A Finite-Element Approach for Calculating Electrical Parameters of Umbilical Cables

This paper presents a systematic approach for calculating electrical per-unit-length parameters of signal cables by the finite-element method. The associated software (UFIELD) has been specifically adapted to umbilical cables used in offshore control applications. Efficient and robust case specification is achieved through a library of predefined, parametrized models for the umbilical elements (signal cables, pipes, armors). Additional features include automated specification of boundary conditions and excitations, adaptive mesh generation, and the handling of twisted elements and layers. The approach is validated against analytical solutions. Application to the Snohvit control umbilical shows excellent agreement with measured signal parameters, for the triad element alone, and for the triad element inside the umbilical. Similar results are obtained for the Ormen Lange quad element.