanical behaviour of the cable the number of cabling stages has been limited to three and no full insulation has been provided between stages. A theoretical approach of losses has been developed, from the basic multifilamentary strand to the last stage, taking into account the complex combined effect of the different twist pitches. Through this evaluation, the contact resistance and the action of stainless steel spacers for the last stage turn to be sufficient to limit a.c losses at an acceptable level in relation with NET specifications. The theoretical approach has been assessed by several experiments: measurements of a.c losses on the basic 1.9 mm strand, on triplets and "six around one" subcables in relation with compression, measurements of contact resistances in different cases and evaluation of the action of chrome plating.
