Rating of pipe type cables with slow circulation of dielectric fluid

This paper presents a new, rigorous approach to calculation of current ratings in pipe type cables with slow circulation of the fluid. Detailed mathematical analysis is presented for the calculation of the hot-spot fluid temperature as a function of the cable geometry and the fluid inlet temperature. The emphasis is placed on real time applications in which the pipe surface temperature is measured. A numerical example from an actual cable installation is presented. A comparison with the commonly applied method based on Buller´s model is offered.