The finite element method has been employed in order to simulate the behaviour of a HTS cable for transport current applications. The E-J model includes an anisotropic dependence of the critical current density Jc and power index n on the local magnetic field, whose magnitude is non-negligible and determines the effective critical current of the cable. The cable consists of four electrically insulated layers, each of them composed by 20 superconducting tapes, providing a total critical current of about 4 kA. In order to obtain a uniform repartition of the current among the layers, a sufficiently high contact resistance has been inserted in the electric circuit. The ac losses and the field distribution have been computed. A comparison is also made with a simple electric model of a HTS cable.